Study on Biodegradation of Alkyl Xanthate Collectors

The biodegradation extent of several alkyl xanthate collectors has been determined according to ISO 7827 and the kinetic model of biodegradation has been discussed. Meanwhile, the impact of molecular structure on biodegradability has been studied. The results indicated that the biodegradation extent of ethyl xanthate, n-butyl xanthate, n-amyl xanthate, isopropyl xanthate and iso-butyl xanthate can attain 96.36%, 81.76%, 73.74%, 63.37% and 60.30%, respectively in 8d. The rate constants (k) follows the order of: k_ethyl>k_n-butyl>k_n-amyl>k_isopropyl>kisobutyl. And their aerobic biodegradation follows the first order reaction kinetics equation. The biodegradation of the xanthates decreases with the DT-90 and half-life time increase with an increase in the length of hydrocarbon chain and number of alkyl lateral chains. Comparing to the hydrocarbon chain length, the branched structure has a more significant effect on the degradability of alkyl xanthates. Through the preliminary study of the biodegradation mechanism of xanthates, it was found that CS₂ and monothiocarbonate are the main products of biodegradation of xanthates and a small amount of oil-like dixanthogen droplets are also produced.