Volume 19, Issue 1

Adopting cotton as the bio-templates, calcium titanate with special morphology (CTCTO) was produced by solgel template method and characterized by XRD, SEM, BET and FTIR. The adsorption and photocatalytic performance had been studied. At the same time, the ability of CTCTO for removing heavy metals in complexing and the chemical oxygen demand (COD Cr ) in water was investigated. The results show that the calcium titanate prepared with this method existed in the shape of broken microtubules. CTCTO had strong adsorption and photocatalysis capacity. In the medium of pH 5-7, when the catalyst loading is 1 g/L, for the initial concentrations of lead 250 mg/L, of cadmium35 mg/L, of nickel 70 mg/L and of methylene blue 10 mg/L, lead, cadmium and nickel are all adsorbed completely within 20 min, and the degradation rate of methylene blue reaches 84.13% within 120 min. For the heavy metals in complexing state, the removal rates of cadmium, lead and nickel reached 100%, and the value of COD Cr also decreased by 56% after one hour of catalyzed sorption. A new method for the simultaneous removal on heavy metals and organics is developed, and it has been used in the treatment of water samples and some satisfying results are obtained.

Plasma decompositions of n-butanol (n-b) in air over working gases of air (n-b/air with 21 vol.% O 2 ) and Ar (nb/ air/Ar with 5 vol.% O 2 ) were studied using an atmospheric-pressure plasma jet (APPJ) reactor with and without Pt/Al 2 O 3 catalyst. The utilization of catalytic APPJ (CAPPJ) shows excellent performance in terms of the conversion of n-butanol in n-b/air of 94.7% and n-b/air/Ar of 99.5% at plasma energy density = 3.75 kJ L -1 and space velocity = 17,400 h -1 . By comparing the working gases of air and Ar, the results indicate that n-b/air/Ar system exhibits slightly better performance than n-b/air system in APPJ and CAPPJ, suggesting that energetic primary electrons from Ar discharge would sufficiently retain the plasma reactive species for facilitating the decomposition of n-butanol. The proposed kinetic models show good agreement with the experimental data of APPJ and CAPPJ. The information obtained is useful for the operation, design and analysis of plasma system.

In this paper, α-Fe 2 O 3 /g-C 3 N 4 composite photocatalysts were fabricated in-situ by a facile hydrothermal method and characterized by Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), scanning electron microscopy (SEM), UV/Vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and surface photovoltage spectroscopy (SPS), respectively. The photocatalytic activity of α-Fe 2 O 3 /g-C 3 N 4 for decolorization of methyl orange (MO) aqueous solution was evaluated. The results show that α-Fe 2 O 3 /g-C 3 N 4 composites exhibit higher photocatalytic performance than the pure g-C 3 N 4 under simulated sun light irradiation. The remarkably increased performance of α-Fe 2 O 3 /g-C 3 N 4 in photocatalysis could be attributed to the increased specific surface area, the enhanced light absorbance, the improved separation efficiency of photo-induced charge carriers and the strong interaction between α-Fe 2 O 3 and g-C 3 N 4 . The enhanced mechanism was proposed and proven by SPS analysis.

In this study, TiO 2 nanotube (TNTs) electrodes were synthesized via direct anodic oxidation and TiO 2 nanotubes modified with Fe 2 O 3 (Fe 2 O 3 /TNTs) electrodes were obtained by electrochemical deposition method. The decolorization of Rhodamine B wastewater by solar photocatalytic/photoelectro-Fenton coupling system was investigated, where Fe 2 O 3 /TNTs electrodes and activated carbon fibre (ACF) were used as anode and cathode, respectively. The results indicated that uniform TiO 2 nanotube was obtained and the diameter ranged from 40 to 50 nm. UV-Vis DRS results revealed that the modified Fe 2 O 3 /TNTs electrodes showed a stronger response in the visible region compared with TNTs electrodes. Parameters had a big influence on solar photocatalytic/ photoelectro-Fenton decolorization of Rhodamine B, the decolorization of Rhodamine B reached 96.6% within 60 min at the optimum conditions. The pseudo-first-order was used to fit the dynamic data with a rate constant of 0.05472 ± 0.00134 min -1 . Hydroxyl radical and photo generated hole were the main active species contributed to Rhodamine B decolorization, making a contribution of 76.6% and 16.6%, respectively.

In this study, the oxidation of methylene blue (MB) over iron oxide magnetic nanoparticles (Fe 3 O 4 ), which effectively activates persulfate anions (S 2 O 8 2− ) to form sulfate free radicals (SO 4 −• ), was explored. In addition, the effect of the initial pH, sodium persulfate (Na 2 S 2 O 8 , PS) concentration, and Fe3O4 content on the decolorization of MB was investigated. The results revealed that the decolorization rate increased when the persulfate concentration increased from 0.03 to 0.12 g/L and the Fe 3 O 4 content from 0.1 to 0.8 g/L. Therefore, the Fe 3 O 4 nanoparticles enhanced the decolorization of MB. The catalyst was analyzed using cyclic voltammetry (CV), three-dimensional excitation-emission fluorescence matrix (EEFM) spectroscopy, and zeta potential measurements. The CV spectra indicated that a reversible redox reaction may explain the high catalytic activity of the catalyst. EEFM was used to evaluate the yield of a fresh Fe 3 O 4 catalyst, and two peaks were observed at EX/EM wavelengths of 230/300 nm and 270/300 nm. Furthermore, the structure and surface morphology of the catalyst were characterized using X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM)-energy dispersive spectroscopy (EDS), respectively. The XRD result confirmed the existence of Fe 3 O 4 in the catalyst. ESEM was used to determine the Fe 3 O 4 particle size, indicating a high degree of nanoparticle dispersion.

Sulfate modified SiO 2 -TiO 2 photocatalysts with different SO 4 2− loadings were prepared by incipient-wetness impregnation method using H 2 SO 4 solution with various concentrations. The as-prepared SO 4 2− /SiO 2- TiO 2 samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer- Emmett-Teller (BET) method, Uv-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and terephthalic acid photoluminescence probing technique (TA-PL), respectively. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic degradation of rhodamine B under ultraviolet light irradiation. The effects of H 2 SO 4 solution concentration on the structure, morphology, surface properties and photocatalytic activity of SO 4 2− /SiO 2- TiO 2 samples were investigated. The results indicated that the catalyst prepared with 4 mol/L H 2 SO 4 solution, it showed the highest photocatalytic activity. The higher photocatalytic activity could be attributed to the improved surface properties and the enhanced separation rate of photoinduced electron-hole pairs.

Gaseous by-products and deposited material obtained from the decomposition of benzene, toluene and xylene in an atmospheric pressure DC corona discharge were minutely investigated by gas chromatograph mass spectrometry and infrared absorption spectroscopy, and the decomposition processes of benzene, toluene and xylene were estimated. It was found that carbon dioxide (CO 2 ), carbon monoxide (CO), formic acid (HCOOH) and formic anhydride ((CHO) 2 ) were the major gaseous by-products from benzene, toluene and xylene, while acetic formic anhydride (CH 3 COOCHO) and acetic acid (CH 3 COOH) were the major by-products from toluene and xylene. Benzaldehyde (C 6 H 5 CHO) and methyl benzaldehyde (CH 3 CH 4 CHO) were produced from toluene and xylene, respectively. It was hypothesized that the decomposition of benzene, toluene, and xylene was initiated by the production of phenyl radicals, phenyl and benzyl radicals, and methyl benzyl and methyl phenyl radicals, respectively. These radicals are deposited on electrodes, wall, etc., resulting in the polymerization of aromatic rings and the substitution of function groups. Also, those radicals are decomposed and converted into by-products described above. In addition, it is probably that benzyl and methyl benzyl radicals are precursors of C 6 H 5 CHO and CH 3 C 6 H 4 CHO, respectively, and that C 6 H 5 CHO and CH 3 C 6 H 4 CHO are decomposed, contributing to by-product production and deposition. Furthermore, some intermediate by-products, produced by the cleavage of the aromatic ring in benzene, toluene and xylene decomposition and containing O=C-O, C=O, O-H, and C-H groups, may be deposit on the electrodes.

Electrocatalytic synthesis of oxalic acid from acetylene has been achieved at Pt electrode. The electrocatalytically synthesized oxalic acid has been characterized by FTIR (Fourier transform infrared spectroscopy) and UV-Vis (UV-Vis spectrophotometry). Influence of electrode material, Na 2 SO 4 concentration, acetone volume fraction, temperature and scan rate have been investigated by CV (cyclic voltammetry). The analysis results show that oxalic acid has been successfully electrocatalytically synthesized from acetylene at the very stable Pt electrode under ambient temperature and pressure, the supporting electrolyte is Na 2 SO 4 (0.5 M) with acetone (2% by volume), the reaction time is 8 h and the conversion efficiency is larger than 20%. The E a (apparent activation energy) of electrocatalytic oxidation reaction of acetylene at the Pt electrode is 14.42 kJ·mol -1 , the electrocatalytic oxidation process of acetylene is irreversible and under adsorption control. In addition, the reaction mechanism of the electrocatalytic oxidation process of acetylene to oxalic acid has been envisaged successfully based on the principle of adsorption and desorption at Pt electrode surface. It exhibits the excellent electrocatalytic performance of Pt in the electrocatalytic oxidation process of acetylene and heralds more broad potential application prospect of acetylene in chemical industry field.

Wastewater from cork processing industry present high levels of organic compounds such as phenolics that must be degraded before discharge into the municipal sewer or into public water courses. The aim of this work was to find out if gamma radiation treatment could increase the biodegradability of recalcitrant compounds using a microbial consortium and a mixed solution of four phenolic acids as a model. Chemical and microbiological analyses were performed in non-irradiated (0 kGy) and irradiated (100 kGy) mixed phenolic acids cultures during incubation time. A preliminary HPLC and GC-MS analysis were performed to detect the major phenolic compounds in cork wastewater samples. Results indicated the presence of gallic, protocatechuic, vanillic and syringic acids in cork boiling water and gallic, protocatechuic and vanillic acids in sediment tank samples. The Total Phenolic content (TP) of mixed phenolic acids cultures during incubation time indicated a decrease of 38% for 100 kGy samples. The HPLC analysis suggested that the radiolytic products of syringic and vanillic acids are protocatechuic and gallic acids. The CFU counts pointed out to a decreasing tendency along the incubation time for phenolic acids cultures (0 kGy and 100 kGy) suggesting a non-degradation trend. The selected microbial consortium was not able to metabolize the phenolic compounds solutions at the used conditions. This could be due to the detected radiolytic degradation dynamics of the phenolic acids considering the antimicrobial activity of these compounds.

The photocatalytic degradation of Methyl orange has been investigated on dynamic solar pilot plant using nonwoven fibers coated with TiO 2 as photocatalyst. The operational parameters, such as initial dye concentration and pH, were studied. Disappearance of color and substrate together with decreases in chemical oxygen demand (COD) and total organic carbon (TOC) content were observed. The photo-decomposition followed pseudo-firstorder kinetics. In addition, the toxicity of some by-products was tested using the earthworm (Eisenia andrei) avoidance test. High sensitivity of E. andrei towards soil wetted with MO solution was observed, while no effects were seen for the same solution after photocatalytic oxidation.

Polyimides were treated to generate hydrophilic surfaces using an atmospheric pressure O 2 -Ar mixed gas plasma. Treatments were carried out in the upstream region of the plasma with the aim of achieving high speed processing without altering the characteristic properties of samples due to high temperatures. Various parameters of the generated plasma were assessed to better understand the processing environment. Using these plasma parameters, the axial variations of constituent species in the plasma were calculated so as to determine the optimum sample position. Moreover, the absolute value of the oxygen atom number density, which is thought to play an important role in the surface treatment, was measured using a heated platinum catalytic probe. Experimental results were used to determine the relationship between the water contact angle on treated surfaces and the oxygen atom fluence and the data were in good agreement with the hydrophilic characteristics obtained during our previous research using surface wave plasma. The effect of oxygen atoms during hydrophilic treatment using an atmospheric pressure microwave-excited plasma source was thus elucidated and high speed surface treatment was demonstrated.

This study evaluated the effectiveness of H 2 O 2 , UV radiation, and H 2 O 2 /UV processes to inactivate total coliforms, Escherichia coli, and Clostridium perfringens bacteria present in a treated sewage. The samples were collected at Samambaia Waste Water Treatment Plant in Campinas, Brazil. The photochemical assays were carried out using 125-3,640 mJ cm −2 doses of UV radiation. The initial H2O2 concentration was 30 mg L −1 . The bacteria were quantified in samples of 100% raw effluent, which had an average of 1.1 × 10 6 most probable number (MPN)/100 mL of total coliforms, 2.3 × 10 5 MPN/100 mL of E. coli, and 1.4 × 10 4 MPN/100 mL of C. perfringens after treatment with activated sludge. Peroxidation did not efficiently inactivate the measured bacteria. The UV process incurred 5-log inactivation for total coliforms and E. coli bacteria, whereas advanced oxidation processes (AOPs) inactivated both bacteria. UV radiation and AOP incurred a 2-log inactivation of C. perfringens.

2-methylisoborneol (2-MIB) is a common odor-causing compound in drinking water with a low odor threshold (10 ng/L). Since conventional treatment processes cannot effectively remove it, this study investigated an advanced oxidation technology: UV/H 2 O 2 decomposing the compound in laboratory and pilot trials. The results show that, in the laboratory trials, the removal efficiency of 2-MIB increased with the concentration of H 2 O 2 increasing; 764 ng/L of 2-MIB was reduced to 2 ng/L after 8 min reaction with 3.92 mg/L of H 2 O 2 ; 702 ng/L of 2-MIB was reduced to 42 ng/L after 8 min reaction with 1.93 mg/L of H 2 O 2 ; the degradation of 2-MIB conformed to first-order kinetics. The data obtained from the pilot trials was analyzed with software Design- Expert, determining the optimal operation conditions (the H 2 O 2 dosage of 6 mg/L, the UV dose of 350 mJ/cm2, and the 2-MIB dose of 275 ng/L) with the highest 2-MIB removal percentage of 96.58%. The reaction rate between UV/H 2 O 2 and 2-MIB was accessed through this software by fitting experimental data.

FeCrBAlMo coating was deposited on an AISI 20 steel substrate by high velocity arc spraying (HVAS). Compared with FeCrBSiMo coating and pristine AISI 20 steel, the microstructure and high temperature oxidation behavior of FeCrBAlMo coating were investigated by optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. Meanwhile, the bonding strength of the coatings was also measured. The results indicated that both coatings were composed of α(Fe,Cr) and Fe 2 O 3 phases. FeCrBAlMo coating had a denser structure and a higher bonding strength than FeCrBSiMo coating. The mass gain of FeCrBAlMo coating after oxidization at high temperatures was distinctly lower than that of FeCrBSiMo coating and AISI 20 steel substrate. In place of silicon, addition of aluminum increased the high temperature oxidation resistance and improved the quality of the coating.

Chemical oxidation with Fenton’s reagent (H 2 O 2 ) was applied to two soils contaminated with TPH (total petroleum hydrocarbons as crude oil). Soil YA contains 2.69% TPH and 11.31% soil organic matter (SOM); the TPH/SOM ratio is 0.24:1.0. Soil XI contains 8.97% TPH and 5.93% SOM, i.e. the TPH/SOM ratio is 1.51:1.0. The results indicate that in soil with a low TPH/SOM ratio (containing a higher percentage of SOM), SOM could be removed easily and consume H 2 O 2 more effectively than crude oil, and O 2 gas may be a major product of the H 2 O 2 decomposition. However, in the soil with a high TPH/SOM ratio, a low initial rate of O 2 generation was obtained, and the SOM may need to be modified to improve the removal of the crude oil in that soil.

0.5%Al-3%In-TiO 2 was prepared using sol-gel method to study the influence of calcination temperature. XRD patterns indicate anatase structure in all of the 0.5%Al-3%In-TiO 2 samples. The crystallite size and cell volume of anatase TiO 2 increase with increasing calcination temperature. The increase of calcination temperature leads to enlarging pore size and shrinking pore volume. The specific surface area, surface adsorbed -OH, and adsorption capacity of the materials decrease with increasing calcination temperature. The 0.5%Al-3%In-TiO 2 sample calcinated at 400 °C has the maximum photocatalytic activity. Photocatalytic degradation of methyl orange can lead to total decoloration in 40 min. Total methyl orange decoloration efficiency decreases from 100% to 85.9% on 0.5%Al-3%In-TiO 2 after 6 reaction cycles.

A comprehensive study of the chemical oxidation degradation of diethyl phthalate (DEP) was conducted through Fenton processes. Effects of various operating parameters that considerably affect DEP decomposition were investigated, including solution pH, H 2 O 2 , Fe 2+ , and DEP concentration. The removal efficiency of DEP achieved 98% under reaction conditions of pH value of 3.0, concentration of 0.3 mM of Fe 2+ , and 6.0 mM of H 2 O 2 after 170 min. In general, DEP degradation in Fenton process was found to occur in two stages, with an extremely fast stage and then a slow one, as a result of change of H 2 O 2 and Fe 2+ initial concentration. Based on the pseudo-steady-state hypothesis of hydroxyl radical formed by the Fenton reaction, a kinetic model for DEP degradation has been proposed which describes the effect of decomposition byproducts on the oxidation reaction. The experiment results also were in good agreement with Behnajady-Modirshahla-Ghanbery (BMG) kinetic model. During the degradation process, seven degradation intermediates of DEP were detected out by means of GC/MS, including ethyl 2-hydroxybenzoate, ethyl 3-hydroxybenzoate, phthalic anhydride, benzoic acid ethyl ester, malonic acid, oxalic acid, and acetic acid. Probable degradation pathway of DEP by the Fenton reaction was also proposed. Inhibitory effects of DEP and intermediate products were investigated in aqueous solution with Photobacterium phosphoreum. Findings indicated that the solution was not completely detoxified even if DEP completely disappeared, further post-treatment was recommended. All these observations have significant potential applications and require further investigation.

This work investigated the degradation of cationic red X-GRL by electrochemical oxidation on a novel PbO 2 anode modified by Ce. The optimized molar ratio of Pb: Ce was 200 mol: 4 mol for the X-GRL and TOC removals. The results showed a high current efficiency for effective X-GRL treatment. Under the optimal condition of current density 50 mA/cm 2 , Na 2 SO 4 0.2 mol/L, initial quality concentration of X-GRL 100 mg/L, after 2h degradation, the X-GRL and TOC removals reached 93.45% and 48.23%, respectively. Based on the degradation intermediates identification, a simplified degradation pathway of cationic red X-GRL was proposed. Based on the analysis of scanning environmental microscopy (SEM), the surface of electrode had a dense structure and the preferred crystalline orientation, which was helpful to improve the catalytic activity of electrode and finally enhance the mineralization of X-GRL.

Corrosion of constructional materials in supercritical water oxidation (SCWO) is one of the main obstacles to commercializing the SCWO process. Statistical analysis of corrosion research results indicate nickel-based alloys are the most widely applied materials in SCWO system among the candidate metals. The present paper reviews the corrosion characteristics of iron-base alloy, nickel-based alloy, titanium-base alloy, ceramics, niobium, tantalum, thallium and gold under the condition of SCWO. The selection scheme of materials is presented in SCWO system flow diagram in detail. The effects of alloying elements on the corrosion behavior of materials in the water environment with high temperature and high pressure water are summarized in this paper. Moreover, some further researches for material corrosion in SCWO process are also proposed. All work was contributed to selecting the appropriate constructional materials and reducing the corrosion damage in SCWO system.

g-C 3 N 4 was prepared by heating different precursors. The photocatalysts were characterized by Brunauer- Emmett-Teller (BET) method, X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectroscopy, particle size analyzer and surface photovoltage (SPV) spectroscopy, respectively. The photocatalytic activities of g-C 3 N 4 prepared by different precursors for decolorization of rhodamine B aqueous solution were evaluated. The results show that g-C 3 N 4 prepared by heating urea exhibits the best photocatalytic activity under simulated solar irradiation, which can be assigned to the relative higher specific surface area, the smaller particle size, the higher separation efficiency of photo-generated charge pairs, the higher adsorption toward rhodamine B aqueous solution.

Cathodic elelectrophoretic deposition was used for growing TiO 2 nanostructed films on stainless steel substrate (SS) in aqueous media. By the use of the commercial TiO 2 P25 and the adoption of continuous voltage, adherent films were successfully obtained. Films were dried at room temperature, annealed at 550 °C and characterized by X-ray diffraction (XRD), optical microscopy, atomic force microscopy (AFM), transmission electronic microscopy (TEM) and nanoindentation. The photocatalytic activity of TiO 2 films was carried out by observing the discoloration of amido black 10B under UV irradiation, for 6 hours. XRD analysis indicated that anatase is the predominant phase with an average crystallite size of 31.02 nm. The rutile phase represents the minor phase with an average percentage of 21.34 % and an average crystallite size of 46.23 nm. The crystallites size doesn’t exceed 50 nm. This result is confirmed by the transmission electronic microscopy. Atomic force microscopy shows that roughness Rms increases with the applied voltage. Mechanical properties indicate an improvement with the applied voltage. The limit values of hardness and elasticity are 427.105 MPa and 36.857 GPa respectively. The same behavior was observed for adhesion strength. The electrode developed at 5V has the best adhesion with a critical load of 1177,968 mN. In addition to these properties, elaborated electrodes are photosensitives with photocurrent values ranging from 0.61 to 1.86 μA cm -2 . The photocatalytic efficiency increases with the applied voltage to reach 86.7% with the electrode elaborated at 5V.

In this study, the clinoptilolite is taken as the matrix, manganese nitrate as a modifier; through a medium temperature calcination pore making technique. Mostly, the micro pores in the matrix have been enlarged through the means of dipping and high temperature calcination modification. A small amount of active catalytic components are exchanged stably between the pores and surface. The mechanism of manufacturing new catalyst is analyzed using test methods of TEM, SEM, EDS, XRD and BET. These test methods testify the existence of active catalytic components of manganese in the Mn-Zeolite, while researching a new type of Mn-zeolite catalyst heterogeneous catalytic mechanism of Fenton and ozone oxidation process. The results show that added Mn-zeolite could improve the oxidation rate from 51% to 100%. Addition of free radical inhibitor, t-butanol, significantly inhibited the catalytic reaction of Fenton and ozone oxidation. This indicated that the mechanism of the reaction of Fenton and ozonation followed the hydroxyl radical.