Removal of Pb(II) and Cd(II) from aqueous solution using alkaline-modified pumice stone powder (PSP): equilibrium, kinetic, and thermodynamic studies.

Adsorption processes of Cd(II) and Pb(II) from aqueous solutions onto pumice stone powder (PSP) were in-vestigated in batch mode. The inuences of solution pH, contact time, adsorbent dosage, initial metal (M) concentration, and temperature on adsorption process were investigated. The kinetic and isotherm data were analysed using different model equations. The adsorption process was consistent with the Langmuir model for both metal ions with high R2 and low χ2 values for both Pb(II) and Cd(II). The maximum monolayer adsorption capacities were 28.09 and 27.17 mg g-1 for Pb(II) and for Cd(II), respectively. The pseudo-second order kinetic model explained the kinetic data as evidenced by the calculated qe (cal) values (10.42 mg g-1 for Pb(II) and 2.62 mg g-1 for Cd(II)) agreeing with the experimental values (9.24 mg g-1 for Pb(II) and 2.49 mg g-1 for Cd(II)). Consequently, the present study demonstrated that PSP could be utilised in adsorptive removal of Cd(II) and Pb(II) ions from aqueous solutions

Fabrication of a sustainable maize stover-graft-methyl methacrylate biopolymer for remediation of methyl red contaminated wasters

In the present study, a sustainable maize stover-g-methyl methacrylate (MS-g-MMA) biopolymer was synthesized by free radical polymerization using benzoyl peroxide initiator and applied in the removal of methyl red dye from aqueous solutions. Monomer concentration, initiator concentration, temperature and reaction time were the synthesis independent variables. The prepared biopolymer was characterized by scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) and fourier transform infrared spectroscopy (FTIR). The effects of pH (2 − 11), contact time (5–300 min), initial concentration (5–50 mg/L), adsorbent dosage (0.2–2 g) and temperature (20–50 °C) were investigated through batch adsorption studies. The optimum conditions were determined to be pH 6, contact time 120 min, adsorbent dosage 0.2 g and initial concentration 5 mg·L− 1. The adsorption kinetic, isotherm and thermodynamic parameters were studied. The kinetic and isotherm data followed pseudo-second-order and Langmuir models, respectively. The maximum adsorption capacities of 13.58 and 23.47 mg/g were achieved for raw and modified maize stover, respectively. The adsorption process was endothermic, spontaneous and chemisorption. This study showed that MS-g-MMA could be applied as a potential biopolymer for the removal of methyl red from aqueous solutions

Preparation of poly(methyl methacrylate)–grafted Hyparrhenia hirta for methyl red removal from colored solutions

Poly(methyl methacrylate)–grafted Hyparrhenia hirta (PMMA-g-Hh) biopolymer was prepared through radical polymerization using potassium persulfate (KPS) and applied in adsorption of methyl red from colored solutions. Solvent amount, initiator concentration, monomer concentration, temperature, and reaction time were the reaction parameters investigated for grafting. The biopolymer was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction spectroscopy (XRD). The adsorption process was investigated with respect to pH, contact time, initial concentration, adsorbent dosage, and temperature. The optimum adsorption parameters were pH 6, contact time 90 min, adsorbent dosage 0.6 g, and initial concentration 50 mg/L. The Langmuir adsorption model best fitted the adsorption process, with maximum adsorption capacities of 19.95, 6.89, and 4.02 mg/g at adsorbent dosages of 0.2, 0.6, and 1.0 g, respectively. The pseudo-second-order model described the kinetics data better. The adsorption process was physical, spontaneous, and endothermic. The adsorbent was still active after 10 adsorption-desorption cycles, showing its suitability for use in colored solutions treatmen