The Adsorption Isotherm and Kinetics Studies of Cu(II) and Cr(III) Metal Ions from Aqueous Solutions on Activated Biosorbent of Coffee Pulp Waste

Heavy metals such as copper and chromium are toxic even trace levels in contaminated water can be harmful to humans. Heavy metals removal from wastewater using low cost technology, resulting in high efficiency and being environmentally friendly, is still a research concern. The purpose of this study is to investigate the possibility of using activated coffee pulp biosorbent to evacuate Cu(II) and Cr(III) heavy metal ions from an aqueous solution. Coffee pulp powder was activated with sodium hydroxide at different ratios of biosorbent to activator. The numerous framework, such as exposure time, initial concentrations of Cu(II) and Cr(III), isotherms as well as kinetic adsorption behaviors, were investigated through a batch adsorption technique. The results revealed the weight ratio of coffee pulp powder to NaOH for the favorable condition for Cu(II) and Cr(III) adsorption was 1:3.75, with their maximum adsorption capacities being 3.7319 ± 0.0058 and 3.3255 ± 0.0129, respectively. The optimum operating conditions were obtained at 60 minutes of contact time, 70 mg/L, and 100 mg/L concentrations for Cu(II) and Cr(III) metal ions, with the adsorption capacity being 2.9155 mg/g and 4,1278 mg/g, respectively. The adsorption behavior of Cu(III) and Cr(III) onto the NaOH-activated coffee pulp biosorbent surface follows the Freundlich isotherm model and correspond to pseudo-second-order. This study proves that biosorbents derived from agricultural waste, such as activated coffee pulp, can be used as an alternative and effective adsorbent to remove Cu (II) and Cr (III) from aqueous solutions..