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The present study describes the facile synthesis of graphene oxide (GO) and GO/carboxymethyl tamarind kernel gum (CMTKG)-based hydrogel composite. The synthesized GO/CMTKG/PAM hydrogel composite was applied as an adsorbent for the selective sequestration of toxic crystal violet (CV) and methylene blue (MB) from an aqueous medium. The impact of various controlling parameters such as contact time, pH, concentration, adsorbent dosage. and temperature was studied. The experimental data obtained from the isotherm and kinetics modeling showed a good correlation with the Langmuir isotherm and pseudo-second-order kinetics model, respectively. The optimized concentration of dye was 40 mg [L.sup.-1] for CV and 20 mg [L.sup.-1] for MB, and the adsorption capacity ([q.sub.max]) was calculated to be 111 mg [g.sup.-1] for CV dye and 25 mg [g.sup.-1] for MB dye. The synthesized adsorbent exhibits excellent recyclability for dye uptake after six consecutive cycles. Furthermore, the simultaneous adsorption of CV and MB from the binary system was carried out to ascertain the utility of the adsorbent in a wide range of adsorption systems. The adsorbent was also found to act as a proficient adsorbent in various water samples. These results demonstrated that synthesized hydrogel can be successfully applied as an adsorbent for the sequestration of dye effluents in real-time applications. Highlights * Hydrogel composite was successfully synthesized via a free radical mechanism. * It is an efficient adsorbent for removing cationic dyes from aqueous solutions. * It shows selectivity towards cationic dyes and works in a binary mixture of cationic dyes. * It shows good removal efficacy in different water samples, including real wastewater samples. * It also shows proficient removal efficacy after six consecutive regeneration cycles. KEYWORDS adsorption, cationic dyes, CMTKG, GO, hydrogel composite, water treatment, 1 | INTRODUCTION Water makes up more than 71% of our planet, but less than 3% is fit for consumption. As a result, many regions of the world face a [...]

This study investigates the development and characterization of chitosan, gelatin, and chitosan/gelatin (Chi/Gel) bioaerogel composites through a facile and eco-friendly approach. The goal is to optimize their structural and functional properties for potential environmental and biomedical applications. Direct freezing and lyophilization approach were used to prepare the aerogels, the focus was on investigating the effects of blending ratios on the density, porosity, surface area, and water absorption capabilities of the aerogels. The results show that Chi/Gel 60/40 composition achieved an optimal balance of structural robustness and functional performance, characterized by a moderate density of 74.2 mg/[cm.sup.3], the highest porosity among the samples at 93.5%, an impressive surface area of 184.8 [m.sup.2]/g, and a water absorption capacity of 28.8 g/g. These results suggest that the synergistic effect of chitosan and gelatin at specific ratios significantly enhances the overall properties of the material. Our findings suggest that Chi/Gel bioaerogels, especially the 60/40 composite, hold great promise for diverse applications. Highlights * All Gelatin/Chitosan bioaerogels exhibited high porosity and low density. * The Chi/Gel 60/40 mix achieved the highest porosity and surface area. * Highest water adsorption was observed in the Chi/Gel 60/40 composite. * Synergistic effects enhanced properties of the Gelatin/Chitosan scaffolds. KEYWORDS bioaerogel, biopolymers, chitosan, eco-friendly, gelatin, porose materials, 1 | INTRODUCTION In recent years, the focus has shifted towards developing aerogels from biopolymers due to their biocompatibility, biodegradability, and abundance. (1,2) Bioaerogels, known for their extraordinary lightweight and [...]

The sodium alginate (SAG) cross-linked poly (allyl amine-co-acrylic acid)/copper oxide [SAG-cl-poly(AAM-co-AA)/CuO] nanocomposite hydrogel (SNCHG) was synthesized by using a free radical initiated cross-linked copolymerization process in-situ. Several characterization techniques namely FTIR, PXRD, FESEM with EDAX, TGA, and BET analysis were employed to characterize the synthesized SNCHG. Water swelling properties together with swelling kinetics of SNCHG were evaluated. The highest swelling (35% after 30 minutes) was found at pH 8. The adsorption property of the developed nanocomposite hydrogel (SNCHG) was evaluated in three pesticides' solution namely chlorpyrifos (CP), phosalone (PL), and 4,4'- dichloro diphenyl dichloro ethane (DD) in water medium. Several factors affecting the adsorption like solution pH, time of adsorption, amount of pesticides, etc. were evaluated. The maximum adsorption were found to be 96.9% for CP at pH 7, 95.85% for PL at pH 7, and 86.72% for DD at pH 4. Pseudo-second order kinetics and both Freundlich and Dubinin-Radushkevich adsorption isotherms were followed in all the three cases. Maximum adsorption capacity ([Q.sub.m]) were found to be 507.61, 158.22, and 132.97 mg [g.sup.-1] for CP, PL, and DD, respectively. The adsorption process was endothermic in nature and spontaneous. Highlights * A novel CuO Nps embedded sodium alginate-based hydrogel is developed. * Increment of surface area and water swelling property are illustrated. * The hydrogel exhibits excellent adsorption property towards pesticides. * The observed affinity of adsorption is chemisorption. KEYWORDS adsorption, desorption, nanocomposite hydrogel, pesticide, sodium alginate, 1 | INTRODUCTION Pesticides are a class of chemical substances usually employed to control various kinds of pests in agricultural, forestry, and domestic activities (1) that can also damage crops [...]

The density functional theory was used to calculate the reaction mechanism and selectivity of nonmetallic single-atom catalysts, such as N, O, and P, doped on graphene in the direct dehydrogenation of propane (PDH). Our results show that the rate-controlling step in PDH varies with the doping atom. We also found that N, O, and P nonmetallic single-atom-doped graphene catalysts showed relatively low adsorption performance for propane and the active site was the C atom adjacent to N, O, and P, rather than the doped atom itself. Interestingly, for the O-doped graphene catalysts, which can reduce the reaction energy harrier hy searching for multiple transition states, and the more transition states in the reaction path, the lower the energy harrier for the reaction rate-controlling step. Finally, the results show that the energy harrier of P-doped propane direct dehydrogenation reflecting the speed control step is the lowest, which is 44.32 kcal*[mol.sup.-1], and the energy barrier of deep dehydrogenation is 53.08 kcal*[mol.sup.-1]; so it has good selectivity. Therefore, the P-doped graphene catalyst has a promising application as a nonmetallic catalyst for the direct PDH, which provides the possibility for the design of cheap and environmentally friendly catalysts. Key words: propane, DFT, direct dehydrogenation, nonmetallic catalyst, graphene, 1. Introduction Propylene occupies an important position in the modern chemical industry and is the main chemical raw material for producing polypropylene, acrylonitrile, and acrylic fibers. (1) With the worldwide [...]

Tetracyclines are a group of very important antibiotics that are still in use. To extract, detect, and remove tetracyclines from the environment, various nanomaterials have been employed. Although gold nanoparticles (AuNPs) are a commonly cited material for these purposes, a fundamental understanding of these tetracycline-AuNP systems is still limited. In this work, the adsorption of tetracycline, oxytetracycline, and doxycycline to AuNPs was studied. The effect on the colloidal stability of AuNPs, adsorption kinetics, and the resulting adsorption isotherms was measured. While millimolar concentrations of the tetracyclines can cause aggregation of AuNPs, saturated monolayer adsorption was achieved with low micromolar concentrations of the tetracyclines. Adsorption was instantaneous, and adsorption to AuNPs enhanced their intrinsic fluorescence instead of quenching. With the assumption that aptamer/target complexes cannot be easily adsorbed by AuNPs compared to free aptamers, a label-free colorimetric detection method was tested. While the label-free sensor showed target-dependent aggregation of AuNPs, a nonbinding mutant aptamer showed the same trend, suggesting that the color change did not reflect aptamer adsorption but other events such as target adsorption. This study indicates the importance of the fundamental understanding of target/AuNP interactions to correctly design aptamer and AuNP-based label-free biosensors. Key words: oxytetracycline, doxycycline, aptamers, gold nanoparticles, biosensors, 1. Introduction Tetracycline antibiotics share a similar structure containing four linearly fused rings. Many of the initially discovered tetracycline antibiotics such as tetracycline and oxytetracycline were later found to have [...]

This paper aimed to reveal the effects of chemisorbed oxygen species on selective catalytic oxidation applied for [H.sub.2]S removal. A sequence of thermal treatments were conducted on [V.sub.2][O.sub.5]/Ti[O.sub.2] samples to prepare catalysts that possess different distributions of oxygen species. Characterization by X-ray photoelectron spectroscopy enabled a distinction among three different chemisorbed oxygen species: [O.sup.-], [O.sub.2.sup.2-], and [O.sub.2.sup.-]. In addition, the dominance of the [O.sup.-] species, which is a very reactive oxygen species for catalytic oxidation reactions, was observed when the catalyst was exposed to 5% [O.sub.2]/[N.sub.2] gas at the low temperature of 30 [degrees]C. It was also found that the N400A30 with the highest ratio of [O.sup.-] species was superior to others at converting [H.sub.2]S into elemental sulfur over the whole range of temperatures: the best S yield of N400A30 was 85% at 130 [degrees]C. These results are promising, as thermal treatments for oxygen adsorption were adopted for the first time to improve the catalytic activity of [H.sub.2]S removal by modulating the proportion of highly reactive [O.sup.-] species. Key words: chemisorbed oxygen species, [V.sub.2][O.sub.5]/Ti[O.sub.2] catalysts, thermal treatments for oxygen adsorption, catalytic oxidation for [H.sub.2]S removal, highly reactive [O.sup.-] species, 1. Introduction Sustainable and renewable energy sources have been intensively investigated as means of meeting the ever-increasing demand for clean energy to realize carbon neutralization against climate change (.1,2) One [...]

We studied the conditions for the adsorption of zinc, cadmium, and mercury(II) ions on a modified adsorbent based on an ARA-8p highly basic anion exchange resin and a Rhodanine derivative, 5-(4-carboxyphenyl-azo)rhodanine (ARA-8p-p-KBAR), in a batch mode. The values of pH, phase contact time, and adsorbate concentration at which the maximum recovery of zinc, cadmium, and mercury(II) ions was achieved were determined. The adsorption capacity of the adsorbent for the adsorbed ions was determined from the obtained adsorption isotherms. The calculated value of the free energy shows that adsorption proceeds with the formation of an ionic bond. Eluents were selected to ensure the quantitative desorption of zinc, cadmium, and mercury(II) ions. The interfering effect of macrocomponents and trace elements of water was studied; zinc, cadmium, and mercury(II) ions were quantitatively adsorbed by this adsorbent from a solution of a complex composition. A procedure was developed for the adsorption-atomic-absorption determination of zinc, cadmium, and mercury(II) ions in various water samples., Author(s): S. M. Uvaisova [sup.1] , M. A. Babuev [sup.2] , U. M. Damyrov [sup.2] Author Affiliations: (1) grid.4886.2, 0000 0001 2192 9124, Dagestan Federal Research Center, Russian Academy of [...]

In this work, we report on the biosorbent bio-composite consisting of pretreated sugarcane bagasse, chitosan, and epichlorohydrin, which was prepared using the blending method for the adsorption of phosphate from aqueous media. The effect of solvent concentration was investigated, and it was observed that the high solvent concentration significantly enhanced the extraction of cellulose. Moreover, pretreatment enhances the compatibility between the extracted cellulose and chitosan. Furthermore, the addition of epichlorohydrin significantly enhanced the adsorption capacity as well as the stability of the synthesized biosorbent bio-composite. Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron microscope, X-ray difraction, and thermogravimetric analysis were used to characterize the prepared bio-composite. Batch studies were conducted to investigate the effectiveness of the bio-composite. The mechanism of adsorption between the biosorbent biocomposite and phosphate was through chemisorption as the data best fitted to the pseudo-second-order kinetic model. The isotherm study showed that the data best fitted to the Freundlich adsorption isotherm model, and the Langmuir adsorption isotherm model showed that the maximum adsorption capacity was 15.26 mg/g. The biosorbent was found to be pH dependent, selective, and recyclable. Key words: sugarcane bagasse, pretreatment, chitosan, epichlorohydrin, biosorbent, phosphate, 1. Introduction The wastewater from the chemical fertilizers industry, agricultural run-ofs, and sewage treatment plant contain pollutants such as phosphate, nitrate, and sulphate ions that have the potential to reduce [...]

A new specific sorbent entitled molecularly imprinted polymer (Fe.sub.3O.sub.4@PDA MIP) was fabricated on the surface of ferroferric oxide nanoparticles with the dummy template of 5,7-dimethoxycoumarin through self-assembly of dopamine which is efficient for recognition and determination of aflatoxin B in food samples coupled with UPLC-FLD with a large volume flow cell. The prepared MIPs were characterized, and the adsorption properties were evaluated. The maximum adsorption capacities were 0.46 mg/g for aflatoxin B1 and 0.047 mg/g for aflatoxin B2. Under optimized conditions, the calibration plots are linear in the range of 0.005-0.5 and 0.001-0.1 ng/mL with LODs of 0.0024 and 0.0004 ng/mL for aflatoxin B1 and aflatoxin B2, respectively. The recoveries from spiked samples are 89.0-105.0% with RSDs of 5.6-7.7% in case of corn, peanut and edible oil. And after 7 cycles, the adsorption capacity of the MIPs did not decrease significantly., Author(s): Lili Suo [sup.1] , Meihua Hu [sup.2] Author Affiliations: (1) grid.507007.5, The collaboration Unit for Field Epidemiology of State Key Laboratory for Infectious Prevention and Control, Jiangxi Provincal Key [...]

This work describes the use of polished silver solid amalgam electrode (p-AgSAE) and square wave voltammetry in the voltammetric determination of folic acid (FA). Experimental and voltammetric parameters were previously optimized. A well-defined voltammetric peak indicated a reversible redox reaction involving reactant and product adsorption on the p-AgSAE surface. A linear relationship between peak current and FA concentration was obtained from 4 x 10.sup.-7 to 1.1 x 10.sup.-5 M with a correlation coefficient of 0.9981, inter-day and intra-day precision of 2.1 and 5.3%, respectively, detection limit of 1.1 x 10.sup.-7 M, and quantification limit of 4 x 10.sup.-7 M. This procedure was applied to FA determination in spinach and corn chip samples using a simple extraction, resulting in good percent recovery that confirmed suitable robustness of the proposed methodology and the use of p-AgSAE as an excellent alternative for FA determination without the use of modified electrodes or toxic waste generation from the mercury electrodes utilization., Author(s): Uarlei Douglas dos Santos [sup.1] , Djenaine De Souza [sup.1] , Sérgio Antônio Spínola Machado [sup.2] Author Affiliations: (1) Laboratory of Electroanalytical Applied to Biotechnology and Food Engineering (LEABE), [...]

A domestic composite material based on silicon carbide and nitrile butadiene rubber was used to identify volatile substances of banana, banana flavor, and creamy chewing candies by passive adsorption in combination with thermal desorption GC-MS. This method can be used to determine a wide range of compounds, for example, esters of carboxylic acids, terpenoids, aldehydes, aromatic hydrocarbons, alkanes, heterocyclic compounds, phenols, glycerides, and fatty acids. The obtained chromatographic profiles of the samples were compared. In the chromatogram of 'Banana' flavor, five peaks (out of eight) corresponded to the compounds that form the aroma of a banana, and in the chromatogram of 'Love is' candies with banana flavor, three corresponding peaks (out of 21) were found., Author(s): E. S. Markova [sup.1] , A. N. Furman [sup.1] , S. P. Shekhtman [sup.1] , A. V. Pirogov [sup.1] , M. V. Popik [sup.1] , O. A. Shpigun [sup.1] [...]

Chitosan magnetic nanoparticles (CTS-Fe.sub.3O.sub.4) were synthesized and used for the adsorption and removal of Everzol Black ED-2R dye from wastewater samples prior to spectrophotometric determination. High adsorption capacity with high surface area after surface modification of this new sorbent by chitosan can result in a satisfactory adsorption recovery. The main factors affecting the adsorption recovery of the analyte that were studied and optimized included pH, ionic strength, adsorbent amount, adsorption and desorption times, and desorption solvent volume. The calibration curve was linear over the range of 1-50 mg/L with determination coefficients >0.991. The detection and quantification limits were found to be 0.04 and 0.15 mg/L, respectively. To evaluate the method accuracy, the recoveries of the spiked samples were measured, excellent precisions (RSD < 1.7%) and good recoveries were obtained for wastewater and lake water samples., Author(s): Arezoo Isalou [sup.1] , Eslam Pourbasheer [sup.2] , Abolghasem Beheshti [sup.1] , Mohammad Reza Ganjali [sup.3] [sup.4] Author Affiliations: (1) grid.412462.7, 0000 0000 8810 3346, Department of Chemistry, Payame [...]

A new strategy was implemented to synthesize hierarchical ZSM-5 zeolite, which uses self-made organosilanized doubleterminal amino polyetheramine (ODAP) as a soft template to generate mesopores. The influence of the additional amount of ODAP on the textural properties and morphologies of the hierarchical ZSM-5 zeolite was investigated. The obtained hierarchical ZSM-5 zeolite was characterized by X-ray diffraction, [N.sub.2] physical adsorption, SEM, temperature-programmed desorption of [NH.sub.3], and other methods. The analysis of the experimental results shows that the maximum total BET specific surface area and mesoporous specific surface area of the optimized hierarchical ZSM-5 zeolite reached 609 and 278 [m.sup.2]/g, respectively. Because the synthesized hierarchical ZSM-5 zeolite has a large mesoporous specific surface area and abundant surface acidity, in terms of reactant conversion and product selectivity, compared with microporous zeolite, it exhibits excellent catalytic performance in the thiophene alkylation desulfurization reaction. This synthesis strategy can be extended to the preparation of zeolites with different framework structures, which is of great significance. Key words: hierarchical ZSM-5 zeolite, organosilanized double-terminal amino polyetheramine, thiophene alkylation Nous avons elabore une nouvelle strategie pour synthetiser la zeolithe ZSM 5 hierarchique, dans laquelle nous employons une polyetheramine a double terminaison aminee organosilanisee (PDTAO) que nous avons fabriquee nous-memes comme modele souple pour generer des mesopores. Nous avons etudie les effets de la quantite ajoutee de PDTAO sur les proprietes texturales et la morphologie de la zeolithe ZSM 5 hierarchique. Nous avons caracterise la zeolithe ZSM 5 hierarchique obtenue par diffraction des rayons X (DRX), adsorption physique d'azote, microscopie electronique a balayage (MEB), desorption thermoprogrammee d'ammoniac (DTP NH3) et d'autres methodes. L'analyse des resultats experimentaux montre que la surface specifique totale maximale determinee par la methode de Brunauer-Emmett-Teller (BET) atteint 609 [m.sup.2]/g et la surface specifique des mesopores de la zeolithe ZSM 5 hierarchique optimisee, 278 [m.sup.2]/g. Sur les plans de la conversion des reactifs et de la selectivity a l'egard des produits, etant donne que la zeolithe ZSM 5 hierarchique synthetisee possede une grande surface specifique mesoporeuse et une acidite de surface abondante par rapport a la zeolithe microporeuse, elle offre d'excellentes performances catalytiques dans la reaction de desulfuration-alkylation du thiophene. Cette strategie de synthese peut etre etendue a la preparation de zeolithes de differentes structures, ce qui se revele d'une grande importance. [Traduit par la Redaction] Mots-cles : zeolithe ZSM-5 hierarchique, polyetheramine a double terminaison aminee organosilanisee, alkylation du thio-phene, Introduction Zeolite as a crystalline aluminosilicate material, based on the unique pores channel of molecular dimension structure, strong Bronsted acidity, large surface area, and high thermal and hydrothermal stability, has [...]

The discovery of radically different antifreeze proteins (AFPs) in fishes during the 1970s and 1980s suggested that these proteins had recently and independently evolved to protect teleosts from freezing in icy seawater. Early forays into the isolation and characterization of AFP genes in these fish showed they were massively amplified, often in long tandem repeats. The work of many labs in the 1980s onward led to the discovery and characterization of AFPs in other kingdoms, such as insects, plants, and many different microorganisms. The distinct ice-binding property that these ice-binding proteins (IBPs) share has facilitated their purification through adsorption to ice, and the ability to produce recombinant versions of IBPs has enabled their structural characterization and the mapping of their ice-binding sites (IBSs) using site-directed mutagenesis. One hypothesis for their ice affinity is that the IBS organizes surface waters into an ice-like pattern that freezes the protein onto ice. With access now to a rapidly expanding database of genomic sequences, it has been possible to trace the origins of some fish AFPs through the process of gene duplication and divergence, and to even show the horizontal transfer of an AFP gene from one species to another. Key words: gene duplication and divergence, multigene family, ice-binding proteins, ice nucleation, lateral gene transfer La decouverte de proteines antigel (PAG) radicalement differentes chez les poissons au cours des annees 1970 et 1980 a suggere que ces proteines avaient recemment et independamment evolue pour proteger les teleosteens de la congelation dans l'eau de mer glacee. Les premieres tentatives d'isolement et de caracterisation des genes de PAG chez ces poissons ont montre qu'ils etaient amplifies de facon massive, souvent en longues repetitions en tandem. Les travaux de nombreux laboratoires a partir des annees 1980 ont conduit a la decouverte et a la caracterisation de PAG dans d'autres regnes tels que les insectes, les plantes et de nombreux micro-organismes differents. La propriete distincte de lier la glace que ces proteines de liaison a la glace (PLG) partagent a facilite leur purification par adsorption a la glace, et la capacite de produire des versions recombinantes des PLG a permis leur caracterisation structurelle et la cartographie de leurs sites de liaison a la glace par mutagenese dirigee. L'une des hypotheses en ce qui concerne leur affinite pour la glace est que le site de liaison a la glace organise les eaux de surface en un motif semblable a la glace, ce qui fige la proteine sur la glace. Grace a l'acces a une base de donnees de sequences genomiques qui est en expansion rapide, il a ete possible de tracer l'origine de certaines PAG des poissons a travers le processus de duplication et de divergence des genes, et meme de montrer le transfert horizontal d'un gene de PAG d'une espece a une autre. [Traduit par la Redaction] Mots-cles : duplication et divergence de genes, famille multigenique, proteines de liaison a la glace, nucleation de la glace, transfert lateral de genes, In graduate school, it is not just what you get to know, it is also who you get to know As an undergraduate student at the University of Wales, I [...]

Hypercrosslinked polymers (HCPs) have aroused considerable attention due to their high chemical stability and potential applications in adsorption. A series of HCPs were prepared via one-step solvent knitting method using the cashew nut shell liquid (CNSL) as bio-based building block. Characterization of the prepared samples was performed by [N.sub.2] adsorption, Fourier transform infrared, Raman spectra, solid-state [sup.13]C NMR spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy, and transmission electron microscopy images. Depending on the [N.sub.2] adsorption, the as-prepared CNSL-HCP4 exhibits the highest specific surface area of 93 [m.sup.2]*[g.sup.-1] and displays a uniform pore-size distribution. TGA results show that the decomposition temperature of the polymers exceeds 350[degrees]C. More significantly, the dynamic adsorption of high concentration of volatile organic compounds (VOCs) was investigated with CNSL-HCP4 under dry and humid conditions. The results show that the maximum adsorption capacity of o-xylene under dry conditions is 217 mg*[g.sup.-1] and its corresponding adsorption amount (208 mg * [g.sup.-1]) decreases slightly under 30% relative humidity condition, indicating that CNSL-HCP4 had a hydrophobic surface. A little decrease in adsorption capacity of o-xylene on CNSL-HCP4 after five recycles confirms the reusability of the CNSL-HCPs. Therefore, CNSL-HCP4 is considered to be a promising candidate for potential adsorbent in recycling the VOCs from the exhaust. KEYWORDS adsorption, hypercrosslinked polymers, recycling, synthesis, 1 | INTRODUCTION Volatile organic compounds (VOCs) are one of the most important air pollutants not only harmful to human [1] but also cause serious environmental problems. [2,3] The global [...]

Polymer metal nano-composites (PMNC) were synthesized by integrating different weight percentage of chitosan (CS), N,N'-methylenebisacrylamide (MBA) crosslinked poly(aciylic acid-co-hydroxyethyl methacrylate) copolymer and Cu nanoparticles (CuNPs). CuNPs were generated in situ during polymerization by reducing CuS[O.sub.4].5[H.sub.2]O with ascorbic acid. The presence of the CuNPs in the polymer network, functionality, crystallinity, morphology, size distribution of the CuNPs, elemental composition, thermal characteristics, network parameters, pH sensitivity, and strength of the composites was evaluated. The CuNP-loaded PMNC4 composite prepared with 10:1 acrylic acid : hydroxyethyl methacrylate molar ratio, 1 wt% each of initiator and MBA crosslinker and 4 wt% CS showed a photodegradation efficiency of 64% in 5 h for 50 mg/L methyl violet dye in water. The same polymer showed a rejection of 91.45% and a mass transfer coefficient of 4.14 * [10.sup.-5] cm/s for continuous adsorption of 20 mg/L Pb(II) ion in water in a fixed bed of height 22 mm for an inflow rate of 30 ml/min. KEYWORDS chitosan, column adsorption of Pb(II) from water, composite adsorbent, copolymer, CuNP, photocatalytic reduction, 1 | INTRODUCTION Nanometals of Ag, Au, Pd, Pt, Co, Ni, and Cu were reported as very efficient catalyst for reduction of organic pollutants such as synthetic dyes [1,2] and [...]

Organic resorcinol formaldehyde aerogels with distinct pore sizes/surface areas in different ratios of (resorcinol/catalyst) R/C = 300, 400, 600 and (resorcinol/ water) R/W = 2 were prepared utilizing sol-gel technique and in-situ modified by incorporating 1 wt% meta-phenylenediamine. The porous nanostructure, surface area, and pore size of the aerogels were characterized by scanning electron microscopy, Brunauer-Emmett-Teller, and Barrett-Joyner-Halenda techniques. Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were employed to get understanding into the chemical structure. Furthermore, we investigated the removal percentage of antibiotic via UV-vis spectroscopy. The ability of modified aerogels in removing Chlortetracycline (CTC) at different pH values (2-12), contact times (2-24 h), initial concentrations of CTC (50-100 mg [L.sup.-1]), and the adsorbent dose (2-10 mg) was evaluated. Consequently, the adsorption optimum conditions were found, the adsorption isotherms were measured, and isotherm models were fitted to the results to interpret the kinetics of adsorption. The obtained fitting parameters using the pseudo-second-order model revealed a well alignment with the experimental data. Finally, we demonstrated that the modified-aerogels have a high capacity in CTC antibiotics removal up to 90% and an adsorption capacity of 440 mg [g.sup.-1] as well as an efficient regeneration capacity for five consecutive cycles without significant degradation of the adsorption properties. KEYWORDS adsorption, Chlortetracycline antibiotics, organic aerogel, poly (m-phenylenediamine), porous structure, resorcinol formaldehyde, 1 | INTRODUCTION The rapid development of urban areas, industrial complexes, and their surroundings along with population growth have increased the importance and necessity of facilities for proper wastewater treatment. [...]

This paper presents a soil-water retention curve (SWRC) model for fine-grained soils. Compared with existing studies, the proposed model accounts for the distinct roles of the volume change of soils on capillarity and adsorption mechanisms. The capillary water is described by a relation that includes the characteristics of the pore-size distributions as parameters, while the absorbed water is modeled by a novel proposition that both considers the phenomenon of capillary condensation and allows for the decoupling between the degree of capillary and adsorptive saturation. Based on this feature, the void ratio effects are considered in a way in which they only affect capillary water, i.e., consistent with how volume change influences soil microstructures. The relative contributions of void ratio effects and hydraulic hysteresis on the path- and history-dependence of a SWRC in [S.sub.r]-s-e space, where [S.sub.r] is degree of saturation, s is matric suction, e is void ratio, for deformable unsaturated soils are examined. The significance of discriminating the effects of volume change on capillary and adsorptive water is illustrated by applying the SWRC model to computing the shear strength of unsaturated soils with different void ratios. The model performance is assessed by comparing against test data reported for four types of fine-grained soils in the literature and those tested for natural loess in this work. Key words: soil-water retention curve, fine-grained soils, capillarity, adsorption, void ratio. Cet article presente un modele de courbe de retention d'eau dans le sol (<< SWRC >>) pour les sols a grains fins. Par rapport aux etudes existantes, le modele propose tient compte des roles distincts du changement de volume des sols sur les mecanismes de capillarite et d'adsorption. L'eau capillaire est decrite par une relation qui inclut les caracteristiques de la distribution de la taille des pores comme parametres, tandis que l'eau absorbee est modelisee par une nouvelle proposition qui tient compte du phenomene de condensation capillaire et permet le decouplage entre le degre de saturation capillaire et celui de saturation par adsorption. Sur la base de cette caracteristique, les effets de l'indice des vides sont consideres de telle sorte qu'ils n'affectent que l'eau capillaire, c'est-a-dire qu'ils sont coherents avec la facon dont le changement de volume influence les microstructures du sol. Les contributions relatives des effets de l'indice des vides et de l'hysteresis hydraulique sur la dependance de la trajectoire et de l'historique de la SWRC dans l'espace [S.sub.r]-s -e, ou [S.sub.r] est le degre de saturation, s est la succion matricielle, e est l'indice des vides, pour les sols non satures deformables sont examinees. L'importance de la separation des effets du changement de volume sur l'eau capillaire et l'eau adsorbee est illustree par l'application du modele SWRC au calcul de la resistance au cisaillement des sols non satures avec differents indice des vides. La performance du modele est evaluee en le comparant aux donnees d'essai rapportees pour quatre types de sols a grains fins dans la litterature et a celles verifiees pour le loess naturel dans ce travail. [Traduit par la Redaction] Mots-cles : courbe de retention d'eau dans le sol, sols a grains fins, capillarite, adsorption, indice des vides., 1. Introduction The peculiarity of unsaturated soils and its importance for engineering applications have been widely recognized in the field of geotechnical engineering (Fredlund and Rahardjo 1993; Sheng 2011; Sheng [...]

The dye-water treatment by polyvinyl alcohol (PVA) is still a challenge as PVA is characterized by its strong affinity to water. Therefore, this study aims to fabricate a functional PVA film with good regeneration ability to remove anionic dyes from aqueous solution using polyamidoamine dendrimers (PAMAM) as a modifier and epichlorohydrin as a cross-linker. Solution casting technique was applied to prepare the functionalized film. The adsorption efficiency of the film was evaluated by studying the effect of various parameters such as PAMAM loading (0,12.5, 25, 50 wt%), initial dye concentration, film dose, solution pH, and adsorption time. The adsorption studies showed that with increasing PAMAM loading, the maximum adsorption capacity of the resulting film increased till it reached up to 73.8 mg/g by the PVA film with 50 wt% PAMAM. For understanding the nature of the adsorption process of the prepared film, the kinetics and isotherm analysis were studied. It was found that the mechanism of dye removal by the prepared film followed pseudo-second-order kinetic and Freundlich isotherm, respectively. The adsorption and regeneration studies indicated that this film has great potential to effectively remove anionic dye from wastewater. KEYWORDS adsorption, anionic dye, grafting, kinetics studies, polyvinyl alcohol, 1 | INTRODUCTION Serious environmental concerns all over the world have been provoked due to the presence of a large number of organic and industrial pollutants in wastewater. [1] These [...]

This work concerns the fabrication of a green, novel, and sustainable system for the efficient removal of methylene blue from aqueous solutions. The proposed system is obtained by using sodium alginate/soybean extract blend reinforced with hemp hurd from agro-waste resources and halloysite nanotubes (HNTs). The ionotropic gelation methodology, using calcium chloride as a crosslinking agent, was easily applied to obtain composite beads. The adsorption studies were carried out up to 24 h using methylene blue as model system. The effect of HNTs on adsorption capacity was investigated proving that an increase in inorganic filler determined an increase in adsorption capacity from 32 to 49 mg/g by adding 35% wt of HNTs. The experimental data were fitted through four different models, demonstrating that the adsorption phenomenon is described by second-order process. Film diffusion and pore diffusion values were evaluated to better investigate the rate controlling mechanisms. Isotherm studies were then carried out to extrapolate thermodynamic parameters. Finally, a possible mechanism of adsorption was proposed on the basis of chemisorption mechanism. Here, we demonstrate that the proposed novel, inexpensive, and sustainable composite material obtained from agro-waste resources has high efficiency in removing a cationic dye from wastewaters. KEYWORDS adsorption, biomaterials, methylene blue, polysaccharides, renewable resources, 1 | INTRODUCTION The wastewaters derived from textiles, food, papers, and many other industries are representing the main source of dye pollution. [1, 2] Due to their toxicity, dyestuffs are [...]

In the present study, for the first time, walnut bloom (WB) powder was used as a natural and economic sorbent for the removal of methylene blue (MB) from an aqueous solution. This new biosorbent was characterized using the following techniques: scanning electron microscopy (SEM), X-ray diffraction (XRD), COHNS, BET (Brunauer-Emmett-Teller) analysis, and Fourier transform infrared (FTIR) spectroscopy. MB removal efficiency and its adsorption onto WB powder were tested in a batch system by varying parameters such as initial dye concentration, contact time, pH, temperature, and dosage of biosorbent in which the removal percentages of ~92% was achieved under the optimum conditions. Equilibrium data and adsorption isotherms fit well with the Langmuir model ([R.sup.2] - 0.999, 0 < [R.sub.L] < 1) with a maximum monolayer adsorption capacity of 46 mg [g.sup.-1]. The chemical kinetics of MB adsorption followed the pseudo second-order model. Also, the magnitude of thermodynamic functions identified the removal of MB. [DELTA]Ho of-7.32 kJ [mol.sup.-1] and [DELTA]So of-4.32 kJ [mol.sup.-1] indicated the spontaneity, exothermicity, and favorability of the adsorption process at room temperature. Key words: methylene blue, removal, walnut bloom powder. Dans le cadre de la presente etude, nous avons ete les premiers a utiliser la poudre de fleurs de noyer (FN) comme sorbant naturel et economique pour l'elimination du bleu de methylene (BM) d'une solution aqueuse. Nous avons caracterise ce nouveau biosorbant a l'aide des techniques suivantes: microscopie electronique a balayage (MEB), diffraction des rayons X (DRX), analyses par la methode de Cohns et la methode de Brunauer-Emmett-Teller (BET) et spectroscopie infrarouge a transformed de Fourier (FTIR). Nous avons evalue l'efficacite de l'elimination du BM et son adsorption sur la poudre de FN dans un systeme de traitement par lots en faisant varier les parametres tels que la concentration initiale du colorant, le temps de contact, le pH, la temperature et la quantite du biosorbant, avec lequel des pourcentages d'elimination d'environ 92 % ont ete atteints en conditions optimales. Les donnees d'equilibre et les isothermes d'adsorption concordaient bien avec le modele de Langmuir ([R.sup.2] - 0,999; 0 < [R.sub.L] < 1), pour une capacite maximale d'adsorption monocouche de 46 mg*[g.sup.-1]. La cinetique de l'adsorption chimique du BM suit le modele de pseudo-second ordre. De plus, l'ordre de grandeur des fonctions thermodynamiques Concorde avec l'elimination du BM. Le [DELTA]?o de -7,32 kJ [mol.sup.-1] et le [DELTA]So de 4,32 kJ [mol.sup.-1] indiquent un processus d'adsorption spontane, exothermique et favorable a temperature ambiante. [Traduit par la Redaction] Mots-cles: bleu de methylene, elimination, poudre de fleurs noyer., Introduction 3,7-Bis(Dimethylamino)-phenothiazine-5-ium chloride or methylene blue (MB) is a heterocyclic aromatic compound that is widely used in a range of different fields, especially in the textile industry. (1) As most [...]

A graft copolymer was prepared by grafting a mixture of 2-acrylamido 2-methyl propane sulfonic acid (AMPS) and acrylic acid (AA) monomers onto the dextrin polysaccharide backbone by free radical copolymerization technique using potassium peroxydisulfate as an initiator in water medium. Several characterization techniques like FT-IR, [sup.1]H and [sup.13]C NMR, XRD, SEM, and EDAX analyses were used to characterize the synthesized polymer. The polymer was used as an efficient adsorbent for the removal of toxic pesticides namely dimethoate (DM), chlorpyrifos (CP), and phosalone (PL) from their aqueous solutions. Various operating variables such as kinetic, isotherm, and thermodynamic parameters were investigated for the three pesticides. The pesticide adsorption process over polymer surface was directed by pseudo-second-order kinetic model. Langmuir and Dubinin-Radushkevich isotherms both correlate well with the equilibrium data. Maximum adsorption capacity ([q.sub.m]) of the polymer was found to be 172.4 mg [g.sup.-1] for DM, 121.95 mg [g.sup.-1] for PL, and 108.69 mg [g.sup.-1] for CP. Thermodynamic parameters showed that the selected pesticides' adsorption onto the polymers was a spontaneous and endothermic process. The preferential pesticide sorption by the graft copolymer followed the order DM > PL > CP. KEYWORDS adsorption, dextrin, graft copolymer, pesticide, 1 | INTRODUCTION Pesticides are chemical compounds having diverse functional groups, which are extensively used throughout the world for controlling a huge variety of pests, which can harm crops and [...]

An ecofriendly and biodegradable porous structure was prepared from drying aqueous foams based on nano fibrillated cellulose (NFC), extracted from softwood pulp by subcritical water/C[O.sub.2] treatment (SC-NFC). The primary aim of this work was to use the modified SC-NFC as stabilizer for a water-based Pickering emulsion which upon drying, yielded porous cellulosic materials, a good dye adsorbent. In order to exploit the carboxymethylated SC-NFC (CMSCNFC, with a degree of substitution of 0.35 and a charge density of 649 [mu]eqv/g) as a stabilizer for water-based Pickering emulsion in subsequent step, an optimized quantity of octyl amine (30 mg/g of SC-NFC) was added to make them partially hydrophobic. A series of dry foam structures were prepared by varying the concentrations of treated CMSC-NFCs and 4 wt% was found to be the optimum concentration to yield foam with high porosity (99%) and low density (0.038 g/cc) along with high compression strength (0.24 MPa), superior to the conventionally extracted NFC. The foams were applied to capture as high as 98% of methylene blue dyes, making them a potential green candidate for treating industrial effluent. In addition, the dye adsorption kinetics and isotherms were found to be well suited with second order kinetics and Langmuir isotherm models. KEYWORDS dye adsorption, foam, nano fibrillated cellulose, Pickering emulsion, subcritical water, 1 | INTRODUCTION Dyes are a commonly generated industrial waste from various industries, such as textile, leather, plastic, paper, and so forth. Industrial wastes such as water-soluble dyes have been [...]

A new chiral stationary phase based on guanine is proposed. An Inerton NAW-HDMS inert substrate modified with 10% guanine under Viedma ripening conditions is chosen as the main test sample. The modified adsorbent obtained by applying guanine in the Viedma ripening mode is capable of chiral recognition. An analysis of the thermodynamic functions of adsorption showed that the differences in molar changes in the internal energy and entropy of the adsorption of enantiomers of haloalkanes are due to the predominant adsorption of one of enantiomers inside a cavity of the supramolecular structure of guanine, and of the other, on its surface. It was found that the proposed stationary phase possesses enantioselectivity with respect to haloalkanes. Racemates of 2-bromoheptane, 1,2-dichloropropane, 1,2-dibromopropane, and 2-chlorobutane were separated by gas chromatography. The best separation was achieved for the 2-chloropentane racemate: the separation factor [alpha] was 2.43., Author(s): N. I. Sairanova [sup.1], Yu. Yu. Gainullina [sup.1] Author Affiliations: (1) grid.77269.3d, 0000 0001 1015 7624, Bashkir State University, Faculty of Chemistry, , 450076, Ufa, Russia Many synthetically produced [...]