Humified insoluble solid for efficient decontamination of nickel and lead in industrial effluents

The aim of the present study was to evaluate the ability to retain heavy metals cations (Ni2+ and Pb2+) from humified insoluble solid (HIS) that remains after the humic substances (HS) are extracted from a vermicompost (VC) in industrial wastewaters. HIS has ionizable functional groups and carbon types belonging to oxygen structures (di-O-Alkyl-C, O-Aromatic, -COOH, -C=O) with potential to establish interactions with heavy metals cations in aqueous dissolution. The kinetic study showed a pseudosecond- order behavior of retention, and the adsorption was best described when data were analyzed using the Freundlich isotherm. The Q(max) for Ni2+ and Pb2+ was 34.1 mg g(-1) (HIS) and 151.1 mg g(-1) (HIS). Scanning electron microscopy (SEM) confirmed the retention of heavy metals on the HIS surface; additionally, the spectra of HIS with retained metals indicated the involvement of the oxygen groups in the interaction withmetals. The effectiveness of HIS to retain Ni2+ and Pb2+ was determined in retention studies with industrial effluents in lab conditions with 5 g, 10 g and 20 g, pH 7, contact time: 150 min and T = 25 degrees C. Tests made with industrials wastewater "Factory of White Ceramic'' showed that the extraction capability of Ni2+ and Pb2+ was 98% and 96%, respectively. These results demonstrate for the first time, the ability of the (HIS) material to be used as remover of heavy metal cations. (C) 2013 Elsevier Ltd. All rights reserved.