Degradation kinetics of azo dye, Acid Blue 161 (AB161), by Fenton and photo-Fenton processes in aqueous solution was investigated. At pH 3.5, the effects of H 2 O 2 , Fe 2? , and H 2 O 2 /Fe 2? molar ratios, on the AB161 decolorization kinetic rates, were evaluated. Experimental results confirmed that the optimal H 2 O 2 /Fe 2? molar ratio of 12 is close to the theoretical value of 11 as predicted by previously developed model. The influence of azo bond loading (L azo bond ), from 0.25 to 1.0, and pH values from 2.5 to 4.0 were evaluated on AB161 decolorization kinetic rates. A correlation between the natural logarithm of the decolorization rates and L azo bond was established at the different pH values. The decolorization rate increased linearly with decreasing L azo bond , in the order of pH: 3.5 [ 3.0 [ 2.5 [ 4.0. UV radiation of Fenton processes increases degradation of AB161 more than 40 % due to the regeneration of Fe 2? through photo-catalytic reactions. This phenomenon was confirmed by measuring H 2 O 2 concentration during the photo-Fenton processes. The results suggest that Fenton processes can effectively decolorize or degrade wastewater containing azo dye, AB161. Photo-Fenton processes may further increase the degradation efficiency of AB161 by 40 %.

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In this research, we constructed chemical sensor for determining mercury in contaminated water because we needed fast, simple, low-cost, and accurate determination of mercury in different environmental systems. The constructed membrane composed of (Poly Vinyl Chloride) PVC as a matrix material, 1,5-diphenylthiocarbazone (dithizone) as electro active compound, and di-n-butyl phthalate (DBPH) as a plasticizer. The optimum membrane composition 30% PVC, 65% DBPH, 5% dithizone exhibited the better Nernstian response. The results showed that probe is high stability along the pH range from (3.5 to 8). The electrode displays a linear log [Hg 2+ ] versus Electromotive Force (EMF) response over a wide concentration range of (5×10 −6 to 1×10 −2 M) with Nernstian slope of 29.7 ± 0.5 mV decade -1 and limit of detection 3×10 −6 M. The proposed sensor shows relatively high selectivity for mercury ion in different matrix solution, other ions had negligible interference effect on the reading.