High crosslinked sodium carboxyl methylstarch- g -poly (acrylic acid- co -acrylamide) resin for heavy metal adsorption:
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RESEARCH ARTICLE
High crosslinked sodium carboxyl methylstarch-g-poly (acrylic acid-co-acrylamide) resin for heavy metal adsorption: its characteristics and mechanisms Ming Zhang 1 & Ping Yang 1 & Guihong Lan 2 & Yongqiang Liu 3 & Qin Cai 1 & Junnan Xi 2 Received: 26 February 2020 / Accepted: 29 June 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract A lower expansive heavy metal adsorbent, high crosslinked sodium carboxyl methylstarch-g-poly (acrylic acid-co-acrylamide) resin (HCAA), has been prepared by enhancing the crosslinking degree of the traditional water-absorbing polymer under the graft copolymerization reaction. Further heavy metal adsorption experiments, morphology analysis, and structure characteristic observations indicate that HCAA resin has an excellent heavy metal adsorption properties for Cr3+, Cu2+, Ni2+, and Zn2+ of 80.08, 158.07, 155.71, and 137.15 mg/g, respectively. The nanoholes in network structures of HCAA resin expanding in solution provide an effective diffusion and exchange channels for heavy metal ions and Na+. The adsorption process of HCAA containing –COONa is attributed to ion exchange process, and its essence is to form the coordination bond with heavy metals. The adsorption capacity differences of –COO− have been explained by using the coordination chemistry theory. In addition, the adsorption selectivity of an expansive adsorbent containing –COONa are heavy metals > H2O >> Na+. Our research puts forward an insight that increasing the crosslinker content on the basis of the traditional super absorbent resin can obtain a lower expansive adsorbent to heavy metal pollutants. Keywords Heavy metal adsorption . Expansive adsorbent . Mechanism . Carboxylic group . Ion exchange
Introduction Environmental pollution containing heavy metal ions in wastewater or soils has increasingly become a widely concerned topic because of its non-biodegradability and high toxicity. In the natural environment, heavy metal pollutants can only be transported from water or soils into the organisms, accompanied by the chemical morphologic transformation,
Responsible Editor: Angeles Blanco * Ping Yang [email protected] 1
College of Architecture and Environment, Sichuan University, Chengdu 610065, China
2
College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, People’s Republic of China
3
Faculty of Engineering and Physical Sciences, University of Southampton, Southampton SO17 1BJ, UK
including exchangeable, carbonate-bound, metal-organic complex-bound metals, and so on (Fiyadh et al. 2019; Hossain et al. 2012). Long-term accumulation of heavy metals has a potential harm to organism health. Thus, various techniques, such as chemical precipitation, membrane separation, biotransformation, and adsorption, have been applied to reduce the heavy metal concentration before discharge (Gupta and Nirwan 2015; Gao et al. 2019a; b; Matlock et al. 2002; Uddin 2017). Among them, only adsorption is very promising which can completely adsorb and enrich
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