Removal of Copper and Hexavalent Chromium Using Immobilized Modified Sludge Biomass Based Adsorbent

Abstract

The present work, deals with the development of an efficient modified sludge biomass (MSB) based adsorbent and subsequent application for the removal of copper and hexavalent chromium from wastewater. Different approaches of immobilization based on the use of polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), calcium alginate (CA), and activated carbon (AC) have been investigated with an objective of obtaining the most efficient biosorbent. Characterization studies for the adsorbents were performed followed by batch studies to compare the efficacy of different adsorbents for metal removal. Using the most efficient biosorbent, continuous operation studies were performed for understanding the effect of operating conditions such as initial pH, flow rate, inlet concentration, and bed height. The adsorption capacity was greatly affected by initial pH, adsorbent amount, contact time, and the type of polymer matrix. The order of adsorption capacities were MSB–PVA–CMC–AC > MSB–PVA–CMC > MSB–PVA > MSB–CA with maximum values being 288.6 and 215.4 mg g−1 for Cu(II) and Cr(VI), respectively. The experimental data were successfully fitted into different isotherms and kinetic models to establish the important design parameters. Reusability studies revealed that the MSB–PVA–CMC biosorbent could be reused for five biosorption–desorption cycles without any significant loss in the adsorption capacity. Overall, the immobilized MSB on PVA–CMC has been demonstrated as an effective biosorbent for removal of copper and chromium.