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Optimization for removal efficiency of fluoride using La(iii)–Al(iii)-activated carbon modified by chemical route

  • Ting Su , Yonghui Song EMAIL logo , Xinzhe Lan and Wenwen Gao
Published/Copyright: August 24, 2020
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Green Processing and Synthesis
From the journal Green Processing and Synthesis Volume 9 Issue 1

Abstract

A simple chemical route was adopted for the preparation of adsorbent to remove fluoride in the simulation solution. In this study, commercially activated carbon (CAC) was used as the raw material, HNO3 (20 wt%), La(NO3)3·2H2O (0.05 mol/L), and Al(NO3)3 (0.10 mol/L) were employed as modification reagents to successfully prepare the CAC adsorbent loaded with the elements La and Al (La(iii)–Al(iii)–CAC). The modified adsorbent was characterized by scanning electron microscopy, energy-dispersive spectroscopy, and Fourier-transform infrared spectroscopy measurements. The effects of variables such as solution pH, adsorption time, initial concentrations, and volume of solution were investigated on adsorption efficiency by the response surface method (RSM). Under optimum conditions, specified as a pH value of 6, an adsorption time of 1.2 h, an initial concentration of 30 mg/L, a solution volume of 25 mL, and the value of RF can reach at 74.11%. From the RSM analysis, the pH value was a significant factor in the adsorption process and the order for these key factors was as follows: pH > adsorption time > solution volume. Meanwhile, there were interactions among these factors. Chemical modification had an important role in pore structure generation and functional group of adsorbent to improve the adsorption efficiency. The removal performance of adsorbent on simulation solution of fluoride also showed the feasibility of adsorbent to be applied in industrial purposes.

Keywords: activated carbon modification; loaded with La and Al; simulation solution of fluoride; removal rate; optimum conditions

Abbreviations

A

Concentration of HNO3

AC

Activated carbon

B

Concentration of La(NO3)3·2H2O

C

Concentration of Al(NO3)3

CAC

Commercially activated carbon

D

Solution volume ratio of La(NO3)3·2H2O and Al(NO3)3

E

Adsorption time

F

pH

EDS

Energy-dispersive spectroscopy

F−

Fluoride ion

FT-IR

Fourier-transform infrared spectroscopy

G

Solution volume

La(iii)–Al(iii)–CAC

La(iii)–Al(iii) loaded on CAC

MCAC

Acid-modified activated carbon

R2

Correlation coefficient

RF

Removal rate of fluoride

RSM

Response surface method

SEM

Scanning electron microscopy

TISBS

Total ionic strength buffer solution.

1 Introduction

Fluoride is a very important trace element for our human body because it has great significance for the body’s growth and development [1,2]. But it has harmful effects such as endocrine disorders [3], the formation of fluoride plaque [4], and even bone cancer [5] when the intake is excessive. Given that the source of fluorine is mainly drinking water, many people are drinking water with an excess amount of fluoride [6,7,8]. Fluoride pollution attracted great attention because it has become a worldwide problem, so it is very much necessary to carry out the research on defluoridation.

There are several methods to remove the fluoride ion (F−), such as limestone precipitation method, ion exchange method, membrane separation method, and adsorption method. Among these strategies, adsorption method is one of the most effective and commonly used methods as it is environmentally friendly [9]. Various adsorbents have been used in the literature for defluoridation of aqueous solution such as activated carbon (AC), activated alumina, zeolites, alumina-based Zr-MOFs, iron-based adsorbents, or some biosorbents. Theoretically, they can be used as adsorbents for fluoride removal because of their unique physical or chemical composition [10,11,12]; however, there are some disadvantages such as highly pH-dependent in regeneration, material loss in adsorption process, and a gap between adsorption properties and desired effect by these strategies. AC is supposed to be a sustainable material for elimination of pollutants from drinking water.

Recently, to improve the adsorption capacity of AC, a number of metal oxides were employed to remove the anionic contaminants [13]; Fe2O3, ZrO2, SnO2, MnO2, and MnFe2O4 can be good choice due to their biocompatibility and chemical stability [14,15,16,17]. Meanwhile, some modified methods of graphene oxide can be referred from previous studies [18,19,20]. Lanthanum is a kind of a rare-earth element, and some compounds of lanthanum were reported to be excellent absorbents of fluoride [21], such as nano-adsorbent of Al–Fe–La [22] and triple-metal composite of Fe–Mg–La [23]. Oxides and hydroxides of aluminum have also been reported to remove fluoride effectively with comparatively low cost [24,25,26]. Thus, a novel La-based and La–Al-based composite or a modified adsorbent will be a good choice for removing fluoride. However, few studies on La–Al adsorbents were reported.

In this work, the cheap AC, the low-cost reagent, and an experimental design technique were combined to explore an easier to handle, faster, more efficient, and cost-effective method to treat the simulation solution of fluoride. RSM is a statistical method used for optimization of the process and evaluation of the significance of the variables and their effects on the response [27]. The results of this study confirm the great potential and applicability of adsorbents for the removal of other ions from industrial wastewater.

2 Experimental methods

2.1 Materials

Commercially activated carbon (CAC) was employed as a raw material in this experiment. The properties of CAC are listed in Table A1 in the Appendix. After being ground and screened until the particle size was less than 0.425 mm, the CAC will be washed five times and dried.

2.2 Methods and design

Preparation of La(iii)–Al(iii)–CAC included two steps: the acid modification process (I) and the La(iii)–Al(iii) loading process (II). A specific mass fraction of nitric acid (HNO3) was involved in process I. A total of 100 mL of HNO3 and CAC (20 g) were mixed in a flask, which was placed in a water bath at a constant temperature of 75°C for 2 h. Then, the CAC was washed to neutral and dried at 100°C for 3 h and the acid-modified activated carbon (MCAC) was obtained. La(NO3)3·2H2O and Al(NO3)3 were employed to load La(iii) and Al(iii) on MCAC. A 10 g MCAC was stirred in 100 mL of mixed solution of La(NO3)3·2H2O and Al(NO3)3 for 24 h. Then, the solid product was carbonized in a tube furnace at 300°C under a N2 atmosphere for 2 h, and after cooling to room temperature, the preparation of La(iii)–Al(iii)–CAC was completed. La(iii)–Al(iii)–CAC will be used as an adsorbent for fluoride. The La(iii)–Al(iii)–CAC was put into the simulation solution of fluoride for a certain time period to perform the adsorption process. Illustration of La(iii)–Al(iii)–CAC preparation and adsorption processes is shown in Figure 1.

Figure 1 Illustration of preparation and adsorption processes.
Figure 1

Illustration of preparation and adsorption processes.

An experimental design for the preparation of La(iii)–Al(iii)–CAC was required to reduce the experimental cost [28]. Factors adopted here were solution concentration (mass fraction) of HNO3 (A), concentration (mass fraction) of La(NO3)3·2H2O (B), concentration (mass fraction) of Al(NO3)3 (C), and solution volume ratio of La(NO3)3·2H2O and Al(NO3)3 (D), each having three levels, as shown in Table 1. The orthogonal array designed by the JMP method (a kind of statistical analysis software designed by SAS company) is listed in Table 2. This reduced the experimental number from 34 = 81 to L15 (34) = 15.

Table 1

Factors and levels for the experimental design

FactorLevel
123
A (%)0.10.20.3
B (mol/L)0.010.030.05
C (mol/L)0.050.100.15
D (–)0.512
Table 2

Orthogonal array for the experiment

No.ABCD
11111
22322
32131
41311
53313
61221
72233
83331
91323
101332
113122
121133
131212
143211
152113

2.3 Calculation of RF

Ion-selective electrode method was explored to calculate the concentration of F−, and a standard curve can be obtained by this method, which is detailed in the Appendix. According to the standard curve, RF can be calculated by the following equation:

(1)RF=C0−C1C0×100%,

where RF,C0, and C1 is the removal rate of F− (%), concentration of F− before and after adsorption processes, respectively (mg/L).

3 Results and discussion

3.1 Confirmation of preparation parameters

The higher the value of RF, the better the adsorption efficiency of La(iii)–Al(iii)–CAC. Table 3 shows the results for 15 runs, and it is easy to find that No. 2 sample got the maximum value of RF, indicating that the optimal preparation parameters were confirmed as A2B3C2D2.

Table 3

RF of samples with different conditions

No.ConditionRF (%)
1A1B1C1D10.25
2A2B3C2D20.58
3A2B1C3D10.41
4A1B3C1D10.23
5A3B3C1D30.27
6A1B2C2D10.18
7A2B2C3D30.41
8A3B3C3D10.38
9A1B3C2D30.21
10A1B3C3D20.32
11A3B1C2D20.27
12A1B1C3D30.38
13A1B2C1D20.15
14A3B2C1D10.29
15A2B1C1D30.44

3.1.1 SEM–EDS analysis of adsorbent

Scanning electron microscopy (SEM) was adopted to show the micromorphology of samples and the corresponding energy-dispersive spectroscopy (EDS) images to prove the successful loading of La(iii) or Al(iii) on La(iii)–Al(iii)–CAC, which were prepared under optimized conditions.

As shown in Figure 2, there were more and denser pore structures on MCAC, indicating that the modification of HNO3 was beneficial for generating the pores. The SEM images of La(iii)–CAC and La(iii)–Al(iii)–CAC are shown in Figure 3. There were many oval pores in Figure 3a which were marked as 1. The surface of La(iii)–CAC was coarse, and finer porous structures were marked as 2. However, the pore structures of La(iii)–Al(iii)–CAC were changed in Figure 3b. The pore structure marked as 1 became a little more regular circle, the finer pore size marked as 2 became larger, and the pores distributed more uniformly, which were suitable for better adsorption capability. The presence of elements La(iii) and Al(iii) were detected from the samples in Figures 3a1, a2 and b1, b2. The weight percentage of La(iii) was 0.86%, which increased obviously to 2.55% after the modification of La(NO3)3·2H2O and Al(NO3)3. More La(iii) content in adsorbent will show better adsorption performance, which was probably caused by the synergistic effect of the two elements in the modification process.

Figure 2 The SEM images of (a) CAC and (b) MCAC.
Figure 2

The SEM images of (a) CAC and (b) MCAC.

Figure 3 The SEM and EDS analyses of La(iii)–Al(iii)–CAC: (a, a1, a2) La(iii)–CAC and (b, b1, b2) La(iii)–Al(iii)–CAC.
Figure 3

The SEM and EDS analyses of La(iii)–Al(iii)–CAC: (a, a1, a2) La(iii)–CAC and (b, b1, b2) La(iii)–Al(iii)–CAC.

3.1.2 FT-IR analysis of adsorbent

The Fourier-transform infrared spectroscopy (FT-IR) spectra of La(iii)–Al(iii)–CAC are shown in Figure 4. Six kinds of absorption peaks in curves were observed at 3,457, 2,905, 2,350, 1,630–1,365, 605, and 425 cm−1, which correspond to the stretching vibration of hydroxyl (–OH), stretching vibration of –CH2–, telescopic vibration of –C≡N, deformation vibration of C–O, stretching vibration of La–O, and bending vibration of Al–O. According to FT-IR analysis of La(iii)–Al(iii)–CAC, the number of oxygen-containing functional groups on adsorbent was increased, and La(iii) and Al(iii) were successfully loaded on CAC and existed in the form of oxide. The reaction equations that may be involved in the modification process are as follows:

(2)HNO3+C→CO2+H2O+NO2,
(3)La(NO3)3→La2O3+NOX,
(4)Al(NO3)3→Al2O3+NOX.
Figure 4 FT-IR spectra of La(iii)–Al(iii)–CAC.
Figure 4

FT-IR spectra of La(iii)–Al(iii)–CAC.

3.2 Single-factor experiment for adsorption process

3.2.1 Effect of initial concentration

The concentration of F− plays an important role in the adsorption process because it can affect the capacity of adsorbents. Seven different concentrations (10, 20, 30, 40, 50, 60, and 70 mg/L) were selected to explore the effect of the initial concentration on the adsorption process of La(iii)–Al(iii)–CAC. The other parameters of adsorption process were fixed as follows: the solution volume was 30 mL, the dosage of La(iii)–Al(iii)–CAC was 1 g, the adsorption time was 1.4 h, and the pH value was 6. RF was calculated after the end of the adsorption process, as shown in Figure 5. RF was improved at the first increase in the initial concentration; it can reach the value of 53.82% when the concentration was 30 mg/L, which was also the maximum value. RF decreases continuously with the increase in concentration, this is because the limited adsorption capacity of adsorbent, which can't absorb more ions [29,30], therefore, the maximum concentration that the La(iii)–Al(iii)–CAC can be loaded was 30 mg/L.

Figure 5 Effect of initial concentration on RF.
Figure 5

Effect of initial concentration on RF.

3.2.2 Effect of adsorption time

The adsorption process means the contact process, and all transfer phenomena such as adsorption are inseparable from contact; therefore, the adsorption time is a fundamental parameter. The other parameters of adsorption process were fixed as follows: the initial concentration was 30 mg/L, the solution volume was 30 mL, the dosage of La(iii)–Al(iii)–CAC was 1 g, and the pH value was 6. The effects of the adsorption time on RF are shown in Figure 6. Clearly, RF of solution increased quickly at the value of 71.2% in the initial stages of the contact period until 1.0 h, and then gradually increased to 71.6% with a prolonged contact time of 1.4 h until equilibrium was reached. There are usually three steps for the adsorption process as follows: external surface adsorption stage, internal surface adsorption stage, and adsorption reaction stage. The adsorption reaction stage is a chemical reaction, which is not involved here, so the decisive step is the other two physical adsorption stages. The increase in RF in initial stages before 1.0 h was contributed to the external surface adsorption process, as all of the active sites on the La(iii)–Al(iii)–CAC were vacant at the first stage of adsorption process and the concentration of solution was also high, so it is easy to increase the amount of adsorption. However, after that stage, the adsorption process mainly depends on the internal surface adsorption. Few surface active sites were available, which lead to the observation of small increase in the uptake of RF. Hence, the suitable time to reach equilibrium was selected as the adsorption time for further experiments.

Figure 6 Effect of adsorption time on RF.
Figure 6

Effect of adsorption time on RF.

3.2.3 Effect of solution volume

The solution volume is also a very important factor of adsorption process because of the relationship between the capacity of an adsorbent and a given initial concentration of solution. Studies were conducted to learn the effect of La(iii)–Al(iii)–CAC on NaF solution with the concentration of 30 mg/L, which was confirmed by experiments before. Seven different solution volumes were employed in the study (10, 25, 40, 55, 70, 85, and 100 mL), the dosage of La(iii)–Al(iii)–CAC was 1 g, the adsorption time was 1.4 h, and the pH value was 6. The RF obtained from experiments is shown in Figure 7. There was a sharply increasing trend as the solution volume increased from 10 to 25 mL, then continued to decline, and the maximum RF was 70.6% at the solution volume of 25 mL. The higher removal percentage in the present experiment contributed to the greater availability of exchangeable sites and larger surface area [31]. More solution volume provided more contact area of La(iii)–Al(iii)–CAC in order to promote the effective adsorption process. However, because of the limited adsorption capacity of La(iii)–Al(iii)–CAC, RF decreased when the solution volume was more than 25 mL. Therefore, 25 mL was used as the optimal solution volume of the adsorption.

Figure 7 Effect of solution volume on RF.
Figure 7

Effect of solution volume on RF.

3.2.4 Effect of pH

It is necessary to analyze the effect of pH as a single factor because the pH value of an aqueous solution is one of the most important factors during the adsorption process, especially when it can affect the existence form of fluorine. The effect of pH was investigated for pH values of 3, 4, 5, 6, 7, 9, and 11. The pH value was adjusted during the experiments by adding a few drops of HCl (1 mol/L) and NaOH (1 mol/L). All other parameters in the adsorption process were kept constant (the dosage of La(iii)–Al(iii)–CAC was 1 g, the initial concentration of NaF solution was 30 mg/L, and the solution volume was 25 mL). The effect of pH value on RF is shown in Figure 8. Figure 7 shows that an uptake of RF significantly increased with an increase in pH value in the solution; it can achieve the peak point at 72.1% when the pH value was 6, and then followed by a downward trend until the pH value was 11. In the pH range of 0–7, fluorine exists in the form of F−, HF, and HF2−, and mainly in the form of HF when pH < 3; therefore, the concentration of F− will not increase at the condition of pH > 3 theoretically. However, there is similarity in chemical bond between F− and OH−, and the OH− will affect the adsorption of F−, making the higher adsorption efficiency to be obtained at a higher pH value and the suitable pH was 6.

Figure 8 Effect of pH on RF.
Figure 8

Effect of pH on RF.

3.3 Response surface method experiment

3.3.1 Design and result

The response surface method (RSM) was adopted to optimize the adsorption process and get a higher RF. Experimental design was carried out by the custom design method in JMP software, and the response item was RF. Three parameters, including adsorption time (E), pH (F), and solution volume (G), were studied and each parameter was set according to single-factor experiment results, as shown in Table 4. In addition, RF is also shown in the last column of this table, which will be discussed later.

Table 4

Experimental design and results

No.E (h)F (–)G (mL)RF (%)
1191059.74
2134062.75
31.262573.87
41.462569.45
51.264072.32
6194060.31
7131064.32
81.232570.84
91.431065.73
101.262573.80
111.494060.41
121.434065.23
131.292564.74
141.491059.33
15162567.20
161.261068.42

3.3.2 Analysis of model

The stepwise regression method was adopted to analyze the experimental data in Table 4. Analysis of variance and significance test for the regression model are listed in Tables 5 and 6, respectively.

Table 5

Analysis of variance for the regression model (R2 = 0.9488)

SourceDfSum of squareMean squareF valueP value
Model9408.34645.371812.35550.0031
Error622.0333.6722
Total15430.379
Table 6

Significance test for the regression coefficients

SourceDfSum of squareF valueP value
E13.36400.91610.3755
F159.049016.08000.0070a
G11.22500.33360.5846
EaE151.320313.97540.0096a
EaF12.20500.60050.4687
FaF164.912817.67680.0057a
EaG10.32000.08710.7778
FaG11.80500.49150.5095
GaG114.70924.00560.0922
  1. a

    Significant influence factor.

The smaller the P value and the larger the F value, the more significant the model. In Table 5, the value of R2 is 0.9488, the F value is 12.3555, and the P value is 0.0031, which indicated that the stepwise regression model was suitable for the analysis of experimental data. Hence, the model can be used to analyze and optimize the adsorption process. When the P value of index was <0.0100, the factor can be interpreted as the extremely significant factor. In Table 6, the significant factor was the pH value, as well as the F (pH) squared and the E (adsorption time) squared, which means the interaction of three factors among them was not a simple linear relationship. The order for these key factors was F > E > G (solution volume).

3.3.3 RSM optimization and verification

The RSM method was employed to analyze the experimental data in Table 6. The quadratic regression surface model was established after eliminating the non-significant items. The model for removal rate (RF) can be calculated by the obtained quadratic regression equation given by:

(5)RF=73.69+0.58X1−2.43X2+0.35X3−4.41X12−0.53X1X2−4.96X22+0.2X1X3+0.475X2X3−2.36X32,

where X1, X2, and X3 are equal to (adsorption time: 1.2)/0.2, (pH value: 6)/3, and (solution volume: 25)/15.

In order to get the optimization conditions for adsorption, interaction effect among three factors was explored by three-dimensional RSM of the quadratic polynomial regression equation, as shown in Figures 9–11.

Figure 9 Interaction of adsorption time and pH on the response surface.
Figure 9

Interaction of adsorption time and pH on the response surface.

Figure 10 Interaction of pH and solution volume on the response surface.
Figure 10

Interaction of pH and solution volume on the response surface.

Figure 11 Interaction of adsorption time and solution volume on the response surface.
Figure 11

Interaction of adsorption time and solution volume on the response surface.

The convex surfaces can be seen on the response surface in Figures 9–11, which means that the model has a stable maximum point in the test range. When the adsorption time was 1.2 h and the pH value was 6, the RF was 74.05%; when the pH value was 6 and the solution volume was 25 mL, the RF was 74.00%; when the adsorption time was 1.2 h and the solution volume was 25 mL, the RF was 73.72%. The maximum RF value was 74.05% by the prediction of Equation 2 and RSM. Therefore, the optimal adsorption process conditions are determined as the adsorption time was 1.2 h, the pH value was 6, and the solution volume was 25 mL. Three parallel adsorption experiments (No. 17, No. 18, and No. 19) were performed in the laboratory with the optimal parameters and the RF was 74.03%, 73.94%, and 74.37%, respectively, and the average RF was 74.11%.

4 Conclusion

La(iii)–Al(iii)–CAC was successfully modified with 20 wt% HNO3, 0.05 mol/L La(NO3)3·2H2O, and 0.10 mol/L Al(NO3)3 in a fast and simple process used for adsorption of F−. Modification increased the number of oxygen-containing functional groups on adsorbent, and La(iii) and Al(iii) were successfully loaded on CAC, which is confirmed by the EDS and FTIR analyses. Experiments were set as a function of the selected variables, concluding the initial concentration of 30 mg/L, the adsorption time of 1.2 h, the pH value of 6, and the solution volume of 25 mL by the optimized method of RSM to obtain the RF value at 74.11%. According to the analysis, the pH value was an extremely significant factor in the adsorption process; meanwhile, the order for these key factors was pH > adsorption time > solution volume. The verification equation was

RF=73.69+0.58X1−2.43X2+0.35X3−4.41X12−0.53X1X2−4.96X22+0.2X1X3+0.475X2X3−2.36X32.

The higher removal efficiency of this adsorbent in simulation solution of fluoride confirmed the great potential and applicability of adsorbent for the removal of other ions from industrial wastewater.

Acknowledgements

The authors are grateful for the financial support of the Natural Science Foundation of Shaanxi Province of China (2019JM-542, 2019JLM-44), the Science and Technology project of Yulin city (2019-83-4, 2019-83-1), and the High-level Talent Start-up Fund of Yulin University (20GK03).

Appendix

Calculation of RF

Electrode is made of LaF3 single crystal, and the potential measured by the electrode is linear with the logarithm of the F− concentration. To draw a standard curve, the standard solution and total ionic strength buffer solution (TISBS) are necessary. Standard solution was NaF (100 mg/L); TISBS was prepared from three reagents such as Na3C6H5O7·2H2O (12 g), NaNO3 (58 g), and C2H4O2 (58 mL); and HCl (1 mol/L) and NaOH (1 mol/L) were used to adjust the pH at 5–6. Pipette a certain volume of standard solution and TISBS, insert the electrode into the test solution, and record the potential value when the digital stable, as shown in Table A2, and the standard curve is shown in Figure A1.

Table S1

Properties of CAC

ItemDataItemData
Raw materialsApricot shellIodine number (mg/g)980
Place of productionZhengzhou/HeNan provinceMethylene blue value (mg/g)120
Moisture (%)≤5Bulk density (g/cm)0.42
Strength (%)≤90pH7
Table S2

Data record

ItemData
NaF concentration (mg/L)2468101214
Log C (−)0.300.600.780.901.01.071.15
Potential value (mv)204197189182175169163
Figure A1 Standard curve of F−.
Figure A1

Standard curve of F−.

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Received: 2020-02-26
Revised: 2020-06-03
Accepted: 2020-06-11
Published Online: 2020-08-24

© 2020 Ting Su et al., published by De Gruyter

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

Articles in the same Issue

  1. Obituary for Prof. Dr. Jun-ichi Yoshida
  2. Regular Articles
  3. Optimization of microwave-assisted manganese leaching from electrolyte manganese residue
  4. Crustacean shell bio-refining to chitin by natural deep eutectic solvents
  5. The kinetics of the extraction of caffeine from guarana seed under the action of ultrasonic field with simultaneous cooling
  6. Biocomposite scaffold preparation from hydroxyapatite extracted from waste bovine bone
  7. A simple room temperature-static bioreactor for effective synthesis of hexyl acetate
  8. Biofabrication of zinc oxide nanoparticles, characterization and cytotoxicity against pediatric leukemia cell lines
  9. Efficient synthesis of palladium nanoparticles using guar gum as stabilizer and their applications as catalyst in reduction reactions and degradation of azo dyes
  10. Isolation of biosurfactant producing bacteria from Potwar oil fields: Effect of non-fossil fuel based carbon sources
  11. Green synthesis, characterization and photocatalytic applications of silver nanoparticles using Diospyros lotus
  12. Dielectric properties and microwave heating behavior of neutral leaching residues from zinc metallurgy in the microwave field
  13. Green synthesis and stabilization of silver nanoparticles using Lysimachia foenum-graecum Hance extract and their antibacterial activity
  14. Microwave-induced heating behavior of Y-TZP ceramics under multiphysics system
  15. Synthesis and catalytic properties of nickel salts of Keggin-type heteropolyacids embedded metal-organic framework hybrid nanocatalyst
  16. Preparation and properties of hydrogel based on sawdust cellulose for environmentally friendly slow release fertilizers
  17. Structural characterization, antioxidant and cytotoxic effects of iron nanoparticles synthesized using Asphodelus aestivus Brot. aqueous extract
  18. Phase transformation involved in the reduction process of magnesium oxide in calcined dolomite by ferrosilicon with additive of aluminum
  19. Green synthesis of TiO2 nanoparticles from Syzygium cumini extract for photo-catalytic removal of lead (Pb) in explosive industrial wastewater
  20. The study on the influence of oxidation degree and temperature on the viscosity of biodiesel
  21. Prepare a catalyst consist of rare earth minerals to denitrate via NH3-SCR
  22. Bacterial nanobiotic potential
  23. Green synthesis and characterization of carboxymethyl guar gum: Application in textile printing technology
  24. Potential of adsorbents from agricultural wastes as alternative fillers in mixed matrix membrane for gas separation: A review
  25. Bactericidal and cytotoxic properties of green synthesized nanosilver using Rosmarinus officinalis leaves
  26. Synthesis of biomass-supported CuNi zero-valent nanoparticles through wetness co-impregnation method for the removal of carcinogenic dyes and nitroarene
  27. Synthesis of 2,2′-dibenzoylaminodiphenyl disulfide based on Aspen Plus simulation and the development of green synthesis processes
  28. Catalytic performance of the biosynthesized AgNps from Bistorta amplexicaule: antifungal, bactericidal, and reduction of carcinogenic 4-nitrophenol
  29. Optical and antimicrobial properties of silver nanoparticles synthesized via green route using honey
  30. Adsorption of l-α-glycerophosphocholine on ion-exchange resin: Equilibrium, kinetic, and thermodynamic studies
  31. Microwave-assisted green synthesis of silver nanoparticles using dried extracts of Chlorella vulgaris and antibacterial activity studies
  32. Preparation of graphene oxide/chitosan complex and its adsorption properties for heavy metal ions
  33. Green synthesis of metal and metal oxide nanoparticles from plant leaf extracts and their applications: A review
  34. Synthesis, characterization, and electrochemical properties of carbon nanotubes used as cathode materials for Al–air batteries from a renewable source of water hyacinth
  35. Optimization of medium–low-grade phosphorus rock carbothermal reduction process by response surface methodology
  36. The study of rod-shaped TiO2 composite material in the protection of stone cultural relics
  37. Eco-friendly synthesis of AuNPs for cutaneous wound-healing applications in nursing care after surgery
  38. Green approach in fabrication of photocatalytic, antimicrobial, and antioxidant zinc oxide nanoparticles – hydrothermal synthesis using clove hydroalcoholic extract and optimization of the process
  39. Green synthesis: Proposed mechanism and factors influencing the synthesis of platinum nanoparticles
  40. Green synthesis of 3-(1-naphthyl), 4-methyl-3-(1-naphthyl) coumarins and 3-phenylcoumarins using dual-frequency ultrasonication
  41. Optimization for removal efficiency of fluoride using La(iii)–Al(iii)-activated carbon modified by chemical route
  42. In vitro biological activity of Hydroclathrus clathratus and its use as an extracellular bioreductant for silver nanoparticle formation
  43. Evaluation of saponin-rich/poor leaf extract-mediated silver nanoparticles and their antifungal capacity
  44. Propylene carbonate synthesis from propylene oxide and CO2 over Ga-Silicate-1 catalyst
  45. Environmentally benevolent synthesis and characterization of silver nanoparticles using Olea ferruginea Royle for antibacterial and antioxidant activities
  46. Eco-synthesis and characterization of titanium nanoparticles: Testing its cytotoxicity and antibacterial effects
  47. A novel biofabrication of gold nanoparticles using Erythrina senegalensis leaf extract and their ameliorative effect on mycoplasmal pneumonia for treating lung infection in nursing care
  48. Phytosynthesis of selenium nanoparticles using the costus extract for bactericidal application against foodborne pathogens
  49. Temperature effects on electrospun chitosan nanofibers
  50. An electrochemical method to investigate the effects of compound composition on gold dissolution in thiosulfate solution
  51. Trillium govanianum Wall. Ex. Royle rhizomes extract-medicated silver nanoparticles and their antimicrobial activity
  52. In vitro bactericidal, antidiabetic, cytotoxic, anticoagulant, and hemolytic effect of green-synthesized silver nanoparticles using Allium sativum clove extract incubated at various temperatures
  53. The green synthesis of N-hydroxyethyl-substituted 1,2,3,4-tetrahydroquinolines with acidic ionic liquid as catalyst
  54. Effect of KMnO4 on catalytic combustion performance of semi-coke
  55. Removal of Congo red and malachite green from aqueous solution using heterogeneous Ag/ZnCo-ZIF catalyst in the presence of hydrogen peroxide
  56. Nucleotide-based green synthesis of lanthanide coordination polymers for tunable white-light emission
  57. Determination of life cycle GHG emission factor for paper products of Vietnam
  58. Parabolic trough solar collectors: A general overview of technology, industrial applications, energy market, modeling, and standards
  59. Structural characteristics of plant cell wall elucidated by solution-state 2D NMR spectroscopy with an optimized procedure
  60. Sustainable utilization of a converter slagging agent prepared by converter precipitator dust and oxide scale
  61. Efficacy of chitosan silver nanoparticles from shrimp-shell wastes against major mosquito vectors of public health importance
  62. Effectiveness of six different methods in green synthesis of selenium nanoparticles using propolis extract: Screening and characterization
  63. Characterizations and analysis of the antioxidant, antimicrobial, and dye reduction ability of green synthesized silver nanoparticles
  64. Foliar applications of bio-fabricated selenium nanoparticles to improve the growth of wheat plants under drought stress
  65. Green synthesis of silver nanoparticles from Valeriana jatamansi shoots extract and its antimicrobial activity
  66. Characterization and biological activities of synthesized zinc oxide nanoparticles using the extract of Acantholimon serotinum
  67. Effect of calcination temperature on rare earth tailing catalysts for catalytic methane combustion
  68. Enhanced diuretic action of furosemide by complexation with β-cyclodextrin in the presence of sodium lauryl sulfate
  69. Development of chitosan/agar-silver nanoparticles-coated paper for antibacterial application
  70. Preparation, characterization, and catalytic performance of Pd–Ni/AC bimetallic nano-catalysts
  71. Acid red G dye removal from aqueous solutions by porous ceramsite produced from solid wastes: Batch and fixed-bed studies
  72. Review Articles
  73. Recent advances in the catalytic applications of GO/rGO for green organic synthesis
https://doi.org/10.1515/gps-2020-0039
Keywords for this article
activated carbon modification; loaded with La and Al; simulation solution of fluoride; removal rate; optimum conditions
Creative Commons
BY 4.0

Articles in the same Issue

  1. Obituary for Prof. Dr. Jun-ichi Yoshida
  2. Regular Articles
  3. Optimization of microwave-assisted manganese leaching from electrolyte manganese residue
  4. Crustacean shell bio-refining to chitin by natural deep eutectic solvents
  5. The kinetics of the extraction of caffeine from guarana seed under the action of ultrasonic field with simultaneous cooling
  6. Biocomposite scaffold preparation from hydroxyapatite extracted from waste bovine bone
  7. A simple room temperature-static bioreactor for effective synthesis of hexyl acetate
  8. Biofabrication of zinc oxide nanoparticles, characterization and cytotoxicity against pediatric leukemia cell lines
  9. Efficient synthesis of palladium nanoparticles using guar gum as stabilizer and their applications as catalyst in reduction reactions and degradation of azo dyes
  10. Isolation of biosurfactant producing bacteria from Potwar oil fields: Effect of non-fossil fuel based carbon sources
  11. Green synthesis, characterization and photocatalytic applications of silver nanoparticles using Diospyros lotus
  12. Dielectric properties and microwave heating behavior of neutral leaching residues from zinc metallurgy in the microwave field
  13. Green synthesis and stabilization of silver nanoparticles using Lysimachia foenum-graecum Hance extract and their antibacterial activity
  14. Microwave-induced heating behavior of Y-TZP ceramics under multiphysics system
  15. Synthesis and catalytic properties of nickel salts of Keggin-type heteropolyacids embedded metal-organic framework hybrid nanocatalyst
  16. Preparation and properties of hydrogel based on sawdust cellulose for environmentally friendly slow release fertilizers
  17. Structural characterization, antioxidant and cytotoxic effects of iron nanoparticles synthesized using Asphodelus aestivus Brot. aqueous extract
  18. Phase transformation involved in the reduction process of magnesium oxide in calcined dolomite by ferrosilicon with additive of aluminum
  19. Green synthesis of TiO2 nanoparticles from Syzygium cumini extract for photo-catalytic removal of lead (Pb) in explosive industrial wastewater
  20. The study on the influence of oxidation degree and temperature on the viscosity of biodiesel
  21. Prepare a catalyst consist of rare earth minerals to denitrate via NH3-SCR
  22. Bacterial nanobiotic potential
  23. Green synthesis and characterization of carboxymethyl guar gum: Application in textile printing technology
  24. Potential of adsorbents from agricultural wastes as alternative fillers in mixed matrix membrane for gas separation: A review
  25. Bactericidal and cytotoxic properties of green synthesized nanosilver using Rosmarinus officinalis leaves
  26. Synthesis of biomass-supported CuNi zero-valent nanoparticles through wetness co-impregnation method for the removal of carcinogenic dyes and nitroarene
  27. Synthesis of 2,2′-dibenzoylaminodiphenyl disulfide based on Aspen Plus simulation and the development of green synthesis processes
  28. Catalytic performance of the biosynthesized AgNps from Bistorta amplexicaule: antifungal, bactericidal, and reduction of carcinogenic 4-nitrophenol
  29. Optical and antimicrobial properties of silver nanoparticles synthesized via green route using honey
  30. Adsorption of l-α-glycerophosphocholine on ion-exchange resin: Equilibrium, kinetic, and thermodynamic studies
  31. Microwave-assisted green synthesis of silver nanoparticles using dried extracts of Chlorella vulgaris and antibacterial activity studies
  32. Preparation of graphene oxide/chitosan complex and its adsorption properties for heavy metal ions
  33. Green synthesis of metal and metal oxide nanoparticles from plant leaf extracts and their applications: A review
  34. Synthesis, characterization, and electrochemical properties of carbon nanotubes used as cathode materials for Al–air batteries from a renewable source of water hyacinth
  35. Optimization of medium–low-grade phosphorus rock carbothermal reduction process by response surface methodology
  36. The study of rod-shaped TiO2 composite material in the protection of stone cultural relics
  37. Eco-friendly synthesis of AuNPs for cutaneous wound-healing applications in nursing care after surgery
  38. Green approach in fabrication of photocatalytic, antimicrobial, and antioxidant zinc oxide nanoparticles – hydrothermal synthesis using clove hydroalcoholic extract and optimization of the process
  39. Green synthesis: Proposed mechanism and factors influencing the synthesis of platinum nanoparticles
  40. Green synthesis of 3-(1-naphthyl), 4-methyl-3-(1-naphthyl) coumarins and 3-phenylcoumarins using dual-frequency ultrasonication
  41. Optimization for removal efficiency of fluoride using La(iii)–Al(iii)-activated carbon modified by chemical route
  42. In vitro biological activity of Hydroclathrus clathratus and its use as an extracellular bioreductant for silver nanoparticle formation
  43. Evaluation of saponin-rich/poor leaf extract-mediated silver nanoparticles and their antifungal capacity
  44. Propylene carbonate synthesis from propylene oxide and CO2 over Ga-Silicate-1 catalyst
  45. Environmentally benevolent synthesis and characterization of silver nanoparticles using Olea ferruginea Royle for antibacterial and antioxidant activities
  46. Eco-synthesis and characterization of titanium nanoparticles: Testing its cytotoxicity and antibacterial effects
  47. A novel biofabrication of gold nanoparticles using Erythrina senegalensis leaf extract and their ameliorative effect on mycoplasmal pneumonia for treating lung infection in nursing care
  48. Phytosynthesis of selenium nanoparticles using the costus extract for bactericidal application against foodborne pathogens
  49. Temperature effects on electrospun chitosan nanofibers
  50. An electrochemical method to investigate the effects of compound composition on gold dissolution in thiosulfate solution
  51. Trillium govanianum Wall. Ex. Royle rhizomes extract-medicated silver nanoparticles and their antimicrobial activity
  52. In vitro bactericidal, antidiabetic, cytotoxic, anticoagulant, and hemolytic effect of green-synthesized silver nanoparticles using Allium sativum clove extract incubated at various temperatures
  53. The green synthesis of N-hydroxyethyl-substituted 1,2,3,4-tetrahydroquinolines with acidic ionic liquid as catalyst
  54. Effect of KMnO4 on catalytic combustion performance of semi-coke
  55. Removal of Congo red and malachite green from aqueous solution using heterogeneous Ag/ZnCo-ZIF catalyst in the presence of hydrogen peroxide
  56. Nucleotide-based green synthesis of lanthanide coordination polymers for tunable white-light emission
  57. Determination of life cycle GHG emission factor for paper products of Vietnam
  58. Parabolic trough solar collectors: A general overview of technology, industrial applications, energy market, modeling, and standards
  59. Structural characteristics of plant cell wall elucidated by solution-state 2D NMR spectroscopy with an optimized procedure
  60. Sustainable utilization of a converter slagging agent prepared by converter precipitator dust and oxide scale
  61. Efficacy of chitosan silver nanoparticles from shrimp-shell wastes against major mosquito vectors of public health importance
  62. Effectiveness of six different methods in green synthesis of selenium nanoparticles using propolis extract: Screening and characterization
  63. Characterizations and analysis of the antioxidant, antimicrobial, and dye reduction ability of green synthesized silver nanoparticles
  64. Foliar applications of bio-fabricated selenium nanoparticles to improve the growth of wheat plants under drought stress
  65. Green synthesis of silver nanoparticles from Valeriana jatamansi shoots extract and its antimicrobial activity
  66. Characterization and biological activities of synthesized zinc oxide nanoparticles using the extract of Acantholimon serotinum
  67. Effect of calcination temperature on rare earth tailing catalysts for catalytic methane combustion
  68. Enhanced diuretic action of furosemide by complexation with β-cyclodextrin in the presence of sodium lauryl sulfate
  69. Development of chitosan/agar-silver nanoparticles-coated paper for antibacterial application
  70. Preparation, characterization, and catalytic performance of Pd–Ni/AC bimetallic nano-catalysts
  71. Acid red G dye removal from aqueous solutions by porous ceramsite produced from solid wastes: Batch and fixed-bed studies
  72. Review Articles
  73. Recent advances in the catalytic applications of GO/rGO for green organic synthesis
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