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Keywords: chelating hybrid composite; chitosan organo-functionalization; Ni (II) biosorption; TiO2 immobilization EN chelating hybrid composite chitosan organo-functionalization Ni (II) biosorption TiO2 immobilization 595 618 24 05/12/22 20220501 NES 220501 1 Introduction Nickel discharge in the form of its organo-nickel complexes, sulfides and oxides from different industries is alarming for our environment and is responsible for several health related issues [[1]]. Experimental kinetic data shows best fitting in Langmuir adsorption model and it indicates monolayer adsorption of Ni(II) ions on the homogenous surface of 3EAA-MCS/TiO SB 2 sb hydrogel beads with a limited number of identical sorption sites. Langmuir adsorption isotherm modeling better explained the sorption process ( I R i SP 2 sp ~ 0.99) and maximum monolayer sorption capacity ( I q i SB I m i sb ) at sorption/desorption dynamic equilibrium was computed as 403 mg/g at optimized pH. [Extracted from the article]

In the present study, a novel biosorbent clay composite, based on carboxymethyl-chitosan/sodium alginate grafted with amino-carbamate moiety/bentonite clay (CA-CMC/Bt) was prepared. The produced sorbent was conditioned in the form of hydrogel beads by ionotropic gelation with Ca(II) ions, and thoroughly characterized using FTIR, XRF, XRD, SEM and zeta potential measurements. FTIR and SEM confirmed the successful grafting and intercalation of clay mineral into modified biopolymer. Hydrogel beads were observed to be very integrated and stable under a wide pH working range (from 2.0 to 12.0). CA-CMC/Bt was employed for adsorptive remediation of Ni(II) from aqueous media. Sorption process was found as a function of various parameters such as sorbent dosage, contact time, pH and initial concentration. Kinetic data could be well explained by pseudo second order rate equation (PSORE), suggesting that complexation or valence forces are playing significant role in the uptake of Ni(II) ions. Isothermal sorption data was analysed using different sorption models such as Langmuir, Freundlich and Sips. Data was well fitted with Langmuir and Sips model, maximum monolayer sorption capacity (qm) was calculated (by non-linear fitting of data) as 159 mg/g at 298 K and pH 5.5. Separation factor (RL) was found as 0 < RL < 1 which indicated favourable sorption. Thermodynamic parameters i.e. ΔGo, ΔHo and ΔSo were quantified and patterned the sorption process as exothermic, spontaneous with increase in system entropy. CA-CMC/Bt was found cost-effective, efficient and reusable material in Ni(II) competitive recovery. [ABSTRACT FROM AUTHOR]

In the present work, Saccharum bengalense (SB) was treated with sulfuric acid to enhance its efficiency. Methyl violet (MV), a cationic dye, was removed from aqueous medium using acid modified S. bengalense (A-SB). Different parameters like adsorbent dosage, stirring speed, temperature, contact time and effect of initial concentration of dye on rate of adsorption of dye from aqueous medium was studied. Experimental data obtained from adsorption of MV was analyzed by applying pseudo first order, pseudo second order and intra- -particle diffusion models and it was found that the data best follows the pseudosecond order kinetics. Thermodynamic parameters indicate that adsorption reaction was spontaneous, feasible and endothermic in nature. Different adsorption isotherm models, like Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin, were used to study the mechanism of adsorption process and experimental data was well fitted by the Langmuir adsorption isotherm. [ABSTRACT FROM AUTHOR]

In the present study, microwave treatedSalvadoraoleoides (MW-SO) has been investigated as a potential biosorbent for the removal of toxic methyl violet dye. A batch adsorption method was experimented for biosorptive removal of toxic methyl violet dye from the aqueous solution. The effect of various operating variables, viz., adsorbent dosage, pH, contact time and temperature on the removal of the dye was studied and it was found that nearly 99% removal of the dye was possible under optimum conditions. Kinetic study revealed that a pseudo-second-order mechanism was predominant and the overall process of the dye adsorption involved more than one step. Hence, in order to investigate the rate determining step, intra-particle diffusion model was applied. Adsorption equilibrium study was made by analyzing Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) adsorption isotherm models and the biosorption data was found to be best represented by the Langmuir model. The biosorption efficiency of MW-SO was also compared with unmodified material, Salvadora oleoides (SO). It was found that the sorption capacity (qmax) increased from 58.5 mg/g to 219.7 mg/g on MW treatment. Determination of thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) confirmed the spontaneous, endothermic and feasible nature of the adsorption process. The preparation of MW-SO did not require any additional chemical treatment and a high percentage removal of methyl violet dye was obtained in much lesser time. Thus, it is in agreement with the principles of green chemistry. The results of the present research work suggest that MW-SO can be used as an environmentally friendly and economical alternative biosorbent for the removal of methyl violet dye from aqueous solutions. [ABSTRACT FROM PUBLISHER]

Densities and sound velocities for aqueous monoethanolamine (MEA) system are reported over the entire composition range at different temperatures (298.15, 303.15, 313.15 and 318.15 K). These experimental data have been further used in calculating the excess molar volume, partial molar volumes, isobaric thermal expansion coefficients and the deviation in isentropic compressibility. The excess molar volumes data were fitted to the Redlich–Kister polynomial equation to obtain their coefficients and standard deviations. The partial molar volume at infinite dilution of both water in MEA and MEA in water and have been determined using two different methods. Knowledge of the above properties of these mixtures is a basis for understanding some of the molecular interactions in these systems. From the analysis of the results, the type of interactions between the MEA and water is discussed in terms of the number and size of the alkyl groups attached to the nitrogen atom of MEA. [ABSTRACT FROM PUBLISHER]

Objective: In this research work, a low-cost biosorbent derived from the pulp of Saccharum bengalense (SB) was used as an adsorbent material for the removal of Cu (II) ions from aqueous solution. Methods: A batch adsorption method was experimented for biosorptive removal of copper ions from the aqueous solution. Results: Nearly 90% removal of copper is possible at initial pH 6.0, under the batch test conditions. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) adsorption isotherms have been applied to describe the biosorption of Cu (II) by SB. It was found that biosorption of Cu (II) by SB followed Langmuir and Freundlich model. The monolayer adsorption capacity of SB as obtained from Langmuir isotherm at 40 °C was found to be 10.42 mg/g at 323K. The Cu (II) adsorption data was analyzed by applying pseudo-first-order and pseudo-second-order kinetic models. The intra- particle diffusion model was applied to investigate the rate-determining step. It was found that the biosorption of Cu (II) ions on SB followed pseudo second-order rate kinetics. Thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) have been calculated respectively revealed the spontaneous, feasible and endothermic nature of adsorption process. Conclusion: The results of the present investigation suggested that biosorbent SB can be used as an economically feasible and environmentally friendly biosorbent for the removal of Cu (II) from aqueous solutions. [ABSTRACT FROM AUTHOR]

Abstract: In this research work, the potential of a novel green material obtained from Saccharum bengalense (SB) plant was investigated for the removal of Ni (II) ions from aqueous solution. Biomaterial SB composed of cellulose macromolecules and was used without any chemical treatment. Batch experiments were performed by considering the effect of contact time, SB concentration, pH of the solution and temperature. Results revealed that ∼87% of Ni was removed from aqueous solution at optimum conditions. Three typical kinetic models namely, pseudo first order, pseudo second order and Elovich equations were applied to interpret the kinetic data. To investigate the rate determining step, the intra-particle diffusion model was applied on the experimental data. The sorption process was well explained with pseudo second-order kinetic model. Adsorption isothermal data was examined by applying classical two parameters (Langmuir, Freundlich, Timken and Dubinin–Radushkevich) and three parameters (Redlich–Peterson, Toth and Sips models) and four parameters Fritz Schlunder Isotherm models. Based on R 2 and χ 2 the equilibrium sorption data was better fitted to Langmuir and Sips isotherm model than any other model. Thermodynamics parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) have been calculated respectively, which revealed the spontaneous, endothermic and feasible nature of adsorption process. The results of the present investigation suggest that S. bengalense can be used as an environmentally benign and low cost biomaterial for nickel removal from aqueous solution. [Copyright &y& Elsevier]

The sorption studies of coomassie brilliant blue (CBB) from aqueous solution have been carried out on wheat bran (WB). Coomassie brilliant blue on wheat bran was used to study the adsorption behavior under various parameters such as pH, dosage amount, and contact time. It was observed that under optimized conditions up to 95.70% dye could be removed from solution onto WB. Langmuir and Freundlich adsorption isotherms were used to elaborate the results. Freundlich model was found to be fitted well and favored multilayer adsorption. The Freundlich constants n and KF were determined as 0.53 and 2.5 × 10-4. Thermodynamic parameters such as ?G, ?H, and ?S studied were taking into account, showed spontaneous and favorable reaction for coomassie brilliant blue on wheat bran. The maximum adsorption capacity qm was found to be 6.410 mg/g. The investigations show that non treated WB is a low-cost adsorbent for the removal of dyes from textile industry effluents. [ABSTRACT FROM AUTHOR]

Sorption studies of hyper toxic Pb(II) ions from aqueous solution were investigated on simple and urea modified Saccharum bengalense (UMSB) biosorbent. Various experimental parameters including pH, temperature, and contact time were studied to evaluate the adsorption behavior. The equilibrium modeling showed that the biosorption data were better represented by the Langmuir and Freundlich models rather than other studied models. Thermodynamic parameters such as changes in standard free energy (DG°), standard enthalpy (DH°), and standard entropy (DS°) revealed the spontaneous, endothermic, and feasible nature of adsorption process. The biosorption process followed the pseudo-secondorder (PSO) model. The intraparticle diffusion model was applied to investigate the rate determining step. The biosorption efficiency of urea modified biosorbent has also been compared with unmodified material. It was found that the sorption capacity (qm) increased from 4.73 to 12.65 mg/g on modification. The results of the present investigation suggested that UMSB can be used as an environmentally and economically feasible alternative biosorbent for the removal of Pb(II) from aqueous solutions. [ABSTRACT FROM AUTHOR]

In present study, pure and amino-carbamate moiety grafted calcium alginate hydrogel beads (CA, PSC-CA) were prepared for their biosorption performance in the recovery of silver ions. The produced sorbents were characterized using FTIR, SEM, EDX and TGA. FTIR and SEM-EDX confirmed the successful modification and loading of silver ions onto hydrogel beads. When compared with CA, PSC-CA showed enhanced sorption but comparable kinetics. Equilibrium sorption studies showed that pH, sorbent dose, contact time and adsorbate concentration influenced the sorption capacity. The uptake kinetic data was well demonstrated by pseudo second order rate equation (PSORE). Elovich equation and the resistance to intra-particle diffusion model (RID) suggested that there were two phases of sorption, first one was rapid followed by relatively slow uptake step. Equilibrium isothermal sorption data was well fitted by Langmuir and Sips models. The separation factor R L was found as 0 < R L < 1 which indicated favourable sorption. The maximum monolayer sorption capacity was computed as 210 mg/g at 298 K. Thermodynamic studies revealed the sorption process to be spontaneous and exothermic. PSC-CA hydrogel beads were found as cost-effective and efficient sorbent for economically-competitive recovery of Ag(I). • Amino-carbamate moiety grafted calcium alginate hydrogel beads (PSC-CA) were prepared and characterized. • This modification introduced amino and amido functionalities (amino-carbamate moieties) on the backbone of the biopolymer. • These new grafted groups might act as soft bases for metal ions present in aqueous medium. • PSC-CA hydrogel beads were used as cost effective and highly efficient sorbent for recovery of silver ions. [ABSTRACT FROM AUTHOR]