Dimethyl Sulfoxide Degradation Research Articles

Spectral and conductivity measurements insights on loading mechanisms of DMSO/water-kaolin complexes

Kaolin, a naturally occurring clay mineral renowned for its distinctive properties, holds significant importance across various industries. The integration of dimethyl sulfoxide (DMSO) into kaolin matrices, both in the presence and absence of water, has been extensively explored for its potential to enhance material characteristics. Addressing debates surrounding the proposed adsorption mechanism for the type I structure of DMSO, this study undertook a comprehensive physicochemical characterization of DMSO-kaolin complexes (DMSO-KCs) derived from untreated (UnK) and HCl-treated (HK) Egyptian ore, with a focus on elucidating the loading mechanism facilitated by water.Key insights gleaned from electrical conductivity, dielectric constant, and Fine Testing Technology – Fourier-transform infrared (FTT-FTIR) measurements, shedding light on the bonding nature of DMSO-KCs. FTT-FTIR analysis revealed two stages of water departure at 180 °C, with the final stage coinciding with the release of pyrolysis gases, confirming the catalytic degradation of DMSO. Through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), two distinct bonding types of DMSO molecules with kaolinite were identified: amorphous adsorbed (type I) and lattice-oriented intercalated (type II).Electrical characteristic evaluations within the temperature range of room temperature (RT) to 260 °C and frequency range of 42 Hz–1 MHz revealed that DMSO intercalation enhances the electrical properties of kaolin. Hydrated DMSO-KCs exhibited higher values of σac and ɛʹ compared to non-hydrated samples. The activation energy (Ea) values for HCl-treated samples were smaller than those of untreated ones. Alternating current (AC) conductivity analysis indicated predominantly ionic behavior with frequency and temperature dependency in both HCl-treated and untreated kaolin. Our findings substantiate the adsorption mechanism of Type I DMSO, highlighting its amorphous nature, instability, and catalytic degradation over time, in contrast to the intercalated type II. This elucidation is pivotal for understanding the behavior of DMSO-KCs across diverse applications, including electronics, ceramics, and materialsscience.

Boosting hydrogen peroxide activation for the high-efficient removal of volatile dimethylsulfoxide over niobium-based catalysts

Dimethyl sulfoxide (DMSO) is an important solvent in numerous industries. The biodegrading process of DMSO is slow and produces toxic volatile compounds including CH3SCH3, CH3SH, and H2S. Hence, it is important to develop chemical methods for treating DMSO-containing wastewater. In the present work, niobium oxyhydroxide and niobium oxide were synthesized and used to activate hydrogen peroxide for the degradation of DMSO to DMSO2. The niobium oxyhydroxide catalyst exhibited much better catalytic activity for DMSO oxidation than niobium oxide. EPR spectra and radical scavenging experiments confirmed that O2•− and 1O2 are the main active species for the oxidation of DMSO. FTIR analysis and DFT calculation confirmed that the surface hydroxyl of niobium oxyhydroxide can be substituted by hydroperoxo group of H2O2 to form Nb−OOH group, which can directly oxidize DMSO or indirectly oxidize DMSO via O2•− and 1O2. However, H2O2 cannot form hydroperoxo group on the surface of niobium oxide, which might trigger the lower activity of niobium oxide catalysts than the niobium oxyhydroxide catalyst. The niobium oxyhydroxide catalyst exhibited good reusability and was promising for the treatment of DMSO-containing wastewater.

Increasing the ⋅OH radical concentration synergistically with plasma electrolysis and ultrasound in aqueous DMSO solution

In recent years, significant increases in waste processing and material engineering have been seen by using advanced oxidation processes. The treatment results and energy yields of these processes are largely determined by the generation and retention of reactive oxygen species (ROS). However, increasing the amount of ROS remains a key challenge because of the unavailability of performance- and energy-efficient techniques. In this study, plasma electrolysis, ultrasound, and plasma electrolysis combined with ultrasound were used to treat dimethyl sulfoxide (DMSO) solutions, and the results showed that the two methods can synergistically convert filament discharge into spark discharge, and the conversion of the discharge mode can significantly increase the concentration of OH radicals and effectively improve the efficiency of DMSO degradation. We verified the rationality of the results by analyzing the mass transfer path of ROS based on the reaction coefficients and found that the ⋅OH radicals in aqueous solution were mainly derived from the decomposition of hydrogen peroxide. These findings indicated that the synergistic action of plasma electrolysis and ultrasound can enhance the production of chemically reactive species, and provide new insights and guiding principles for the future translation of this combined strategy into real-life applications. Our results demonstrated that the synergistic strategy of ultrasound and plasma electrolysis is feasible in the switching mode and increasing the ROS, and may open new routes for materials engineering and pollutant degradation.

Photosensitized Degradation of DMSO Initiated by PAHs at the Air‐Water Interface, as an Alternative Source of Organic Sulfur Compounds to the Atmosphere

AbstractThe photochemical reactions of organic compounds at the water surface lead to the formation of gas‐phase molecules that may contribute to new particle formation in the atmosphere. Here, we observe the formation of organic sulfur (OS) compounds that are known secondary organic aerosol (SOA) precursors, upon irradiation of aqueous solutions containing typical polycyclic aromatic hydrocarbons (PAHs) such as pyrene, fluoranthene, and phenanthrene as well as dimethylsulfoxide (DMSO). The reactivity between the excited triplet states of PAHs (3PAHs*) and DMSO was determined by transient absorption spectroscopy and a tentative reaction mechanism for DMSO degradation was proposed, supported by theoretical calculations of the reaction Gibbs energies. In all cases, we observe rapid formation of methanesulfonic acid, methanesulfinic acid, methylsulfonylmethane, ethyl methanesulfonate, hydroxymethanesulfonic acid, and 2‐hydroxyethanesulfonic acid by use of novel membrane inlet‐single photon ionization‐time of flight mass spectrometry. These results suggest that ubiquitous PAHs and DMSO at the sea surface may represent an alternative source of OS compounds during daytime, through photochemical processes that should be considered in future models to better represent the SOA formation processes in the atmosphere.

Microfluidic synthesis of ZnWO4 nanoparticles and its performance in DMSO-containing wastewater treatment

A systematic comparison between batch and continuous microfluidics systems was conducted for the synthesis of ZnWO4 nanoparticles. A series of ZnWO4 nanoparticles were prepared by different operating modes, initial concentration of reactants and residence time. The features of ZnWO4 nanoparticles including microscopic morphology, particle size distribution and chemical structure were systematically characterized. The results showed that the continuous microfluidics system could obtain ZnWO4 nanoparticles with a more uniform particle size compared with batch system. The size of ZnWO4 are reduced from 92.6 to 65.2 nm by changing the reaction system. Besides, a low concentration of reactants is more suitable for preparing smaller particles ZnWO4 nanoparticles. The average diameters of prepared ZnWO4 nanoparticles was reduced to 50 nm in the condition that the residence time was 20 s and the concentration of reactants was 0.1 mol/L. Afterward, the degradation of dimethyl sulfoxide (DMSO) in the wastewaters was used as a probe reaction to evaluate the catalysis performance of prepared ZnWO4 nanoparticles. This work indicates the potential opportunity of versatile continuous microfluidics technique for the fabrication of various multifunctional metal tungstates nanoparticles.

A comparative study on the removal of dimethyl sulfoxide from water using microbubbles and millibubbles of ozone

Ozone-based microbubble-aided technology has been gaining popularity as a new potential alternative method for the oxidation of organic pollutants present in water/wastewater. In this work, the potential of the ozone microbubbles (OMBs) for the oxidation of dimethyl sulfoxide (DMSO) was investigated, and the results were compared with those of the conventional ozone millibubbles (OMLBs). Keeping constant other operational parameters, the OMLBs needed a longer time for complete removal of DMSO, and hence a higher consumption of ozone took place. Therefore, a higher stoichiometric ratios of ozone consumed to the DMSO removed was obtained for the OMLBs. Higher ozone utilization efficiencies were observed for the OMBs (i.e., 65–79 %) than the OMLBs (i.e., 21–48 %). Coupling of H2O2 with the ozonation systems improved the oxidation of DMSO by enhancing the formation of ·OH. Conversely, a large dosage of H2O2 had a negative effect. The degradation of DMSO to methane sulfonic acid (MSA) was achieved via two paths (i.e., direct conversion to MSA by the reaction with ·OH, and a two-stage conversion via the formation of DMSO2 by molecular ozone, followed by further oxidation of DMSO2 to MSA by the ·OH). In terms of the TOC removal efficiency, the effectiveness was in the following order: OMLBs < OMLBs/H2O2 < OMBs < OMBs/H2O2. Oxidation of DMSO by ozone followed an overall second-order kinetics for the OMBs, and first-order kinetics for the OMLB system. Higher enhancement factor and volumetric mass transfer coefficient were obtained for the OMBs as compared to OMLBs.

Treatment of DMSO and DMAC wastewaters of various industries by employing Fenton process: Process performance and kinetics study

Nowadays, the treatment of dimethyl sulfoxide (DMSO) and N, N-dimethylacetamide (DMAC) wastewaters are a serious concern because of the use of these materials as a solvent in various industries such as pharmaceutical, electronic and acrylic fiber manufacturing process. In this research, employing of Fenton process for treatment of DMSO and DMAC wastewaters by considering the effect of operating parameters such as different initial DMSO and DMAC concentration, reaction time, initial pH, and different concentrations of Fenton’s reagent were investigated. Experimental results illustrated that the maximum degradation efficiency for the treatment of synthetic DMSO wastewater was equal to 89.9 %, 89.7 %, 94.5 %, and 97.6 %, for initial concentration of DMSO equal to 250, 500, 1000, and 2000 mg.L−1, respectively. The maximum degradation efficiency of 81.9 %, 92.9 %, 94.8 %, and 95.8 % was reached at best operational conditions of the Fenton process for 250, 500, 1000, and 2000 mg.L−1 initial concentration of synthetic DMAC wastewater respectively. Kinetics study results presented that the kinetic reaction of DMSO and DMAC degradation by the Fenton process at all initial concentrations were well fitted with the BMG model.

Biological treatment of DMSO-containing wastewater from semiconductor industry under aerobic and methanogenic conditions

This study evaluated biological treatment of dimethyl sulfoxide (DMSO)-containing wastewater from semiconductor industry under aerobic and anaerobic conditions. DMSO concentration as higher as 1.5 g/L did not inhibit DMSO degradation efficiency in aerobic membrane bioreactor (MBR), while specific DMSO degradation rate at different initial DMSO-to-biomass (S0/X0) ratios from batch tests seemed to follow the Haldane-type kinetics. According to the microbial community analysis, Proteobacteria decreased from 88.2% to 26% as influent DMSO concentration increased, while Bacteroidetes, Parcubacteria, Saccharibacteria increased. Within the Bacteroidetes class, Flavobacterium and Laribacter genus significantly increased from less than 0.05%–26.8% and 13.4%, respectively, which might both be related to the DMS degradation. Hyphomicrobium and Thiobacillus, known as aerobic DMSO and DMS degraders, instead, decreased at higher DMSO conditions. Under methanogenic conditions, batch results implied DMSO concentrations higher than 3 g/L could be inhibitory, while DMSO and COD removal achieved 100% and 93%, respectively, using a pilot-scale anaerobic fluidized bed membrane bioreactor (AFMBR) with influent DMSO below 1.5 g/L. Results of terminal restriction fragment length polymorphism (TRFLP) analysis targeting on mcrA functional gene revealed that Methanomethylovorans sp. was dominant in AFMBR after 54 days of operation, indicating its importance on degrading DMS and mathanethiol (MT).

Synthesis and characterization of direct Z-scheme CdS/TiO2 nanocatalyst and evaluate its photodegradation efficiency in wastewater treatment systems

In the present research, the photocatalytic degradation of dimethyl sulfoxide (DMSO), a reference substance for determination of photocatalytic efficiency of wastewater treatment systems, in the presence of CdS/TiO2 nanoparticles under visible light irradiation was investigated. For this purpose, an ultrasonic method combined by microemulsion was used to synthesize CdS/TiO2 core/shell nanoparticles in a mild condition without surfactant. The morphology, structure and properties of the nanoparticles were studied via X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible spectra (UV–vis), Fourier transform near IR (FTIR), energy-dispersive X-ray (EDAX) and dynamic light scattering (DLS). The TEM image clearly indicated the size of non-agglomerated nanoparticles in the absence of surfactant, are almost 10 nm in a spherical shape. UV–vis spectra for these particles revealed a red shift in absorption edge up to 570 nm which was in green area. The photodegradation studies were performed in a batch photoreactor with a sun simulator lamp. The degradation efficiency of nanoparticles was investigated by high-performance liquid chromatography (HPLC) device and high degradation efficiency up to 80% was recognized with this method. Also, kinetic study of photodegradation of nanoparticles was performed in an arbitrary point and the rate of DMSO degradation was fitted to Langmuir–Hinshelwood kinetic model and consequently, K parameter, has been determined.

Examining Acid Formation During the Selective Dehydration of Fructose to 5-Hydroxymethylfurfural in Dimethyl Sulfoxide and Water.

Sustainable conversion of biomass, including fructose dehydration to 5-hydroxymethylfurfural (HMF), remains a challenge. Fructose can be selectively dehydrated to HMF in dimethyl sulfoxide (DMSO) without addition of an acid catalyst. The role of DMSO is examined starting with either fructose or HMF in DMSO/water. With increasing DMSO content, it is observed that fructose conversion, HMF selectivity, and post-reaction solution acidity increase. Although DMSO degradation to sulfuric acid is a potential source of acidity and reactivity, a barium chloride precipitation test demonstrates that sulfate ions are not detectable after reaction, suggesting that DMSO is stable during reaction at 120 °C and 150 °C with oxygen present. Instead, the majority of the acidic species produced are formic acid, levulinic acid, and humins. These acids have a minimal effect on fructose conversion in DMSO. These results suggest that DMSO promotes fructose conversion mainly through solvation effects and not as an origin of acid catalysis. For HMF stabilization, the optimal molar fraction of DMSO in water is 0.20-0.43. Overall, these results indicate that DMSO can promote fructose dehydration to HMF at 120 °C.

Realization of Stable Cathode-Electrolyte Interfaces in DMSO Based Li-O2 Batteries: Experimental and Theoretical Perspectives

One of the primary challenges impeding realization of the non-aqueous Li-O2 battery is finding a solvent that is chemically and electrochemically stable under cell operating conditions. Dimethyl sulfoxide (DMSO) is an attractive candidate for rechargeable Li-O2 battery studies; however, there is still significant controversy regarding its stability on the Li-O2 cathode surface. We report here results from a model cathode system featuring various atomic layer deposited (ALD) catalysts including Ru, RuO2, and Pt on a mesoporous CNT sponge to study the OER/ORR behavior in DMSO-based Li-O2 cells. We performed multiple experiments (in-situ XPS, FTIR, Raman, and XRD) which assess the stability of the DMSO-Li2O2 interface and report perspectives on previously published studies. Our electrochemical experiments demonstrate long term, stable cycling of DMSO-based Li-O2 cells. This work is complemented by density functional theory calculations of DMSO degradation pathways on Li2O2. Both experimental and theoretical evidence strongly suggest that oxidation of DMSO on the surface of Li2O2 is very unlikely to spontaneously occur and will take place only under certain conditions and to a minor extent under controlled operating voltages and in cell environments free of acidic function groups (either in the electrolyte or porous scaffold). Figure 1

Degradation of dimethyl sulfoxide through fluidized-bed Fenton process: kinetic analysis

In this study, fluidized-bed Fenton process (FBF) was used to degrade dimethyl sulfoxide (DMSO), one of the most widely used solvents. Oxidation by Fenton’s reagent, Fe+2 and H2O2, is one of the cheapest advanced oxidation processes due to the high availability of the reagents. FBF is a modified approach that reduces the large amount of iron oxide sludge formed in conventional Fenton process. The optimal treatment efficiencies by FBF with 2 h of reaction were 95.22 % of DMSO degradation and 34.38 % of COD removal at the conditions of 5 mM DMSO, 68.97 g/L SiO2 carrier, pHinitial 3.0, 5 mM Fe2+, and 32.5 mM H2O2. The kinetic study was also done to investigate the two stages involved in the oxidation. The first stage fitted the zero reaction order with overall initial rate’s apparent rate constant, k 1, of −0.099. The second stage fitted the first order of DMSO degradation, with rate constant, k 2, of −0.0005.

Realization of Stable Cathode-Electrolyte Interfaces in DMSO Based Li-Air Batteries: Experimental and Theoretical Perspectives

Electrochemical power sources based on metal anodes have specific energy density much higher than conventional Li ion batteries, due to the high energy density of the metal anode (3842mAh/g1 for Li). Rechargeable aprotic Li-O2batteries consume oxygen from the surrounding environment during discharge to form Li oxides on the cathode scaffold, using reactions (1) [anode] Li(s) ↔ Li+ + e− (2) [cathode] Li+ + ½ O2 (g)+ e− ↔ ½ Li2O2(s), (3) [cathode] Li+ + e− + ¼ O2 (g) ↔ ½ Li2O (s), The cathode reaction requires large over-potentials for charging due to the mass transfer resistance of reagents to the active sites on its surface, decreasing the round trip efficiency, making recharge of the Li-O2cell difficult. To overcome these problems, the cathode needs good electrical conductivity and a porous structure that enables facile diffusion of oxygen and can accommodate the reduced oxygen species in the pores. Two significant challenges exist in the use of the traditional activated carbon material as the cathode of the Li-O2 system. First, in the presence of Li2O2 the carbon electrode becomes relatively unstable even at low voltages (<3.5V). (Itkis et al., 2013) Second, cathode structures must be porous to accommodate a substantial amount of Li–peroxide (Li2O2) without blocking ion transport channels in the cathode. An additional major obstacle for the realization of the non-aqueous Li-O2 battery is finding a solvent that is chemically and electrochemically stable under cell operating conditions. Dimethyl sulfoxide (DMSO) is an attractive candidate for rechargeable Li-O2 battery studies(Peng, Freunberger, Chen, & Bruce, 2012); however, there is still significant controversy regarding its stability on the Li-O2cathode surface(Kwabi et al., 2014). We report here results from a model cathode systems which enable determination of the effects of various catalysts on the OER/ORR reactions in the DMSO based Li-O2 cell. Mesoporous CNT sponge is used as the model cathode material, decorated with catalyst nanoparticles by nucleation-controlled atomic layer deposition (ALD) of Ru, RuO2, MnOx, and Pt catalyst components whose loading and composition are controlled by manipulating the ALD conditions. We performed multiple experiments (in-situ XPS, FTIR, Raman, and XRD) which assess the stability of the DMSO-Li2O2 interface and report perspectives on previously published studies. Our electrochemical experiments show long term stable cycling of a DMSO-based operating Li-O2 cell with a Catlyst@carbon nanotube core-shell cathode fabricated via atomic layer deposition. This work is complemented by density functional theory calculations of DMSO degradation pathways on Li2O2. Both experimental and theoretical evidence strongly suggests that DMSO is chemically and electrochemically stable on the surface of Li2O2 under the reported operating conditions.

Degradation of dimethyl sulfoxide through fluidized-bed Fenton process

Dimethyl sulfoxide (DMSO), one of the most widely used solvent, was subjected to fluidized-bed Fenton oxidation in this study. Fenton oxidation is considered one of the cheapest advanced oxidation processes due to high availability of Fenton’s reagents Fe2+ and H2O2, wherein, Fe2+ catalyzes hydroxyl radical production from H2O2. Fluidized-bed Fenton process is a modified approach which is also used to address the production of large amount of iron oxide sludge in conventional Fenton process. Parametric study is included in this research using initial conditions of pH 2–7, 0.5–7.25mM Fe2+, 5–87.5mM H2O2, and 5–50mM DMSO. Fluidized-bed Fenton oxidation of 5mM DMSO using 68.97g/L SiO2 carrier at initial conditions of pH 3, 5mM Fe2+, and 32.5mM H2O2 resulted to 95.22% DMSO degradation, 34.38% TOC removal and 0.304mM sulfate/mM DMSO0 production in 2h. The study shows that the intermediate product which was most difficult to oxidize and contributed most to the residual TOC was methanesulfonate.

DMSO-Li2O2 Interface in the Rechargeable Li-O2 Battery Cathode: Theoretical and Experimental Perspectives on Stability.

One of the greatest obstacles for the realization of the nonaqueous Li-O2 battery is finding a solvent that is chemically and electrochemically stable under cell operating conditions. Dimethyl sulfoxide (DMSO) is an attractive candidate for rechargeable Li-O2 battery studies; however, there is still significant controversy regarding its stability on the Li-O2 cathode surface. We performed multiple experiments (in situ XPS, FTIR, Raman, and XRD) which assess the stability of the DMSO-Li2O2 interface and report perspectives on previously published studies. Our electrochemical experiments show long-term stable cycling of a DMSO-based operating Li-O2 cell with a platinum@carbon nanotube core-shell cathode fabricated via atomic layer deposition, specifically with >45 cycles of 40 h of discharge per cycle. This work is complemented by density functional theory calculations of DMSO degradation pathways on Li2O2. Both experimental and theoretical evidence strongly suggests that DMSO is chemically and electrochemically stable on the surface of Li2O2 under the reported operating conditions.

Treatment of thin film transistor-liquid crystal display (TFT-LCD) wastewater by the electro-Fenton process

In this study, the electro-Fenton process was used to treat synthetic and actual TFT-LCD wastewaters. TFT-LCD wastewater contains high amounts of organic solvents mainly dimethyl sulfoxide (DMSO). For the simulated TFT-LCD wastewater, response surface methodology (RSM) was used to fit experimental data to empirical models with the responses, %DMSO removal and H2O2 efficiency (Δ[H2O2]/Δ[DMSO]). Among the studied independent variables that affect DMSO degradation efficiency, Fe2+ loading was found to be the most dominant, then pH and, H2O2 loading being the least significant. DMSO removal and H2O2 efficiency improved with high Fe2+ loading, low H2O2 loading and low solution pH. The observed decrease in pH was attributed to the production of acidic degradation intermediates of DMSO. At 5mM DMSO loading, treatment efficiency reached 100% DMSO removal. The electro-Fenton technology was also applied to real TFT-LCD wastewater resulting in TOC and COD removals of 68% and 79%, respectively.

Factors affecting degradation of dimethyl sulfoxide (DMSO) by fluidized-bed Fenton process.

In this study, the target compound is dimethyl sulfoxide (DMSO), which is used as a photoresist stripping solvent in the semiconductor and thin-film transistor liquid crystal display (TFT-LCD) manufacturing processes. The effects of the operating parameters (pH, Fe(2+) and H2O2 concentrations) on the degradation of DMSO in the fluidized-bed Fenton process were examined. This study used the Box-Behnken design (BBD) to investigate the optimum conditions of DMSO degradation. The highest DMSO removal was 98 % for pH 3, when the H2O2 to Fe(2+) molar ratio was 12. At pH 2 and 4, the highest DMSO removal was 82 %, when the H2O2 to Fe(2+) molar ratio was 6.5. The correlation of DMSO removal showed that the effect of the parameters on DMSO removal followed the order Fe(2+) > H2O2 > pH. From the BBD prediction, the optimum conditions were pH 3, 5 mM of Fe(2+), and 60 mM of H2O2. The difference between the experimental value (98 %) and the predicted value (96 %) was not significant. The removal efficiencies of DMSO, chemical oxygen demand (COD), total organic carbon (TOC), and iron in the fluidized-bed Fenton process were higher than those in the traditional Fenton process.

Comparison of dimethyl sulfoxide degradation by different Fenton processes

Degradation of dimethyl sulfoxide (DMSO) was examined under varying parameters, including initial pH, initial Fe2+, initial H2O2, initial DMSO concentrations and current density. Efficiency in terms of degradation of DMSO and removal of total organic carbon (TOC) was also compared among Fenton, photo-Fenton and photoelectro-Fenton (PEF) processes. Effects of inorganic ions, namely Cl−, F− and PO43-, on DMSO degradation by the electro-Fenton (EF) process were also studied. The experimental results showed that the optimum pH was 2. The DMSO degradation in the double-cathode EF reactor reached 100% when current density and Fe2+ concentration exceeded 1.5A and 2.0mM, respectively. During DMSO degradation, application of electricity by EF process obtained a higher DMSO degradation rate compared to UV-assisted Fenton process. The DMSO degradation rate after 20min was 2.5 times higher in the PEF process than in the Fenton process. Between 20min and 120min, the DMSO degradation rates of the Fenton, photo-Fenton, single-cathode EF, double-cathode EF and PEF processes differed by 34%, 50%, 62%, 57% and 59%, respectively. The rate constant of double-cathode EF process was six times higher than the conventional Fenton process. The order of inhibiting effects of inorganic ions on DMSO degradation was PO43->F−>Cl−.

Linking TFT-LCD wastewater treatment performance to microbial population abundance of Hyphomicrobium and Thiobacillus spp.

This study investigated the linkage between performance of two full-scale membrane bioreactor (MBR) systems treating thin-film transistor liquid crystal display (TFT-LCD) wastewater and the population dynamics of dimethylsulfoxide (DMSO)/dimethylsulfide (DMS) degrading bacteria. High DMSO degradation efficiencies were achieved in both MBRs, while the levels of nitrification inhibition due to DMS production from DMSO degradation were different in the two MBRs. The results of real-time PCR targeting on DMSO/DMS degrading populations, including Hyphomicrobium and Thiobacillus spp., indicated that a higher DMSO oxidation efficiency occurred at a higher Hyphomicrobium spp. abundance in the systems, suggesting that Hyphomicrobium spp. may be more important for complete DMSO oxidation to sulfate compared with Thiobacillus spp. Furthermore, Thiobacillus spp. was more abundant during poor nitrification, while Hyphomicrobium spp. was more abundant during good nitrification. It is suggested that microbial population of DMSO/DMS degrading bacteria is closely linking to both DMSO/DMS degradation efficiency and nitrification performance.

The catalytic role of tungsten electrode material in the plasmachemical activity of a pulsed corona discharge in water

The effects of tungsten material used as a high-voltage needle electrode on the production of hydrogen peroxide and the degradation of dimethylsulfoxide (DMSO) caused by a pulsed corona discharge in water were investigated. A reactor of needle–plate electrode geometry was used. The erosion of the tungsten electrodes by the discharge was evaluated. The yields of H2O2 production and the decomposition of DMSO by the discharge, which were obtained using the tungsten electrodes, were compared with those determined for titanium electrodes. The electrode erosion increased significantly with an increase in the solution conductivity. A large fraction (50–70%) of the eroded tungsten electrode material was released into the solution in dissolved form as tungstate ions. A correlation between the amount of eroded tungsten material released into the solution and the chemical effects induced by the discharge was determined. Lower yields of H2O2 and a higher degradation of DMSO by the discharge were obtained using the tungsten electrodes than were determined using titanium electrodes. Tungstate ions were shown to play a dominant role in the decomposition of H2O2, which was produced by the discharge using a tungsten electrode. The higher degradation of DMSO that was determined for tungsten was attributed to the tungstate-catalyzed oxidation of DMSO by H2O2, in addition to the oxidation of DMSO by OH radicals. Such a mechanism was supported by the detection of degradation by-products of DMSO (methanesulfonate, sulfate and dimethyl sulfone). The catalytic role of tungstate ions in the plasmachemical activity of the discharge generated using a tungsten electrode was also demonstrated on a pH-dependent decomposition of H2O2 and DMSO.