Abstract Advanced oxidation processes (AOPs) constitute a promising technology to treat wastewater containing organic pollutants that are not easily biodegradable. They have received increasing attention in the research and development of wastewater treatment technologies in recent decades for their removal or degradation of recalcitrant pollutants or as pretreatments to convert pollutants into smaller compounds, which can be treated using conventional biological methods. Polyvinyl alcohol (PVA) is a typical refractory organic pollutant. It has received special attention due to its low biodegradability and the large amount of PVA-containing wastewater discharged from textile and paper mills. This review focuses on PVA removal and PVA wastewater pretreatment by AOPs, which include ozonation, Fenton oxidation, persulfate oxidation, ultrasound cavitation, ionizing radiation, photocatalytic oxidation, wet air oxidation and electrochemical oxidation. The mechanistic degradation pathways of PVA by AOPs are also discussed. In addition, a new classification of AOPs is applied for PVA treatment.
{"title":"Degradation of PVA (polyvinyl alcohol) in wastewater by advanced oxidation processes","authors":"Weihua Sun, Lu-jun Chen, Jianlong Wang","doi":"10.1515/jaots-2017-0018","DOIUrl":"https://doi.org/10.1515/jaots-2017-0018","url":null,"abstract":"Abstract Advanced oxidation processes (AOPs) constitute a promising technology to treat wastewater containing organic pollutants that are not easily biodegradable. They have received increasing attention in the research and development of wastewater treatment technologies in recent decades for their removal or degradation of recalcitrant pollutants or as pretreatments to convert pollutants into smaller compounds, which can be treated using conventional biological methods. Polyvinyl alcohol (PVA) is a typical refractory organic pollutant. It has received special attention due to its low biodegradability and the large amount of PVA-containing wastewater discharged from textile and paper mills. This review focuses on PVA removal and PVA wastewater pretreatment by AOPs, which include ozonation, Fenton oxidation, persulfate oxidation, ultrasound cavitation, ionizing radiation, photocatalytic oxidation, wet air oxidation and electrochemical oxidation. The mechanistic degradation pathways of PVA by AOPs are also discussed. In addition, a new classification of AOPs is applied for PVA treatment.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75026583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dan-dan Yuan, L. Tian, Xiaoyan Shen, X. Sui, Baohui Wang
Abstract Separation of oil and water is well known as a key process in the oil industry. For the purpose of improving the efficiency of the oil-water separation, a novel ClO2-oxidation-based demulsification method for the treatment of oil-water transition layer in oil settling tanks was proposed and studied in the present paper. A series of lab experiments were performed to investigate the techniques and conditions of the ClO2-oxidation-based demulsification, including the reaction temperature, time, concentration, etc. It was observed that a high dehydration rate of 86.11 % was achieved under an optimal reaction condition of 50oC, 4 hours, 3.5‰ ClO2 concentration and 0.5 % acid by volume. Tests concerning the corrosion to the steel tank illustrated that the corrosion rate of water layer after treated by ClO2 was lowered to 0.151 mm/a, which was below the national standard. Based on the theoretical analysis and experimental results, a mechanism was presented for understanding the ClO2 demulsification. The developed ClO2-oxidation-based demulsification technology can be practically applied to the pilot operations in oilfields.
{"title":"ClO2-oxidation-based demulsification of oil-water transition layer in oilfields: An experimental study","authors":"Dan-dan Yuan, L. Tian, Xiaoyan Shen, X. Sui, Baohui Wang","doi":"10.1515/jaots-2017-0011","DOIUrl":"https://doi.org/10.1515/jaots-2017-0011","url":null,"abstract":"Abstract Separation of oil and water is well known as a key process in the oil industry. For the purpose of improving the efficiency of the oil-water separation, a novel ClO2-oxidation-based demulsification method for the treatment of oil-water transition layer in oil settling tanks was proposed and studied in the present paper. A series of lab experiments were performed to investigate the techniques and conditions of the ClO2-oxidation-based demulsification, including the reaction temperature, time, concentration, etc. It was observed that a high dehydration rate of 86.11 % was achieved under an optimal reaction condition of 50oC, 4 hours, 3.5‰ ClO2 concentration and 0.5 % acid by volume. Tests concerning the corrosion to the steel tank illustrated that the corrosion rate of water layer after treated by ClO2 was lowered to 0.151 mm/a, which was below the national standard. Based on the theoretical analysis and experimental results, a mechanism was presented for understanding the ClO2 demulsification. The developed ClO2-oxidation-based demulsification technology can be practically applied to the pilot operations in oilfields.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82291337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract We develop numerical model to discuss the number density and excitation kinetics of O(1D) state in low-pressure discharge oxygen plasma. The governing equations are the Boltzmann equation to describe the electron energy distribution function and the rate equations of the relevant excited states. We have calculated them back and forth until self-consistent solution is obtained. When the rate coefficient of the electron impact dissociation of O2 to O(3P) and O(1D) atoms is assumed to be functions of electron temperature Te with Maxwellian electron energy distribution, the obtained results are found to be inappropriate. When the rate coefficients are written as functions of electron energy distribution function, satisfactory results are obtained as number density distribution of excited states. We also experimentally examined and confirmed the validity of the model by actinometry measurement for number density of the O(3P) state. It is found that we should consider the electron energy distribution function in describing the excitation kinetics of O(1D) state in low-pressure oxygen plasma.
{"title":"Excitation Kinetics of Oxygen O(1D) State in Low-Pressure Oxygen Plasma and the Effect of Electron Energy Distribution Function","authors":"Junya Konno, A. Nezu, H. Matsuura, H. Akatsuka","doi":"10.1515/jaots-2017-0002","DOIUrl":"https://doi.org/10.1515/jaots-2017-0002","url":null,"abstract":"Abstract We develop numerical model to discuss the number density and excitation kinetics of O(1D) state in low-pressure discharge oxygen plasma. The governing equations are the Boltzmann equation to describe the electron energy distribution function and the rate equations of the relevant excited states. We have calculated them back and forth until self-consistent solution is obtained. When the rate coefficient of the electron impact dissociation of O2 to O(3P) and O(1D) atoms is assumed to be functions of electron temperature Te with Maxwellian electron energy distribution, the obtained results are found to be inappropriate. When the rate coefficients are written as functions of electron energy distribution function, satisfactory results are obtained as number density distribution of excited states. We also experimentally examined and confirmed the validity of the model by actinometry measurement for number density of the O(3P) state. It is found that we should consider the electron energy distribution function in describing the excitation kinetics of O(1D) state in low-pressure oxygen plasma.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77702455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The effects of calcination temperature on properties of porous lanthanum titanate using PEG4000 template in a sol-gel route were studied. Photocatalytic degradation of Reactive Brilliant Red X3B on the materials was evaluated. Monoclinic La2Ti2O7 was synthesized in all the samples. The growing up of La2Ti2O7 crystals leads to apparent increases in crystallite size and cell volume with increasing calcination temperature. The Eg values for the samples are 3.38, 3.40, 3.33 3.36 and 3.44 eV when calcination temperature increases from 600 °C to 1,000 °C. High temperature calcination leads to apparent loss of both specific surface area and pore volume, although the average pore size is nearly unchanged. The decoloration efficiency by adsorption is in close relationship to the surface area of the materials. The sample prepared at 900 °C has the maximum photocatalytic activity on degradation of Reactive Brilliant Red X3B in aqueous solution. A continuous loss of degradation efficiency is observed after recycling of the material due to complex reasons.
{"title":"Effects of calcination temperature on sol-gel synthesis of porous La2Ti2O7 photocatalyst on degradation of Reactive Brilliant Red X3B","authors":"D. Han, Zheng Ma, Ling Du, Wenjie Zhang","doi":"10.1515/jaots-2016-0160","DOIUrl":"https://doi.org/10.1515/jaots-2016-0160","url":null,"abstract":"Abstract The effects of calcination temperature on properties of porous lanthanum titanate using PEG4000 template in a sol-gel route were studied. Photocatalytic degradation of Reactive Brilliant Red X3B on the materials was evaluated. Monoclinic La2Ti2O7 was synthesized in all the samples. The growing up of La2Ti2O7 crystals leads to apparent increases in crystallite size and cell volume with increasing calcination temperature. The Eg values for the samples are 3.38, 3.40, 3.33 3.36 and 3.44 eV when calcination temperature increases from 600 °C to 1,000 °C. High temperature calcination leads to apparent loss of both specific surface area and pore volume, although the average pore size is nearly unchanged. The decoloration efficiency by adsorption is in close relationship to the surface area of the materials. The sample prepared at 900 °C has the maximum photocatalytic activity on degradation of Reactive Brilliant Red X3B in aqueous solution. A continuous loss of degradation efficiency is observed after recycling of the material due to complex reasons.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82442112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Flower-structured BiOBr photocatalyst has been synthesized successfully with Gemini surfactant as bromine source through chemical precipitation procedure. The structure, morphology and optical absorption property of the product have been characterized. The results reveal that the product is pure tetragonal phase BiOBr with band gap energy (Eg) of 2.7 eV. Gemini surfactant 1,2-bis (dodecyldimethylammonio) ethane dibromide exhibits a significantly impact on the morphology of flower-structured BiOBr. A possible formation mechanism is proposed. In addition, the BiOBr shows excellent photocatalytic activity and high stability towards rhodamine B (RhB) degradation, which can be attributed to its flower-shaped structure, low Eg, and high photocurrent density. Considering the facile and eco-friendly procedure for the fabrication of BiOBr with superior visible light-induced photoactivity, it is possible to apply this semiconductor material in the field of waste water treatment practically.
{"title":"Gemini surfactant-assisted synthesis of BiOBr with superior visible light-induced photocatalytic activity towards RhB degradation","authors":"X. Mao, Min Li, Hui Li","doi":"10.1515/jaots-2017-0003","DOIUrl":"https://doi.org/10.1515/jaots-2017-0003","url":null,"abstract":"Abstract Flower-structured BiOBr photocatalyst has been synthesized successfully with Gemini surfactant as bromine source through chemical precipitation procedure. The structure, morphology and optical absorption property of the product have been characterized. The results reveal that the product is pure tetragonal phase BiOBr with band gap energy (Eg) of 2.7 eV. Gemini surfactant 1,2-bis (dodecyldimethylammonio) ethane dibromide exhibits a significantly impact on the morphology of flower-structured BiOBr. A possible formation mechanism is proposed. In addition, the BiOBr shows excellent photocatalytic activity and high stability towards rhodamine B (RhB) degradation, which can be attributed to its flower-shaped structure, low Eg, and high photocurrent density. Considering the facile and eco-friendly procedure for the fabrication of BiOBr with superior visible light-induced photoactivity, it is possible to apply this semiconductor material in the field of waste water treatment practically.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87885739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract A high salinity wastewater from epoxy resin was treated with the catalytic wet peroxide oxidation (CWPO) process, so that it can be reused as the chlor-alkali process feedstock. Both bench and pilot scale trials were conducted out in this research. The effect of oxidant (hydrogen peroxide) and catalyst (ferrous sulfate) dosages, and their dosing methods, pH value, temperature, and reaction time on TOC removal by the CWPO process were evaluated through bench experiment. The obtained optimal reaction conditions for the CWPO process were as following: H2O2 dosage = 0.735 M, Fe2+ dosage = 0.027 M, temperature = 90ºC, pH = 3.0–3.5, and reaction time = 200 min. Multiple additions of oxidant and catalyst significantly enhanced TOC removal compared to adding the same total dosage in one step. In a pilot trail, 735 moles of H2O2 and 27 moles of Fe2+ were continuously added to a 1000 L wastewater over 3 hours while the pH and temperature of the reaction solution were automatically controlled at 3.3 ± 0.5 and 90 ± 2℃, respectively, the wastewater TOC values were reduced to less than 150 mg/L from 2500–2700 mg/L, which satisfies the influent TOC limit (200 mg/L) of the diaphragm electrolytic cell. In addition, both the iron ion and sulfate ion concentrations in the pilot effluent were less than their influent limits of the diaphragm electrolytic cell, thus the treated wastewater had been successfully applied in a chlor-alkali plant for production chlorine and caustic soda.
{"title":"Treatment of high salinity wastewater using CWPO process for reuse","authors":"Yakun Zhuo, Mei Sheng, Xueke Liang, Guomin Cao","doi":"10.1515/jaots-2017-0024","DOIUrl":"https://doi.org/10.1515/jaots-2017-0024","url":null,"abstract":"Abstract A high salinity wastewater from epoxy resin was treated with the catalytic wet peroxide oxidation (CWPO) process, so that it can be reused as the chlor-alkali process feedstock. Both bench and pilot scale trials were conducted out in this research. The effect of oxidant (hydrogen peroxide) and catalyst (ferrous sulfate) dosages, and their dosing methods, pH value, temperature, and reaction time on TOC removal by the CWPO process were evaluated through bench experiment. The obtained optimal reaction conditions for the CWPO process were as following: H2O2 dosage = 0.735 M, Fe2+ dosage = 0.027 M, temperature = 90ºC, pH = 3.0–3.5, and reaction time = 200 min. Multiple additions of oxidant and catalyst significantly enhanced TOC removal compared to adding the same total dosage in one step. In a pilot trail, 735 moles of H2O2 and 27 moles of Fe2+ were continuously added to a 1000 L wastewater over 3 hours while the pH and temperature of the reaction solution were automatically controlled at 3.3 ± 0.5 and 90 ± 2℃, respectively, the wastewater TOC values were reduced to less than 150 mg/L from 2500–2700 mg/L, which satisfies the influent TOC limit (200 mg/L) of the diaphragm electrolytic cell. In addition, both the iron ion and sulfate ion concentrations in the pilot effluent were less than their influent limits of the diaphragm electrolytic cell, thus the treated wastewater had been successfully applied in a chlor-alkali plant for production chlorine and caustic soda.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"145 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77418279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Nagaraju, R. Khunphonoi, Shivaraju Harikaranahalli Puttaiah, Totsaporn Suwannaruang, Chatkamol Kaewbuddee, K. Wantala
Abstract In the present research, titanium nanotubes were synthesized via the soft hydrothermal method. A study on the effect of the synthesizing parameters such as aging temperature and time of the hydrothermal process on the photocatalytic paraquat degradation was explored. Central Composite Design (CCD) was used to determine the influence of the preparation parameter on the optimal condition, main and interaction effects on crystalline size, percent paraquat removal by adsorption and photocatalytic degradation as responses. The XRD pattern of the synthesized nanomaterial reported the anatase phase of titania nanotubes. SEM image of the prepared nanomaterial clearly indicated the agglomerated with tubular structure. Band gap energy of the nanotubes was found lower than that of the pure anatase TiO2. Paraquat removal by adsorption is more effective than by photocatalytic degradation. The error of the model remains insignificant for all the three responses.
{"title":"Photocatalytic paraquat degradation over TiO2 modified by hydrothermal technique in alkaline solution","authors":"P. Nagaraju, R. Khunphonoi, Shivaraju Harikaranahalli Puttaiah, Totsaporn Suwannaruang, Chatkamol Kaewbuddee, K. Wantala","doi":"10.1515/jaots-2017-0004","DOIUrl":"https://doi.org/10.1515/jaots-2017-0004","url":null,"abstract":"Abstract In the present research, titanium nanotubes were synthesized via the soft hydrothermal method. A study on the effect of the synthesizing parameters such as aging temperature and time of the hydrothermal process on the photocatalytic paraquat degradation was explored. Central Composite Design (CCD) was used to determine the influence of the preparation parameter on the optimal condition, main and interaction effects on crystalline size, percent paraquat removal by adsorption and photocatalytic degradation as responses. The XRD pattern of the synthesized nanomaterial reported the anatase phase of titania nanotubes. SEM image of the prepared nanomaterial clearly indicated the agglomerated with tubular structure. Band gap energy of the nanotubes was found lower than that of the pure anatase TiO2. Paraquat removal by adsorption is more effective than by photocatalytic degradation. The error of the model remains insignificant for all the three responses.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86567817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Siripattanakul-Ratpukdi, A. Vangnai, Warayut Patichot
Abstract Profenofos, an organophosphorus pesticide, has been reported its contamination in groundwater. The current study emphasized on the use of integrated bioaugmentation and biostimulation techniques to enhance profenofos bioremediation. A profenofos-degrading consortium including Pseudomonas strains was chosen as a bioaugmented culture. For stimulated condition adjustment, sodium succinate as an additional organic carbon supplement (4-500 mg-carbon/L) was applied in batch experiment. Column experiment was carried out for investigating profenofos remediation with different infiltration rates and cell numbers of 25 to 100 cm/d and 105 and 1015 CFU/mL, respectively. The batch result showed that the experiment with sodium succinate supplement efficiently degraded profenofos of more than 80%. At profenofos concentrations of 20 to 120 mg/L, the profenofos degradation ranged from 85 to 91%. For the column experiment, profenofos removal was between 30 to more than 90%. The infiltration rates and microbial numbers significantly affected the profenofos degradation. Lower infiltration rates or higher cell number resulted in higher profenofos removal performance. Based on the result from this study, it indicated that the profenofos degradation by the bioaugmented consortium under stimulated condition is effective and potential for future remediation practice.
{"title":"Enhancement of Profenofos Remediation Using Stimulated Bioaugmentation Technique","authors":"S. Siripattanakul-Ratpukdi, A. Vangnai, Warayut Patichot","doi":"10.1515/JAOTS-2017-0025","DOIUrl":"https://doi.org/10.1515/JAOTS-2017-0025","url":null,"abstract":"Abstract Profenofos, an organophosphorus pesticide, has been reported its contamination in groundwater. The current study emphasized on the use of integrated bioaugmentation and biostimulation techniques to enhance profenofos bioremediation. A profenofos-degrading consortium including Pseudomonas strains was chosen as a bioaugmented culture. For stimulated condition adjustment, sodium succinate as an additional organic carbon supplement (4-500 mg-carbon/L) was applied in batch experiment. Column experiment was carried out for investigating profenofos remediation with different infiltration rates and cell numbers of 25 to 100 cm/d and 105 and 1015 CFU/mL, respectively. The batch result showed that the experiment with sodium succinate supplement efficiently degraded profenofos of more than 80%. At profenofos concentrations of 20 to 120 mg/L, the profenofos degradation ranged from 85 to 91%. For the column experiment, profenofos removal was between 30 to more than 90%. The infiltration rates and microbial numbers significantly affected the profenofos degradation. Lower infiltration rates or higher cell number resulted in higher profenofos removal performance. Based on the result from this study, it indicated that the profenofos degradation by the bioaugmented consortium under stimulated condition is effective and potential for future remediation practice.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82260883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract A bacterial culture, which was mixed by three thermophilic iron-oxidizing bacteria, namely Sulfobacillus thermosulfidooxidans, Leptospirillum ferriphilum and Acidithiobacillus caldus, was used to solubilize low grade rock phosphate (RP) in 9K basal salts medium containing pyrite as an energy substrate. Culture of a single mesophilic iron-oxidizing bacterium Acidithiobacillus ferrooxidans was used as control. Experimental results show that the phosphate solubilizing capacity of the mixed thermophilic iron-oxidizing bacteria was more effective than that of the single bacterium, and such positive effect was mainly attributed to the bioaugmentation of pyrite oxidation with coinoculation of these thermophilic iron-oxidizing bacteria. Results also show that the biosolubilization of low-grade RP by the mixed thermophilic iron-oxidizing bacteria was influenced markedly by environmental conditions. The highest phosphate releasing rate was achieved at 45-50°C. The rate of phosphate released was highest when the pH was at range from 2.0 to 2.5. The increase in pulp density generates a decrease in the phosphate releasing rate, if the pulp density exceeded 3% w/v. The culture led to the highest phosphate releasing rate when the mass ratio of pyrite to RP was at 2:1 or 3:1. However, volume ratio between thermophilic iron-oxidizing bacteria had no significant effect on the rate of phosphate released.
{"title":"Biosolubilization of low-grade rock phosphate by mixed thermophilic iron-oxidizing bacteria","authors":"C. Xiao, Guang Xu, Qi Wang, R. Chi","doi":"10.1515/JAOTS-2017-0023","DOIUrl":"https://doi.org/10.1515/JAOTS-2017-0023","url":null,"abstract":"Abstract A bacterial culture, which was mixed by three thermophilic iron-oxidizing bacteria, namely Sulfobacillus thermosulfidooxidans, Leptospirillum ferriphilum and Acidithiobacillus caldus, was used to solubilize low grade rock phosphate (RP) in 9K basal salts medium containing pyrite as an energy substrate. Culture of a single mesophilic iron-oxidizing bacterium Acidithiobacillus ferrooxidans was used as control. Experimental results show that the phosphate solubilizing capacity of the mixed thermophilic iron-oxidizing bacteria was more effective than that of the single bacterium, and such positive effect was mainly attributed to the bioaugmentation of pyrite oxidation with coinoculation of these thermophilic iron-oxidizing bacteria. Results also show that the biosolubilization of low-grade RP by the mixed thermophilic iron-oxidizing bacteria was influenced markedly by environmental conditions. The highest phosphate releasing rate was achieved at 45-50°C. The rate of phosphate released was highest when the pH was at range from 2.0 to 2.5. The increase in pulp density generates a decrease in the phosphate releasing rate, if the pulp density exceeded 3% w/v. The culture led to the highest phosphate releasing rate when the mass ratio of pyrite to RP was at 2:1 or 3:1. However, volume ratio between thermophilic iron-oxidizing bacteria had no significant effect on the rate of phosphate released.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"73 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88803476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract: Three novel, modified PbO2 electrodes with porous titanium as the substrate were successfully prepared by the anodic deposition method. The modified electrodes contained CNT, Bi, or a combination of the two. Their microstructure and electrochemical properties were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction, linear sweep voltammetry and cyclic voltammetry. Further, their electrochemical active surface area was determined, and their capacity to generate hydroxyl radicals and induce electrochemical degradation of methyl orange was studied. Compared with pure PbO2, electrodes with CNT-PbO2, Bi-PbO2, and the Bi-CNT combination had PbO2 films with educed crystal sizes, which increased their specific surface area and active sites for electrochemical reactions. The Bi-CNT-PbO2 electrode had the highest oxygen evolution over potential, while the generation of hydroxyl radical (·OH) and the electro-catalytic degradation of methyl orange were significantly increased with the Bi-CNT electrode. It was demonstrated that this modification can significantly enhance performance in electro-oxidation processes, including degradation compounds. Such improvements can be of importance for the removal of organic pollutants from effluents.
{"title":"Comparative studies on the performance of porous Ti/Sno2-Sb2O3/Pbo2 enhanced by CNT and Bi Co-doped electrodes for methyl orange oxidation","authors":"Wei Zhao, Juntao Xing, Donghui Chen, Jia Shen","doi":"10.1515/jaots-2016-0181","DOIUrl":"https://doi.org/10.1515/jaots-2016-0181","url":null,"abstract":"Abstract: Three novel, modified PbO2 electrodes with porous titanium as the substrate were successfully prepared by the anodic deposition method. The modified electrodes contained CNT, Bi, or a combination of the two. Their microstructure and electrochemical properties were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction, linear sweep voltammetry and cyclic voltammetry. Further, their electrochemical active surface area was determined, and their capacity to generate hydroxyl radicals and induce electrochemical degradation of methyl orange was studied. Compared with pure PbO2, electrodes with CNT-PbO2, Bi-PbO2, and the Bi-CNT combination had PbO2 films with educed crystal sizes, which increased their specific surface area and active sites for electrochemical reactions. The Bi-CNT-PbO2 electrode had the highest oxygen evolution over potential, while the generation of hydroxyl radical (·OH) and the electro-catalytic degradation of methyl orange were significantly increased with the Bi-CNT electrode. It was demonstrated that this modification can significantly enhance performance in electro-oxidation processes, including degradation compounds. Such improvements can be of importance for the removal of organic pollutants from effluents.","PeriodicalId":14870,"journal":{"name":"Journal of Advanced Oxidation Technologies","volume":"88 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73225106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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