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Titanium dioxide (Degussa P25) was supported onto two different aluminosilicate zeolites (ZSM-5) and anchored on three silica gels using two separate preparation methods to study the effect of the catalyst components and the preparation method on the photoactivity of composite catalysts. The photoactivity was investigated by tracking phenol disappearance in a batch UVA light-emitting diode reactor. An easily separable photocatalyst with higher photoactivity than commercial Degussa P25 was developed using Degussa P25, ZSM-5 (SiO 2 /Al 2 O 3 = 280) and silica gel (particle size 0.2–0.5 mm and pore size 40 Å). The optimum composition was found to be P25:ZSM-5:silica gel = 0.3 : 0.5 : 0.5 g l −1 . SEM photographs show that the distribution of the composite catalyst components prepared without a binder was better than that prepared with a binder. The efficiency of photocatalytic ozonation of sulfamethoxazole (SMX) using the new photocatalyst was assessed and compared to that of commercially available Degussa P25. It was found that photocatalytic ozonation promoted the SMX disappearance and mineralization. PZS was superior to Degussa P25 with respect to photocatalysis and photocatalytic ozonation. The enhancement was attributed to the synergetic effect between adsorption, ozonation and/or photocatalytic oxidation.

In this paper, degradation of sufolane in an acidic or near neutral pH using Fenton or modified Fenton catalysts was investigated. The catalysts included nitrilotriacetic acid (NTA) iron complex and several commercially available products marketed as neutral pH catalysts. The experiments were conducted both in lab synthetic water and sulfolane contaminated groundwater. Our results showed that more than 99% of sulfolane can be removed by the classic Fenton-like reagent in acidic condition. At near neutral pH, 60% of sulfolane reduction in groundwater was achieved by adding NTA/Fe(III)/H2O2. Among the four commercially available products investigated, ethylenediaminetetraacetic acid (EDTA) chelated iron showed the most positive result in sulfolane degradation in the groundwater. Fifty percent of sulfolane in groundwater degraded when EDTA chelated iron was used with hydrogen peroxide. The decomplexation of chelated iron during reaction caused iron to precipitate and led to the cessation of the reaction.

This research describes the full scale evaluation and testing of an integrated PCBs treatment system. Experiments were conducted on organic soil contaminated with PCBs. The result showed that a removal efficiency of 95% can be achieved using a three cycle isopropyl alcohol (IPA) extraction. It also showed that at least 80% of IPA can be recycled and reused for further extraction of PCBs. The concentrated PCB extracts can be photodechlorinated in an alkaline condition. The successful testing of this integrated PCB treatment system demonstrates this technology to be a promising solution to a very difficult problem.

Project Report 2001-15

Project Report 1999-23