Removal of copper(II) using deacetylated konjac glucomannan conjugated soy protein isolate

•A novel biosorbent (DKGM-C-SPI) was prepared and characterized.•DKGM-C-SPI showed desired adsorption performance for Cu2+ ions.•SPI enhanced Cu2+ ions sorption performance of DKGM.•Maximum sorption capacity of DKGM-C-SPI for Cu2+ ions was 62.50 mg g−1.

In this study, an environmentally friendly biosorbent deacetylated konjac glucomannan conjugated soy protein isolate (abbreviated as DKGM-C-SPI) was prepared for Cu2+ ions removal from aqueous solution. Scanning electron microscopy, Fourier transform infrared spectroscopy and zeta potential analysis revealed successful conjugation of soy protein isolate (SPI) onto deacetylated konjac glucomannan (DKGM) matrix. A comparative adsorption performance of DKGM-C-SPI and DKGM was tested to remove Cu2+ ions from aqueous solution. DKGM-C-SPI showed the desired adsorption performance for Cu2+ ions. The adsorption equilibrium of DKGM-C-SPI was achieved within 30 min. The adsorption behavior of DKGM-C-SPI followed a pseudo-second-order reaction model. The maximum Cu2+ ion adsorption capacities obtained from the Langmuir isotherms fit were shown to be 62.50 mg g−1 for DKGM-C-SPI and 12.23 mg g−1 for DKGM. This impressive increase about 5 times in Cu2+ ion adsorption capacity is attributed to the strong Cu2+ ion chelating ability of the soy protein isolate (SPI) on the DKGM matrix. These results confirm that the DKGM-C-SPI biosorbent has a potential for Cu2+ ion extraction from wastewater.

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