Preparation of cellulose-based porous adsorption materials derived from corn straw for wastewater purification

Various methods have been used to cope with heavy metal ion contamination in wastewater, which caused serious hazards to ecological and human health. Adsorption is one of the most frequent, economical and effective methods for removing these contaminants. Herein, a porous and amino-rich cellulose-based composite adsorbent (PEI-PCS) with anisotropic property was successfully prepared by covalently cross-linking polyethyleneimine on delignified corn straw. Combined with the porosity of straw substrate and the chelating ability of amino group to metal ions, the as-prepared PEI-PCS exhibited universality (various metal ions), rapid adsorption behavior (within 180 min achieve adsorption equilibrium), high adsorption capacity (85.47 mg g^-1 for Cu(II)), and good durability (70 % of adsorption efficiency after 5 cycles). In addition, the adsorption process was conformed to pseudo-second-order dynamics and the Langmuir isotherm models. Lastly, the adsorption mechanism was also elucidated. This study provides a sustainable pathway for the manufacture of efficient biomass-based adsorbents and confirms that functionalized corn straw is a promising material for the treatment of heavy metal ions.