Adsorption Mechanism of Composite Whisker on Copper Ions and Lead Ions

Experimental and DFT study of Cu(II) removed by Na-montmorillonite

The experimental and theoretical studies on the adsorption of Cu(II) on the surface of Na-montmorillonite (Na-Mt) were reported. Effects of batch adsorption experimental parameters were studied. Density functional theory and molecular dynamics simulations were used to study the adsorption of Cu(II) on montmorillonite (001) surface. The adsorption reached equilibrium within 80 min and the adsorption capacity was 35.23 mg·g^-1 at 25 °C. The adsorption data of Cu(II) were consistent with pseudo-second-order kinetics and Langmuir isotherm models. The adsorption process was dominated by physical adsorption (E_a was 37.08 kJ·mol^-1) with spontaneous endothermic behavior. The influence of coexisting cations on the adsorption capacity of Cu(II) was Mg(II) > Co(II) > Ca(II) > Na(I). The simulation results demonstrated that there were no significant differences in the adsorption energy of Cu(II) at the four adsorption sites on the montmorillonite (001) surface. Cu(II) had more electron transfer than Na(I). The diffusion coefficient of Cu(II) in the aqueous solution system containing montmorillonite was 0.85×10^-10 m²·s^-1. Considerable amounts of Cu(II) ions were adsorbed at a distance of 0.26 and 2.25 Å from the montmorillonite (001) surface. The simulation results provided strong supporting evidence for experimental conclusions.

Fabrication of Biochar Materials from Biowaste Coffee Grounds and Assessment of Its Adsorbent Efficiency for Remediation of Water-Soluble Pharmaceuticals

Biowaste coffee grounds have been recognized as an effective and relatively low-cost adsorbent to complement conventional treatment techniques for removing emerging contaminants (ECs) from the waste stream through modification to useful biochar. The purpose of this study was to make biochar from biowaste coffee grounds through the pyrolysis process and investigate its potential capacity for the removal of pharmaceuticals from water. The biochar was prepared by pyrolysis process under argon gas conditions, and its adsorption capacity for pharmaceuticals was evaluated. The as-prepared biochar shows a surface area of 232 m2 g−1. The adsorption of salicylic acid, diclofenac, and caffeine onto the biochar show adsorption capacities of 40.47 mg g−1, 38.52 mg g−1, and 75.46 mg g−1, respectively. The morphology, functional groups, crystallinity, and specific surface area were determined by SEM, FTIR, XRD, and BET techniques, respectively. Kinetic results reveal that the experimental data fit the pseudo-second-order model and the Temkin isotherm model. In conclusion, these results illustrate the potential of biochar produced from biowaste coffee grounds could play an important role in environmental pollution mitigation by enhancing removal of pharmaceuticals from conventional wastewater treatment effluent, thereby minimizing their potential risks in the environment.