Heavy metals removal from industrial effluent using cocosnucifera shells waste derived activated carbon

The current study investigated the performance of activated carbon (AC), which was produced from waste cocosnucifera shells and impregnated with potassium hydroxide (KOH), in eliminating heavy metals (HMs) from aqueous solutions and actual tannery wastewater. KOH-modified AC exhibits a porous and amorphous structure. It displayed a 53.442 m²/g surface area that was rich in carboxylic functional groups. It performs very well for removing heavy metals (HMs) from aqueous solutions, as evidenced by the removal of over 80% of Cd, Pb, Mn, Ni, and Cu from aqueous solutions under both optimized and non-optimized reaction conditions. However, when evaluated for the removal of HMs from actual wastewater, its effectiveness was dramatically reduced, falling from 80% to less than 50% under non-optimized conditions. Its efficiency in actual wastewater was enhanced via optimizing reaction parameters such as contact duration (x₁), HM concentration (x₂), pH (x₃), AC dosage (x₄), and reaction temperature (x₅) using response surface methods. The maximum sorption capacity of HMs was attained at optimum conditions of 18.10 min, 59.72 mg/L, 9.10, 0.74 g, and 32.76 °C resulting to over 95% removal of HMs. A combination of thermodynamic data, adsorption models, and adsorption isotherms suggested that HMs were chemisorbing on KOH-modified AC. It showed outstanding potential for desorption and reusability when regenerated using hydrochloric acid (HCl).