Degradation of Carbofuran in Water by Solar Photocatalysis in Presence of Photosensitizers

The effect of the presence of photosensitizers, methylene blue (MB) and rose Bengal (RB), on the degradation of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) in water in a solar photocatalytic system was investigated. It was found that as compared to MB, RB generally showed a stronger effect on the decomposition of carbofuran under comparable conditions. Among the conditions studied, adding 2 × 10^?6 M of RB, that corresponding to 2% of the initial concentration of carbofuran solution in the system, rendered the most effective degradation of carbofuran. As a result, a carbofuran removal percentage of 69.9%, a mineralization efficiency of 28.0%, and a microtoxicity reduction of 65.0% could be achieved. The degradation and mineralization of carbofuran was found to follow the pseudo-first order reaction kinetics. The decomposition mechanism of carbofuran was further investigated through identification of the intermediates to elaborate the influence of dye photosensitizer on the solar photocatalysis of carbofuran in water. On the basis of the intermediates identified, including carbofuran phenol, 3-hydroxy carbofuran phenol, and substituted alcohols (3-phenoxy 1-propanol, 2-ethyl 1-hexanol, 2-butoxyl ethanol), it appears that hydrolysis and hydroxylation were the two key mechanisms for decomposing carbofuran during the process of solar photocatalysis with the aid of dye photosensitizer.     

Accelerated degradation of carbofuran in standing water from carbofuran‐retreated Azolla plots

Abstract

Carbofuran (2, 3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranyl N‐methylcarbamate) was mixed with standing water from six flooded Azolla (a fern harboring a nitrogen fixing alga, Anabaena azollae) plots that had been regularly treated with carbofuran before. The insecticide completely disappeared in 5 to 10 days when mixed with water from three of the six plots. The enrichment culture, prepared by further additions of carbofuran to the standing water from an Azolla plot, degraded bendiocarb (2, 2‐dimethyl‐l, 3‐benzidioxol‐4‐yl‐N‐methylcarbamate), carbofuran and carbosulfan [2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl (di‐n‐butyl‐aoinosulfenyl) methyl‐carbamate ] in that order. Enrichment culture, upon sterilization by autoclavlng, lost its ability to degrade carbofuran. Evidently, accelerated degradation of carbofuran in standing water from retreated Azolla plots was mediated by microorganisms.     

Removal of mixed pesticides from drinking water system by photodegradation using suspended and immobilized TiO2

Lindane (1α, 2α, 3β, 4α, 5α, 6β-hexachloro cyclohexane), methyl parathion (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) and dichlorvos (2,2-dichlorovinyl-O-O-dimethyl phosphate) are removed from water individually and as a mixture by photo degradation using suspended and immobilized forms of TiO₂ (Degussa P-25). Studies were conducted to optimize the coating thickness of immobilized photo catalyst. The rate of degradation of pesticides was compared in both suspended and immobilized TiO₂ systems. Degradation studies of mixed pesticides were carried out with low concentrations (1.0 and 2.5 mg/L) of pesticides. Only three intermediate byproducts such as methyl paraoxon, O,O,O-trimethyl phosphonic thionate and p-nitrophenol were observed during the methyl parathion degradation in suspended, immobilized TiO₂ systems and mixed pesticides degradation studies. At the end of the reaction methyl parathion and its by-products were completely degraded. During lindane degradation hexachloro cyclohexane, pentachloro cyclohexane, hexachloro benzene, 1-hydroxy 2,3,4,5,6-chlorocyclohexane, 1-hydroxy 2,3,4,5,6-chlorobenzene, pentachloro cyclopentadiene, 1,2,3,4,5-hydroxy cyclopentene and 1,2,3-hydroxy cyclobutane were identified in suspended and immobilized TiO₂ systems, whereas only hexachloro cyclohexane, pentachloro cyclohexane, hexachloro benzene and pentachloro cyclopentadiene were observed during mixed pesticides degradation. No intermediate by-product was observed during the photo degradation of dichlorvos. Langmuir-Hinshelwood pseudo first order kinetic equation showed that there was not much change in the rates of degradation in both suspended and immobilized TiO₂ systems irrespective of the pesticide. During mixed pesticides degradation, the degradation pattern was not similar to that of single pesticide.     

TiO2纳米管催化活性再生处理技术简

采用H₂O₂、Fe₂（SO₄）₃和Fenton溶液对失活的TiO₂纳米管进行再生处理,重点考察了3种溶液的浓度和处理时间等对再生效果的影响,初步分析了经处理后TiO₂纳米管催化活性得到再生或增强的机理。结果表明,经H₂O₂溶液处理后TiO₂催化活性能得到有效再生,经Fe₂（SO₄）₃和Fenton溶液处理后其催化活性不仅得到再生,还能显著增强,这与H₂O₂和Fenton的强氧化作用,及进入TiO₂纳米管的Fe³⁺的阻止电子-空穴对再复合作用有关。     

Photocatalytic degradation of p,p′-DDT under UV and visible light using interstitial N-doped TiO2

1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (or p,p′-DDT) is one of the most persistent pesticides. It is resistant to breakdown in nature and cause the water contamination problem. In this work, a major objective was to demonstrate the application of N-doped TiO₂ in degradation and mineralization of the p,p′-DDT under UV and visible light in aqueous solution. The N-doped TiO₂ nanopowders were prepared by a simple modified sol–gel procedure using diethanolamine (DEA) as a nitrogen source. The catalyst characteristics were investigated using XRD, SEM, TEM, and XPS. The adsorption and photocatalytic oxidation of p,p′-DDT using the synthesized N-doped TiO₂ under UV and visible light were conducted in a batch photocatalytic experiment. The kinetics and p,p′-DDT degradation performance of the N-doped TiO₂ were evaluated. Results show that the N-doped TiO₂ can degrade p,p′-DDT effectively under both UV and visible lights. The rate constant of the p,p′-DDT degradation under UV light was only 0.0121 min^?1, whereas the rate constant of the p,p′-DDT degradation under visible light was 0.1282 min^?1. Under visible light, the 100% degradation of p,p′-DDT were obtained from N-doped TiO₂ catalyst. The reaction rate of p,p′-DDT degradation using N-doped TiO₂ under visible light was sixfold higher than that under UV light. According to Langmuir-Hinshelwood model, the adsorption equilibrium constant (K) for the N-doped TiO₂ under visible light was 0.03078 L mg^?1, and the apparent reaction rate constant (k) was 1.3941 mg L^?1-min. Major intermediates detected during the p,p′-DDT degradation were p,p′-DDE, o,p′-DDE, p,p′-DDD and p,p′-DDD. Results from this work can be applied further for the breakdown of p,p′-DDT molecule in the real contaminated water using this technology.     

CuO/TiO2-H2O2可见光催化亚甲基蓝脱色效果及影响因素研究

以水解法制备的锐钛矿型TiO2为载体,制备了CuO/TiO2型光催化剂.以亚甲基蓝为对象,在可见光照射下研究了H2O3加入量、pH值和催化剂投加量对脱色效果的影响,同时与改性前的TiO2催化剂进行了脱色效果的对比.结果表明亚甲基蓝在碱性条件下能较好脱色,H2O2用量和CuO/TiO2催化剂投加量分别为每1 000 mL反应液各加入10 mL和0.1 g时脱色最好;另外,TiO2催化剂也在碱性条件下能较好脱色,H2O2用量和催化剂投加量分别为每1 000 mL反应液各加入12.5 mL和0.1 g时脱色最好.最优条件下对比实验表明,CuO/TiO2型催化剂在可见光照射下具有很高的催化活性,亚甲基蓝2 h脱色率达到88%,远好于改性前的TiO2和Degussa P25催化剂.     

Photocatalytic degradation of gaseous toluene over Ag-doping TiO₂ nanotube powder prepared by anodization coupled with impregnation method

In this work, Ag-doping TiO₂ nanotubes were prepared and employed as the photocatalyst for the degradation of toluene. The TiO₂ nanotube powder was produced by the rapid-breakdown potentiostatic anodization of Ti foil in chloride-containing electrolytes, and then doped with Ag through an incipient wetness impregnation method. The samples were characterized by scanning electron microscope, high-resolution transmission electron microscopy, X-ray diffraction, surface photovoltage measurements, X-ray photoelectron spectroscopy and N₂ adsorption. The nanotubular TiO₂ photocatalysts showed an outer diameter of approximately 40 nm, fine mesoporous structure and high specific surface area. The photocatalytic activity of Ag-doping TiO₂ nanotube powder was evaluated through photooxidation of gaseous toluene. The results indicated that the degradation efficiency of toluene could get 98% after 4 h reaction using the Ag-doping TiO₂ nanotubes as the photocatalyst under UV light illumination, which was higher than that of the pure TiO₂ nanotubes, Ag-doping P25 or P25. Benzaldehyde species could be observed during the photocatalytic oxidation monitored by in situ FTIR, and the formed benzaldehyde intermediate during reaction would be partially oxidized into CO₂ and H₂O.     

H4SiW12O40/TiO2/beads光催化降解亚甲基蓝的研究

以钛酸四丁酯为原料,空心微珠为载体,采用溶胶凝胶法制备TiO₂/beads光催化剂载体,然后浸渍法制备出H₄SiW₁₂O₄₀/TiO₂/beads表面负载修饰型复合光催化剂,并运用SEM、XRD、FT-IR和DRS对催化剂进行表征和分析。研究了H₄SiW₁₂O₄₀/TiO₂/beads对亚甲基蓝降解的光催化活性,考察了光强度、pH值、曝气量、底物浓度和催化剂用量等对催化效率的影响。实验结果表明,在中性条件下,H₄SiW₁₂O₄₀/TiO₂/beads催化剂的投加量为0.25 g/L,浓度为7.5 mg/L的亚甲基蓝溶液在250 W的紫外灯和600 W的可见光灯下光照60 min降解率分别可达到94.5%和55%。     

Biodegradation of carbofuran in soils within Nzoia River Basin,Kenya

Carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) has been used within the Nzoia River Basin (NRB), especially in Bunyala Rice Irrigation Schemes, in Kenya for the control of pests. In this study, the capacity of native bacteria to degrade carbofuran in soils from NRB was investigated. A gram positive, rod-shaped bacteria capable of degrading carbofuran was isolated through liquid cultures with carbofuran as the only carbon and nitrogen source. The isolate degraded 98% of 100-μg mL^?1 carbofuran within 10 days with the formation of carbofuran phenol as the only detectable metabolite. The degradation of carbofuran was followed by measuring its residues in liquid cultures using high performance liquid chromatography (HPLC). Physical and morphological characteristics as well as molecular characterization confirmed the bacterial isolate to be a member of Bacillus species. The results indicate that this strain of Bacillus sp. could be considered as Bacillus cereus or Bacillus thuringiensis with a bootstrap value of 100% similar to the 16S rRNA gene sequences. The biodegradation capability of the native strains in this study indicates that they have great potential for application in bioremediation of carbofuran-contaminated soil sites.     

Removal of AOX, total nitrogen and chlorinated lignin from bleached Kraft mill effluents by UV oxidation in the presence of hydrogen peroxide utilizing TiO2 as photocatalyst

Background, aim, and scope  The pulp and paper industry is the sixth largest polluter discharging a variety of gaseous, liquid, and solid wastes into the environment. Effluents from bleached Kraft mill effluents (BKME) are polluting waters to a great extent These effluents cause considerable damage to the receiving waters if discharged untreated since they have high levels of biological oxygen demand (BOD), chemical oxygen demand (COD), chlorinated compounds (measured as AOX), suspended solids (mainly fibers), fatty acids, tannins, resin acids, lignin and its derivatives, sulfur and sulfur compounds, etc. This study aimed to remove adsorbed organic halogen (AOX), total nitrogen, and lignin-degrading products in the wastewater (4,500 m³/h) from the paper mill in the pulp and paper industry, which is discharged to sea from a plant located in western Turkey. Materials and methods  The photocatalytic degradation of AOX, total nitrogen, and chlorinated lignin in BKME have been investigated in different parameters, such as time, H₂O₂ and TiO₂ concentration. In addition, for investigating the effect of chlorine on the removal of lignin, pure lignin solution was prepared in equal amounts to chlorinated lignin degradation products found in BKME. The same experiments were conducted for this solution. Experiments were carried out in photocatalytic reactor made of Pyrex glass. The mercury lamp was used as a radiation source. All irradiation was carried out under constant stirring. The existence of dissolved O₂ is an important factor which increases the photocatalytic degradation. Hence, we used an air pump for the aeration of the wastewater solutions. The temperature of the wastewater was controlled and adjusted to 25°C by thermostat pump in conjunction with a cooler. At the end of all experiments, AOX, total nitrogen and lignin concentrations were analyzed according to standard methods. All experiments were performed in duplicate and average values were used. Results and discussion  When the effect of H₂O₂ and time were investigated, it was observed that the AOX concentration increased from 3.0 to 11.0 mg/L by only UV. However, when H₂O₂ was added, AOX concentration decreased from approximately 3.0 to 0.0 mg/L. The optimal conditions for the removal of AOX appear to be an initial H₂O₂ concentration of 20.0 mL/L and reaction time of 50 min. In addition, at the same experiment conditions, it was seen that the total nitrogen concentration decreased from 23.0 to 15.0 mg/L by only UV and by increasing H₂O₂ concentration, the concentration of 20.0 mL/L H₂O₂ appears to be optimal (9.0 mg/L). The AOX, total nitrogen and lignin degradation products and pure lignin go through a minimum when the concentration of H₂O₂ and TiO₂ increases at constant pH and UV intensity. The kinetics for the degradation of AOX, total nitrogen and lignin degradation products followed a pseudo-first order law with respect to the products, and the degradation rates (min⁻¹) for the UV/TiO₂/H₂O₂ system were higher than that of the corresponding values for the UV/H₂O₂ system. Conclusions  The AOX, total nitrogen and lignin concentration go through a minimum when the concentration of H₂O₂ and TiO₂ increases at constant pH and UV intensity. It was found that the UV/TiO₂/H₂O₂ system has proved capable of the degradation of total nitrogen as well as chlorinated and degraded lignin in BKME. Recommendations and perspectives  The photocatalytic process can be considered a suitable alternative for the remove of some compounds from the BKME. Nevertheless, further studies should be carried out to confirm the practical feasibility of BKME. Another result obtained from the study is that pre-purification carried out with UV/TiO₂/H₂O₂ photocatalytic process may constitute an important step for further purification processes such as adsorption, membrane processes, etc.     

臭氧辅助UV/Fenton法处理电镀添加剂生产废水

采用臭氧辅助光芬顿法处理电镀添加剂生产废水,考察双氧水、FeSO₄·7H₂O、pH和反应时间等因素对废水COD和UV₂₅₄去除的影响。实验结果表明,pH=4,臭氧通入量为0.25 g,双氧水的投加量93.3 mL/L,FeSO₄·7H₂O投加量为5.3 g/L,最佳反应时间为30 min,COD和UV₂₅₄去除率分别达到92.64%和87.95%。这表明,臭氧辅助光芬顿法对电镀添加剂生产废水处理效果显著,处理时间大大减少。     

Photocatalytic oxidation of xenobiotics in water with immobilized TIO2 on agitator

Abstract

A novel photocatalytic oxidation reactor, using Degussa P‐25 T_iO₂ as a stationary phase with a thickness of 1.5–2.0 um on the blades of agitator, was developed to study the photocatalytic oxidation of xenobiotics. Particularly in this device, separation of photocatalyst from the purified water after oxidation reaction was not necessary, and no other aeration equipment was required to supply oxygen. To examine the efficiency of this device, photocatalytic degradation of xenobiotic organics such as carbofuran was studied as an example. Results indicated that carbofuran could be degraded completely with mineralization efficiency of 20 % after 6 hours of oxidation under the imposed conditions. The mineralization rate of carbofuran was found to follow the pseudo‐first order reaction kinetics. Moreover, the rate constant of mineralization was found to be proportional to T_iO₂ film area and the square root of UV light intensity. These results implied the mineralization efficiency of carbofuran could be improved through increasing T_iO₂ film area and UV light intensity. Accordingly, this novel device showed potential application for degrading xenobiotics in water.     

Comparative studies of the Fe–UV, H2O2–UV, TiO2–UV/vis systems for the decolorization of a textile dye X-3B in water

The degradation of a common textile dye, Reactive-brilliant red X-3B, by several advanced oxidation technologies was studied in an air-saturated aqueous solution. The dye was resistant to the UV illumination (wavelength λ  320 nm), but was decolorized when one of Fe³⁺, H₂O₂ and TiO₂ components was present. The decolorization rate was observed to be quite different for each system, and the relative order evaluated under comparable conditions followed the order of Fe²⁺–H₂O₂–UV  Fe²⁺–H₂O₂ > Fe³⁺–H₂O₂–UV > Fe³⁺–H₂O₂ > Fe³⁺–TiO₂–UV > TiO₂–UV > Fe³⁺–UV > TiO₂–visible light (λ  450 nm) > H₂O₂–UV > Fe²⁺–UV. The mechanism for each process is discussed, and linked together for understanding the observed differences in reactivity.     

Effectiveness evaluation of glyphosate oxidation employing the H2O2/UVC process: Toxicity assays with Vibrio fischeri and Rhinella arenarum tadpoles

The H₂O₂/UVC process was applied to the photodegradation of a commercial formulation of glyphosate in water. Two organisms (Vibrio fischeri bacteria and Rhinella arenarum tadpoles) were used to investigate the toxicity of glyphosate in samples M_1, M₂, and M₃ following different photodegradation reaction times (120, 240 and 360 min, respectively) that had differing amounts of residual H₂O₂. Subsamples of M₁, M₂, and M₃ were then used to create samples M_1,E, M_2,E and M_3,E in which the H₂O₂ had been removed. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were measured in tadpoles to determine possible sub-lethal effects. In V. fischeri, M_1,E, which was collected early in the photodegradation process, caused 52% inhibition, while M_3,E, which was collected at the end of the photodegradation process, caused only 17% inhibition. Survival of tadpoles was 100% in samples M₂, M₃, and in M_1,E, M_2,E and M_3,E. The lowest percentages of enzymatic inhibition were observed in samples without removal of H₂O₂: 13.96% (AChE) and 16% (BChE) for M₂, and 24.12% (AChE) and 13.83% (BChE) for M₃. These results show the efficiency of the H₂O₂/UVC process in reducing the toxicity of water or wastewater polluted by commercial formulations of glyphosate. According to the ecotoxicity assays, the conditions corresponding to M₂ (11 ± 1 mg a.e. L^?1 glyphosate and 11 ± 1 mg L^?1 H₂O₂) could be used as a final point for glyphosate treatment with the H₂O₂/UV process.     

Photocatalytic mineralization of glyphosate in a small-scale plug flow simulation reactor by UV/TiO2

The present work involves the photocatalytic mineralization of glyphosate on a plug flow reactor by UV/TiO₂. The effect of catalyst loading shows an optimal value (0.4 g L^?1) which is necessary to mineralize glyphosate. The kinetic rate of glyphosate mineralization decreases with the increasing initial concentration of glyphosate, and the data can be described using the first-order model. An alkaline environment is conducive to glyphosate mineralization. The mineralization efficiency increases with elevated flow rate to 114 mL min^?1, which is followed by a decrease with a further increase in flow rate due to the reduction of the residence time. The presence of external oxidants (K₂S₂O₈, H₂O₂ and KBrO₃) and photosencitizer (humic acid) can significantly enhance glyphosate mineralization. Photocatalysis oxidation ability of the three studied oxidants decrease in the order of: S₂O₈ ^2? > BrO₃ ^? > H₂O₂. Finally, the Langmuir–Hinshelwood (L-H) model was used to rationalize the mechanisms of reactions occurring on TiO₂ surfaces and L-H model constants were also determined.     

填料塔中Na_2CO_3吸收高浓度H_2S的传质特性

在填料吸收塔中考察了Na2CO3溶液吸收高浓度H2S气体的气液传质特性。通过测量填料塔进出口气体中H2S浓度计算了Na2CO3溶液吸收高浓度H2S气体的总体积传质系数(KGa),并研究了进气流速、吸收液流量、吸收温度和吸收液浓度对KGa的影响。结果表明,KGa随Na2CO3浓度、吸收液流量的增加而增加,随吸收温度、进气流速的升高而降低;在高浓度H2S吸收过程中液相传质阻力不能忽略。     

原位水解生成的羟基氧化铁凝聚吸附除磷效能与机制简

将不同摩尔比Fe³⁺与OH^-（[Fe³⁺]：[OH^-]=1：0、1：1、1：2和1：3）反应获得原位水解生成的羟基氧化铁（in situ FeO_xH_y）,研究了具有不同水解程度的羟基氧化铁对凝聚吸附除磷效能与机制。研究显示,In situ FeO_xH_y对磷的去除率随铁投量增大而升高,且均在中性pH范围内具有最佳除磷效果;在相同铁投量条件下,磷去除率随着[OH^-]：[Fe³⁺]的升高而降低;当体系碱度较低时（pH<6）,引入OH^-可促进Fe³⁺水解而提高除磷效果。4种羟基氧化铁均可在15 s内可快速吸附磷,且吸附过程符合准二级动力学模型;Freundlich模型均可很好地描述磷在4种羟基氧化铁表面的吸附行为。磷酸盐吸附后,In situ FeO_xH_y表面Zeta电位明显降低,且[Fe³⁺]：[OH^-]为1：0的羟基氧化铁降低最为显著。结合MINITEQ计算软件磷酸盐、铁盐形态分析结果显示,对于碱度较低的体系,通过投加一定量OH^-可促进Fe³⁺水解,进而使得其更易与水中H₂PO₄^-与HPO₄^2-结合,生成具有多核羟基的磷酸铁络合物,进而提高除磷效果。     

改进钒基SCR脱硝催化剂的抗碱金属中毒性能

以锐钛矿型二氧化钛和钛钨粉(5%WO3-TiO2)为载体,制备了系列钒和钨负载量不同的钒钛催化剂,考察碱金属和碱土金属(钾、钠和钙)对催化剂在氨选择性催化还原(NH3-SCR)氮氧化物反应中催化活性的影响。钾、钠和钙对钒钛催化剂的中毒影响大小顺序为钾钠钙。提高钒钛催化剂中钒的含量可显著提高催化剂的SCR活性和抗碱金属中毒性能,但高钒负载量(4.5%V2O5)造成催化剂氮气选择性明显下降,氧化亚氮生成显著增加。钨的添加有利于提高钒钛催化剂的低温活性和抗碱金属中毒性能,对氮气选择性无明显影响。     

Photocatalytic Oxidation of Volatile Organic Compounds Using Fluorescent Visible Light

Abstract

Photocatalytic oxidation (PCO) of volatile organic compounds (VOCs) is a highly attractive alternative technology for purification and deodorization of indoor air. The main objectives of this study were to demonstrate that a common fluorescent visible light (FVL) lamp can be used to effectively remove by PCO low concentrations of VOCs from slightly contaminated air and to provide some fundamental and technical details on the process. The target VOC was n-butanol, which is a standard reference odorant. Its PCO was studied under a long residence time in a 3.7-L cylindrical reactor with commercial titanium dioxide (TiO₂) as the reference photocatalyst and using mostly FVL for illumination. For comparison only, a UV (black) light lamp was used. The gas-phase products were detected and quantified online by gas chromatography (GC). The effects of reactor residence time, of inlet concentration, and of the relative light intensity on the efficiency of the process were also evaluated. At a high n-butanol concentration (0.1 vol %), butanal and propanal were identified as the intermediate products of the process; ethanal appeared when the initial concentration was <850 ppm_v. This indicates that PCO leading to CO₂ and H₂O is relatively slow and proceeds in a stepwise manner. Although the efficiency of the process with an FVL lamp was significantly lower than when using a UV black light, complete PCO of low concentrations was achieved for 100 ppm_v. In a search for a material with photoactivation extended to higher wavelengths or increased photo-activity, several samples of transition metal- or silver ion-doped (2 atomic %) TiO₂ as well as SrTi_1xFe_xO₃ (x = 0.1 and 0.15) perovskites were included in the study. None of these materials was more active than pure TiO₂. The results of this study open new horizons in the area of indoor air quality (IAQ) control.     

Photocatalytic degradation of the herbicide pendimethalin using nanoparticles of BaTiO3/TiO2 prepared by gel to crystalline conversion method: A kinetic approach

Photocatalytic degradation of the herbicide, pendimethalin (PM) was investigated with BaTiO₃/TiO₂ UV light system in the presence of peroxide and persulphate species in aqueous medium. The nanoparticles of BaTiO₃ and TiO₂ were obtained by gel to crystallite conversion method. These photo catalysts are characterized by energy dispersive x-ray analysis (EDX), scanning electron microscope (SEM), x-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) adsorption isotherm and reflectance spectral studies. The quantum yields for TiO₂ and BaTiO₃ for the degradation reactions are 3.166 Einstein m^?2 s^?1 and 2.729 Einstein m^?2 s^?1 and catalytic efficiencies are 6.0444 × 10^?7 mg^?2h^?1L² and 5.403 × 10^?7 mg^?2h^?1L², respectively as calculated from experimental results. BaTiO₃ exhibited comparable photocatalytic efficiency in the degradation of pendimethalin as the most widely used TiO₂ photocatalyst. The persulphate played an important role in enhancing the rate of degradation of pendimethalin when compared to hydrogen peroxide. The degradation process of pendimethalin followed the first-order kinetics and it is in agreement with Langmuir-Hinshelwood model of surface mechanism. The reason for high stability of pendimethalin for UV-degradation even in the presence of catalyst and oxidizing agents were explored. The higher rate of degradation was observed in alkaline medium at pH 11. The degradation process was monitored by spectroscopic techniques such as ultra violet-visible (UV-Vis), infrared (IR) and gas chromatography mass spectroscopy (GC-MS). The major intermediate products identified were: N-propyl-2-nitro-6-amino-3, 4-xylidine, (2, 3-dimethyl-5-nitro-6-hydroxy amine) phenol and N-Propyl-3, 4-dimethyl-2, 6-dinitroaniline by GC-MS analysis and the probable reaction mechanism has been proposed based on these products.