Multicomponent heavy metals adsorption by raw coir dust and processed coir pith: experimental investigation and life cycle analysis

Abstract

Coir is an abundant bio-resource coming out as coconut industry residues. With the high fiber content and porous surface area, coir can be utilized as an adsorbent for heavy metal removal from water. This study investigates the capability of multi-component heavy metal removal using raw coir dust and processed coir pith. The capabilities of raw coir dust and processed coir pith samples to remove the major heavy metals are measured by the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) method. Raw coir dust indicates higher capabilities of heavy metal removal, compared with processed coir pith, recording the highest efficiencies of 17.66%, 21.27%, 18.90%, 6.66%, 12.87%, 21.63%, and 24.29%, for As, Cd, Cr, Cu, Mn, Ni, and Pb, respectively. The study also evaluates life cycle energy consumption and global warming impact of the two adsorbents. Production of one tonne of processed coir pith accounts for a life cycle energy consumption of 705.53 MJ and global warming impact of 248.15 kg CO 2eq while raw coir dust shows insignificant life cycle energy consumption and global warming potential. The effect of adsorption conditions on heavy metal removal efficiencies, stage-wise life cycle analysis, and the appropriateness of coir as environmentally benign heavy metal adsorbents are discussed.