Startseite Thermal and Morphology Properties of Cellulose Nanofiber from TEMPO-oxidized Lower part of Empty Fruit Bunches (LEFB)
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Thermal and Morphology Properties of Cellulose Nanofiber from TEMPO-oxidized Lower part of Empty Fruit Bunches (LEFB)

  • Mahendra I.P. , Wirjosentono B. EMAIL logo , Tamrin , Ismail H. und Mendez J.A.
Veröffentlicht/Copyright: 12. August 2019
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Open Chemistry
Aus der Zeitschrift Open Chemistry Band 17 Heft 1

Abstract

Cellulose nanofiber (CNF) gel has been obtained from TEMPO-oxidized differently treated lower part of empty fruit bunches (LEFB) of oil palm. Three kinds of materials were initially used: (i) α-cellulose, (ii) raw LEFB fiber two-times bleaching, and (iii) raw LEFB three-times bleaching. The obtained nanofibers (CNF1, CNF2 and CNF3, respectively) were then characterized using several methods, e.g. FT-IR, SEM, UV-Visible, TEM, XRD and TGA. The LEFB at different levels of bleaching showed that the Kappa number decreased with the increase of the bleaching levels. The decrease of lignin and hemicellulose content affected the increase of the yield of fibrillation and optical transmittance of CNF2 and CNF3 gels. The FT-IR analysis confirmed the presence of lignin and hemicellulose in the CNF2 and CNF3 film. Based on TEM analysis, the lignin and hemicellulose content significantly affected the particle structure of CNFs, i.e. CNF1 was found as a bundle of fibril, while the CNF2 and CNF3 were visualized as individual fibers and interwoven nanofibril overlapping each other, respectively. The XRD data of the CNF’s film showed that CNF2 and CNF3 have a lower crystallinity index (CI) than CNF1. The presence of lignin and hemicellulose in the CNFs decreased its decomposition temperature.

Keywords: TEMPO; Cellulose Nanofiber; Bleaching level; Empty Fruit Bunch; Oil Palm

1 Introduction

As one of the largest palm oil exporters and producers, Indonesia has 11.12 million hectares of land that cultivates the oil palm, which produced 31 million tons of CPO, in 2016; and which also produced 125.46 million tons waste of the empty fruit bunch (EFB) [1]. The lower part of the empty fruit bunch (LEFB) oil palm can be categorized as lignocellulosic waste, which consists of cellulose, hemicellulose, lignin, extractive components and ash (Table 1). The high content of cellulose in this lignocellulosic waste can be utilized as raw material for CNF production.

Table 1

The oil palm fiber’s composition (wt.%) [20].

PartCelluloseHemicelluloseLigninExtractiveAsh
KlasonAcid Soluble
Trunk30.633.224.73.83.64.1
EFB37.935.022.91.12.71.5

CNF has wide areas of application due to its interesting properties, such as low weight, high aspect ratio, high reinforcing potential, and large surface area [2,3]. CNF can also be applied in a variety of industrial areas or applications, such as nanofiller for polymeric nanocomposite, packaging and food packaging, paper printing, antibacterial paper, and conductive paper [3, 4, 5, 6, 7].

The separation of CNF from the cellulose fibers is problematic because the fibers are connected to one another via hydrogen bonds and van der Waals interactions. Several methods can be used to separate CNF from the cellulose fiber, such as chemical, mechanical and chemo-mechanical treatments. For the chemical treatment, sulphuric acid hydrolysis was used to obtain cellulose nanofiber from the EFB with the yield of fibrillation around 30% [8]. The acid hydrolysis method was combined with a high pressure homogenizer to obtain the homogenous size of nanofiber from the microfibril cellulose fiber [9]. Ultrasonication using oscillating power was a mechanical approach to obtaining nanosized fiber from isolated micro-size cellulose fiber.

In the past decade, CNF with individual nanofibril was successfully obtained using 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) catalytic oxidation treatment with the addition of NaClO and NaBr (pH 10) [10,11]. TEMPO catalytic oxidation was used to obtain cellulose nanofibril with the various kinds of cellulosic materials, such as eucalyptus pulp [12], N. oceanica microalgae [13], commercial microcrystalline [14], bacterial cellulose [15], and various plant holocelluloses [16]. However, to date, no studies have been found on the preparation of CNF from the LEFB raw fiber and LEFB α-cellulose through TEMPO catalytic oxidation. The previous studies focused on the isolation of nanocrystalline cellulose [17] and CNF from EFB were prepared using H2SO4 hydrolysis; the thickness of obtained fiber ranged from 1-3.5 nm [18].

The characteristics of CNF, especially the morphology and thermal properties, depend on the source of starting materials (fiber) and precise treatment conditions (concentration, temperature, and reaction time). However, past studies had focused on the effects of different bleaching level towards the characteristics of the obtained fiber. The bleaching treatment has been identified as an important parameter to be considered during the preparation of nanocellulose [19]. Therefore, this research was focused on the thermal and morphology properties of CNFs that were prepared from several differently treated LEFBs, especially where the level of LEFB bleaching was concerned. The isolation of CNF was performed using α-cellulose and raw LEFB fiber. Specifically, the raw fiber of LEFB was treated by removing lignin and hemicellulose during the bleaching treatment. In the end, α-cellulose and the bleached LEFB were oxidized using TEMPO and passed through the high-pressure homogenizer to improve the possibility of obtaining nanosized fiber. This study aims to utilize LEFB fiber, an abundant renewable source as a raw material for the production of CNF using the TEMPO method that combines high pressure homogenization as a chemo-mechanical treatment. This study will open up new avenues for the effective utilization of the underutilized resources for the preparation of nanoscale materials. In addition, the FT-IR, SEM, TEM, XRD and TGA were employed to evaluate the properties of CNF.

2 Experimental Method

2.1 Materials

LEFB was obtained from a oil palm plantation in Riau, Indonesia. Hydrogen peroxide (50 wt.%), 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO), sodium hypochlorite and sodium bromide were purchased from Sigma Aldrich. Nitric acid (70 wt.%), sodium nitrite, sodium hydroxide, and sodium sulfite were purchased form Merck. All chemicals were used without additional treatment.

2.2 Method A

2.2.1 Preparation of the LEFB fiber

The lower part of the empty fruit bunch (LEFB) was chopped to a dimension of 1 cm x 1 cm. The lower part of the LEFB was then dried at 80oC for 48 h and ground to a fine powder (the powder was sieved through 200 μm particle size).

2.2.2 Preparation of α-cellulose

The isolation of cellulose followed the modified method that was described by Ohwoavworhua et al. [21]. About 75 g of the LEFB was weighed then soaked with 1 L of 3,5 wt.% HNO3 and 10 mg of NaNO2 at 90oC for 2 hours. The neutralized fibers reacted with 750 mL of 2 wt.% NaOH and Na2SO3 at 50oC for 1 h. The obtained fibers were neutralized using distillate water and bleached with 250 mL of 1,75 wt.% NaClO. The fibers were washed using distillated water, and the filtrated water was tested by AgNO3 to verify that it was free of chloride ions. After this which was to remove the hemicellulose components, the powder was soaked in 1,75 wt.% NaOH at 80oC and washed until it reached a pH of 7. The residue was then bleached using 10 wt.% H2O2 at 60oC for 15 minutes and washed until the pH was neutral.

2.2.3 Preparation of Nano Fibrillated Cellulose (CNF)

The TEMPO oxidized CNF was prepared from α-cellulose by following the method that is described by Saito et al. [11]. The TEMPO and NaBr with the amount of 0.016 and 0.1 g/g of fiber were added respectively into the dispersion of α-cellulose with a consistency of 1%. After a good dispersion was obtained, 7.2 wt.% of NaClO was added to the slurry until the concentration of NaClO reached 10 mmol/ g of cellulose. The TEMPO reaction was maintained at pH 10 for 5 h by the addition of NaOH 0.5 N. Then, the oxidized α-cellulose was thoroughly filtrated and washed three times. The mixture was homogenized at 8000 rpm, then continued with ultrasonication for 4 minutes. This cellulose product was coded as CNF1.

2.3 Method B

2.3.1 Fiber Conditioning

The LEFB fiber was chopped using knives mill from Agrimsa (St. Adria` del Beso’s, Spain) provided with a 10 mm mesh. 100 g of fiber was subjected to the bleaching process using 10 wt.% of H2O2 (1:10); the pH was kept at 10 by adding dropwise NaOH 4 N. Then the mixture was stirred at 1000 rpm for 2 h at room temperature. The neutral bleach was rinsed with water and passed to the Sprout-Waldron defibrator (model 105-A) to increase the fiber individualization. The obtained fiber was filtered and and measured for moisture content. Fiber (10 wt.% of dry weight) was milled in a PFI mill (NPFI 02 Metrosec S.A) at 4000 revolutions. The milled fiber was dispersed in solution of 1 wt.% of H2O2 (1:10) and the pH was adjusted to 10 by adding dropwise NaOH 4 N. The mixture was stirred at 1000 rpm for 2 h at room temperature. The second bleached fiber was then dispersed in 5 wt.% of H2O2 (1:10) and the pH was adjusted to 10 by adding dropwise NaOH 4 N. The mixture was stirred at 1000 rpm and 60oC of temperature for 2 h. The bleached product was filtrated and washed until a neutral pH was obtained and stored at 15oC.

2.3.2 Preparation of Nano fibrillated Cellulose / Lignocellulose

The bleached LEFB fiber was pre-treated with TEMPO/ NaClO/ NaBr according to the previous steps (2.2.3. CNF oxidized TEMPO of α-cellulose). The oxidized LEFB was washed three times. According to the bleaching level, the CNF was coded as CNF2 (second bleaching) and CNF3 (third bleaching). The carboxyl content and cationic demand of CNF2 and CNF3 were 985 μmol/g and 1.238,8 μeq/g, respectively. Those values confirmed the presence of carboxylic group as the result of TEMPO oxidation reaction.

2.4 Fibrillation Process

The fibrillation process was performed using a high-pressure homogenizer (NS1001L PANDA 2K-GEA) by passing 1 wt.% fiber suspension. The operational conditions were set to 600 bars of pressure and the fiber was passed through the machine six times. The obtained transparent gel-like suspension was preserved at 4oC.

2.5 Characterization

2.5.1 Kappa Number

Kappa number, which is a measure of the lignin content of the fiber was determined by the titration method in accordance with TAPPI standard T-236 cm-85.

2.5.2 Optical Transmittance and Yield of Fibrillation

The transmittance of the CNF suspension (0.1 wt.%) was determined at 400-800 nm using a UV-Vis Spechtrophotometer 160A (Shimadzu). The yield of fibrillation was determined after the centrifugation process of 100 mL of the CNF suspension (0.1 wt.%) at 4.500 rpm for 20 min. The yield fibrillation was calculated using the equation below:

(1)Yield%=1−weightofdriedfiberweightofdilutedsamplex%Scx100%

where %Sc refers to the solid content of the diluted fiber.

2.5.3 FT-IR analysis

The spectra of α-cellulose powder and all CNF’s film were recorded on the FT-IR spectrophotometer 8201PC Shimadzu. The sample was pulverized and mixed with KBr with composition of sample 1 mg/100 mg. The sample was scanned 64 times, with the spectra transmittance region between a wavenumber 4000 to 500cm-1 at 4 cm-1 of resolution.

2.5.4 XRD analysis

The XRD experiment was performed using XRD Shimadzu 6100 X-ray diffractometers. The α-cellulose powder and all CNF’s film were scanned in the reflection mode using an incident X-ray of CuKα with a wavelength of 1.54 Å at a step width of 0.05 o min-1 from 2θ = 0-80o. The crystallinity index (CrI) was defined by Segal [22] Eq. (2):

(2)CrI%=I002−I100I002x100

where I002 and I100 were the intensity peak for the crystalline cellulose and amorphous cellulose, respectively.

2.5.5 Surface morphological characterization

The surface morphological characterization of α-cellulose powder and all CNF’s gel were carried out under a scanning electron microscope (SEM) using ZEISS EVO MA 10. The α-cellulose was gold-sputtered using a sputter coater. The transparent gel-like suspension of CNF was placed on the sample holder. After being dried, all CNFs were gold-sputtered using a sputter coater to enhance the conductivity of the sample.

2.5.6 TEM analysis

The structural dimensions of all CNF’s gel were observed by TEM JEOL JEM 1400 with an accelerated voltage of 80 kV. The sample was dissolved in water to obtain a suspension. A drop of suspension was placed on copper grids coated with a carbon supported film; the solvent evaporated.

2.5.7 Thermal Analysis (TGA)

The thermal stability of α-cellulose powder and all CNF’s film was examined by thermogravimetric analysis (TGA) using TG/DTA STA 7300 with the range of temperature of 30-600oC (2oC/min). The heating process was carried out under a nitrogen atmosphere to prevent any thermoxidative degradation. The residual mass at 600oC was directly obtained from the measurement data.

2.5.8 Ethical Approval

The conducted research is not related to either human or animal use.

3 Result and Discussion

α-cellulose was successfully isolated from cleaned and dried LEFB through a straightforward two-step process, such as the delignification and hemicellulose removing process. The LEFB powder color turned white after delignification and hemicellulose removal. After confirmation through FT-IR analysis (Figure 1), the obtained white powder was identified as α-cellulose. In the spectrum of isolated α-cellulose form the LEFB, it had a similar band with the reference of α-cellulose but different in intensity.

Figure 1 FT-IR spectra of α-cellulose and all CNF products.
Figure 1

FT-IR spectra of α-cellulose and all CNF products.

The FT-IR spectra of all CNFs that were prepared from LEFB is shown in Figure 1. The presence of ν(O-H) stretching and ν(CH3)/ ν(CH) groups in the FT-IR spectra of all CNFs are shown as signals around 3300-3600 and 2800-2900 cm-1, respectively. The presence of a carboxylic group can be confirmed from a specific band at 1650 cm-1. It indicates that absorbed water was present by the result of carboxylate group interaction. The presence of lignin can be confirmed by the presence of a band around 1510-1400 cm-1. This result is in line with the result of Ahuja et al. [23]. The raw fiber, after chemical treatment, will have a significant difference in FT-IR spectra, especially around 1510 and 1420 cm-1. The significant decrease of those areas is considered to be the partial removal of lignin.

The oxidation of the hydroxyl group at C6 of cellulose mediated by TEMPO (Figure 2), was done solely for this position. The oxidation reaction mechanism of cellulose through the TEMPO oxidation was relatively selective, simple and efficient. The oxidation process using TEMPO was combined with the presence of NaClO/NaBr or NaClO/NaClO2 as the primary oxidants, and the reaction could be performed within a wide range of pH, notably pH 4-10 [16,24, 25, 26, 27, 28]. Before the TEMPO-oxidized treatment, in method B, the fiber was processed with mechanical treatments using Sprout-Waldron and PFI-mill. These mechanical treatments facilitated the TEMPO-oxidized fiber to pass through the homogenizer and to allow the fiber to have a greater capacity for hydration and swelling. Without these mechanical treatments, the TEMPO-oxidized fiber could not have passed through the homogenizer because of the significant difference in fiber size. As a result, the nanosized particle of the CNF can be seen in Figure 3 and Figure 5.

Figure 2 Pathway of oxidation process of C6 primary hydroxyl to carboxylate group [24].
Figure 2

Pathway of oxidation process of C6 primary hydroxyl to carboxylate group [24].

Figure 3 The SEM images of (a) α-cellulose, (b) CNF1, (c) CNF2 and (d) CNF3.
Figure 3

The SEM images of (a) α-cellulose, (b) CNF1, (c) CNF2 and (d) CNF3.

Figure 4 UV-Vis transmittance spectra of CNF.
Figure 4

UV-Vis transmittance spectra of CNF.

Figure 5 TEM images of all CNF (a) CNF1, (b) CNF2 and (c) CNF3.
Figure 5

TEM images of all CNF (a) CNF1, (b) CNF2 and (c) CNF3.

The morphology of the isolated α-cellulose and CNF is shown in Figure 3. The morphology of α-cellulose powder (Figure 3a) showed curled and well-defined fibrils as the impact of interfibrillar hydrogen bonding of the hydroxyl group on the fibril surface. The isolated α-cellulose fibers have an average diameter of 27.3 ± 7.4 μm.

The observation of the dried transparent gel-like suspension of CNFs revealed that the width of the fibril was in the range of 10-130 nm (Figure 3b-d). The interwoven nanofibril overlapping each other was only observed in the CNF3. This result shows evidence of the potential of CNF to be a good nanofiller when it is incorporated with the polymer matrix through an entanglement mechanism.

The interwoven fibril was not observed in the CNF1 and CNF2 samples, but from these fibers, a bundle of fibril formed aggregates. The aggregates confirm that the nanofibril resulted from the physical break-up of the aggregated microfibril [29].

The Kappa number of the bleached fiber decreased inversely with the increase of the bleaching treatment (Table 2). The Kappa number is used to determine the amount of lignin in the fiber sample; in other words the Kappa number shows a direct relationship with the lignin content of the fiber. The combination effect between hydrogen peroxide and sodium hydroxide during the bleaching process at 60oC seemed to remove the hemicellulose and lignin content significantly; with this treatment a higher content of cellulose could be obtained [30]. The content of hemicelluloses in the fiber was controlled through bleaching treatment that was supported under alkaline conditions [31]. The results of the Kappa number supported the FT-IR spectra (Figure 1), and that the lignin in the treated fiber was partially removed.

Table 2

Characteristic of CNF from LEFB.

CodeKappa NumberYield of Fibrillation (%)
CNF1Not measured76.00
CNF29.378.11
CNF33.890.00

An additional effect of the level of bleaching is shown through the yield of the fibrillation value. The increase of the bleaching treatment in CNF2 and CNF3 has a positive impact to the increase of the yield fibrillation. The yield of fibrillation is dependent on the reduction of the Kappa number or lignin content [31,32]. This relationship can be determined by using an indirect method of measuring the transmittance of CNF suspension (Figure 4).

The suspension with a lower fibrillated CNF will scatter more light than the suspension with a higher yield of fibrillation. The third bleached fiber (CNF3) has a lower Kappa number (3.8) than the second bleached fiber (9.3) (CNF2). It showed the third bleached fiber had a slightly higher light transmittance and yield of fibrillation than the second bleached fiber. These results were relatively close when compared to the CNF obtained from the eucalyptus fiber that was processed with TEMPO/NaClO/NaBr [12,32]. The content of lignin also influenced the properties of the TEMPO-oxidized nanofiber. The presence of lignin during the TEMPO-oxidized reaction caused the fiber not to be perfectly oxidized by TEMPO/ NaClO/ NaBr, because some parts of the oxidant reacted with the lignin in the fiber to promote the delignification process. This is shown by the dark color of the solution during the oxidation reaction. CNF1 had a lower value of the yield of fibrillation, and it can be assumed it was due to an impact of the low content of hemicellulose [31]. The optical transmittance measurement can be used to evaluate the opacity of the obtained CNF fiber as well. The CNF3 is optically transparent, which showed a 90% light transmittance at a wavelength above 500 nm. On the other hand, CNF1 and CNF2 had relatively low light transmittance compared to CNF3, about 70% light transmittance at a wavelength above 500 nm. CNF1 and CNF2 exhibit a transmittance of 80% at a wavelength of 790 and 660 nm, respectively. The material which has more than 80% light transmittance is considered transparent [33].

TEM analysis was performed to obtain the accurate data about the widths of all prepared CNFs. From the TEM observation shown in Figure 5, the morphology of CNF from CNF1, CNF2 and CNF3 obtained with and without high pressure homogenization is quite different. All prepared CNFs showed that the diameter of CNF has a nanosized scale with a width ranging from 3 to 50 nm and several microns of length.

Figure 5a shows the shape of the CNF1 fiber, forming a bundle of microfibrils with the dimensions of 324 and 167 nm of length and width, respectively. This phenomenon occurred due to the low content of hemicellulose, where as stated by Chaker et al, hemicellulose content was found to have an influence towards the aggregation of fibers [31]. The high content of hemicellulose in the fiber made the fiber stays apart as an individual fiber. Figures 5b and 5c, show the obtained fiber CNF2 and CNF3 respectively. They have different appearances compared to CNF1. The

CNF2 fiber is more individualized than CNF1 and CNF3. This is the impact of CNF2 having a higher content of hemicellulose than CNF3. The CNF3 has a high potential to lose the hemicellulose content than CNF2 because of the higher number of bleaching treatments on CNF3 compared to CNF2. A thin web like fiber was observed in CNF3. The fiber formed a highly interwoven microfibril overlapping each other. This formation could improve the potential of CNF3 as a nanofiller when utilized in a polymer matrix, as it has a higher value of aspect ratio than CNF2, i.e 265.19 (CNF3) and 229.09 (CNF2).

The XRD patterns of the α-cellulose powder and CNFs from LEFB are shown in Figure 6. The presence of the crystalline region is not only represented by the diffraction peak at 2θ = 22.5o but also 14.8 and 16.5o which points to the 1ī0 and 110 lattice planes of cellulose [34,35]. In Figure 6, both the peaks at 14.8 and 16.5o are not observed, as the presence of those peaks depends on the source of the fiber [35]. The crystallinity index (CI) of α-cellulose is slightly higher than the CNF1, CNF2 and CNF3 which were 73,69; 73,45; 43,61 and 55,26%, respectively. The lower value of the crystallinity index after the TEMPO oxidation reaction and fibrillation treatment was also supported by Rohaizu and Wanrosli [34] and Besbes et al. [29]. The lower value of CNF2 and CNF3 than the α-cellulose could be caused by the presence of lignin and hemicellulose. The crystallinity index between CNF2 and CNF3 is influenced by the number of bleaching level, in which NF3 has a higher value of crystallinity index than CNF2.

Figure 6 XRD spectra of α-cellulose and CNFs.
Figure 6

XRD spectra of α-cellulose and CNFs.

The TGA data of all cellulosic materials can be used to determine the thermal stability and the degradation temperature of each sample (α-cellulose, CNF1, CNF2 and CNF3). The thermogravimetric and derivative thermogravimetric analysis of those cellulosic materials are shown in Figure 7.

Figure 7 TGA and DTG curves of (a) α-cellulose, (b) CNF1, (c) CNF2 and (d) CNF3.
Figure 7

TGA and DTG curves of (a) α-cellulose, (b) CNF1, (c) CNF2 and (d) CNF3.

The pyrolysis process is one process that can occur during the thermos-degradation process. Table 3 shows that the α-cellulose decomposed at the range of 276331oC, but the decomposition temperature of CNF1 was slightly lower at 235-320oC. This lower value could be an implication of the smaller dimension of CNF1 fiber than α-cellulose fiber. The smaller dimension of fiber leads to the improvement of a specific surface area [36]. The lower thermal stability of CNF1 than α-cellulose is also caused by the surface modification of α-cellulose through the TEMPO oxidation, specifically it was suggested by the presence of the decarboxylation step as a result of the TEMPO-mediated oxidation. In the previous work of Fukuzumi et al, [25] the nanofibril cellulose was obtained from different sources, but had a similar carboxyl content which started to degrade at a similar temperature. Also, due to the chemical treatment using TEMPO, there is a possibility that the decrease of the degree of polymerization had an impact due to the decrease in the molecular weight of lignocellulose nanofiber leading to the decomposition process in the lower temperature [37].

Table 3

Thermal analysis data of α-cellulose, CNF1, CNF2 and CNF3.

Temperature of weight loss at specific mass
MaterialT10% (°C)T50% (°C)TOnset (°C)TMax (°C)Residue (%)CI (%)
Cellulose293.67332.16276.95331.002.3173.69
CNF1251.62315.89235.81320.857.7673.45
CNF2194.70323.75139.03292.0227.7543.61
CNF3136.25301.01126.04291.0213.8455.26

From the CNF2 and CNF3 thermal analysis, the onset temperature occurred at 139 and 126°C, which is much lower than for the CNF1 and α-cellulose. Table 3 shows that the thermal stability of CNF1 is better than CNF2 and CNF3. This aligns with the explanation of other previous results [36,38, 39, 40, 41]. The phenomenon that occurred on CNF1 is the impact of the oxidation reaction by TEMPO [25,41, 42, 43], but the phenomenon of CNF2 and CNF3 is caused by the lignin contamination [44]. The presence of lignin was supported by the lower value of the crystallinity index, especially of CNF2 and CNF3. Lignin and hemicellulose are called non-cellulosic amorphous polysaccharide which degrade at lower temperatures than the fiber which has a high crystallinity index.

To support the influence of lignocellulosic material in CNF, TGA analysis of lignin from other reports showed two steps of degradation. The first degradation occurred at around 100oC that attributed to water evaporation. The second step was the decomposition of hemicellulose and cellulose that occurred between 200oC and 400oC [39,45], respectively. The presence of lignin in CNF2 and CNF3 caused the reduction of the thermal stability. This statement can be used to explain the lower value of the degradation temperature of CNF2 and CNF3 compared to CNF1 and α-cellulose. The presence of lignin and hemicellulose in the fiber is one factor that influences the thermal stability of fiber. Based on the onset temperature value of CNF2 and CNF3, the lignin content plays a role to make the LCNF more thermally stable. It is due to the covalent linkage between lignin and cellulose fiber. As in Figure 7, especially for CNF3, there is an additional peak at 563oC that indicates the decomposition temperature of cellulose and hemicellulose or the decomposition of char [46,47]. This statement is supported by Nair & Yan [48] and Espinosa et al. [49], due to the presence of aromatic group, carbon-carbon bonds, lignin has a wide range of decomposition temperatures between 240-600oC, and with very few occurring around 400-600oC referring to the decomposition of cellulose and hemicellulose.

The residual mass of CNF1 at 600oC is higher than α-cellulose, and the thermal stability of CNF1 is less stable than α-cellulose. The thermal stability of CNF1 has been explained in the previous paragraph. The dehydration process at low temperatures can influence the yield of char. This reaction will induce the decomposition to occur at low temperatures. Table 3 also shows that CNF2 and CNF3 degraded more over a large temperature range. This can be influenced by the presence of lignin and hemicellulose of those materials. The removal of lignin and hemicellulose can be observed from the TGA graph. For lignin removal, as depicted in literature, the amount of residual mass is in the range between 250-600oC. This decreases with the increasing number of bleaching level [50,51]. On the other hand, the hemicellulose removal can be observed through the disappearance of the shoulder at 275oC of DTG curves [52]. In the DTG curve of CNF2 and CNF3, a shoulder shape that is identical to hemicellulose could be found at around 240-275oC. The residual mass of CNF2 and CNF3 decreased with the increasing in bleaching level (CNF2 = 2x bleaching and CNF3 = 3x bleaching). These results indicated increasing the number of bleaching level could enhance the removal of lignin and hemicellulose in the fiber.

4 Conclusion

Cellulose nanofiber (CNF) has been isolated from LEFB by the TEMPO-oxidized method. The TEMPO-oxidized is performed in three kinds of fiber, notably (i) α-cellulose of LEFB, (ii) raw fiber of LEFB with 2x bleaching level and (iii) raw fiber of LEFB with 3x bleaching level. The FT-IR spectra of α-cellulose and all CNFs showed almost similar bands, especially in the CNF2 and CNF3 where there was a different signal that confirmed the presence of lignin and hemicellulose. Those components influenced the morphology and thermal properties of fibers. The morphology analysis of α-cellulose confirmed that α-cellulose showed curled and well-defined fibrils. The XRD analysis revealed the crystallinity index of CNF1 was higher than CNF2 and CNF3 due to the removal of lignin and hemicellulose. In other analyses using TEM, CNF1 consisted of a bundle of microfibrils; however, different results were obtained on CNF2 and CNF3. The CNF2 fiber was more individualized than CNF3, and it can be assumed that CNF2 has a higher content of hemicellulose than CNF3. The thermal analysis showed the thermal stability of CNF1 (235-320oC) was better than CNF2 (139-292oC) and CNF3 (126-291oC). The residual mass of CNF2 was higher than CNF1 and CNF3.

Acknowledgement

Author thanks the Indonesian Ministry of Research, Technology and Higher Education (KEMENRISTEKDIKTI) for the PMDSU scholarship program and the financial support to conduct the research internship through PKPI-PMDSU 2017.

  1. Conflict of Interest: Authors declare no conflict of interest

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Received: 2018-08-14
Accepted: 2019-03-19
Published Online: 2019-08-12

© 2019 Mahendra, I.P. et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 Public License.

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  119. Synthesis of Graphene Oxide Through Ultrasonic Assisted Electrochemical Exfoliation
  120. Special Issue on ISCMP 2018
  121. Synthesis and antiproliferative evaluation of some 1,4-naphthoquinone derivatives against human cervical cancer cells
  122. The influence of the grafted aryl groups on the solvation properties of the graphyne and graphdiyne - a MD study
  123. Electrochemical modification of platinum and glassy carbon surfaces with pyridine layers and their use as complexing agents for copper (II) ions
  124. Effect of Electrospinning Process on Total Antioxidant Activity of Electrospun Nanofibers Containing Grape Seed Extract
  125. Effect Of Thermal Treatment Of Trepel At Temperature Range 800-1200˚C
  126. Topical Issue on Agriculture
  127. The effect of Cladophora glomerata exudates on the amino acid composition of Cladophora fracta and Rhizoclonium sp.
  128. Influence of the Static Magnetic Field and Algal Extract on the Germination of Soybean Seeds
  129. The use of UV-induced fluorescence for the assessment of homogeneity of granular mixtures
  130. The use of microorganisms as bio-fertilizers in the cultivation of white lupine
  131. Lyophilized apples on flax oil and ethyl esters of flax oil - stability and antioxidant evaluation
  132. Production of phosphorus biofertilizer based on the renewable materials in large laboratory scale
  133. Human health risk assessment of potential toxic elements in paddy soil and rice (Oryza sativa) from Ugbawka fields, Enugu, Nigeria
  134. Recovery of phosphates(V) from wastewaters of different chemical composition
  135. Special Issue on the 4th Green Chemistry 2018
  136. Dead zone for hydrogenation of propylene reaction carried out on commercial catalyst pellets
  137. Improved thermally stable oligoetherols from 6-aminouracil, ethylene carbonate and boric acid
  138. The role of a chemical loop in removal of hazardous contaminants from coke oven wastewater during its treatment
  139. Combating paraben pollution in surface waters with a variety of photocatalyzed systems: Looking for the most efficient technology
  140. Special Issue on Chemistry Today for Tomorrow 2019
  141. Applying Discriminant and Cluster Analyses to Separate Allergenic from Non-allergenic Proteins
  142. Chemometric Expertise Of Clinical Monitoring Data Of Prolactinoma Patients
  143. Chemomertic Risk Assessment of Soil Pollution
  144. New composite sorbent for speciation analysis of soluble chromium in textiles
  145. Photocatalytic activity of NiFe2O4 and Zn0.5Ni0.5Fe2O4 modified by Eu(III) and Tb(III) for decomposition of Malachite Green
  146. Photophysical and antibacterial activity of light-activated quaternary eosin Y
  147. Spectral properties and biological activity of La(III) and Nd(III) Monensinates
  148. Special Issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  149. Soil organic carbon mineralization in relation to microbial dynamics in subtropical red soils dominated by differently sized aggregates
  150. A potential reusable fluorescent aptasensor based on magnetic nanoparticles for ochratoxin A analysis
  151. Special Issue on 13th JCC 2018
  152. Fluorescence study of 5-nitroisatin Schiff base immobilized on SBA-15 for sensing Fe3+
  153. Thermal and Morphology Properties of Cellulose Nanofiber from TEMPO-oxidized Lower part of Empty Fruit Bunches (LEFB)
  154. Encapsulation of Vitamin C in Sesame Liposomes: Computational and Experimental Studies
  155. A comparative study of the utilization of synthetic foaming agent and aluminum powder as pore-forming agents in lightweight geopolymer synthesis
  156. Synthesis of high surface area mesoporous silica SBA-15 by adjusting hydrothermal treatment time and the amount of polyvinyl alcohol
  157. Review of large-pore mesostructured cellular foam (MCF) silica and its applications
  158. Ion Exchange of Benzoate in Ni-Al-Benzoate Layered Double Hydroxide by Amoxicillin
  159. Synthesis And Characterization Of CoMo/Mordenite Catalyst For Hydrotreatment Of Lignin Compound Models
  160. Production of Biodiesel from Nyamplung (Calophyllum inophyllum L.) using Microwave with CaO Catalyst from Eggshell Waste: Optimization of Transesterification Process Parameters
  161. The Study of the Optical Properties of C60 Fullerene in Different Organic Solvents
  162. Composite Material Consisting of HKUST-1 and Indonesian Activated Natural Zeolite and its Application in CO2 Capture
  163. Topical Issue on Environmental Chemistry
  164. Ionic liquids modified cobalt/ZSM-5 as a highly efficient catalyst for enhancing the selectivity towards KA oil in the aerobic oxidation of cyclohexane
  165. Application of Thermal Resistant Gemini Surfactants in Highly Thixotropic Water-in-oil Drilling Fluid System
  166. Screening Study on Rheological Behavior and Phase Transition Point of Polymer-containing Fluids produced under the Oil Freezing Point Temperature
  167. The Chemical Softening Effect and Mechanism of Low Rank Coal Soaked in Alkaline Solution
  168. The Influence Of NO/O2 On The NOx Storage Properties Over A Pt-Ba-Ce/γ-Al2O3 Catalyst
  169. Special Issue on the International conference CosCI 2018
  170. Design of SiO2/TiO2 that Synergistically Increases The Hydrophobicity of Methyltrimethoxysilane Coated Glass
  171. Antidiabetes and Antioxidant agents from Clausena excavata root as medicinal plant of Myanmar
  172. Development of a Gold Immunochromatographic Assay Method Using Candida Biofilm Antigen as a Bioreceptor for Candidiasis in Rats
  173. Special Issue on Applied Biochemistry and Biotechnology 2019
  174. Adsorption of copper ions on Magnolia officinalis residues after solid-phase fermentation with Phanerochaete chrysosporium
  175. Erratum
  176. Erratum to: Sand Dune Characterization For Preparing Metallurgical Grade Silicon
https://doi.org/10.1515/chem-2019-0063
Schlagwörter für diesen Artikel
TEMPO; Cellulose Nanofiber; Bleaching level; Empty Fruit Bunch; Oil Palm
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Artikel in diesem Heft

  1. Regular Articles
  2. Research on correlation of compositions with oestrogenic activity of Cistanche based on LC/Q-TOF-MS/MS technology
  3. Efficacy of Pyrus elaeagnifolia subsp. elaeagnifolia in acetic acid–induced colitis model
  4. Anti-inflammatory and antinociceptive features of Bryonia alba L.: As a possible alternative in treating rheumatism
  5. High efficiency liposome fusion induced by reducing undesired membrane peptides interaction
  6. Prediction of the Blood-Brain Barrier Permeability Using RP-18 Thin Layer Chromatography
  7. Phytic Acid Extracted from Rice Bran as a Growth Promoter for Euglena gracilis
  8. Development of a validated spectrofluorimetric method for assay of sotalol hydrochloride in tablets and human plasma: application for stability-indicating studies
  9. Topological Indices of Hyaluronic Acid-Paclitaxel Conjugates’ Molecular Structure in Cancer Treatment
  10. Thermodynamic properties of the bubble growth process in a pool boiling of water-ethanol mixture two-component system
  11. Critical Roles of the PI3K-Akt-mTOR Signaling Pathway in Apoptosis and Autophagy of Astrocytes Induced by Methamphetamine
  12. Characteristics of Stable Hydrogen and Oxygen Isotopes of Soil Moisture under Different Land Use in Dry Hot Valley of Yuanmou
  13. Specific, highly sensitive and simple spectrofluorimetric method for quantification of daclatasvir in HCV human plasma patients and in tablets dosage form
  14. Chromium-modified cobalt molybdenum nitrides as catalysts for ammonia synthesis
  15. Langerhans cell-like dendritic cells treated with ginsenoside Rh2 regulate the differentiation of Th1 and Th2 cells in vivo
  16. Identification of Powdery Mildew Blumeria graminis f. sp. tritici Resistance Genes in Selected Wheat Varieties and Development of Multiplex PCR
  17. Computational Analysis of new Degree-based descriptors of oxide networks
  18. The Use Of Chemical Composition And Additives To Classify Petrol And Diesel Using Gas Chromatography–Mass Spectrometry And Chemometric Analysis: A Uk Study
  19. Minimal Energy Tree with 4 Branched Vertices
  20. Jatropha seed oil derived poly(esteramide-urethane)/ fumed silica nanocomposite coatings for corrosion protection
  21. Calculating topological indices of certain OTIS interconnection networks
  22. Energy storage analysis of R125 in UIO-66 and MOF-5 nanoparticles: A molecular simulation study
  23. Velvet Antler compounds targeting major cell signaling pathways in osteosarcoma - a new insight into mediating the process of invasion and metastasis in OS
  24. Effects of Azadirachta Indica Leaf Extract, Capping Agents, on the Synthesis of Pure And Cu Doped ZnO-Nanoparticles: A Green Approach and Microbial Activity
  25. Aqueous Micro-hydration of Na+(H2O)n=1-7 Clusters: DFT Study
  26. A proposed image-based detection of methamidophos pesticide using peroxyoxalate chemiluminescence system
  27. Phytochemical screening and estrogenic activity of total glycosides of Cistanche deserticola
  28. Biological evaluation of a series of benzothiazole derivatives as mosquitocidal agents
  29. Chemical pretreatments of Trapa bispinosa's peel (TBP) biosorbent to enhance adsorption capacity for Pb(ll)
  30. Dynamic Changes in MMP1 and TIMP1 in the Antifibrotic Process of Dahuang Zhechong Pill in Rats with Liver Fibrosis
  31. The Optimization and Production of Ginkgolide B Lipid Microemulsion
  32. Photodynamic Therapy Enhanced the Antitumor Effects of Berberine on HeLa Cells
  33. Chiral and Achiral Enantiomeric Separation of (±)-Alprenolol
  34. Correlation of Water Fluoride with Body Fluids, Dental Fluorosis and FT4, FT3 –TSH Disruption among Children in an Endemic Fluorosis area in Pakistan
  35. A one-step incubation ELISA kit for rapid determination of dibutyl phthalate in water, beverage and liquor
  36. Free Radical Scavenging Activity of Essential Oil of Eugenia caryophylata from Amboina Island and Derivatives of Eugenol
  37. Effects of Blue and Red Light On Growth And Nitrate Metabolism In Pakchoi
  38. miRNA-199a-5p functions as a tumor suppressor in prolactinomas
  39. Solar photodegradation of carbamazepine from aqueous solutions using a compound parabolic concentrator equipped with a sun tracking system
  40. Influence of sub-inhibitory concentration of selected plant essential oils on the physical and biochemical properties of Pseudomonas orientalis
  41. Preparation and spectroscopic studies of Fe(II), Ru(II), Pd(II) and Zn(II) complexes of Schiff base containing terephthalaldehyde and their transfer hydrogenation and Suzuki-Miyaura coupling reaction
  42. Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)
  43. Synthesis, characterization (IR, 1H, 13C & 31P NMR), fungicidal, herbicidal and molecular docking evaluation of steroid phosphorus compounds
  44. Analysis and Biological Evaluation of Arisaema Amuremse Maxim Essential Oil
  45. A preliminary assessment of potential ecological risk and soil contamination by heavy metals around a cement factory, western Saudi Arabia
  46. Anti- inflammatory effect of Prunus tomentosa Thunb total flavones in LPS-induced RAW264.7 cells
  47. Collaborative Influence of Elevated CO2 Concentration and High Temperature on Potato Biomass Accumulation and Characteristics
  48. Methods of extraction, physicochemical properties of alginates and their applications in biomedical field – a review
  49. Characteristics of liposomes derived from egg yolk
  50. Preparation of ternary ZnO/Ag/cellulose and its enhanced photocatalytic degradation property on phenol and benzene in VOCs
  51. Influence of Human Serum Albumin Glycation on the Binding Affinities for Natural Flavonoids
  52. Synthesis and antioxidant activity of 2-methylthio-pyrido[3,2-e][1,2,4] triazolo[1,5-a]pyrimidines
  53. Comparative study on the antioxidant activities of ten common flower teas from China
  54. Molecular Properties of Symmetrical Networks Using Topological Polynomials
  55. Synthesis of Co3O4 Nano Aggregates by Co-precipitation Method and its Catalytic and Fuel Additive Applications
  56. Phytochemical analysis, Antioxidant and Antiprotoscolices potential of ethanol extracts of selected plants species against Echinococcus granulosus: In-vitro study
  57. Silver nanoparticles enhanced fluorescence for sensitive determination of fluoroquinolones in water solutions
  58. Simultaneous Quantification of the New Psychoactive Substances 3-FMC, 3-FPM, 4-CEC, and 4-BMC in Human Blood using GC-MS
  59. Biodiesel Production by Lipids From Indonesian strain of Microalgae Chlorella vulgaris
  60. Miscibility studies of polystyrene/polyvinyl chloride blend in presence of organoclay
  61. Antibacterial Activities of Transition Metal complexes of Mesocyclic Amidine 1,4-diazacycloheptane (DACH)
  62. Novel 1,8-Naphthyridine Derivatives: Design, Synthesis and in vitro screening of their cytotoxic activity against MCF7 cell line
  63. Investigation of Stress Corrosion Cracking Behaviour of Mg-Al-Zn Alloys in Different pH Environments by SSRT Method
  64. Various Combinations of Flame Retardants for Poly (vinyl chloride)
  65. Phenolic compounds and biological activities of rye (Secale cereale L.) grains
  66. Oxidative degradation of gentamicin present in water by an electro-Fenton process and biodegradability improvement
  67. Optimizing Suitable Conditions for the Removal of Ammonium Nitrogen by a Microbe Isolated from Chicken Manure
  68. Anti-inflammatory, antipyretic, analgesic, and antioxidant activities of Haloxylon salicornicum aqueous fraction
  69. The anti-corrosion behaviour of Satureja montana L. extract on iron in NaCl solution
  70. Interleukin-4, hemopexin, and lipoprotein-associated phospholipase A2 are significantly increased in patients with unstable carotid plaque
  71. A comparative study of the crystal structures of 2-(4-(2-(4-(3-chlorophenyl)pipera -zinyl)ethyl) benzyl)isoindoline-1,3-dione by synchrotron radiation X-ray powder diffraction and single-crystal X-ray diffraction
  72. Conceptual DFT as a Novel Chemoinformatics Tool for Studying the Chemical Reactivity Properties of the Amatoxin Family of Fungal Peptides
  73. Occurrence of Aflatoxin M1 in Milk-based Mithae samples from Pakistan
  74. Kinetics of Iron Removal From Ti-Extraction Blast Furnace Slag by Chlorination Calcination
  75. Increasing the activity of DNAzyme based on the telomeric sequence: 2’-OMe-RNA and LNA modifications
  76. Exploring the optoelectronic properties of a chromene-appended pyrimidone derivative for photovoltaic applications
  77. Effect of He Qi San on DNA Methylation in Type 2 Diabetes Mellitus Patients with Phlegm-blood Stasis Syndrome
  78. Cyclodextrin potentiometric sensors based on selective recognition sites for procainamide: Comparative and theoretical study
  79. Greener synthesis of dimethyl carbonate from carbon dioxide and methanol using a tunable ionic liquid catalyst
  80. Nonisothermal Cold Crystallization Kinetics of Poly(lactic acid)/Bacterial Poly(hydroxyoctanoate) (PHO)/Talc
  81. Enhanced adsorption of sulfonamide antibiotics in water by modified biochar derived from bagasse
  82. Study on the Mechanism of Shugan Xiaozhi Fang on Cells with Non-alcoholic Fatty Liver Disease
  83. Comparative Effects of Salt and Alkali Stress on Antioxidant System in Cotton (Gossypium Hirsutum L.) Leaves
  84. Optimization of chromatographic systems for analysis of selected psychotropic drugs and their metabolites in serum and saliva by HPLC in order to monitor therapeutic drugs
  85. Electrocatalytic Properties of Ni-Doped BaFe12O19 for Oxygen Evolution in Alkaline Solution
  86. Study on the removal of high contents of ammonium from piggery wastewater by clinoptilolite and the corresponding mechanisms
  87. Phytochemistry and toxicological assessment of Bryonia dioica roots used in north-African alternative medicine
  88. The essential oil composition of selected Hemerocallis cultivars and their biological activity
  89. Mechanical Properties of Carbon Fiber Reinforced Nanocrystalline Nickel Composite Electroforming Deposit
  90. Anti-c-myc efficacy block EGFL7 induced prolactinoma tumorigenesis
  91. Topical Issue on Applications of Mathematics in Chemistry
  92. Zagreb Connection Number Index of Nanotubes and Regular Hexagonal Lattice
  93. The Sanskruti index of trees and unicyclic graphs
  94. Valency-based molecular descriptors of Bakelite network BNmn
  95. Computing Topological Indices for Para-Line Graphs of Anthracene
  96. Zagreb Polynomials and redefined Zagreb indices of Dendrimers and Polyomino Chains
  97. Topological Descriptor of 2-Dimensional Silicon Carbons and Their Applications
  98. Topological invariants for the line graphs of some classes of graphs
  99. Words for maximal Subgroups of Fi24‘
  100. Generators of Maximal Subgroups of Harada-Norton and some Linear Groups
  101. Special Issue on POKOCHA 2018
  102. Influence of Production Parameters on the Content of Polyphenolic Compounds in Extruded Porridge Enriched with Chokeberry Fruit (Aronia melanocarpa (Michx.) Elliott)
  103. Effects of Supercritical Carbon Dioxide Extraction (SC-CO2) on the content of tiliroside in the extracts from Tilia L. flowers
  104. Impact of xanthan gum addition on phenolic acids composition and selected properties of new gluten-free maize-field bean pasta
  105. Impact of storage temperature and time on Moldavian dragonhead oil – spectroscopic and chemometric analysis
  106. The effect of selected substances on the stability of standard solutions in voltammetric analysis of ascorbic acid in fruit juices
  107. Determination of the content of Pb, Cd, Cu, Zn in dairy products from various regions of Poland
  108. Special Issue on IC3PE 2018 Conference
  109. The Photocatalytic Activity of Zns-TiO2 on a Carbon Fiber Prepared by Chemical Bath Deposition
  110. N-octyl chitosan derivatives as amphiphilic carrier agents for herbicide formulations
  111. Kinetics and Mechanistic Study of Hydrolysis of Adenosine Monophosphate Disodium Salt (AMPNa2) in Acidic and Alkaline Media
  112. Antimalarial Activity of Andrographis Paniculata Ness‘s N-hexane Extract and Its Major Compounds
  113. Special Issue on ABB2018 Conference
  114. Special Issue on ICCESEN 2017
  115. Theoretical Diagnostics of Second and Third-order Hyperpolarizabilities of Several Acid Derivatives
  116. Determination of Gamma Rays Efficiency Against Rhizoctonia solani in Potatoes
  117. Studies On Compatibilization Of Recycled Polyethylene/Thermoplastic Starch Blends By Using Different Compatibilizer
  118. Liquid−Liquid Extraction of Linalool from Methyl Eugenol with 1-Ethyl-3-methylimidazolium Hydrogen Sulfate [EMIM][HSO4] Ionic Liquid
  119. Synthesis of Graphene Oxide Through Ultrasonic Assisted Electrochemical Exfoliation
  120. Special Issue on ISCMP 2018
  121. Synthesis and antiproliferative evaluation of some 1,4-naphthoquinone derivatives against human cervical cancer cells
  122. The influence of the grafted aryl groups on the solvation properties of the graphyne and graphdiyne - a MD study
  123. Electrochemical modification of platinum and glassy carbon surfaces with pyridine layers and their use as complexing agents for copper (II) ions
  124. Effect of Electrospinning Process on Total Antioxidant Activity of Electrospun Nanofibers Containing Grape Seed Extract
  125. Effect Of Thermal Treatment Of Trepel At Temperature Range 800-1200˚C
  126. Topical Issue on Agriculture
  127. The effect of Cladophora glomerata exudates on the amino acid composition of Cladophora fracta and Rhizoclonium sp.
  128. Influence of the Static Magnetic Field and Algal Extract on the Germination of Soybean Seeds
  129. The use of UV-induced fluorescence for the assessment of homogeneity of granular mixtures
  130. The use of microorganisms as bio-fertilizers in the cultivation of white lupine
  131. Lyophilized apples on flax oil and ethyl esters of flax oil - stability and antioxidant evaluation
  132. Production of phosphorus biofertilizer based on the renewable materials in large laboratory scale
  133. Human health risk assessment of potential toxic elements in paddy soil and rice (Oryza sativa) from Ugbawka fields, Enugu, Nigeria
  134. Recovery of phosphates(V) from wastewaters of different chemical composition
  135. Special Issue on the 4th Green Chemistry 2018
  136. Dead zone for hydrogenation of propylene reaction carried out on commercial catalyst pellets
  137. Improved thermally stable oligoetherols from 6-aminouracil, ethylene carbonate and boric acid
  138. The role of a chemical loop in removal of hazardous contaminants from coke oven wastewater during its treatment
  139. Combating paraben pollution in surface waters with a variety of photocatalyzed systems: Looking for the most efficient technology
  140. Special Issue on Chemistry Today for Tomorrow 2019
  141. Applying Discriminant and Cluster Analyses to Separate Allergenic from Non-allergenic Proteins
  142. Chemometric Expertise Of Clinical Monitoring Data Of Prolactinoma Patients
  143. Chemomertic Risk Assessment of Soil Pollution
  144. New composite sorbent for speciation analysis of soluble chromium in textiles
  145. Photocatalytic activity of NiFe2O4 and Zn0.5Ni0.5Fe2O4 modified by Eu(III) and Tb(III) for decomposition of Malachite Green
  146. Photophysical and antibacterial activity of light-activated quaternary eosin Y
  147. Spectral properties and biological activity of La(III) and Nd(III) Monensinates
  148. Special Issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  149. Soil organic carbon mineralization in relation to microbial dynamics in subtropical red soils dominated by differently sized aggregates
  150. A potential reusable fluorescent aptasensor based on magnetic nanoparticles for ochratoxin A analysis
  151. Special Issue on 13th JCC 2018
  152. Fluorescence study of 5-nitroisatin Schiff base immobilized on SBA-15 for sensing Fe3+
  153. Thermal and Morphology Properties of Cellulose Nanofiber from TEMPO-oxidized Lower part of Empty Fruit Bunches (LEFB)
  154. Encapsulation of Vitamin C in Sesame Liposomes: Computational and Experimental Studies
  155. A comparative study of the utilization of synthetic foaming agent and aluminum powder as pore-forming agents in lightweight geopolymer synthesis
  156. Synthesis of high surface area mesoporous silica SBA-15 by adjusting hydrothermal treatment time and the amount of polyvinyl alcohol
  157. Review of large-pore mesostructured cellular foam (MCF) silica and its applications
  158. Ion Exchange of Benzoate in Ni-Al-Benzoate Layered Double Hydroxide by Amoxicillin
  159. Synthesis And Characterization Of CoMo/Mordenite Catalyst For Hydrotreatment Of Lignin Compound Models
  160. Production of Biodiesel from Nyamplung (Calophyllum inophyllum L.) using Microwave with CaO Catalyst from Eggshell Waste: Optimization of Transesterification Process Parameters
  161. The Study of the Optical Properties of C60 Fullerene in Different Organic Solvents
  162. Composite Material Consisting of HKUST-1 and Indonesian Activated Natural Zeolite and its Application in CO2 Capture
  163. Topical Issue on Environmental Chemistry
  164. Ionic liquids modified cobalt/ZSM-5 as a highly efficient catalyst for enhancing the selectivity towards KA oil in the aerobic oxidation of cyclohexane
  165. Application of Thermal Resistant Gemini Surfactants in Highly Thixotropic Water-in-oil Drilling Fluid System
  166. Screening Study on Rheological Behavior and Phase Transition Point of Polymer-containing Fluids produced under the Oil Freezing Point Temperature
  167. The Chemical Softening Effect and Mechanism of Low Rank Coal Soaked in Alkaline Solution
  168. The Influence Of NO/O2 On The NOx Storage Properties Over A Pt-Ba-Ce/γ-Al2O3 Catalyst
  169. Special Issue on the International conference CosCI 2018
  170. Design of SiO2/TiO2 that Synergistically Increases The Hydrophobicity of Methyltrimethoxysilane Coated Glass
  171. Antidiabetes and Antioxidant agents from Clausena excavata root as medicinal plant of Myanmar
  172. Development of a Gold Immunochromatographic Assay Method Using Candida Biofilm Antigen as a Bioreceptor for Candidiasis in Rats
  173. Special Issue on Applied Biochemistry and Biotechnology 2019
  174. Adsorption of copper ions on Magnolia officinalis residues after solid-phase fermentation with Phanerochaete chrysosporium
  175. Erratum
  176. Erratum to: Sand Dune Characterization For Preparing Metallurgical Grade Silicon
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