Bioadsorbents from algae residues for heavy metal ions adsorption: chemical modification, adsorption behaviour and mechanism

ABSTRACT

Biosorption is an emerging technology for the removal of heavy metals from industrial wastewater by natural or modified biomass. In this study, we proposed a novel protocol for making full use of seaweeds. Brown seaweed Sargassum carpophyllum residue (SCR) and green seaweed Caulerpa lentillifera residue (CLR) were obtained after extraction of the bioactive polysaccharides. The obtained residues were further chemical modified by butanedioic anhydride to obtained respective carboxylated product, named CSCR and CCLR. According to the titration results, CSCR and CCLR contained 2.77 and 2.12 mmol/g of carboxyl group. After modification, the adsorption capacity for metal ions increased by 3–6 times. The adsorption capacity of CSCR for Cu²⁺, Pb²⁺, Cd²⁺ and Mn²⁺ was 52.37, 107.11, 85.62, and 43.52 mg/g, and that of CCLR was 78.10, 108.80, 87.30 and 57.80 mg/g, respectively. The adsorption was well described by the pseudo-second-order kinetic model and Langmuir adsorption isotherm equation.

GRAPHICAL ABSTRACT

KEYWORDS:

• Algae residue
• carboxylation
• butanedioic anhydride
• metal ion
• adsorption

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Key Research and Development Plan of Hainan Province [grant number ZDYF2018232]; the Project of Scientific Research Platform Construction of Hainan University [grant number ZY2019HN09]; and the Science and Technology Planning Project of Haikou [grant number 2016030]. The authors also thank the financial support from the Key Laboratory of Water Pollution Treatment and Resource Reuse of Hainan Province.