Lead (Pb2+) removal in water using different forms of spent arabica coffee grounds at varying contact time

Abstract

The availability of clean water for drinking and domestic use is a basic human right, but it is oftentimes denied to some users due to lack of facilities that could clean water. The use of cheap and abundant biomaterials can help solve this problem. Spent coffee grounds is a biomaterial that can remove heavy metals, such as lead (Pb²⁺) in water. In this study, the Ultraviolet Visible Spectrophotometry analysis resulted in the computation of the Total Removal Efficiency (R%) on lead (Pb²⁺) in water using raw, crushed, carbonized, and chemically treated spent coffee grounds of the Arabica variety. The crushed and carbonized samples had the highest Total Removal Efficiency (R%) at a shorter coffee-lead contact time. This is due to the exposure of more surfaces as seen in the Scanning Electron Microscopy micrographs, where more open pores and deeper cages or crevices are exposed for metal adsorption. The Atomic % of elemental Carbon was also high for the crushed sample. FTIR analysis revealed that the presence of charged amines (C=NH⁺) in the carbonized and chemically treated samples resulted to lead (Pb²⁺) adsorption in a short time. Abundant and cheap waste biomaterials, such as spent Arabica coffee grounds can exceed the Total Removal Efficiency (R%) on lead (Pb²⁺) of commercially available activated carbon.