Perchlorate degradation using a titanium and membrane hybrid (TMH) system: Transport, adsorption, chemical reduction

Perchlorate was reduced without adding high concentrations of acid into the contaminated water using a titanium membrane hybrid (TMH) system. The TMH treatment system was developed and a physicochemical model was built to describe transport and degradation of perchlorate in this system. A critical part of the TMH system is an anion permeable membrane that separates a degradation zone that contains Ti(III) from a contaminated zoned that contains perchlorate. The membrane adsorbs anions such as perchlorate and allows them to be transported to the other zone. Adsorption capacities of three membranes (AMX, ACS, ACM) for perchlorate were evaluated and found to be comparable and their adsorption behaviors followed the Freundlich model well. The ACM membrane showed more rapid transport of perchlorate initially (4 h), but the difference is negligible at later times (1 day). The AMX membrane allowed more hydrogen ions and Ti(III) to diffuse into the contamination zone than did other membranes. The proposed mathematical model predicts the performance and behavior of the TMH system for different physical and chemical conditions. It successfully described adsorption, diffusion and reduction of perchlorate in the system.