Ammonium Perchlorate-Binding Poly(allylamide hydrochloride) Hydrogels for Wastewater Remediation

摘要

Systems that are capable of removing highly toxic anions from wastewater effluents, even at extremely low concentrations, are a major need in the defense industry. This study reports on the features of two new batch and continuous-Bow sorption processes with regard to ultimate removal and recovery of the perchlorate (ClO_4) anion from ammonium perchlorate (NH_4ClO_4) wastewater. The sorbent devel- oped is a crosslinked poly(allylamine hydrochloride) (P AA. HCl) polymeric hydrogel. The pH-sensitive PAA.HCl hydrogels were synthesized by chemically crosslinking a solu- tion of linear PAA.HCl chains with epichlorohydrin (EPI). The perchlorate-binding , capacity of the polymer gels was measured in standard solutions and studied as a function of gel synthesis parameters. Equilibrium perchlorate loadings of 5770 +-870 mg ClO4/g gel were calculated from measurement of the decrease in perchlorate : concentration in aqueous standard solutions using UV-Vis spectrophotometry. Batch experiments in wastewater originating from the Naval Surface Warfare Center (NSWC) Indian Head Division showed that perchlorate concentrations decreased by: 85%.. Preliminary lab-scale packed-column experiments in wastewater achieved up to 40% reduction in total perchlorate content. The regeneration ability of the gels was demonstrated by release of the bound perchlorate anions, upon washing with a 1lf : NaOH solution, providing opportunities to recover and reuse the hydrogel over multiple : regeneration cycles. The PAA.HCl hydrogels are demonstrated to be appropriate ma- c terials for treating wastewaters that contain ammonium perchlorate.