Cross-Linked Amidoximated Poly(acrylonitrile-acrylic acid) Microspheres with Exceptional Adsorption Capacity, Reusability towards Copper(II): Batch and Column Studies

s: Acrylonitrile-based adsorbents are effective candidates for metal ions removal from wastewater. However, their performance is often limited by their unsatisfied stability, reusability, and sorption efficiency. In this contribution, the amino group of urea was cross-linked with the carboxyl group of the firstly formed AN (acrylonitrile) and AA (acrylic acid) copolymer to improve the strength, while the cyanide group of AN was dedicatedly reacted with hydroxylamine hydrochloride to obtain an amidoxime group endowing the strong adsorption capacity for Cu (II). The optimum adsorption conditions of the as-prepared adsorbent for Cu (II) were at 25 degrees C and pH 7, which only consumed 60 min to reach the adsorption equilibrium. The theoretical maximum adsorption capacity was 176.717 mg g(-1). The amidoxime group on the surface of the adsorbent was inherently entitled to the outstanding adsorption capacity. Langmuir and pseudo-second-order model fitted the adsorption process. Furthermore, there still retained 84.4 % of the original adsorption capacity after seven cycles. Under column adsorption, the adsorbed particles were surprisingly lumped together, which can be easily taken out entirely after adsorption for recycling collection. Overall, the obtained acrylonitrile-based adsorbents, easily regenerated with high performance and excellent sorption efficiency, should be a promising sorbent.

Automated summary

In this study, acrylonitrile-based adsorbents were modified by cross-linking the amino group and carboxyl group to improve stability and strength, and by reacting the cyanide group with hydroxylamine hydrochloride to enhance adsorption capacity for Cu (II). The optimized conditions for Cu (II) adsorption were 25 degrees C and pH 7, with a equilibrium time of 60 minutes. The adsorbent showed high adsorption capacity and retained a significant portion of its original capacity after multiple cycles.