Electrochemical characterization of benzotriazole derivatives and their behavior in industrial waste treatment

Benzotriazole derivatives form very strong bonds with transition metals, and are the most widely used type of industrial corrosion inhibitor. Because of their unique chemical architecture—an aromatic ring conjugated to a triazole ring—this class of compounds has a strong amphipathic behavior that enables them to bind metal ions, while at the same time, maintain a strong surface sorption character. The environmental chemistry of benzotriazoles and their metal immobilization potential remains relatively unknown. Of particular environmental engineering interest are the most commercially significant and lowest cost benzotriazoles, which are simple methylated derivatives. Methylated benzotriazoles retain selective biodegradation responses and carry a significant degree of toxicity and environmental risk as judged by common ecosystem receptor models.; Because of their large scale application and wide-spread occurrence, a highly selective, rapid and economical differential pulse polarographic method (DPP) was developed for the quantitation of benzotriazole derivatives in environmental samples with method detection limit an order of magnitude lower than current chromatographic techniques (c.a. < 50 μg/L). Using differential pulse polarography, the stability constants of commercially significant corrosion inhibitors were determined. 4- and 5-methylbenzotriazole coordinate strongly with Cu (II) and Co (III), overall conditional stability constants were determined to be 1015 and 108, respectively. Polarographic analyses were extended to confirm that methylbenzotriazole also binds strongly to redox-active metals in the active sites of some ubiquitous enzymes. This selective type of metal coordination may represent a mechanism for a novel mode of toxicity.; Many different benzotriazole derivatives were tested for the effects of substitution on their environmental biodegradation potential for the sole purpose of lowering their acute toxicity without compromising corrosion inhibiting functions. 5-Carboxybenzotriazole was the most readily degradable of all the benzotriazole derivatives tested, and was completely mineralized by soil and activated sludge bacteria regardless of acclimation conditions. Carboxy derivatives may be a good industrial alternative to conventional non-degradable benzotriazoles in terms of their treatment potential and environmental compatibility.; Results suggested that some types of activated carbon can sequester benzotriazoles from pH neutral and solutions, and be useful in some industrial waste treatment and biological waste treatment scenarios—where toxicity to a biological process is an issue, or where an effluent limit must be met. This sorption behavior may be extended to enhance the metal immobilization potential of some activated carbons.; The amphipathic behavior and metal-binding capacity of benzotriazoles were leveraged to remove selected transition metal ions (Pb, Cu, and Zn) from model industrial wastewaters and acid mine drainage. The amount of metal ions sequestered from solution was sensitive to pH changes as well as the metal to ligand ratio.