Home Production of a bioflocculant by using activated sludge and its application in Pb(II) removal from aqueous solution
Article Open Access

Production of a bioflocculant by using activated sludge and its application in Pb(II) removal from aqueous solution

  • Zibo Yan , Li Peng , Miao Deng and Jinhui Lin EMAIL logo
Published/Copyright: May 4, 2020

Abstract

In this study, the characteristics of a bioflocculant produced by using activated sludge as raw materials were investigated. The performance of this bioflocculant in the removal of Pb(II) from aqueous solution and the corresponding mechanisms were determined as well. After cultivating a bioflocculant-producing strain in an alkaline thermal pre-treatment sludge for 60 h, approximately 4.45 g of bioflocculant containing a protein backbone was harvested from 1 L of fermentation broth. This bioflocculant can remove 98.5% of Pb(II) from aqueous solutions under optimal conditions, which include a bioflocculant dosage of 6 mg/L and a CaCl2 concentration of 70 mg/L at a pH of 6.5.

1 Introduction

As economies develop, more and more heavy metal-containing wastewater is generated, and the release of these heavy metals cause serious environmental pollution and threaten human health [1]. Pb(II) is one of the most toxic heavy metals that contaminate the wastewater produced by plating, tanneries, oil refining, mining and other activities, and this ion causes many human diseases, including anemia, hepatitis, nephrite syndrome, kidney failure, and diseases of the nervous system [2, 3, 4]. Therefore, removal of Pb(II) from wastewater is necessary and urgent for the protection of human health as well as the environment.

Various of methods have been developed for the removal Pb(II) from wastewater, and the most commonly used have been precipitation, adsorption, ion-exchange, filtration, electroplating, flocculation and coagulation [5,6]. There are some significant problem when these methods are applied to the removal of Pb(II) from wastewater, such as high energy consumption and a high yield of toxic sludge [7]. The development environment friendly technologies for the removal of Pb(II) is thus of both academic and practical interest.

Flocculation has attracted significant attention because of its advantages, which include effectiveness, efficiency, stability, and wide practicability [8,9]. However, widely used chemical flocculants have been shown to cause health problems and secondary environmental pollution [10,11], which greatly restrict the wide applications of these flocculants. These limitations have become especially important in light of increasingly stringent drainage rules that have gradually emerged. Bioflocculants, both active secreted by microorganisms and released upon cell lysis, are a kind of environmentally-friendly material with the advantages of non-toxicity and biodegradability, and they have been recognized as an alternative to the use of chemical flocculants in wastewater treatment [12]. Because of all of these factors, in recent years, the use of bioflocculants has been considered to be a potential solution to environmental pollution [13].

A high production cost has long been the main obstacle to the widespread use of bioflocculants [14]; thus, the search for low-cost substrates for the production of bioflocculants by cultivated microorganisms is of great practical significance. A potential source of such substrates is waste activated sludge, which is being generated in increasing amounts by wastewater treatment plants (WWTPs) all over the world [15]; for example, approximately 9.2 million tons of waste activated sludge were produced in China in 2017 [16]. The management of waste activated sludge is one of the most serious challenges for WWTPs, as it accounts for 60% of total operational expenses [17,18]. From the perspective of resource utilization, activated sludge contains macromolecular compounds, such as polysaccharides, proteins, and cellulose, which have been proposed as sources of bioflocculants. Thus, microorganisms that can effectively utilize these substrates in activated sludge to produce bioflocculants are of academic and practical interests.

The aim of the present study was to produce a bioflocculant by using activated sludge as a raw material and to investigate the performance of the bioflocculant in the removal of Pb(II) from aqueous solutions. In the production of bioflocculants, effects of the pre-treatment of activated sludge on bioflocculant yield were determined. In addition, the composition of the bioflocculant was analyzed, and a series of experiments were performed to investigate the effects of bioflocculant dosage, pH value and contact time on the removal of Pb(II).

2 Materials and Methods

2.1 Activated sludge

Activated sludge samples were obtained from Sanwayao sewage treatment plant, Sichuan province, China. This sewage treatment plant treats approximately 50,000 m3 of domestic sewage per day by using Anaerobic-Anoxic-Oxic (A2/O) technology. Samples of sludge were collected from secondary sedimentation tanks. Prior to bioflocculant production, raw sludge samples were subjected to sterilization (ST), alkaline–thermal (ALT) and acid–thermal (ACT) treatments. Sterilization (steam sterilization) was performed 30 min at 121ºC according to [19]. ALT treatment was carried out by autoclaving at 121ºC for 30 min after adjusting the pH value of the sludge to 10 with 1 M sodium hydroxide (NaOH). In ACT treatment, the pH value of the sludge was adjusted to 2 using 1 M hydrochloric acid (HCl) prior to autoclaving for 30 min at 121ºC.

2.2 Bioflocculant production

The bioflocculant–producing strain used in the following experiments was Saccharomyces cerevisiae, purchased from the China Center for Type Culture Collection. To produce bioflocculant, the strain was inoculated in 100 mL of pre-treated activated sludge and incubated on a reciprocal shaker (SHA–A) at 150 rpm and 35ºC. After 60 h of cultivation, the fermentation broth with the flocculating components was obtained. The fermentation broth was centrifuged at 5000 rpm for 30 min to remove cells, and the supernatant with the flocculating components initially remained in this liquid form. Cold ethanol (4ºC) was added to the liquid at a volume ratio of 2:1. After precipitation for 24 h, the resulting precipitate was collected by centrifugation at 5000 rpm for 30 min. The pellet represented the crude bioflocculant [20]. The crude bioflocculant was dissolved in deionized water and purified by dialyzing overnight and was then lyophilized [21].

The total sugar of the bioflocculant was determined by the phenol–sulfuric acid method [22]. The protein of the bioflocculant was determined by the Bradford method [23]. The molecular weight of the bioflocculant was determined by gel permeation chromatography (GPC).

2.3 Pb(II) removal tests by the bioflocculant

Pb(NO3)2 (Hengxing Chemicals, China) was prepared by dilution of a 50 mg/L stock solution. Adsorption experiments were conducted to determine the effects of the bioflocculant dosage and solution pH in the presence of Ca2+ on the removal of Pb(II) from Pb(NO3)2 solutions. Before treatment, the pH of 300 mL of the above Pb(NO3)2 solution, as determined with a PHS-3C pH meter, was adjusted using 1 M NaOH or HCl. Subsequently, CaCl2 and the bioflocculant (both prepared as 1 g/L solutions) were added into the beaker in turn. Next, the mixture was vigorously stirred (300 rpm) for 1 min and slowly stirred (80 rpm) for 4 min, and then allowed to stand for 10 min using a six–breaker jar tester. Finally, the supernatant was collected and the residual Pb(II) was determined. The removal efficiency (RE) and removal capacity of Pb(II) were calculated as follows:

(1)RE%=C0Ce/C0×100
(2)Removalcapacity=C0CeV/WR

Where C0 and Ce were the initial and equilibrium Pb(II) concentrations (mg/L), respectively. V was the volume of the Pb(NO3)2 solution (L), and WR was the weight of the bioflocculant used (g).

All of the measurements in this study were carried out in triplicate.

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

3 Results and discussion

3.1 Bioflocculant production

Although a single sample of sludge was used to produce the input for bioflocculant production by a single strain, various pre-treatments of the sludge led to distinct bioflocculant yields. As seen in Figure 1, in this study, 4.45, 2.58 and 0.76 g of purified bioflocculant were harvested per L of fermentation broth of ALT, ST and ACT sludge, respectively. All of these yields from pre-treated sludge were higher than that harvested from raw sludge (0.12 g/L). The variations in bioflocculant yields from different fermented broths were attributed to the specific chemical/ physical changes induced by different treatments of the treated sludge [24].

Figure 1 Effects of sludge pre-treatment on bioflocculant yield. [Error bars refer to standard deviation (3 replicates for each treatment)].
Figure 1

Effects of sludge pre-treatment on bioflocculant yield. [Error bars refer to standard deviation (3 replicates for each treatment)].

Generally, treatment of sludge results in decomposition of organic components (including proteins and polysaccharides) of the material and the release of soluble carbon, and this soluble carbon is more suitable for utilization by microorganisms for bioflocculant production [25]. In this study, we found that bioflocculant yields following different pre-treatments were increased compared with that from the raw sludge, which might be explained by increases of soluble carbon levels that occurred regardless of the treatment method. The bioflocculant yield from the ALT sludge was the highest, meaning that the increase in soluble carbon likely was the highest in this case. Chen et al. [26] reported that under alkaline conditions, the soluble chemical oxygen demand and other low molecular weight soluble carbons were increased by sludge sterilization, and that these factors reached higher levels relative to acid treatment. Sun et al. [27] similarly concluded that sludge solubilization significantly increased with alkaline treatment and to a lesser extent by acid treatment. Aravinthan et al. [28] reported that mostly proteins of the sludge were solubilized by alkaline treatment whereas carbohydrate portions of the sludge preferentially solubilized by acid treatment. The carbon sources, nitrogenous organic materials, and nature of nutrients available in the medium change with the type of treatment and therefore can change bioflocculant secretion patterns and correspondingly the bioflocculant yields [29].

3.2 Characteristics of the bioflocculant

It has been reported that protein-dependent bioflocculants are sensitive to heat, while those whose active ingredient is polysaccharide are thermostable. These results might be explained by the fact that proteins can be denatured under hot conditions [25]. In the present work, the fermentation broth, which contains the flocculating components, from ALT-pretreated sludge was divided into 12 equal parts and separately treated at increasing temperatures over the range 10-120ºC for 30 min, after which the flocculating activities towards a kaolin suspension (4 g/L) were measured according to the method reported by [19].

Results (Table 1) showed that more than 90% of the flocculating activities of the fermentation broth were retained when the temperature was lower than 60ºC. However, when the temperature was adjusted to 90ºC, the flocculating activity declined to about 50%, which was further decreased to approximately 10% upon pretreatment at 120ºC (Table 1). The poor heat stability indicated that the bioflocculant produced when ALT-pretreated sludge is used as a precursor may have protein as a primary component. These results are consistent with those found by [19,25].

Table 1

Thermal stability of the bioflocculant harvested from ALT sludge.

Temperature (°C)102030405060708090100110120
Flocculating rate (%)76.788.595.392.791.288.672.464.851.537.622.812.3

Chemical analyses showed that the protein content of the bioflocculant was 94.7% (w/w), while the polysaccharide content was 5.2% (w/w). The molecular weight of the bioflocculant was 4.24×105 Da. Notably, other researchers have found that flocculant activity increases with increasing molecular weight [27].

3.3 Treatment of Pb(II) aqueous solution by the bioflocculant

Figure2 depicts the effects of bioflocculant dosage on the removal of Pb(II) without adjustment of the pH of the solution. In the presence of 50 mg/L CaCl2, the removal efficiency of Pb(II) increased rapidly with increasing bioflocculant dosages from 0 to 6 mg/L. The maximum removal efficiency of 92.5% was obtained at the optimum bioflocculant dosage of 6 mg/L, and the corresponding removal capacity of Pb(II) by the bioflocculant was 77.1 mg/g. However, increasing the bioflocculant dosage above 6 mg/L had negligible effects on the increase in Pb(II) removal, which might be explained by the formation of aggregates at higher solid/liquid ratios or to precipitation of particles [4].

Figure 2 Effects of bioflocculant dosage on the removal of Pb(II) from aqueous solution. [Error bars refer to standard deviation (3 replicates for each treatment)].
Figure 2

Effects of bioflocculant dosage on the removal of Pb(II) from aqueous solution. [Error bars refer to standard deviation (3 replicates for each treatment)].

To determine the role of CaCl2 in Pb(II) removal by the bioflocculant, the effect of CaCl2 was investigated by adding different mass fractions of CaCl2 and 6 mg/L of the bioflocculant into 1L of 50 mg/L Pb(NO3)2 solutions without adjustment of the pH of the solutions. It can be seen from Figure3 that the removal efficiency of Pb(II) was relatively low (36.3%) without the addition of CaCl2, but that the removal efficiency increased rapidly with increasing CaCl2. The maximum value of 97.6% appeared when the CaCl2 concentration was 70 mg/L, and the corresponding removal capacity of Pb(II) by the bioflocculant under this condition was 81.3 mg/g. Feng et al. [4] reported that the Ca2+ might increase the initial adsorption capacity of a bioflocculant by decreasing its negative charge. However, excessive Ca2+ (>70 mg/L) had negative effects on the Pb(II) removal efficiency, which may be due to competition between the Pb(II) and excess Ca2+ for the key functional groups of the bioflocculant such as –OH and –COO- [5].

Figure 3 Effects of CaCl2 dosage on the removal of Pb(II) from aqueous solution. [Error bars refer to standard deviation (3 replicates for each treatment)].
Figure 3

Effects of CaCl2 dosage on the removal of Pb(II) from aqueous solution. [Error bars refer to standard deviation (3 replicates for each treatment)].

The effects of solution pH value on the removal of Pb(II) by the bioflocculant were examined after 6 mg/L of bioflocculant and 70 mg/L of CaCl2 were added into 1 L of Pb(NO3)2 solution. The pH values of the solutions were adjusted in the range of 2.5-7.5 to avoid the precipitation of Pb(II) in alkaline condition. As seen in Figure4, at pH 6.5, the removal efficiency of Pb(II) increased gradually and peaked at 98.5%, and at this pH, the corresponding removal capacity of Pb(II) by the bioflocculant was 50 mg/g. A similar optimal pH of 6 for Pb(II) removal has been reported by [5]. At low pH, the removal of Pb(II) was not optimal, likely because of competition for the functional groups of the bioflocculant between hydrogen ions (H+) and Pb(II) [30].

Figure 4 Effects of solution pH value on the removal of Pb(II) from aqueous solution. [Error bars refer to standard deviation (3 replicates for each treatment)].
Figure 4

Effects of solution pH value on the removal of Pb(II) from aqueous solution. [Error bars refer to standard deviation (3 replicates for each treatment)].

4 Conclusions

This study demonstrates the successful production of a bioflocculant from activated sludge; after cultivation of the microorganism in ALT-sludge for 60 h, a relatively high yield of 4.45 g of protein-based bioflocculant was obtained per L of broth. This bioflocculant was most effective in the removal of Pb(II) from aqueous solution at pH 6.5, and the maximum removal efficiency of Pb(II) and the corresponding removal capacity were 98.5% and 82.1 mg/g. In conclusion, bioflocculants may be a feasible way to remove Pb(II) from wastewaters.

Acknowledgment

The authors would like to acknowledge the financially support for this study from the Plan Program for Science and Technology of Sichuan province Deyang city (No: 2014ZZ052).

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

References

[1] Schneegurt MA, Jain JC, Menicucci JA, Brown SA, Kemner KM, Garofalo DF, et al. Biomass byproducts for the remediation of wastewaters contaminated with toxic metals. Environ Sci Technol. 2001; 35(8): 3786-91.10.1021/es010766eSearch in Google Scholar PubMed

[2] Li F, Zhang JD, Jiang W, Liu CY, Zhang ZM, Zhang CD, et al. Spatial health risk assessment and hierarchical risk management for mercury in soils from a typical contaminated site, China. Environ Geochem Health. 2017; 39: 923-34.10.1007/s10653-016-9864-7Search in Google Scholar PubMed

[3] Li F, Zhang JD, Liu CY, Xiao M, Wu Z. Distribution, bioavailability and probabilistic integrated ecological risk assessment of heavy metals in sediments from Honghu Lake, China. Process Saf Environ Prot. 2018; 116: 169-79.10.1016/j.psep.2018.02.007Search in Google Scholar

[4] Feng J, Yang ZH, Zeng GM, Huang J, Xu HY, Zhang YY, et al. The adsorption behavior and mechanism investigation of Pb(II) removal by flocculation using microbial flocculant GA1. Bioresour Technol. 2013; 148: 414-21.10.1016/j.biortech.2013.09.011Search in Google Scholar PubMed

[5] Guo JY, Yu J. Sorption characteristics and mechanisms of Pb(II) from aqueous solution by using bioflocculant MBFR10543. App Microbiol Biotechnol. 2014; 98: 6431-41.10.1007/s00253-014-5681-zSearch in Google Scholar PubMed

[6] Karatas M. Removal of Pb(II) from water by natural zeolitic tuff: kinetics and thermodynamics. J Hazard Mater. 2012; 199-200: 383-9.10.1016/j.jhazmat.2011.11.035Search in Google Scholar PubMed

[7] Chakravarty S, Mohanty A, Sudha TN, Upadhyay AK, Konar J, Sircar JK, et al. Removal of Pb(II) ions from aqueous solution by adsorption using bael leaves Aegle marmelos J Hazard Mater. 2010; 173(1-3): 502-9.10.1016/j.jhazmat.2009.08.113Search in Google Scholar PubMed

[8] Aljuboori AH, Idris A, Al-Joubory HH, Uemura Y, Ibn Abubakar BS. Flocculation behavior and mechanism of bioflocculant produced by Aspergillus flavus. J Environ Manage. 2015; 150: 466-71.10.1016/j.jenvman.2014.12.035Search in Google Scholar PubMed

[9] Guo JY, Chen C. Sludge conditioning using the composite of a bioflocculant and PAC for enhancement in dewaterability. Chemosphere. 2017; 185: 277-83.10.1016/j.chemosphere.2017.06.111Search in Google Scholar PubMed

[10] Guo, JY, Chen C, Jiang SL, Zhou YL. Feasibility and mechanism of combined conditioning with coagulant and flocculant to enhance sludge dewatering. ACS Sustain Chem Eng. 2018; 6(8): 10758-65.10.1021/acssuschemeng.8b02086Search in Google Scholar

[11] Okaiyeto K, Nwodo UU, Leonard VM, Arinze SO, Anthony IO. Characterization of a bioflocculant (MBF-UFH) produced by Bacillus sp. AEMREG7. Int J Mol Sci. 2015; 16(6): 12986-3003.10.3390/ijms160612986Search in Google Scholar PubMed PubMed Central

[12] Cao G, Zhang Y. Production of a bioflocculant from methanol wastewater and its application in arsenite removal. Chemosphere. 2015; 141: 274-81.10.1016/j.chemosphere.2015.08.009Search in Google Scholar PubMed

[13] Wang L, Ma F, Lee DJ, Wang AJ, Ren NQ. Bioflocculants from hydrolysates of corn stover using isolated strain Ochrobactrum ciceri W2. Bioresour Technol. 2013; 145: 259-63.10.1016/j.biortech.2012.11.020Search in Google Scholar PubMed

[14] Giri SS, Harshiny M, Sen SS, Sukumaran V, Park SC. Production and characterization of a thermostable bioflocculant from Bacillus subtilis F9, isolated from wastewater sludge. Ecotox Environ Safe.2015; 121: 45-50.10.1016/j.ecoenv.2015.06.010Search in Google Scholar PubMed

[15] Guo JY, Jiang SL, Pang YJ. Rice straw biochar modified by aluminum chloride enhances the dewatering of the sludge from municipal sewage treatment plant. Sci Total Environ. 2019; 654: 338-44.10.1016/j.scitotenv.2018.10.429Search in Google Scholar PubMed

[16] Liu CG. Enhancement of dewaterability and heavy metals solubilization of waste activated sludge conditioned by natural vanadium-titanium magnetite-activated peroxymonosulfate oxidation with rice husk. Chem Eng J. 2019; 359: 217-24.10.1016/j.cej.2018.11.139Search in Google Scholar

[17] Guo JY, Zhou YL. Transformation of heavy metals and dewaterability of waste activated sludge during the conditioning by Fe2+ -activated peroxymonosulfate oxidation combined with rice straw biochar as skeleton builder. https://doi.org/10.1016/j.chemosphere.2019.12462810.1016/j.chemosphere.2019.124628Search in Google Scholar PubMed

[18] Liu CG, Lai LD, Yang X. Sewage sludge conditioning by Fe(II)-activated persulphate oxidation combined with skeleton builders for enhancing dewaterability. Water Environ J. 2016; 30: 96-101.10.1111/wej.12167Search in Google Scholar

[19] Guo JY, Yang CP, Peng LY. Preparation and characteristics of bacterial polymer using pre-treated sludge from swine wastewater treatment plant. Bioresour Technol. 2014; 152: 490-8.10.1016/j.biortech.2013.11.037Search in Google Scholar PubMed

[20] Pu SY, Qin LL, Che JP, Zhang BR, Xu M. Preparation and application of a novel bioflocculant by two strains of Rhizopus sp. using potato starch wastewater as nutrilite. Bioresour Technol. 2014; 162: 184-91.10.1016/j.biortech.2014.03.124Search in Google Scholar PubMed

[21] Liu WJ, Wang K, Li BZ, Yuan HL, Yang JS. Production and characterization of an intracellular bioflocculant by Chryseobacterium daeguense W6 cultured in low nutrition medium. Bioresour Technol. 2010; 101: 1044-8.10.1016/j.biortech.2009.08.108Search in Google Scholar

[22] Chaplin MF, Kennedy JF. Carbohydrate Analysis, second Ed, Oxford University Press, New York. 1994.Search in Google Scholar

[23] Bradford MM. A rapid and sensitive method for the quantization of microgram quantities of protein utilizing the principle of protein–dye binding. Anal Biochem. 1976; 72(1-2): 248-54.10.1016/0003-2697(76)90527-3Search in Google Scholar

[24] More TT, Yan S, Hoang NV, Tyagi RD, Surampalli RY. Bacterial polymer production using pre-treated sludge as raw material and its flocculation and dewatering potential. Bioresour Technol. 2012; 121: 425-31.10.1016/j.biortech.2012.06.075Search in Google Scholar PubMed

[25] Gong WX, Wang SG, Sun XF, Liu X.W, Yue QY, Gao BY. Bioflocculant production by culture of serratia ficaria and its application in wastewater treatment. Bioresour Technol. 2008; 99: 4668-74.10.1016/j.biortech.2007.09.077Search in Google Scholar PubMed

[26] Chen Y, Jiang S, Yuan H, Zhou Q, Gu G. Hydrolysis and acidification of waste activated sludge at different pHs. Water Res. 2007; 41(3): 683-9.10.1016/j.watres.2006.07.030Search in Google Scholar PubMed

[27] Sun J, Zhang XH, Miao XJ, Zhou JT. Preparation and characteristics of bioflocculants from excess biological sludge. Bioresour Technol. 2012; 126: 362-6.10.1016/j.biortech.2012.08.042Search in Google Scholar PubMed

[28] Aravinthan V, Mino T, Takizawa S, Satoh H, Matsuo T. Sludge hydrolysate as a carbon source for denitrification. Water Sci Technol. 2001; 43: 191-9.10.2166/wst.2001.0047Search in Google Scholar

[29] Jorand F, Guicherd P, Urbain V, Manem J, Block JC. Hydrophobicity of activated sludge flocs and laboratory–grown bacteria. Water Sci Technol. 1994; 30(11): 211-8.10.2166/wst.1994.0561Search in Google Scholar

[30] Huang W, Liu ZM. Biosorption of Cd(II)/Pb(II) from aqueous solution by biosurfactant-producing bacteria: Isotherm kinetic characteristic and mechanism studies. Colloid Surface B. 2013; 105: 113-9.10.1016/j.colsurfb.2012.12.040Search in Google Scholar PubMed

Received: 2019-08-08
Accepted: 2019-12-13
Published Online: 2020-05-04

© 2020 Zibo Yan 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. Regular Articles
  2. Electrochemical antioxidant screening and evaluation based on guanine and chitosan immobilized MoS2 nanosheet modified glassy carbon electrode (guanine/CS/MoS2/GCE)
  3. Kinetic models of the extraction of vanillic acid from pumpkin seeds
  4. On the maximum ABC index of bipartite graphs without pendent vertices
  5. Estimation of the total antioxidant potential in the meat samples using thin-layer chromatography
  6. Molecular dynamics simulation of sI methane hydrate under compression and tension
  7. Spatial distribution and potential ecological risk assessment of some trace elements in sediments and grey mangrove (Avicennia marina) along the Arabian Gulf coast, Saudi Arabia
  8. Amino-functionalized graphene oxide for Cr(VI), Cu(II), Pb(II) and Cd(II) removal from industrial wastewater
  9. Chemical composition and in vitro activity of Origanum vulgare L., Satureja hortensis L., Thymus serpyllum L. and Thymus vulgaris L. essential oils towards oral isolates of Candida albicans and Candida glabrata
  10. Effect of excess Fluoride consumption on Urine-Serum Fluorides, Dental state and Thyroid Hormones among children in “Talab Sarai” Punjab Pakistan
  11. Design, Synthesis and Characterization of Novel Isoxazole Tagged Indole Hybrid Compounds
  12. Comparison of kinetic and enzymatic properties of intracellular phosphoserine aminotransferases from alkaliphilic and neutralophilic bacteria
  13. Green Organic Solvent-Free Oxidation of Alkylarenes with tert-Butyl Hydroperoxide Catalyzed by Water-Soluble Copper Complex
  14. Ducrosia ismaelis Asch. essential oil: chemical composition profile and anticancer, antimicrobial and antioxidant potential assessment
  15. DFT calculations as an efficient tool for prediction of Raman and infra-red spectra and activities of newly synthesized cathinones
  16. Influence of Chemical Osmosis on Solute Transport and Fluid Velocity in Clay Soils
  17. A New fatty acid and some triterpenoids from propolis of Nkambe (North-West Region, Cameroon) and evaluation of the antiradical scavenging activity of their extracts
  18. Antiplasmodial Activity of Stigmastane Steroids from Dryobalanops oblongifolia Stem Bark
  19. Rapid identification of direct-acting pancreatic protectants from Cyclocarya paliurus leaves tea by the method of serum pharmacochemistry combined with target cell extraction
  20. Immobilization of Pseudomonas aeruginosa static biomass on eggshell powder for on-line preconcentration and determination of Cr (VI)
  21. Assessment of methyl 2-({[(4,6-dimethoxypyrimidin-2-yl)carbamoyl] sulfamoyl}methyl)benzoate through biotic and abiotic degradation modes
  22. Stability of natural polyphenol fisetin in eye drops Stability of fisetin in eye drops
  23. Production of a bioflocculant by using activated sludge and its application in Pb(II) removal from aqueous solution
  24. Molecular Properties of Carbon Crystal Cubic Structures
  25. Synthesis and characterization of calcium carbonate whisker from yellow phosphorus slag
  26. Study on the interaction between catechin and cholesterol by the density functional theory
  27. Analysis of some pharmaceuticals in the presence of their synthetic impurities by applying hybrid micelle liquid chromatography
  28. Two mixed-ligand coordination polymers based on 2,5-thiophenedicarboxylic acid and flexible N-donor ligands: the protective effect on periodontitis via reducing the release of IL-1β and TNF-α
  29. Incorporation of silver stearate nanoparticles in methacrylate polymeric monoliths for hemeprotein isolation
  30. Development of ultrasound-assisted dispersive solid-phase microextraction based on mesoporous carbon coated with silica@iron oxide nanocomposite for preconcentration of Te and Tl in natural water systems
  31. N,N′-Bis[2-hydroxynaphthylidene]/[2-methoxybenzylidene]amino]oxamides and their divalent manganese complexes: Isolation, spectral characterization, morphology, antibacterial and cytotoxicity against leukemia cells
  32. Determination of the content of selected trace elements in Polish commercial fruit juices and health risk assessment
  33. Diorganotin(iv) benzyldithiocarbamate complexes: synthesis, characterization, and thermal and cytotoxicity study
  34. Keratin 17 is induced in prurigo nodularis lesions
  35. Anticancer, antioxidant, and acute toxicity studies of a Saudi polyherbal formulation, PHF5
  36. LaCoO3 perovskite-type catalysts in syngas conversion
  37. Comparative studies of two vegetal extracts from Stokesia laevis and Geranium pratense: polyphenol profile, cytotoxic effect and antiproliferative activity
  38. Fragmentation pattern of certain isatin–indole antiproliferative conjugates with application to identify their in vitro metabolic profiles in rat liver microsomes by liquid chromatography tandem mass spectrometry
  39. Investigation of polyphenol profile, antioxidant activity and hepatoprotective potential of Aconogonon alpinum (All.) Schur roots
  40. Lead discovery of a guanidinyl tryptophan derivative on amyloid cascade inhibition
  41. Physicochemical evaluation of the fruit pulp of Opuntia spp growing in the Mediterranean area under hard climate conditions
  42. Electronic structural properties of amino/hydroxyl functionalized imidazolium-based bromide ionic liquids
  43. New Schiff bases of 2-(quinolin-8-yloxy)acetohydrazide and their Cu(ii), and Zn(ii) metal complexes: their in vitro antimicrobial potentials and in silico physicochemical and pharmacokinetics properties
  44. Treatment of adhesions after Achilles tendon injury using focused ultrasound with targeted bFGF plasmid-loaded cationic microbubbles
  45. Synthesis of orotic acid derivatives and their effects on stem cell proliferation
  46. Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis
  47. Fe3O4@urea/HITh-SO3H as an efficient and reusable catalyst for the solvent-free synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives
  48. Adsorption kinetic characteristics of molybdenum in yellow-brown soil in response to pH and phosphate
  49. Enhancement of thermal properties of bio-based microcapsules intended for textile applications
  50. Exploring the effect of khat (Catha edulis) chewing on the pharmacokinetics of the antiplatelet drug clopidogrel in rats using the newly developed LC-MS/MS technique
  51. A green strategy for obtaining anthraquinones from Rheum tanguticum by subcritical water
  52. Cadmium (Cd) chloride affects the nutrient uptake and Cd-resistant bacterium reduces the adsorption of Cd in muskmelon plants
  53. Removal of H2S by vermicompost biofilter and analysis on bacterial community
  54. Structural cytotoxicity relationship of 2-phenoxy(thiomethyl)pyridotriazolopyrimidines: Quantum chemical calculations and statistical analysis
  55. A self-breaking supramolecular plugging system as lost circulation material in oilfield
  56. Synthesis, characterization, and pharmacological evaluation of thiourea derivatives
  57. Application of drug–metal ion interaction principle in conductometric determination of imatinib, sorafenib, gefitinib and bosutinib
  58. Synthesis and characterization of a novel chitosan-grafted-polyorthoethylaniline biocomposite and utilization for dye removal from water
  59. Optimisation of urine sample preparation for shotgun proteomics
  60. DFT investigations on arylsulphonyl pyrazole derivatives as potential ligands of selected kinases
  61. Treatment of Parkinson’s disease using focused ultrasound with GDNF retrovirus-loaded microbubbles to open the blood–brain barrier
  62. New derivatives of a natural nordentatin
  63. Fluorescence biomarkers of malignant melanoma detectable in urine
  64. Study of the remediation effects of passivation materials on Pb-contaminated soil
  65. Saliva proteomic analysis reveals possible biomarkers of renal cell carcinoma
  66. Withania frutescens: Chemical characterization, analgesic, anti-inflammatory, and healing activities
  67. Design, synthesis and pharmacological profile of (−)-verbenone hydrazones
  68. Synthesis of magnesium carbonate hydrate from natural talc
  69. Stability-indicating HPLC-DAD assay for simultaneous quantification of hydrocortisone 21 acetate, dexamethasone, and fluocinolone acetonide in cosmetics
  70. A novel lactose biosensor based on electrochemically synthesized 3,4-ethylenedioxythiophene/thiophene (EDOT/Th) copolymer
  71. Citrullus colocynthis (L.) Schrad: Chemical characterization, scavenging and cytotoxic activities
  72. Development and validation of a high performance liquid chromatography/diode array detection method for estrogen determination: Application to residual analysis in meat products
  73. PCSK9 concentrations in different stages of subclinical atherosclerosis and their relationship with inflammation
  74. Development of trace analysis for alkyl methanesulfonates in the delgocitinib drug substance using GC-FID and liquid–liquid extraction with ionic liquid
  75. Electrochemical evaluation of the antioxidant capacity of natural compounds on glassy carbon electrode modified with guanine-, polythionine-, and nitrogen-doped graphene
  76. A Dy(iii)–organic framework as a fluorescent probe for highly selective detection of picric acid and treatment activity on human lung cancer cells
  77. A Zn(ii)–organic cage with semirigid ligand for solvent-free cyanosilylation and inhibitory effect on ovarian cancer cell migration and invasion ability via regulating mi-RNA16 expression
  78. Polyphenol content and antioxidant activities of Prunus padus L. and Prunus serotina L. leaves: Electrochemical and spectrophotometric approach and their antimicrobial properties
  79. The combined use of GC, PDSC and FT-IR techniques to characterize fat extracted from commercial complete dry pet food for adult cats
  80. MALDI-TOF MS profiling in the discovery and identification of salivary proteomic patterns of temporomandibular joint disorders
  81. Concentrations of dioxins, furans and dioxin-like PCBs in natural animal feed additives
  82. Structure and some physicochemical and functional properties of water treated under ammonia with low-temperature low-pressure glow plasma of low frequency
  83. Mesoscale nanoparticles encapsulated with emodin for targeting antifibrosis in animal models
  84. Amine-functionalized magnetic activated carbon as an adsorbent for preconcentration and determination of acidic drugs in environmental water samples using HPLC-DAD
  85. Antioxidant activity as a response to cadmium pollution in three durum wheat genotypes differing in salt-tolerance
  86. A promising naphthoquinone [8-hydroxy-2-(2-thienylcarbonyl)naphtho[2,3-b]thiophene-4,9-dione] exerts anti-colorectal cancer activity through ferroptosis and inhibition of MAPK signaling pathway based on RNA sequencing
  87. Synthesis and efficacy of herbicidal ionic liquids with chlorsulfuron as the anion
  88. Effect of isovalent substitution on the crystal structure and properties of two-slab indates BaLa2−xSmxIn2O7
  89. Synthesis, spectral and thermo-kinetics explorations of Schiff-base derived metal complexes
  90. An improved reduction method for phase stability testing in the single-phase region
  91. Comparative analysis of chemical composition of some commercially important fishes with an emphasis on various Malaysian diets
  92. Development of a solventless stir bar sorptive extraction/thermal desorption large volume injection capillary gas chromatographic-mass spectrometric method for ultra-trace determination of pyrethroids pesticides in river and tap water samples
  93. A turbidity sensor development based on NL-PI observers: Experimental application to the control of a Sinaloa’s River Spirulina maxima cultivation
  94. Deep desulfurization of sintering flue gas in iron and steel works based on low-temperature oxidation
  95. Investigations of metallic elements and phenolics in Chinese medicinal plants
  96. Influence of site-classification approach on geochemical background values
  97. Effects of ageing on the surface characteristics and Cu(ii) adsorption behaviour of rice husk biochar in soil
  98. Adsorption and sugarcane-bagasse-derived activated carbon-based mitigation of 1-[2-(2-chloroethoxy)phenyl]sulfonyl-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl) urea-contaminated soils
  99. Antimicrobial and antifungal activities of bifunctional cooper(ii) complexes with non-steroidal anti-inflammatory drugs, flufenamic, mefenamic and tolfenamic acids and 1,10-phenanthroline
  100. Application of selenium and silicon to alleviate short-term drought stress in French marigold (Tagetes patula L.) as a model plant species
  101. Screening and analysis of xanthine oxidase inhibitors in jute leaves and their protective effects against hydrogen peroxide-induced oxidative stress in cells
  102. Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease
  103. A study of in vitro metabolism and cytotoxicity of mephedrone and methoxetamine in human and pig liver models using GC/MS and LC/MS analyses
  104. A new phenyl alkyl ester and a new combretin triterpene derivative from Combretum fragrans F. Hoffm (Combretaceae) and antiproliferative activity
  105. Erratum
  106. Erratum to: A one-step incubation ELISA kit for rapid determination of dibutyl phthalate in water, beverage and liquor
  107. Review Articles
  108. Sinoporphyrin sodium, a novel sensitizer for photodynamic and sonodynamic therapy
  109. Natural products isolated from Casimiroa
  110. Plant description, phytochemical constituents and bioactivities of Syzygium genus: A review
  111. Evaluation of elastomeric heat shielding materials as insulators for solid propellant rocket motors: A short review
  112. Special Issue on Applied Biochemistry and Biotechnology 2019
  113. An overview of Monascus fermentation processes for monacolin K production
  114. Study on online soft sensor method of total sugar content in chlorotetracycline fermentation tank
  115. Studies on the Anti-Gouty Arthritis and Anti-hyperuricemia Properties of Astilbin in Animal Models
  116. Effects of organic fertilizer on water use, photosynthetic characteristics, and fruit quality of pear jujube in northern Shaanxi
  117. Characteristics of the root exudate release system of typical plants in plateau lakeside wetland under phosphorus stress conditions
  118. Characterization of soil water by the means of hydrogen and oxygen isotope ratio at dry-wet season under different soil layers in the dry-hot valley of Jinsha River
  119. Composition and diurnal variation of floral scent emission in Rosa rugosa Thunb. and Tulipa gesneriana L.
  120. Preparation of a novel ginkgolide B niosomal composite drug
  121. The degradation, biodegradability and toxicity evaluation of sulfamethazine antibiotics by gamma radiation
  122. Special issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  123. Insight into the cadmium and zinc binding potential of humic acids derived from composts by EEM spectra combined with PARAFAC analysis
  124. Source apportionment of soil contamination based on multivariate receptor and robust geostatistics in a typical rural–urban area, Wuhan city, middle China
  125. Special Issue on 13th JCC 2018
  126. The Role of H2C2O4 and Na2CO3 as Precipitating Agents on The Physichochemical Properties and Photocatalytic Activity of Bismuth Oxide
  127. Preparation of magnetite-silica–cetyltrimethylammonium for phenol removal based on adsolubilization
  128. Topical Issue on Agriculture
  129. Size-dependent growth kinetics of struvite crystals in wastewater with calcium ions
  130. The effect of silica-calcite sedimentary rock contained in the chicken broiler diet on the overall quality of chicken muscles
  131. Physicochemical properties of selected herbicidal products containing nicosulfuron as an active ingredient
  132. Lycopene in tomatoes and tomato products
  133. Fluorescence in the assessment of the share of a key component in the mixing of feed
  134. Sulfur application alleviates chromium stress in maize and wheat
  135. Effectiveness of removal of sulphur compounds from the air after 3 years of biofiltration with a mixture of compost soil, peat, coconut fibre and oak bark
  136. Special Issue on the 4th Green Chemistry 2018
  137. Study and fire test of banana fibre reinforced composites with flame retardance properties
  138. Special Issue on the International conference CosCI 2018
  139. Disintegration, In vitro Dissolution, and Drug Release Kinetics Profiles of k-Carrageenan-based Nutraceutical Hard-shell Capsules Containing Salicylamide
  140. Synthesis of amorphous aluminosilicate from impure Indonesian kaolin
  141. Special Issue on the International Conf on Science, Applied Science, Teaching and Education 2019
  142. Functionalization of Congo red dye as a light harvester on solar cell
  143. The effect of nitrite food preservatives added to se’i meat on the expression of wild-type p53 protein
  144. Biocompatibility and osteoconductivity of scaffold porous composite collagen–hydroxyapatite based coral for bone regeneration
  145. Special Issue on the Joint Science Congress of Materials and Polymers (ISCMP 2019)
  146. Effect of natural boron mineral use on the essential oil ratio and components of Musk Sage (Salvia sclarea L.)
  147. A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent
  148. A study on the bacterial adhesion of Streptococcus mutans in various dental ceramics: In vitro study
  149. Corrosion study of copper in aqueous sulfuric acid solution in the presence of (2E,5E)-2,5-dibenzylidenecyclopentanone and (2E,5E)-bis[(4-dimethylamino)benzylidene]cyclopentanone: Experimental and theoretical study
  150. Special Issue on Chemistry Today for Tomorrow 2019
  151. Diabetes mellitus type 2: Exploratory data analysis based on clinical reading
  152. Multivariate analysis for the classification of copper–lead and copper–zinc glasses
  153. Special Issue on Advances in Chemistry and Polymers
  154. The spatial and temporal distribution of cationic and anionic radicals in early embryo implantation
  155. Special Issue on 3rd IC3PE 2020
  156. Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications
  157. Special Issue on IC3PE 2018/2019 Conference
  158. Exergy analysis of conventional and hydrothermal liquefaction–esterification processes of microalgae for biodiesel production
  159. Advancing biodiesel production from microalgae Spirulina sp. by a simultaneous extraction–transesterification process using palm oil as a co-solvent of methanol
  160. Topical Issue on Applications of Mathematics in Chemistry
  161. Omega and the related counting polynomials of some chemical structures
  162. M-polynomial and topological indices of zigzag edge coronoid fused by starphene
Downloaded on 10.9.2025 from https://www.degruyterbrill.com/document/doi/10.1515/chem-2020-0024/html
Scroll to top button