Md. Nahid Pervez,Felix Y. Telegin,Yingjie Cai,Dongsheng Xia,Tiziano Zarra,Vincenzo Naddeo
In this study, a Fenton-activated persulfate (Fe2+/PS) system was introduced for the efficient degradation of Mordant Blue 9 (MB 9) as a textile dye in an aqueous solution. Results showed that the degradation of MB 9 was markedly influenced by operational parameters, such as initial pH, PS concentration, Fe2+concentration, and initial dye concentration. Optimal reaction conditions were then determined. Inorganic anions, such as Cl−and HCO3−, enhanced the degradation efficiency of MB 9 under optimal conditions. Addition of HCO3−reduced the degradation performance of MB 9, whereas the addition of Cl−increased the degradation percentage of MB 9. In addition, quenching experiments were conducted using methanol and tert-butyl alcohol as scavengers, and methanol was identified as an effective scavenger. Thus, the degradation of MB 9 was attributed to SO4•−and•OH radicals. The degradation and mineralization efficiency of MB 9 was significantly reduced using the conventional Fenton process i.e., Fe2+/ hydrogen peroxide (HP) because of the formation of a Fe complex during degradation. Meanwhile, the Fe2+/persulfate (PS) system improved the degradation and mineralization performance.Keywords:Fenton-activated;Fe-complex;persulfate;mordant dyes;scavengers
In this paper, the kinetic characteristics and cycle stability of Fe-complex/TiO 2 in the process of degradation of phenolic pollutants and reduction of heavy metal Cr(VI) were studied systematically. First, the structural characteristics and photocatalytic activities of Fe(III)-(8-hydroxyquinoline-5-carboxylic acid)-TiO 2 (Fe-HQC-TiO 2 ) nanoparticle to degrade phenolic pollutants and reduce Cr(VI) simultaneously had been investigated. Compared with the single degradation, the efficiency of synergistic degradation/reduction had been improved and the degradation/reduction rate had been obviously accelerated. In particular, the cyclic stability of Fe-HQC-TiO 2 photocatalyst decreased obviously when it was used to reduce Cr(VI) alone, but it could still keep above 90% after three cycles when it was used for reduction of Cr(VI) and degradation of phenol synergistically. Second, to Fe-HQS/TiO 2 nanoparticle or Fe-HQS/TiO 2 nanotube (HQS (8-hydroxyquinoline-5-sulfonic acid)), the synergistic degradation/reduction (2,4-dichlorophenol/Cr(VI)) efficiencies were always greater than those of a single degradation/reduction and the time was greatly reduced. All the results indicated that there were interactions between Cr(VI) and phenol or 2,4-dichlorophenol in the photocatalytic process. The possible mechanism of synergistic accelerated degradation of phenolic compounds and reduction of Cr(VI) was proposed by analyzing and testing the surface characteristics of photocatalyst and the properties of photocatalytic system during the synergistic degradation/reduction.
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