Degradation Of Benzophenone Research Articles

Benzophenone biodegradation and characterization of malodorous gas emissions during co-composting of food waste with sawdust and mature compost

Benzophenone (BP) and its derivatives are extensively used as ultraviolet filters in modern society and increasingly being released into the environment. Co-composting of food waste with sawdust and mature compost was successfully demonstrated to treat high BP concentration (927 ± 229 mg kg−1), with a removal efficiency of 97% after 35 days of incubation. The highest biodegradation rate of 55 mg kg−1day−1 was observed at the thermophilic stage. The biodegradation followed second-order kinetics, and the half-life of BP was 1.3 days during the co-composting process. Additionally, malodorous gas emissions from the co-composting process were also analyzed. The malodorous compounds, including ammonia (NH3), hydrogen sulfide (H2S), and volatile organic sulfide compounds (VOSCs), peaked at the thermophilic phase. NH3 and H2S were the main components contributing to 92% and 7.6% of the total malodorous concentration (617 ppm). Dimethyl disulfide (28.9 ppb) and dimethyl sulfide (23.5 ppb) concentrations accounted for ∼58.9% of the total VOSC emitted. The malodorous emissions were positively correlated with temperature, pH, and negative with oxygen content during the co-composting. Sawdust and mature compost enhanced oxygen penetration in the compost mixture and thereby reduced odor emission. These results support that co-composting could be a technically and economically feasible treatment technology for the degradation of BP and can be used to treat other emerging organic pollutants.

Greywater treatment using modified solar photocatalyst- degradation, kinetics, pathway and toxicity analysis

Solar photocatalytic treatment of greywater, collected from a residential apartment, was performed in the study using nitrogen-doped TiO2 (NP-TiO2) coated on gravels. XRD pattern displayed dominance of the anatase phase of NP-TiO2. Morphological analysis by SEM images indicated the improved porous structure of NP-TiO2 with an average particle size of 109.11 nm with a size range of 91–120 nm. Elemental analysis confirmed the formation of NP-TiO2 by the doping of N into the P-25 structure, and UV–visible spectroscopy results showed improvement in visible light absorption. The efficacy of greywater treatment was evaluated in terms of the degradation of organics, nutrients, surfactants and benzophenone (BP). Solar photocatalytic degradation resulted in significant removal of organics (total organic carbon, TOC removal of 93.7%), with a degradation rate of 0.393 h−1. A maximum of 50% TKN removal efficiency was achieved with photocatalytic oxidation to nitrate. Furthermore, the nitrate removal efficiency of 43% was observed due to the photocatalytic reduction. The maximum removal efficiency of phosphate, surfactant and BP was 55, 75, and 98.5%, respectively. Besides, toxicity in terms of bioluminescence inhibition (for 30 min incubation) showed a reduction from 13.6 to 4% for the treated greywater. The non-specific hydroxyl radical attack, demethylation, and bond cleavage between the carbonyl group and benzene ring carrying hydroxyl and methoxy groups were the dominant mechanism of BP degradation. The catalyst reusability test showed ~0.7% and ~1.5% decrease in TOC and BP removal efficiencies, respectively, after three consecutive cycles.

Sulphate radical oxidation of benzophenone: kinetics, mechanisms and influence of water matrix anions

ABSTRACT Benzophenone (BP) is an emerging contaminant that is widely distributed in soil, groundwater, sediment and surface water. In this study, the degradation kinetics, mechanisms, and influence of anions on thermally activated persulphate (TAP) oxidation of BP were systematically investigated. BP degradation was promoted by elevated temperature. The BP degradation data fitted well to the Arrhenius equation with calculated activation energy of 122.8 kJ/mol. BP degradation was also promoted by alkaline pH and high persulphate concentrations. Radical scavenging experiments suggested that both SO4 •− and HO• were involved in BP oxidation. Ultra-high-performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS) identified six degradation intermediates. Based on these results, two possible reaction pathways were proposed. Water matrix anions had complex impacts on BP degradation by TAP. Cl− had dual effects on the reaction: low concentration promoted it while high concentration inhibited it. Br− strongly suppressed the reaction. SO4 2− and NO3 − did not affect the reaction. Overall, this study shows that thermally activated persulphate can effectively remove BP and water matrix anions greatly influence the reaction.

Influence of water matrix on benzophenone degradation by UV-irradiation

This study presents the results from a bench-scale UV irradiation experiment of benzophenone (BP) in different water matrices. Despite the reported resistance of BP to UV-irradiation, it was successfully degraded in solution when intensively irradiated by UV light in a batch reactor for 4 h. In this way, it was possible to remove 56 and 45 % of 1.0 and 10 ?g?L-1 of BP in Milli-Q water, respectively. The addition of a mixture of anions suppressed the degradation of BP at the lower concentration level by 20 %. The addition of a dissolved organic carbon (DOC) surrogate mixture (DOC:BP mole ratio of 3000:1) increased the degradation of BP in Milli-Q water (removal 80 %). At 1.0 ?g?L-1 of BP and 1.0 mg?L-1 of DOC, removal was 70 %, while at 10 ?g?L-1 of BP and 10 mg?L-1 of DOC, there was no observable difference in removal compared with the removal in Milli-Q water. The results show that both DOC and anions influence the photodegradation of BP. Furthermore, it was shown that the removal efficiency depends on the concentration of BP. These findings show the importance of a detailed characterisation of the water matrix in studies relating to the removal of micropollutants during UV irradiation.

Insight into the Degradation of Two Benzophenone-Type UV Filters by the UV/H2O2 Advanced Oxidation Process

Environmental problems caused by UV filters, a group of emerging contaminants, have attracted much attention. The removal of two typical UV filters benzophenone (BP) and 4,4′-dihydroxy-benzophenone (HBP) in water was investigated by the UV/H2O2 process. The response surface methodology (RSM) and central composite design (CCD) were applied to investigate the effects of the process parameters on the degradation rate constants, including the initial contaminant concentration, H2O2 dose, and UV light intensity. BP is more easily degraded by the UV/H2O2 process. Both processes followed pseudo-first-order kinetics. The results obtained with the built RSM model are in accordance with the experimental results (adjusted coefficients R2(adj)= 0.9835 and 0.9778 for BP and HBP, respectively). For both processes, the initial contaminant concentration (exerting a negative effect) were the most important factors controlling the degradation, followed by H2O2 dose and UV intensity (exerting positive effects). A total of 15 BP degradation products and 13 HBP degradation products during the UV/H2O2 process were identified by LC/MS and GC/MS. A series of OH radical irritated reactions, including hydroxylation, carboxylation, and ring cleavage, led to the final degradation of BP and HBP. Degradation pathways of BP and HBP were also proposed. On the whole, this work is a unique contribution to the systematic elucidation of BP and HBP degradation by the UV/H2O2 process.

Increased photocatalytic activity of Zn(II)/Cu(II) oxides and sulfides by coupling and supporting them onto clinoptilolite nanoparticles in the degradation of benzophenone aqueous solution

Photocatalytic activity of the coupled ZnO–CuO and ZnS–CuS semiconductors supported onto clinoptilolite nanoparticles (CNP) and micronized one (CMP) was studied in photodegradation of benzophenone (BP) aqueous solution. The ZnO–CuO/CNP (or MCP) and ZnS–CuS/CNP (or MCP) catalysts were prepared via calcination and sulfiding of their Zn(II)–Cu(II) ion-exchanged samples, respectively. XRD patterns confirmed loading of the mentioned semiconductors onto the zeolite, and nano dimension of the catalysts was confirmed by XRD and TEM results. Typical Tauc plots obtained from UV–vis DRS spectra showed red shifts for the band gap energies of the supported coupled semiconductors with respect to the supported monocomponent ones especially for ZnO/NCP and ZnS/NCP catalysts. Also, in both indirect and direct transitions, these red shifts were more considerable in the oxidic systems with respect to the sulfidic systems. Accordingly, the supported oxidic systems showed better photocatalytic activity than the sulfidic one. In the oxidic systems changing the dose of CuO played important role while in the sulfidic systems ZnS played considerable role in the degradation of BP. In the used systems, CuO and ZnS played the main e/h generators in the oxidic and sulfidic systems, respectively, while ZnO and CuS played the preventer e/h recombination. Based on the results, production of e/h is the rate limiting step in the used systems. The maximum degradation activity of the catalysts was obtained at: 0.12gL−1 of ZnO0.80–CuO3.18/NCP and 0.10gL−1 of ZnS1.39–CuS2.88/NCP catalysts, initial BP concentration of 30mgL−1 at pH 7.5.

The natural degradation of benzophenone at low concentration in aquatic environments.

The natural degradation caused by sun irradiation and microbes in aquatic environments is of major significance in the elimination process of benzophenone (BP). In this study, the fate of BP in surface water at a low concentration of 10 μg/L was investigated, including both photodegradation and microbial degradation. The result showed that the photodegradation rate of BP was affected by several parameters such as the initial concentration, continuous input, and the presence of the analogue, ions and small molecules. Meanwhile, the rate of microbial degradation of BP was mainly influenced by the kind and amount of microbes in the environmental water.

Degradation of benzophenone in aqueous solution by Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation

Comparative studies of ozonation alone, ceramic honeycomb-catalyzed and Mn-Fe-K modified ceramic honeycomb catalyzed ozonation processes have been undertaken with benzophenone as the model organic pollutant. The experimental results showed that the presence of Mn-Fe-K modified ceramic honeycombs significantly increased the removal rate of benzophenone and TOC compared with that achieved by ozonation alone or ceramic honeycomb-catalyzed ozonation. The electron paramagnetic resonance (EPR) experiments verified that higher benzophenone removal rate was attribute to more hydroxyl radicals generated in the Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation. Under the conditions of this experiment, the degradation rate of all the three ozonation processes are increasing with the amount of catalyst, temperature and value of pH increased in the solution. We also investigated the effects of different process of ozone addition, the optimum conditions for preparing catalyst and influence of the Mn-Fe-K modified ceramic honeycomb after multiple-repeated use.

Degradation of Benzophenone, a Potential Xenoestrogen, by a Yeast Isolated from the Activated Sludge of a Sewage Treatment Plant in Hokkaido

Benzophenone (BPH) is an important intermediate in the production of medicines and cosmetics, but is also known as a xenoestrogen in its effect on mammals. We screened BPH-degrading microbes for potential bioremediation, and found degradation activity in the activated sludge of a sewage treatment plant in Hokkaido. A microbial strain with notable BPH-degrading activity (strain MU-1) was isolated from the sample. MU-1 degraded more than 95% of BPH (100–1000 ppm) as a sole carbon source within several days. However, it took a relatively long time for MU-1 to degrade a high concentration of BPH (5000–10,000 ppm), probably due to a toxic effect of BPH. The GC/MS analysis of the metabolites of BPH degradation suggested that BPH was degraded into hydrophilic compounds with very low molecular mass via conversion to phenol. The phylogenetic study based on rDNA sequences suggested that MU-1 was the black yeast Rhinocladiella aquaspersa. To our knowledge, this is the first report describing a BPH-degrading microbe.