Study On The Charateristics And Mechanism Of Biodegradation Of Typical Hydroxamic Acid Floatation Collectors

With the prosperity of the minerals market and the soaring of minerals price, in order to further improve the recovery rate of minerals, mineral processing is being continuously extended; mineral processing reagents are widely used and even abused, which has brought economic benefit to the market but also caused tremendous harm to the environment. Hydroxamic acid, as a new type of chelating flotation collector, is widely used in the beneficiation process. But research on biological treatment of hydroxamic acid is less, at the same time almost no research on the actual flotation beneficiation wastewater containing hydroxamic acid. So the study of hydroxamic acid collector and the biodegradability of flotation test wastewater containing hydroxamic acid under aerobic and anaerobic conditions were conducted to clarify its law and mechanism of biological degradation to provide a theoretical basis for the biological treatment of real flotation beneficiation wastewater containing hydroxamic acid.The research on the biodegradation of hydroxamic acid collectors with different initial concentrations indicated that:the biodegradable of benzohydroxamic acid rose perpendicularly with time, which was followed the grade0dynamic model. The biodegradable salicyl hydroxamic acid, N-hydroxy phthalimide and H205rapidly changed in the early stage and then flattened. The higher the initial concentration, the more difficult of biodegradation carried on. The processes followed grade1dynamic model. Meanwhile, the biodegradation of the hydroxyl acid collectors with different structures differed greatly. Benzohydroxamic acid, salicyl hydroxamic acid and N-hydroxy phthalimide belonged to readily biodegradable collector. But the H205belonged to difficultly to be biodegradable collector, whose biodegradability sharply declined with the increasing of initial concentration.The research on the biodegradability of H205, which was a kind of difficultly-biodegradable hydroxyl acid collector, under four anaerobic conditions (general anaerobic, denitrifying anaerobic, sulfate anaerobicd and Fe(III) anaerobic) indicated that:the degradation rate of the H205in the different anaerobic degradation system followed the order of: kFe(III) anaerobic> ksulfate anaerobic> kdenitrifying anaerobic> kgencral anaerobic. Fe(III) was the the most appropriate electronic receptors to the anaerobic biodegradation of H205. All biodegradation processes of H205under different anaerobic conditions followed grade1dynamic model. The dynamic modeles were C=29.86e-0.01477t, C=29.91e-0.04276t,C=29.89e-0.02623t, C=29.95e-0.05597t. Moreover, contrasting the processes of aerobic biodegradation and Fe(III) anaerobic biodegradation of H205, the way to biodegradation combining aerobic biodegradation and Fe(III) reduction anaerobic biodegradation fit for the biodegradation of H205.The research on the biodegradation of the flotation test wastewater containing hydroxyl acid collector under aerobic single matrix condition, aerobic co-substrates condition and Fe(III) anaerobic condition showed that:5%was the best sludge concentration for the biodegradation of the pilot wastewater containing salicylic hydroxamic acid, and the the biodegradation increased from54.25%to91.38%when sodium acetate15mg·L-1and yeast extract30mg·L-1were put in. Meanwhile, the CODCr descended to21.64mg·L-1, conformanced to grade1of the national standard.8%was the best sludge concentration for the biodegradation of the pilot wastewater containing H205, and the the biodegradation increased for20.21%to52.39%when sodium acetate15mg·L-1and yeast extract30mg·L-1were put in. Meanwhile, the CODCr decreased from125.56mg·L-1to76.86mg·L-1. The effect of Fe(III) anaerobic biodegradation was not as good as anaerobic degradation of metabolism.At the end, the biodegradation pathways of hydroximic acid were analysized. In the degradation process of hydroximic acid, oximido is ruptured to form aryl hydroximic acid and hydroxylamine firstly. Then hydroxylamine is oxidized furthermore to form NH3and H2O. Aryl hydroximic acid with only one benzene ring is generated to o-benzenediol then via O-hydroxy-cutting, and muconic acid is produced. Finaly, CO2and H2O are produced by TCA. Aryl hydroximic acid with naphthalene is generated to salicylic acid via ring opening, and then enters the TCA.