From garbage to biosorbent: overview raw and hexane purified almond shells for nickel (II) ions removal

The main purpose of the experimental study is to examine Ni(II) biosorption capacities of raw (RAS) and hexane pretreated (HPAS) almond shells by applying them to wastewater. In the context of the study, batch experiments were conducted to investigate the influence of various parameters, including temperature, RAS and HPAS dosages, pH, and contact time, on the removal efficiency of Ni(II). FTIR and SEM–EDX analyses were performed to determine the functional groups and surface morphology of RAS and HPAS. Adsorption capacities were calculated using different isotherm and kinetic models with the obtained experimental data. It was determined that under optimum conditions (2 g RAS/HPAS, pH 5.87, 10 min, 20 °C), maximum removal efficiencies of Ni(II) for RAS and HPAS were 72% and 81.25%, respectively. The equilibrium adsorption fitted the Langmuir isotherm and pseudo-second-order kinetic. The optimum adsorption capacities for RAS and HPAS were found to be 3.60 and 5.67 mg/g, respectively. Four separate error functions were used to evaluate the suitability of isotherm and kinetic models under equilibrium conditions: MPSD, HYBRID, NSD, and ARE. The findings of the error analysis showed that the HYBRID functions were the smallest in all models. The thermodynamic parameters showed that the process was feasible and exothermic. Experimental results demonstrate that RAS and HPAS are economical and readily available adsorbents for the removal of Ni(II) from aqueous solution. It was also found to give satisfactory results for the removal of Ni(II) without the need for rather expensive modified methods.