Heavy metal adsorption potential of weed compost derived humic substances

The chemical pollution due to anthropogenic origin especially through heavy metals, pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls are serious threats to the environment, and their main sources are industry, transport, and agriculture. Most of these pollutants reach and accumulate air, water and/or soil and threaten the life on this planet. In this context, this paper mainly evaluates the Cadmium (Cd) and Lead (Pb) adsorption potential of weed compost derived humic substances for detoxification of these two heavy metals. Weed compost was produced during August to December from locally available weeds such as Chromolaena odorata, Macaranga peltata, Lantana camara, and Mikania micarantha in 3:2:1:1 proportion, and humic substances such as humic acid (HA) and fulvic acid (FA) were extracted using standard procedure. In particular, six different concentrations (2-10 mg) of lead nitrate and cadmium nitrate were used to study the adsorption of Cd2+ and Pb2+ onto HA and FA. The findings demonstrated that the adsorption of cadmium and lead on humic substances were positively correlated, increased with increase in concentrations of the metal ions. For Cd, HA showed maximum adsorption of 383.5 ppm at 10 mg, while FA showed 340.50 ppm. For Pb, HA and FA showed adsorption of 605.60 ppm and 595.60 ppm, respectively, at 10 mg. Lead adsorption by humic substances surpassed that of cadmium. In addition to heavy metal adsorption, this study also characterized the structural and functional properties of humic substances. The study revealed the heavy metal adsorption potential of weed compost derived humic substances.