Facile preparation of chitosan copper complex and selective adsorption of methyl orange

Purpose The effective removal of harmful dyes from wastewater with green methods is still one of global challenges, and it has attracted great interest. The design and preparation of adsorbent is the core of an adsorption system. From the viewpoint of sustainable development, adsorbents with fewer preparation steps, simpler preparation process, less use of organic solvents are urgently needed and favorable for the adsorption process. In addition, adsorption efficiency is another important factor to be considered. Design/methodology/approach Chitosan metal complex (CTS-Cu) was prepared via a green and facile method with distilled water, and then it was characterized by a series of techniques. Applying the complex, this study was sought to detect the efficacy of removing organic dyes from aqueous solution. Findings The methyl orange (MO) adsorption was significantly affected by adsorption temperature and ionic strength. The adsorption capacity of CTS-Cu for MO was as high as 344.10 mg/g, while that of chitosan (CTS) was 34.14 mg/g at 45°C, indicating the superior advantage of modification and relatively higher affinity of the former adsorbent. It was interesting to find that CTS-Cu exhibited certain adsorption selectivity of MO to methylene blue (MB). However, CTS had certain adsorption selectivity of MB to MO. Research limitations/implications The chitosan–metal complexes with other metals have been prepared. The adsorption behaviors for organic dyes of these materials need further and future investigation. Practical implications CTS-Cu was prepared with distilled water as solvent under room temperature. The costs of CTS and CTS-Cu were relatively low. CTS-Cu could effectively enrich anionic dyes like MO from aqueous solution. Originality/value The preparation process of CTS-Cu was simple and relatively green. The adsorption capacity of CTS-Cu for MO was excellent, and it exhibited certain adsorption selectivity for MO.