Nanoalginate based biosorbent for the removal of lead ions from aqueous solutions: Equilibrium and kinetic studies.

Population explosion, depletion of water resources and prolonged droughts and floods due to climatic change lead to scarcity of pure and hygienic drinking water in most of the developing countries. Recently nanomaterials attained considerable attention as biosorbent for water purification purpose. However difficulties in removing polymeric surfactants and organic solvents used for nanoproduction and instability of the generated nanoparticles limit the scope of this approach in water cleanup. Here, we describe a novel green method for synthesizing polysaccharide nanoparticles in aqueous medium using honey as the capping agent. The highly stable alginate nanoparticles, characterized by various microscopic and spectroscopic techniques, exhibited a maximum uptake capacity of 333 mg g (-1)of Pb(II) ions from aqueous solution. The effect of various parameters such as initial metal concentration, pH, contact time, temperature and adsorbent dose on sorption process was investigated in batch mode technique. The maximum removal percentage was 94.81 at 45 °C and at pH 4.5 in 60 min contact time. The biosorption followed Freundlich model indicating multilayer adsorption and pseudo second order kinetics. The mechanism involves both surface adsorption and pore diffusion. The positive values of ΔH°, ∆S° and the negative value of ΔG°, confirmed the endothermic nature, randomness and spontaneity of biosorption process.

Biosorption of Cd(II) from aqueous solution using xanthated nano banana cellulose: equilibrium and kinetic studies.

Present study explored the biosorption capacity of xanthated nano banana cellulose (XNBC) for Cd(II) from aqueous solution. The biosorbent containing sulfur-bearing groups have a high affinity for heavy metals. Sulfur can be considered as a soft ligand group having strong affinity for cadmium. In the present study, the influence of various important parameters such as pH, time, biosorbent dose and initial Cd(II) concentration on the biosorption capacity were investigated. The maximum biosorption capacity of XNBC for Cd(II) was found to be 154.26 mg g⁻¹ at 298 K. The Cd(II) sorption of XNBC was confirmed by SEM-EDS and XRF analysis. The isotherms such as Langmuir, Freundlich, Redlich-Peterson and Tempkin were studied. The Langmuir and the Redlich-Peterson isotherms had been well fitted the biosorption of Cd(II) with xanthated nano banana cellulose. The kinetics of Cd(II) removal using XNBC was well explained by second-order kinetic model. The thermodynamic parameters were also evaluated from the biosorption measurements. Among the various desorbing agents tested, the desorbing efficiency was found to be maximum with 0.1 mol L⁻¹ HCl. It was found that XNBC is also suitable to be used under column operation.

Biosorption of Cr(VI) from aqueous solution by chemically modified potato starch: equilibrium and kinetic studies.

The biosorption capacity of chemically modified potato starch (CPS) for Cr(VI) from aqueous solution was investigated. The materials derived from carbohydrates are biodegradable and are generally regarded as safe and environmentally acceptable. The hydroxyl, carboxyl and carbonyl groups are responsible for the biosorption process. In the present study, the influence of various important parameters such as pH, time, biosorbent dose and initial Cr(VI) concentration on the biosorption capacity were investigated. The isotherms such as Langmuir, Freundlich and Tempkin were studied. The Freundlich and the Redlich-Peterson isotherms had been well fitted the biosorption of Cr(VI) with chemically modified potato starch. The kinetics of Cr(VI) removal using chemically modified potato starch was well explained by second-order kinetic model. The thermodynamic parameters were also evaluated from the biosorption measurements. Among the various desorbing agents tested, 98.2 percent chromium recovery was achieved with 0.1molL(-1) NaOH.