Heavy metals uptake from aqueous solutions and industrial wastewaters by humic acid-immobilized polymer/bentonite composite: Kinetics and equilibrium modeling

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 156; no. 1; pp. 146 - 156
• Main Authors: Anirudhan, T.S., Suchithra, P.S.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 2010; Elsevier
• Subjects: Adsorbents; Adsorption; Applied sciences; Aqueous solutions; Bentonite; Chemical engineering; Exact sciences and technology; General purification processes; Heavy metal ion; Humic acid; Ion exchange; Mathematical models; Metal ions; Pollution; Polymer/clay composite; Regeneration; Waste water; Wastewater; Wastewaters; Water treatment and pollution; Regeneration; Adsorption; Wastewater; Humic acid; Polymer/clay composite; Heavy metal ion; Second order; Organic matter; Adsorption isotherm; Adsorption capacity; Metal ion; Modeling; Composite material; Waste water; Batchwise; pH; Ion exchange; Complexation; Uptake; Langmuir isotherm; Heavy metal; Industrial waste water; Ionic strength; Kinetics; Aqueous solution
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2009.10.011

This study explored the feasibility of utilizing a novel adsorbent, humic acid-immobilized-amine-modified polyacrylamide/bentonite composite (HA-Am-PAA-B) for the adsorption of Cu(II), Zn(II) and Co(II) ions from aqueous solutions. The FTIR and XRD analyses were done to characterize the adsorbent material. The effects of pH, contact time, initial adsorbate concentration, ionic strength and adsorbent dose on adsorption of metal ions were investigated using batch adsorption experiments. The optimum pH for Cu(II), Zn(II) and Co(II) adsorption was observed at 5.0, 9.0 and 8.0, respectively. The mechanism for the removal of metal ions by HA-Am-PAA-B was based on ion exchange and complexation reactions. Metal removal by HA-Am-PAA-B followed a pseudo-second-order kinetics and equilibrium was achieved within 120 min. The suitability of Langmuir, Freundlich and Dubinin-Radushkevich adsorption models to the equilibrium data was investigated. The adsorption was well described by the Langmuir isotherm model. The maximum monolayer adsorption capacity was 106.2, 96.1 and 52.9 mg g −1 for Cu(II), Zn(II) and Co(II) ions, respectively, at 30 °C. The efficiency of HA-Am-PAA-B in removing metal ions from different industry wastewaters was tested. Adsorbed metal ions were desorbed effectively (97.7 for Cu(II), 98.5 for Zn(II) and 99.2% for Co(II)) by 0.1 M HCl. The reusability of the HA-Am-PAA-B for several cycles was also demonstrated.