Photoelectrocatalytic activity of immobilized Yb doped WO3 photocatalyst for degradation of methyl orange dye

Pure WOand Yb:WOthin films have been synthesized by spray pyrolysis technique. Effect of Yb doping concentration on photoelectrochemical, structural, morphological and optical properties of thin films are studied. X-ray diffraction analysis shows that all thin films are polycrystalline nature and exhibit monoclinic crystal structure. The 3 at% Yb:WOfilm shows superior photoelectrochemical（PEC） performance than that of pure WOfilm and it shows maximum photocurrent density（Iph= 1090 μA/cm） having onset potentials around +0.3 V/SCE in 0.01 M HClO. The photoelectrocatalytic process is more effective than that of the photocatalytic process for degradation of methyl orange（MO） dye. Yb doping in WOphotocatalyst is greatly effective to degrade MO dye. The enhancement in photoelectrocatalytic activity is mainly due to the suppressing the recombination rate of photogenerated electron-hole pairs. The mineralization of MO dye in aqueous solution is studied by measuring chemical oxygen demand（COD） values.

Adsorption Behavior of Methyl Orange onto Modified Ultrafine Coal Powder

甲基橘子的吸附被学习到极其细小的煤粉末(UCP ) 和从水的答案的修改的极其细小的煤粉末(MUCP ) 上，在哪个接触时间，剂量，温度， pH，和甲基橘子的影响在答案的集中被调查。由 UCP 和 MUCP 的甲基橘子的吸附动力学能被 Lagergren 一阶、假的秒顺序描述运动模型分别地。甲基橘子的吸附等温线跟随 Freundlich 和兰米尔等温线方程到在 303， 313 和 323 K 的 MUCP 上。Δ 的价值；为甲基橘子吸附的 G 0 是 − 到 MUCP 上； 22.55， −； 23.10 并且 −； 23.79 kJ·；在 303， 313，和 323 K 的摩尔 −1 分别地。Δ 的价值； H 0 和 Δ； S 0 是 −； 3.74 kJ·；摩尔 −1 和 61.99 J·；摩尔 −1, 分别地。吸附过程自发、发热。

Photocatalytic reaction kinetics model based on electrical double layer theoryⅡ. Infrared spectroscopic characterization of methyl orange adsorption on TiO_2 surface

In the process of heterogeneous photo catalytic degradation, the reaction rate depends strongly on the property of organic binding on the surface. It is important to identify the adsorption of organic compounds on TiO 2 surface to understand the mechanism of degradation and proper kinetics expression. The infrared spectroscopy was used to analyze the methyl orange adsorption on TiO 2 surface in aqueous solutions in different pH ranges. The variation of the surface complexation of methyl orange formed on the TiO 2 surface in different acid and basic media was discussed. And the adsorption amounts were also qualitatively analyzed. Methyl orange has strong, weak and little adsorption on the TiO 2 surface in acid, basic and near neutral solution, respectively.

Photocatalytic reaction kinetics model based on electrical double layer theory Ⅲ.Surface complexation model of methyl orange adsorption on TiO_2 surface

Based on the infrared characterization of methyl orange adsorption on TiO 2 surface and the titration of TiO 2, the triple layer model of methyl orange adsorption on TiO 2 was established according to electric double theory. The software FITEQL3.1 was applied to calculate the distribution of organic adsorption on TiO 2 surface by introducing dummy components to help to overcome mathematical difficulties. It is shown that the chem. adsorption species of methyl orange have a great adsorption amount. The adsorption constants of three kinds of surface complexation expressed as SOH +org -,SOH 2org 2 and SOHorg - are 5.98, 17.57 and -4.2, respectively.

Selective-adsorption Removal of Methyl Orange(MO) by CTAB-assisted AgBr Powder

The AgBr powder was prepared by a hydrothermal method via a reaction of AgNO3 with hexadecyltrimethy ammonium bromide（CTAB）,namely,CTAB-assisted synthesis method.The selective-adsorption ability of the AgBr samples for the MO was evaluated in a MO and Rhodamine B mixed solution via ultraviolet-visible spectra.Compared with the AgBr sample prepared from NaBr solution,it was found that the AgBr powder synthesized by CTAB-assisted method exhibited high selective-adsorption performance for the MO in the MO-RhB mixed system.After aged for 60 min,the MO could be efficiently removed by CTAB-assisted AgBr powder.Considering the potential wide applications of the selective adsorption,the CTAB-assisted AgBr provides a new and efficient method for the removal of various dyes and is possible to be widely used in industries.

Removal of Methyl Orange from Aqueous Solution by Mineral-based Porous Granulated Material

Sodium bentonite, graphite, light calcium carbonate and diatomite were used as parent minerals for the mineral-based porous granulated material （MPGM） which was tested for the removal of methyl orange （MO）, a cationic dye, fIom aqueous solution. The adsorption capacity was evaluated under the conditions of varied initial pH, adsorbent dosage, dye concentration, temperature, reaction time, and static regeneration. Experimental results showed that the maximum capacity of MPGM adsorbing MO was more than 80 mg·g-1 The adsorption equilibrium and kinetics of MPGM followed typical pseudo-first-order and Langmuir adsorption models respectively. The thermodynamic parameters of △G°, △H° and △S° showed that the adsorption was an endothermic and spontaneous process without remarkable change. The spent MPGM was regenerated 5 times and probable pathway for the efficient and re-utilizing adsorbent has been proposed. The results indicate that MPGM has a structure of silicon-aluminium-calcium-carbon, and could be employed as porous, low density, and large specific surface area alternatives for the removal of cations dyes from industrial wastewater.

Photodegradation of methyl orange by BiOI-sensitized TiO_2

BiOI-sensitized titanium dioxide (TiO2) photocatalysts were prepared by a deposition method at room temperature and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller surface area measurements. The photocatalytic activities of the catalysts were evaluated for the degradation of methyl orange (MO) solution under UV and visible light irradiation. The effects of catalyst amount, initial pH value, initial concentration of MO, as well as KI amount were investigated. The repeatability of photocatalytic activity of the 1.7% BiOI/TiO2 catalyst was also tested. It is shown that BiOI sensitization enhances the photocatalytic activities of TiO2. With BiOI content increasing, the photocatalytic activities of BiOI/TiO2 under UV and visible light irradiation first increase, reaching a maximum around BiOI content of 1.7%, and then decrease with further increasing BiOI content. The 1.7% BiOI/TiO2 catalyst obviously exhibits much higher visible light photocatalytic activity than P25, and its UV light photocatalytic activity is slightly higher than that of P25. Under the conditions of a catalytic dose of 1.5 g.L-1, initial pH of 3.0, initial MO concentration of 20 mg.L-1, UV power of 300 W, and air flow rate of 0.8 L.min-1, complete degradatio is achieved within 60 min. The repeatability of photocatalytic activity of the 1.7% BiOI/TiO2 catalyst is highly reliable.

Mechanisms of Enhancement of Photocatalytic Properties and Activity of Nd^(3+)-Doped TiO_2 for Methyl Orange Degradation

Nd^(3+)-doped TiO_2 powders were prepared by the sol-gel method. Their crystal pattern and parameter, the specific surface area, the surface chemical state of Ti and the ratio of O/Ti were characterized. The results show that Nd impurity hinders the crystal transformation, and decreases the relative intensity of (101) peak. The crystallite sizes of Nd^(3+)-doped TiO_2 powders decrease while their specific surface area increase owing to the Nd^(3+) doping. The XPS measurement shows that the content of Ti(Ⅲ) and ratio of O/Ti on their surfaces increase significantly with the increase of Nd^(3+) dosage. The adsorption and photodegradation experiments show that the optimum molar content of Nd^(3+) is 1.2%.

Photocatalytic Dye Methyl Orange Decomposition on Ternary Sulfide (CdIn2S4) under Visible-light

A novel and efficient photocatalyst, CdIn2S4, was simply prepared by a programmed temperature hydrothermal method. The product had a nanometer size （10-15 nm） and strong absorption in the range of 200 to 580 nm, and it exhibited visible-light photocatalytic activity to decompose dye methyl orange in aqueous system.

Hydrothermal Synthesis of H_3PW_(12)O_(40)/TiO_2 Nanometer Photocatalyst and Its Catalytic Performance for Methyl Orange

H3PW12O40/TiO2 nanometer photocatalyst was prepared by one step hydrothermal synthesis from H3PW12O40·nH20 and Ti（OBu）4, simultaneously realizing the load and modification of H3PW12O40. The catalyst was characterized by Fourier transform infrared spectroscopy（FTIR）, powder X-ray diffraction（XRD）, nitrogen adsorp- tion-desorption analysis and scanning electron microscopy（SEM）. The results show that the catalyst is Keggin struc- ture and crystallized in anatase structure, the diameter and specific area of the prepared catalyst are 3.8 nm and 177.9 m^2/g, respectively, and its dispersity is better. The photocatalytic properties were compared for TiO2H3PW12O40/TiO2 prepared by impregnation and H3PW12O40/TiO2 prepared by hydrothermal method with methyl orange as a probe. The effects of H3PW12O40 loadings, crystallization method, initial pH and concentration of dye solution on the degradation of methyl orange were investigated.

Sonocatalytic degradation of methyl orange in the presence of (nanometer and ordinary) anatase TiO_2 powders

The nanometer and ordinary anatase titanium dioxide(TiO_2) powders were adopted as the sonocatalysts for the degradation of methyl orange used as a model compound for the first time. It was found that the sonocatalytic degradation effect of methyl orange in the presence of TiO_2 powder were much better than that without TiO_2, but the sonocatalytic activity of the nanometer anatase TiO_2 particle was obviously higher than that of ordinary anatase TiO_2 particle. Although there are many factors influencing sonocatalytic degradation of methyl orange, the experimental results showed that the best degradation ratio of methyl orange could be obtained when the experimental conditions were: initial concentration 15 mg/L, nanometer anatase TiO_2 adding amount 750 mg/L, ultrasonic frequency 40 kHz, output power 50 W, pH = 3.0 and temperature 40℃ within 150 min. In addition, the catalytic activity of reused nanometer anatase TiO_2 catalyst was also studied and found to decline gradually comparing with initial nanometer anatase TiO_2 catalyst. All experiments indicated that the method of the sonocatalytic degradation of organic pollutants in the presence of TiO_2 powder was an advisable choice for non- or low-transparent organic wastewaters.

Investigation of Photocatalytic Degradation of Methyl Orange by Using Nano-Sized ZnO Catalysts

Nano-sized ZnO catalysts were prepared by a direct precipitation method under the optimal conditions (cal-cination of precursors at 550?C for 120 min). The as-synthesized ZnO catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-Vis spectroscopy. The photocatalytic prop-erties of ZnO nanoparticles were investigated via methyl orange (MO) as a model organic compound under UV light irradiation. The influence of operating parameters on MO degradation including the amount of ZnO catalysts, pH value of solutions, and the photodegradation temperature was thoroughly examined. In addition, the kinetic process of photocatalytic degradation of MO using nano-sized ZnO catalyst was also examined, and the degradation of MO follow the first order kinetics.

Photocatalytic Degradation of Organic Dye Methyl Orange with Phosphotungstic Acid

Silicotungstic acid and phosphotungstic acid were prepared and characterized by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD). The results showed that the prepared catalysts possess classical Keggin structure. The factors on the degradation of methyl orange, such as the kind of catalyst, the amount of catalyst, the original concentration of dye and illumination time were investigated under metal halide lamp. The degradation of methyl orange is up to 93.6% with phosphotungstic acid at the best reaction conditions at 8.89 g/L concentration of phosphotungstic acid, 5.56 mg/L concentration of methyl orange and 80 min illumination time.

Fabrication of chitosan microspheres for efficient adsorption of methyl orange

In this article, morphology, structure and size controllable chitosan microspheres with high mechanical strength were synthesized by microfluidic technology combining chemical crosslinking and used as an adsorbent for methyl orange. The synthesized adsorbents were characterized using scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR), and an Energy Dispersive Spectrometer(EDS). The effect of pH revealed that the adsorption process depended on pH and the pH variation of methyl orange solution after adsorption indicated that adsorption capacity was affected through the associated role of chitosan nature and pH variation. Experimental results suggested that the as-prepared chitosan microspheres were controlled within a narrow size distribution(coefficients of variation is 1.81%), whose adsorption capacity reached to 207 mg·g^(-1) and mechanical strength was suitable to resist forces. In addition, the adsorption isotherm was well fitted with the Langmuir model, and the adsorption kinetic was best described by the pseudo-second-order kinetic model.The high performance microfluidic-synthesized chitosan microspheres have promising potentials in the applications of removing dyes from wastewater.

Degradation of Methyl Orange in Water by Contact Glow Discharge Electrolysis

The degradation of methyl orange in a neutral phosphate buffer solution was investigated by means of contact glow discharge electrolysis （CGDE）. The methyl oranges were degraded and eventually decomposed into inorganic carbon when CGDE was conducted under the applied DC voltage of 480 V and current of ca. 80 mA. As the intermediate products, some phenolic compounds were detected as well as carboxylic acids. Experimental results showed that the oxidation process followed the first-order reaction law. Based on the analysis of the ultraviolet （UV） spectra of the solution and the intermediate products from High Pressure Liquid Chromatography-Mass Spectrum （HPLC-MS）, the reaction pathway was proposed. The attack of hydroxyl radicals was considered to be a key step to start the whole oxidation process.

Hydrothermal Synthesis of CdIn_2S_4 and Photocatalytic Degradation of Methyl Orange under Visible-light Irradiation

CdIn2S4 microspheres were synthesized by a facile hydrothermal method with the temperature ranging from 120 to 200 ℃. X-ray diffraction, UV-vis diffuse reflectance spectroscopy, nitrogen sorption analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy were used to characterize the products. It was found that the crystallographic structure and optical property of the products synthesized at different temperature were almost the same. The SBEX of CdIn2S4 products decreased when the synthesized temperature increased, and the largest SBET was 33.16 m2 g-1 （120 ℃ sample）. The degradation of methyl orange （MO） under the visible-light irradiation had been used as a probe reaction to investigate the photocatalytic activity of the as-prepared CdIn2S4, which showed that the CdIn2S4 sample synthesized at 120 ℃ presented the best photocatalytic activity for MO degradation.

Enhanced Adsorption of Methyl Orange onto Self-assembled Hydrogel with Anatase Titania Nanotube and Graphene

A novel composites hydrogel adsorbent was facilely synthesized for efficient removal of acid dyes from aqueous solution.The composite hydrogel consisting of TiO_2 nanotubes(TN) and graphene oxide(GO)(H-TN-GO) was characterized by BrunauerEmmett-Teller(BET),transmission electron microscope(TEM),scanning electron microscope(SEM),Raman spectra and X-ray photoelectron spectroscope(XPS).Experimental results elucidated that columnar hydrogel could be tunably prepared with self-assembly by adjusting the proportion of GO/TN,mixing time and pH.The properties of adsorption and regeneration on methyl orange(MO)onto H-TN-GO were investigated respectively.The maximal adsorption capacity of H-TN-GO for MO reached 933.8 and 513.7mg/g under the pH of 4.0 and 6.8,respectively.The adsorption capacity of MO reached the maximum when pH was equivalent to4.0,which attributed to increasing electrostatic attraction.Besides,the adsorption behavior was fitted reasonably better with Freundlich isotherm model than Langmuir model;the adsorption speed was rapid and the removal ratio almost reached 99.5% when the concentration of MO was less than 100 mg/L.After the used adsorbent was irradiated with the ultraviolet ray of 500 W for 3 h,its adsorption capacity could be recovered without significant loss.

Ultrasonic Degradation of Methyl Orange in Presence of Y2O3 Doping Anatase TiO2 Catalyst

Various affecting factors and degradation mechanism were studied on ultrasonic degradation of methyl orange adopting Y2O3 doping anatase TiO2 catalyst prepared in laboratory.In the experiment, the UV-VIS spectrophotometer was used to follow and inspect the degradation process of methyl orange.The results indicate that the ultrasonic degradation ratios of methyl orange in the presence of anatase TiO2 catalyst are much better than those without catalyst.Moreover, the catalytic performance of Y2O3 doping anatase TiO2 catalyst is obviously higher than that of anatase TiO2 catalyst without doping.The optimal conditions were adopted in this work and the degradation and COD elimination ratio of methyl orange got to98% and 99.0% in 90 min, respectively.