Catalytic degradation of carbamazepine by surface modified zerovalent copper via activation of peroxymonosulfate: Mechanism, degradation pathways and ecotoxicity.

ABSTRACTIn this research work, surface modified nano zerovalent copper (nZVC) was prepared using simple borohydride reduction method. The spectroscopic and crystallographic results revealed the successful synthesis of surface modified nano zerovalent copper (nZVC) using solvents i.e., ethanol (ETOH), ethylene glycol (EG) and tween80 (T80). The as-synthesized material was fully characterized for morphological surface and crystal structural properties. The results indicated that EG provides excellent synthesis environment to nZVC compared to ETOH and T80 in terms of good dispersion, high surface area and excellent catalytic properties. The catalytic efficiency of nZVC/EG was investigated alone as well as with the addition of peroxymonosulfate (PMS) in the absence of light. The degradation results demonstrated that the involvement of PMS synergistically boosted the catalytic efficiency of synthesized nZVC/EG material. Furthermore, the degradation products (DPs) of CBZ were determined by GC-MS and subsequently the degradation pathways were proposed. The ecotoxicity analysis of the DPs was also explored. The proposed (nZVC/EG/PMS) system is economical and efficient and thus could be applied for the degradation of CBZ from aquatic system after altering the degradation pathways in such a way that results in harmless products formation

Solar light responsive bismuth doped titania with Ti\u3csup\u3e3+\u3c/sup\u3e for efficient photocatalytic degradation of flumequine: Synergistic role of peroxymonosulfate

© 2019 Elsevier B.V. The present study is focused on the synthesis of a novel solar light responsive bismuth doped titania (Bi-TiO2) through a facile so-gel technique by applying various wt% of Bi. The as-synthesized Bi-TiO2 showed superior photocatalytic performance than un-doped TiO2 towards degradation of flumequine (FLU) under solar light irradiation. The as-synthesized material was thoroughly characterized to examine its structure, morphology and chemical states. The EPR analysis revealed the existence of Ti3+ ion and oxygen vacancy, which is created due to Bi-doping. The as-synthesized Bi-TiO2 with 5 wt% Bi (TBi5) showed excellent photocatalytic performance as compared to their counterparts. The photocatalytic activity of TBi5 was further improved when added with peroxymonosulfate (HSO5−) and increased with increasing [HSO5−]0. The mechanistic investigation and radical scavenging studies revealed that [rad]OH and SO4[rad]− are involved in the degradation of FLU by the as-synthesized material. The bimolecular rate constants of [rad]OH and SO4[rad]− were calculated to be 9.1 × 109 M−1s−1 and 8.5 × 109 M−1s−1, respectively. The photocatalytic performance of the as-synthesized TBi5 coupled with HSO5− under solar light irradiation towards degradation of FLU in Milli-Q water (MW), tape water (TW) and synthetic wastewater (SWW) was 92, 82 and 70% with kapp values of 0.093, 0.085 and 0.066 min−1, respectively. Furthermore, the degradation pathways of FLU were predicted on the basis of its degradation products (DPs). The high mineralization of FLU as well as the evaluation of non-toxic DPs suggests that solar light/TBi5/HSO5− is a promising advanced oxidation process for the future wastewater treatment applications

Development of zerovalent iron and titania (Fe0/TiO2) composite for oxidative degradation of dichlorophene in aqueous solution: synergistic role of peroxymonosulfate (HSO5−)

Abstract Binary composite of zerovalent iron and titanium dioxide (Fe0/TiO2) was synthesized for the catalytic removal of dichlorophene (DCP) in the presence of peroxymonosulfate (PMS). The as-prepared composite (Fe0/TiO2) exhibits synergistic effect and enhanced properties like improved catalytic activity of catalyst and greater magnetic property for facile recycling of catalyst. The results showed that without addition of PMS at reaction time of 50 min, the percent degradation of DCP by TiO2, Fe0, and Fe0/TiO2 was just 5%, 11%, and 12%, respectively. However, with the addition of 0.8 mM PMS, at 10 min of reaction time, the catalytic degradation performance of Fe0, TiO2, and Fe0/TiO2 was significantly improved to 82%, 18%, and 88%, respectively. The as-prepared catalyst was fully characterized to evaluate its structure, chemical states, and morphology. Scanning electron microscopy results showed that in composite TiO2 causes dispersion of agglomerated iron particles which enhances porosity and surface area of the composites and X-ray diffraction (XRD), energy dispersive X-ray (EDX), and Fourier-transform infrared (FTIR) results revealed successful incorporation of Fe0, and oxides of Fe and TiO2 in the composite. The adsorption–desorption analysis verifies that the surface area of Fe0/TiO2 is significantly larger than bare Fe0 and TiO2. Moreover, the surface area, particle size, and crystal size of Fe0/TiO2 was surface area = 85 m2 g−1, particle size = 0.35 μm, and crystal size = 0.16 nm as compared to TiO2 alone (surface area = 22 m2 g−1, particle size = 4.25 μm, and crystal size = 25.4 nm) and Fe0 alone (surface area = 65 m2 g−1, particle size = 0.9 μm, and crystal size = 7.87 nm). The as-synthesized material showed excellent degradation performance in synthesized wastewater as well. The degradation products and their toxicities were evaluated and the resulted degradation mechanism was proposed accordingly. The toxicity values decreased in order of DP1 \u3e DP5 \u3e DP2 \u3e DP3 \u3e DP4 and the LC50 values toward fish for 96-h duration decreased from 0.531 to 67.2. This suggests that the proposed technology is an excellent option for the treatment of antibiotic containing wastewater.Graphical abstrac

Bismuth-Doped Nano Zerovalent Iron: A Novel Catalyst for Chloramphenicol Degradation and Hydrogen Production

© In this study, we showed that doping bismuth (Bi) at the surface of Fe0 (Bi/Fe0, bimetallic iron system) - synthesized by a simple borohydride reduction method - can considerably accelerate the reductive degradation of chloramphenicol (CHP). At a reaction time of 12 min, 62, 68, 74, 95, and 82% degradation of CHP was achieved with Fe0, Bi/Fe0-1 [1% (w/w) of Bi], Bi/Fe0-3 [3% (w/w) of Bi], Bi/Fe0-5 [5% (w/w) of Bi], and Bi/Fe0-8 [8% (w/w) of Bi], respectively. Further improvements in the degradation efficiency of CHP were observed by combining the peroxymonosulfate (HSO5-) with Bi/Fe0-5 (i.e., 81% by Bi/Fe0-5 and 98% by the Bi/Fe0-5/HSO5- system at 8 min of treatment). Interestingly, both Fe0 and Bi/Fe0-5 showed effective H2 production under dark conditions that reached 544 and 712 μM by Fe0 and Bi/Fe0-5, respectively, in 70 mL of aqueous solution containing 0.07 g (i.e., at 1 g L-1 concentration) of the catalyst at ambient temperature