Shella Permatasari Santoso, Alfin Kurniawan, Artik Elisa Angkawijaya, Hardy Shuwanto, I.D.A.A. Warmadewanthi, Chang-Wei Hsieh, Hsien-Yi Hsu, Felycia Edi Soetaredjo, Suryadi Ismadji, Kuan-Chen Cheng
The contamination of drinking water and freshwater by heavy metals has become a growing concern for human health and environment that calls for immediate remedial action. Adsorption process has been proved to be a promising technology for producing treated water that complies with drinking water standards. In this work, we describe a facile and low-cost approach to fabricate porous calcium alginate composite sponges containing exfoliated bentonite clay (denoted as CRAB) by saponin-assisted foaming and external gelation techniques for efficient removal of Cu2+ and Cr6+ ions from aqueous solution and real world water samples. The formation of exfoliated organoclay within the composite matrix was achieved by intercalation of saponin into the interlayer spacing of bentonite and subsequent penetration of alginate chains. Morphological and textural characterizations revealed that the resultant CRAB sponges mainly exhibited meso- and macropores in their interior. The formation of calcium alginate-organoclay exfoliated composites was also verified by the XRD results. The performance of CRAB sponges in removing Cu2+ and Cr6+ ions from aqueous solution was evaluated under different environmental conditions including temperature, pH, ionic strength, and background electrolyte. The results demonstrated that the uptake capacity of Cu(II) and Cr(VI) increased with increasing temperature, suggesting the endothermic nature of the adsorption process. The Freundlich isotherm model was found to better interpret the equilibrium adsorption behaviors of Cu2+ and Cr6+ ions onto the investigated sorbents than the Langmuir model. The sorption kinetics for these metal ions followed a pseudo-first-order model. Reusability tests for CRAB sponge demonstrated that the sorption capacity of the sorbent is well maintained over three successive adsorption–desorption cycles. Together, these results indicate the great potential of low-cost and sustainable CRAB sponges for remediation of water polluted with copper and hexavalent chromium ions. © 2022 Elsevier B.V.
Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Kalijudan 37, Surabaya, 60114, Indonesia; Collaborative Research Center for Zero Waste and Sustainability, Jl. Kalijudan 37, East Java, Surabaya, 60114, Indonesia; Research Group for Advanced Materials and Sustainable Catalysis (AMSC), State Key Laboratory Breeding Base of Green Chemistry and Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310032, China; Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, No. 43, Sec 4, Keelung Road, Taipei, 106, Taiwan; Plant Lipid Research Team, RIKEN Center for Sustainable Resource Science, Yokohama, 230-0045, Japan; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Road, Taipei, 106, Taiwan; Department of Industrial Engineering, Universitas Prima Indonesia, Jalan Sampul No. 4, North Sumatra, Medan, 20118, Indonesia; Department of Environmental Engineering, Faculty of Civil, Environmental, Geo Engineering, Institut Teknologi Sepuluh Nopember, Kampus ITS Sukolilo, Surabaya, 60111, Indonesia; Department of Food Science and Biotechnology, National Chung Hsing University, South Dist., Taichung City, 40227, Taiwan; Department of Medical Research, China Medical University Hospital, North Dist., Taichung City, 404333, Taiwan; School of Energy and Environment, Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong; Shenzhen Research Institute of City University of Hong Kong, Shenzhen, 518057, China; Institute of Food Science and Technology, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan; Institute of Biotechnology, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan; Department of Medical Research, China Medical University Hospital, Taichung, 40402, Taiwan; Department of Optometry, Asia University, 500, Lioufeng Road, Wufeng, Taichung, 41354, Taiwan