Adsorption of Lead, Chromium and Copper from Aqueous Phase Using Orange Peels as Low-Cost Adsorbent

Abstract

Adsorption is a highly effective technique for eliminating toxic metals from the environment. Lead (Pb), Chromium (Cr), and Copper (Cu) are some of the most dangerous and carcinogenic toxic metals that can contaminate water resources. The aim of this work was to evaluate the efficacy of orange peels as a cost-effective adsorbent for the elimination of toxic metals, including lead, chromium, and copper, from wastewater. The orange peels were obtained, cut into pieces, washed, and grounded to powder. Dosages of the orange peels weighed as 1g, 2g, 3g, 4g, and 5g were added to the prepared standard solutions of toxic metals (Pb, Cr and Cu) at varied levels of 1 mg/L, 10 mg/L, 20 mg/L, 30 mg/L, as well as 50 mg/L. The results obtained for the removal efficacy for the toxic metals Pb, Cr, and Cu ranged from 98.77% to 99.81%, 96.72% to 99.58%, and 96.33% to 45.73%, respectively. Langmuir as well as Freundlich isotherms were used to characterize the interactions between the toxic metals and the orange peels as well as the adsorption capacities of each metal. Both the Langmuir and Freundlich isotherm models indicated that orange peels are effectual adsorbents for the elimination of hazardous metals out of the aqueous solutions. Langmuir's adsorption isotherm model yielded the most accurate representation of toxic metal adsorption by the orange peels.  For nearly all of the examined toxic metals, the pH at which the studies were carried out demonstrated very high elimination effectiveness, except copper which encountered low elimination when pH was increasing. Based on our findings, orange peels can be good adsorbent for remediating wastewaters that are contaminated with toxic metals.