Preparation and characteristics of anion exchanger from corn stalks

Anion exchangers were prepared from corn stalks (CS) after reaction with epichlorohydrin and triethylamine by using diethylenetriamine (DETA) as modifying agent in the presence of N,N-dimethylformamide (DMF). The synthesis conditions for preparing corn stalks quaternary amino anion exchanger (CS-QE) by the single-factor experiments were optimized, with removal capacity of Cr(VI) and the production yield as indicators. Factors like CS dosage, volumes of organic liquid chemicals and synthesis temperatures were investigated. The optimal synthesis parameters were CS:epichlorohydrin:DMF:DETA:triethylamine = 3 g:10 mL:8 mL:6 mL:10 mL. The optimal experimental temperature in the synthesis process was 100 °C. A relatively large removal (99.4%) was attained from a solution as concentrated as 200 mg/L at natural pH (about 4.7) with an optimized adsorbent dosage of 2 g/L. The performance of CS-QE was characterized by SEM, BET surface area, FTIR and Raman spectroscopic analysis. The FTIR spectrums analysis validated that a large number of amino groups with positive charge were conducted into the structure of CS-QE. The Raman shift of the Cr(VI) peak indicated the electrostatic attraction between the Cr(VI) ions and positively charged amine sites.

Research highlights
► Anion exchanger was prepared from corn stalks by the single-factor experiments.
► Its performance was characterized by SEM, BET, FTIR and Raman analysis.
► A large number of amino groups with positive charge were detected in the adsorbent.
► The optimized anion exchanger has an excellent Cr(VI) removal capacity.