A comparative investigation of NdSrCu1-xCoxO4-σ and Sm1:8Ce0:2Cu1-xCoxO4-σ(x: 0-0.4) for NO decomposition

A series of single-phase T-structured NdSrCu1??xCoxO4?? with oxygen vacancies and T0-structured Sm1:8Ce0:2Cu1??xCoxO4?? (x: 0–0.4) with oxygen excess were prepared using ultrasound-assisted citric acid complexing method, and characterized by means of techniques such as thermogravimetric analysis and NO temperature-programmed desorption (NO-TPD). The catalytic activities of these materials were evaluated for the decomposition of NO. It was found that the NdSrCu1??xCoxO4?? catalysts were of oxygen vacancies whereas the Sm1:8Ce0:2Cu1??xCoxO4?? ones possessed excessive oxygen (i.e., over-stoichiometric oxygen); with a rise in Co doping level, the oxygen vacancy density of NdSrCu1??xCoxO4?? decreased while the over-stoichiometric oxygen amount of Sm1:8Ce0:2Cu1??xCoxO4?? increased. The NO-TPD results revealed that NO could be activated much easier over the oxygen-deficient perovskite-like oxides than over the oxygen-excessive perovskite-like oxides, with the NdSrCuO3:702 catalyst showing the best e ciency in activating NO molecules. Under the conditions of 1.0% NO/helium, 2800 hr??1, and 600–900°C, the catalytic activity of NO decomposition followed the order of NdSrCuO3:702 > NdSrCu0:8Co0:2O3:736 > NdSrCu0:6Co0:4O3:789 > Sm1:8Ce0:2Cu0:6Co0:4O4:187 > Sm1:8Ce0:2Cu0:8Co0:2O4:104 > Sm1:8Ce0:2CuO4:045, in concord with the sequence of decreasing oxygen vacancy or oxygen excess density. Based on the results, we concluded that the higher oxygen vacancy density and the stronger Cu3+/Cu2+ redox ability of NdSrCu1??xCoxO4?? account for the easier activation of NO and consequently improve the catalytic activity of NO decomposition over the catalysts.     

Reduction of NO by CO using Pd–CeTb and Pd–CeZr catalysts supported on SiO_2 and La_2O_3–Al_2O_3

The catalytic activity of Pd catalysts supported on Ce0.73Tb0.27 O x/Si O2, Ce0.6Zr0.4O x/Si O2,Ce0.73Tb0.27 O x/La2O3–Al2O3and Ce0.6Zr0.4O x/La2O3–Al2O3was studied using the reduction of NO by CO. The catalysts were characterized by X-ray fluorescence, surface area, X-ray diffraction, temperature-programmed reduction, CO chemisorption and oxygen storage capacity. Temperature-programmed reduction results indicated that Tb or Zr incorporation improves the reducibility and oxygen storage capacity. CO chemisorption data suggested the presence of large Pd O particles due to the low CO/Pd ratio. No significant differences were obtained in light off temperatures(T Light off) for all Pd catalysts and the most active was1.5%Pd/Ce0.6Zr0.4O x/Si O2.     

Simultaneous removing SO2 and NO by a new system containing cobalt complex

Absorption and catalytic oxidation of nitric oxide can be achieved by using cobalt（Ⅲ） ethylenediamine （Co（en）3^3＋. When simultaneous absorbing SO2 and NO, the precipitation of Co2（SO3）3 will be yielded and the NO removal will be decreased. A new catalyst system using Co（en）3^3＋ coupled with urea has been developed to simultaneous remove NO and SO2 in the flue gas. NO is absorbed and catalytically oxidized to nitrite and nitrate by Co（en）3^3＋. The dissolved oxygen in scrubbing solution from the feed stream acts as oxidant. Urea restrains the precipitation of Co2（SO3）3 by oxidizing SO3^2-to SO4^2- as COSO4 is more soluble in water. The experimental results proved that nearly all SO3^2- can be oxidized to SO4^2- and the high NO and SO2 removal could be obtained with the new system. The NO removal is influenced by gas flow rate, the concentration of Co（en）3^3＋ and urea in the absorption solution, the temperature of the scrubbing solution and the content of oxygen in the flue gas. The low gas flow rate is favorable to increase the NO removal. The experiments proved that the NO removal could be maintained at more than 95% by the system of 0.02 mol/L Co（en）3^3＋ and 1% urea at 50℃ with 10% O2 in the flue gas.     

VxMn(4 − x)Mo3Ce3/Ti catalysts for selective catalytic reduction of NO by NH3

A series of vanadium based catalysts(VxMn(4-x)Mo3Ce3/Ti) with different vanadium(x wt.%) and manganese((4-x) wt.%) contents have been prepared by the wet impregnation method and investigated for selective catalytic reduction(SCR) of NO_x by NH_3 in the presence of 8 vol.% H_2O and 500 ppm V SO_2.The physicochemical characteristics of the catalysts were thoroughly characterized.The SCR of NO_x by NH_3(NH_3-SCR) activity, especially the low-temperature activity, significantly increased with increasing V_2O_5 content in the catalyst until the V_2O_5 content reached 1.5 wt.%, which corresponds well with the redox properties of the catalyst.All of the metal oxides were well dispersed and strongly interacted with each other on the catalyst surface.V mainly exists in the V~(5+)state in the catalysts.The strong synergistic effect between the vanadium and cerium species led to formation of more Ce~(3+)species, and that between the vanadium and manganese species contributed to formation of more manganese species with low valences.All of the catalysts exhibited strong acidity, while the redox properties determined the NH_3-SCR activity, especially the low-temperature activity.H_2O and SO_2 had severe inhibiting effects on the activity of V1.5Mn2.5Mo3Ce3/Ti.However, good H_2O and SO_2 resistance and high NO_x conversion by V1.5Mn2.5Mo3Ce3/Ti could be achieved in the presence of SO_2 and almost no decline was observed in a long-term test at 275℃ for 168 hr in the presence of SO_2 and H_2O, which can be attributed to the sulfate species formed on the catalyst surface.     

Removal of formaldehyde over MnxCe1-xO2 catalysts: Thermal catalytic oxidation versus ozone catalytic oxidation

MnxCe1- xO2（x： 0.3–0.9） prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde（HCHO）. At x = 0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of Ce O2 to form a solid solution. The catalytic activity was best at x = 0.5, at which the temperature of 100% removal rate is the lowest（270°C）. The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5 wt.% Cu Oxinto Mn0.5Ce0.5O2. With ozone catalytic oxidation, HCHO（61 ppm） in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV（gas hourly space velocity） of 10,000 hr-1at 25°C. The effect of the molar ratio of O3 to HCHO was also investigated. As O3/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O3/HCHO ratio of 8, the mineralization efficiency of HCHO to CO2 was 86.1%. At 25°C, the p-type oxide semiconductor（Mn0.5Ce0.5O2） exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as Ti O2, which had a low ozone decomposition efficiency（9.81%）. At a GHSV of 10,000 hr-1, [O3]/[HCHO] = 3 and temperature of 25°C, a high HCHO removal efficiency（≥ 81.2%） was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal.     

Toluene decomposition performance and NOx by-product formation during a DBD-catalyst process

Characteristics of toluene decomposition and formation of nitrogen oxide(NOx) by-products were investigated in a dielectric barrier discharge(DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide(Mn Ox), iron oxide(Fe Ox), cobalt oxide(Co Ox) and copper oxide(Cu O), supported on Al2O3/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO2 selectivity. In addition, NOx was suppressed with the decrease of specific energy density(SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the Cu O catalyst showed the best performance in NOx suppression. The Mn Ox catalyst exhibited the lowest concentration of O3 and highest CO2 selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression.     

Photoreaction of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea in simulated atmosphere

Thephotoreactionofl-(2-chlorobenzoyl)-3-(4-chlorophenyl)urea(ccu)in simulated atmosphere was studkd．Rate constants and half-lives of this compound in nitrogen，air and oxygen，upon irradiation with Xenon lamp，were determined．Statistical treatment ofexperimental results indicated that photoreactions in nitrogen and air were of the first order，while that in oxygen was closer to the second order．The main products of photoreaction of this compound were 2-chlorobenzamide，4-chlorophenyl urea，4-chloro aniline，and 2-chloro-N-(4-chlorophenyl)benzamide，and the possible pathways of photodecomposition were suggested．     

Oxidation of diesel soot on binary oxide CuCr(Co)-based monoliths

Binary oxide systems(Cu Cr2O4, Cu Co2O4), deposited onto cordierite monoliths of honeycomb structure with a second support(finely dispersed Al2O3), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine’s gas exhausts(O2, NOx, H2 O, CO2) and O3 as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO2. Oxidants used can be arranged with reference to decreasing their activity in a following series: O3 NO2> H2 O > NO > O2> CO2. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O3 occurs intensively(in the presence of copper chromite based catalyst) even at closing to ambient temperatures.Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem.     

Characterization and performance of Pt/SBA-15 for low-temperature SCR of NO by C3H6

Pt supported on mesoporous silica SBA-15 was investigated as a catalyst for low temperature selective catalytic reduction(SCR) of NO by C 3 H 6 in the presence of excess oxygen.The prepared catalysts were characterized by means of XRD,BET surface area,TEM,NO-TPD,NO/C 3 H 6-TPO,NH 3-TPD,XPS and 27 Al MAS NMR.The effects of Pt loading amount,O 2 /C 3 H 6 concentration,and incorporation of Al into SBA-15 have been studied.It was found that the removal efficiency increased significantly after Pt loading,but an optimal loading amount was observed.In particular,under an atmosphere of 150 ppm NO,150 ppm C 3 H 6,and 18 vol.% O 2,0.5% Pt/SBA-15 showed remarkably high catalytic performance giving 80.1% NOx reduction and 87.04% C 3 H 6 conversion simultaneously at 140°C.The enhanced SCR activity of Pt/SBA-15 is associated with its outstanding oxidation activities of NO to NO 2 and C 3 H 6 to CO 2 in low temperature range.The research results also suggested that higher concentration of O 2 and higher concentration of C 3 H 6 favored NO removal.The incorporation of Al into SBA-15 improved catalytic performance,which could be ascribed to the enhancement of catalyst surface acidity caused by tetrahedrally coordinated AlO 4.Moreover,the catalysts could be easily reused and possessed good stability.     

Ce-promoted Mn/ZSM-5 catalysts for highly efficient decomposition of ozone

Manganese oxides supported by ZSM-5 zeolite (Mn/ZSM-5) as well as their further modified by Ce promoter were achieved by simple impregnation method for ozone catalytic decomposition. The yCe20Mn/ZSM-5–81 catalyst with 8% Ce loading showed the highest catalytic activity at relative humidity of 50% and a space velocity of 360 L/(g × hr), giving 93% conversion of 600 ppm O₃ after 5 hr. Moreover, this sample still maintained highly activity and stability in humid air with 50%–70% relative humidity. Series of physicochemical characterization including X-ray diffraction, temperature-programmed technology (NH₃-TPD and H₂-TPR), X-ray photoelectron spectroscopy and oxygen isotopic exchange were introduced to disclose the structure-performance relationship. The results indicated that moderate Si/Al ratio (81) of zeolite support was beneficial for ozone decomposition owing to the synergies of acidity and hydrophobicity. Furthermore, compared with 20Mn/ZSM-5-81, Ce doping could enhance the amount of low valance manganese (such as Mn²⁺ and Mn³⁺). Besides, the Ce³⁺/Ce⁴⁺ ratio of 8Ce20Mn/ZSM-5-81 sample was higher than that of 4Ce20Mn/ZSM-5-81. Additionally, the synergy between the MnO_x and CeO₂ could easily transfer electron via the redox cycle, thus resulting in an increased reducibility at low temperatures and high concentration of surface oxygen. This study provides important insights to the utilization of porous zeolite with high surface area to disperse active component of manganese for ozone decomposition.     

Study on the photoreaction of 1-(2-chlorohenzoyl)-3-(4-chlorophenyl 1 urea in methanol

A photoreaction of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl)urea(CCU)m methanol was studied．Rate constants of its reactions，which are found both of the first order，in methanol solution saturated with N₂ or O₂ upon irradiation with xenon lamp,are determined to be O,118 and O.129 h^-1，respectively．Its half life changes from 5.37 to 4.42 h when the light intensity is changed from O.50 to O.62 cal/cm²．min．The main photoproducts identified arc 2-chloro-benzamide．N-phenyl methylearbamate，N-(4-chlorophenyl) methylcarbamate，4-chlorophenyl urea and others．Meanwhile．the mechanism of the photochemical reaction of this compound in methanol was discussed．     

Sm_xCe_(1-x)VO_4纳米粒子对四环素抗生素的光降解机制

以硝酸钐、硝酸铈和钒酸钠为原料,采用共沉法制备不同Sm/Ce摩尔比的Sm_xCe_(1-x)VO_4纳米复合材料,考察其可见光降解四环素抗生素的催化性能。利用XRD、SEM、TEM、HRTEM、XPS、N_2-sorption和UV-vis DRS等手段表征样品。与Sm VO_4和Ce VO_4纳米粒子相比,Sm_xCe_(1-x)VO_4纳米复合物对四环素抗生素具有更好的可见光催化活性,且对四环素的光降解效率随着Sm/Ce摩尔比的减小先增大后减小。Sm/Ce摩尔比2∶3的Sm_(0.4)Ce_(0.6)VO_4纳米复合材料表现出最好的可见光催化活性,且在相同实验条件下循环使用5次后的光催化活性轻微降低。这归因于Sm_(0.4)Ce_(0.6)VO_4纳米复合材料有利于增强可见光区域的光电子捕获能力,降低光生电子-空穴对的复合和提高光生电子在异质结界面的快速传递。超氧自由基(·O~(2-))和空穴(h~+)是参与Sm_(0.4)Ce_(0.6)VO_4纳米催化剂可见光降解四环素的主要活性物质,其中超氧自由基的影响作用更为显著。     

Effect of SiO2 addition on NH4HSO4 decomposition and SO2 poisoning over V2O5–MoO3/TiO2–CeO2 catalyst

The deposition of NH₄HSO₄ and the poisoning effect of SO₂ on SCR catalyst are the main obstacles that restrict the industrial application of CeO₂-doped SCR catalysts. In this work, deposited NH₄HSO₄ decomposition behavior and SO₂ poisoning over V₂O₅–MoO₃/TiO₂ catalysts modified with CeO₂ and SiO₂ were investigated. By the means of characterization analysis, it was found that the addition of SiO₂ into VMo/Ti–Ce had an impact on the interaction existed between catalyst surface atoms and NH₄HSO₄. Temperature-programmed methods and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments indicated that the doping of SiO₂ promoted the decomposition of deposited NH₄HSO₄ on VMo/Ti–Ce catalyst surface by reducing the thermal stability of NH₄HSO₄ and enhancing the NH₄HSO₄ reactivity with NO in low temperature. And this improvement may be the reason for the better catalytic activity than VMo/Ti–Ce in the case of NH₄HSO₄ deposition. Accompanied with cerium sulfate species generated over catalyst surface, the conversion of SO₂ to SO₃ was inhibited in SiCe mixed catalyst. The addition of SiO₂ could promote the decomposition of cerium sulfate, which may be a potential strategy to enhance the resistance of SO₂ poisoning over CeO₂-modifed catalysts.     

Innovatively employing magnetic CuO nanosheet to activate peroxymonosulfate for the treatment of high-salinity organic wastewater

Magnetic CuO nanosheet(Mag-CuO), as a cheap, stable, efficient and easily separated peroxymonosulfate(PMS) activator, was prepared by a simple one-step precipitation method for the removal of organic compounds from salt-containing wastewater.The experiments showed that the removal efficiencies of various organic pollutants including Acid Orange 7, Methylene Blue, Rhodamine B and atrazine in a high-salinity system(0.2 mol/L Na_2SO_4) with the Mag-CuO/PMS process were 95.81%, 74.57%, 100% and 100%,respectively.Meanwhile, Mag-CuO still maintained excellent catalytic activity in other salt systems including one or more salt components(NaCl, NaNO_3, Na_2HPO_4, NaHCO_3).A radical-quenching study and electron paramagnetic resonance analysis confirmed that singlet oxygen(~1O_2) was the dominant reactive oxygen species for the oxidation of organic pollutants in high-salinity systems, which is less susceptible to hindrance by background constituents in wastewater than radicals(~·OH or SO_4~(·-)).The surface hydroxylation of the catalyst and catalytic redox cycle including Cu and Fe are responsible for the generation of~1O_2.The developed Mag-CuO catalyst shows good application prospects for the removal of organic pollutants from saline wastewater.     

Removal of VOCs from gas streams with double perovskite-type catalysts

Double perovskite-type catalysts including La2 CoMnO_6 and La_2 CuMnO_6 are first evaluated for the effectiveness in removing volatile organic compounds(VOCs), and single perovskites(La CoO_3, LaMnO_3, and La Cu O3) are also tested for comparison. All perovskites are tested with the gas hourly space velocity(GHSV) of 30,000 hr~(-1), and the temperature range of100–600°C for C_7H_8 removal. Experimental results indicate that double perovskites have better activity if compared with single perovskites. Especially, toluene(C_7H_8) can be completely oxidized to CO_2 at 300°C as La2 Co MnO_6 is applied. Characterization of catalysts indicates that double perovskites own unique surface properties and are of higher amounts of lattice oxygen,leading to higher activity. Additionally, apparent activation energy of 68 k J/mol is calculated using Mars-van Krevelen model for C7 H8 oxidation with La2 Co Mn O6 as catalyst. For durability test, both La2 Co Mn O6 and La_2 CuMnO_6 maintain high C7 H8 removal efficiencies of 100% and98%, respectively, at 300°C and 30,000 hr~(-1), and they also show good resistance to CO_2(5%) and H2 O(g)(5%) of the gas streams tested. For various VOCs including isopropyl alcohol(C_3H_8 O),ethanal(C_2H_4O), and ethylene(C_2H_4) tested, as high as 100% efficiency could be achieved with double perovskite-type catalysts operated at 300–350°C, indicating that double perovskites are promising catalysts for VOCs removal.     

Porous FeOx/BiVO4-δS0.08：Highly efficient photocatalysts for the degradation of Methylene Blue under visible-light illumination

Porous S-doped bismuth vanadate with an olive-like morphology and its supported iron oxide （y wt.% FeOx/BiVO4-δS0.08, y = 0.06, 0.76, and 1.40） photocatalysts were fabricated using the dodecylamine-assisted alcohol-hydrothermal and incipient wetness impregnation methods, respectively. It is shown that the y wt.% FeOx/BiVO4-δS0.08 photocatalysts contained a monoclinic scheetlite BiVO4 phase with a porous olive-like morphology, a surface area of 8.8-9.2 m^2/g, and a bandgap energy of 2.38-2.42 eV. There was co-presence of surface Bi^5＋, Bi^3＋, V^5＋, V^3＋, Fe^3＋, and Fe^2＋ species in y wt.% FeOx/BiVO4-δS0.08. The 1.40 wt.% FeOx/BiVO4-δS0.08 sample performed the best for Methylene Blue degradation under visible-light illumination. The photocatalytic mechanism was also discussed. We believe that the sulfur and FeOx co-doping, higher oxygen adspecies concentration, and lower baudgap energy were responsible for the excellent visible-light-driven catalytic activity of 1.40 wt.% FeOx/BiVO4-δS0.08.     

Simultaneous removal of gaseous CO and elemental mercury over Cu-Co modified activated coke at low temperature

Cu-Co multiple-oxides modified on HNO₃-pretreated activated coke (AC_N) were optimized for the simultaneous removal of gaseous CO and elemental mercury (Hg⁰) at low temperature (< 200 °C). It was found that 2%CuOx-10%CoOx/AC_N catalyst calcined at 400°C resulted in the coexistence of complex oxides including CuO, Cu₂O, Co₃O₄, Co₂O₃ and CoO phases, which might be good for the simultaneous catalytic oxidation of CO by Co-species and removal of Hg⁰ by Cu-species, benefiting from the synergistic catalysis during the electro-interaction between Co and Cu cations (CoO ? Co₃O₄ and Cu₂O ? CuO). The catalysis removal of CO oxidation was obviously depended on the reaction temperature obtaining 94.7% at 200 °C, while no obvious promoting effect on the Hg⁰ removal (68.3%-78.7%). These materials were very substitute for the removal of CO and Hg° from the flue gas with the conditions of 8–20 vol.% O₂ and flue-gas temperature below 200 °C. The removal of Hg° followed the combination processes of adsorption and catalytic oxidation reaction via Langmuir-Hinshelwood mechanism, while the catalysis of CO abided by the Mars-van Krevelen mechanism with lattice oxygen species.     

Hydrolysis of l-(2-chlorobenzoy|)-3-(4-chlorophenyl) urea in aquatic system

The degradation of the insect growth regulator 1-(2-chlorobenzoyl)-3-(4-chlorophenyl)urea (CCU)was studied both in distilled water and in buffer solution．The experimental results indicated that CCU is not stable in aqueous solution and easily decomposes in alkaline water．At pH 6 and pH 10，the half lives (T_v2)of hydrolysis arc about 9 days and 2 days，respectively．The rate of hydrolysis increases as either the concentration of alkalinity or temperature increases．At [NaOH]=0.01865 mol/L，with every lO^oC increase in temperature，the reaction rate increases about 3 times．the activation energy for hydrolysis is 7l.56 kJ/mol．Basic catalyzed degradation of CCU at levels greatly above its solubility in water resulted in rapid degradation to as many as four identified products：(4-chlorophenyl)urea，2-chlorobenzoic acid，2-chlorobenzamide，and 4-chloroaniline．The major products were(4-chlorophenyl)urea and 2-chlorobenzoic acid．     

Residue and persistence of insecticide l-(2-chlorobenzoyl)-3-(4-chlorophenyl)urea in C hinese cabbage and soils in the Northern China

The residue and persistence of the insect growth regulator 1-(2-(chlorobenzoyl)-3-(4-chlorophenyl)urga(CCU)in Chinese cabbage and soil in the field were studied in Northern China during 1988-1989．The degradation of CCU in soils was also studied under laboratory conditions．The CCU was found to be unstable in Chmese cabbage and soil in field．The half-life ofCCU was 13.2-14.0 days in Chinese cabbage and 8.8-27.0 days in soil,respectively．Three ppm as the maximum residue level for CCU in Chinese cabbage and 21 days as the preharvest interval for the vegetable treated with CCU were recommendced．     

Numerical sim ulation of transport and transform ation of insecticide 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea in unsaturated soil

A numerical simulation model of pesticide transport and transformation in unsaturated soil is presented in this paper．The model was developed under basic principles of movement of water and solute in soil under transient condition and overall consideration water flow：pesticide convection，diffusion, dispersion，sorption and degradation．The model was tested for the persistence and leaching of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl)urea(CCU)using data from soil columns under laboratory conditions．The results of the test indicate that the modeling approach is simple and effective in describing movement and transformation of pesticides in soils．