TOC Removal Efficiency Research Articles

Synthesis of modified ZnO nanorods and investigation of its application for removal of phthalate from landfill leachate: A case study in Aradkouh landfill site.

In this study, zinc oxide nanorods, co-doped with iron and silver, were synthesized in a co-precipitation method. Its properties were determined using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), Brunauer-Emmett-Teller (BET), Dynamic light scattering (DLS) and X-ray photoelectron spectroscopy (XPS) analysis. The results of FE-SEM and TEM showed that zinc oxide nanoparticles synthesized and co-doped with iron and silver were formed as separate nanorods. Also, the average values of DBP and DEHP amount of phthalates in the leachate from the landfill site of Aradkouh were obtained 52.5 and 94.69mg/L, respectively. The highest removal efficiency in real samples for phthalates was found to be 52%. The highest removal efficiency of TOC were was 61%. The synthesized nanostructure could have proper efficiency in removal of phthalates from water sources under the visible light of LED lamp.

A microwave radiation-enhanced Fe-C/persulfate system for the treatment of refractory organic matter from biologically treated landfill leachate.

In this study, a microwave (MW) radiation enhanced Fe–C/PS system was used to treat refractory organic matter in biologically-treated landfill leachate. The effects of important influencing factors on the refractory organic matter in biologically treated landfill leachate were explored, and the main reactive oxygen species produced in the system were verified. The mechanism by which humus was degraded was investigated by analyzing effectiveness of organics removal in different systems, and comparative analysis was conducted on the Fe–C materials before and after the reaction. The results showed that degradation capacity and reaction rate of the system could be improved with an increase in the Fe–C/PS dosage and MW power, while initial acidic conditions were also conducive to the degradation of organic matter. Under the conditions of an Fe–C of 1 g L−1, PS dosage of 30 mM, MW power of 240 W, and reaction time of 10 min, the UV254, TOC, and CN removal efficiencies were 51.48%, 94.56%, and 51.59%, respectively. In the MW/Fe–C/PS system, a large amount of and a small amount of ˙OH were generated by the thermal activation of PS to remove organic matter. The removal efficiency of organic matter could be further improved via the homogeneous catalytic oxidation and heterogeneous adsorption catalytic oxidation of Fe–C materials. In addition, the MW/Fe–C/PS system was effective for removing refractory organic matter from the leachates from four typical treatment systems: DTRO, SAARB, MBR, and NF. The MW/Fe–C/PS system has the potential to be widely applied for the treatment of landfill leachate.

A POM-based copper-coordination polymer crystal material for phenolic compound degradation by immobilizing horseradish peroxidase.

A new polyoxometalate (POM)-based organic-inorganic hybrid Cu-coordination polymer, namely {((Cu(bipy))2(μ-PhPO3)2Cu(bipy))2H(PCuW11O39)·3H2O}n (denoted as compound 1, bipy = 2,2'-bipyridine, PhPO3 = phenylphosphonate), was self-assembled hydrothermally. Single-crystal X-ray diffraction (SC-XRD) analysis shows that two unique types of 1D chains are present in compound 1, i.e. Cu(II)-organophosphine and organonitrogen complex cation ([((Cu(bipy))2(μ-PhPO3)2Cu(bipy))2]4+) chains and Cu-monosubstituted Keggin-type polyoxoanion ([PCuW11O39]5-) chains, forming a hetero-POM. Crystalline compound 1 as a new enzyme immobilization support exhibited a high horseradish peroxidase (HRP) loading capacity (268 mg g-1). The powder X-ray diffraction (PXRD), FTIR, zeta potential, confocal laser scanning microscopy (CLSM) and circular dichroism (CD) results show that HRP is only immobilized on the surface of compound 1 through simple physical adsorption without a secondary structure change. This POM-immobilized enzyme (HRP/1) was first used for degradation of pollutants in wastewater, and it showed a high degradation efficiency and TOC removal efficiency for phenol, 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) within 30 min reaction time. Moreover, HRP/1 exhibited better operational and storage stabilities and reusability compared with free HRP. This work suggests that POMs can be used as new supports for enzyme immobilization and POM-immobilized enzymes may be used as a new kind of biocatalyst for degradation of phenolic pollutants.

Photocatalytic degradation and adsorption of herbicide 2,4-dichlorophenoxyacetic acid from aqueous solution using TiO2/BiOBr/Bi2S3 nanostructure stabilized on the activated carbon under visible light

TiO2/BiOBr/Bi2S3 nanostructure impregnated on the activated carbon (AC) was synthesized, in order to achieve considerable synergy between photocatalysis and adsorption for 2,4-dichlorophenoxyacetic acid (2,4-D) removal from polluted water. The XRD, XRF, EDX, FE-SEM, and FT-IR analyses confirmed successful formation of the catalyst. The results of UV-DRS analysis, showed the estimated band gaps obtained were about 2.8 eV and 2.55 eV for the TiO2/BiOBr and TiO2/BiOBr/Bi2S3 nanostructures respectively showing high potential for the wide range of visible and solar spectrum. The photocatalytic degradation results based on the response surface methodology (RSM) experimental design confirmed that initial 2,4-D concentration, pH, catalyst concentration, irradiation time and the interaction between TiO2/BiOBr/Bi2S3/AC concentration and irradiation time had the most effects, respectively. The best results were obtained under the optimum conditions (2,4-D = 90 mg/L, pH = 3, catalyst = 0.6 mg/L and irradiation time = 90 min) on which the pollutant removal efficiency was 98 % and TOC removal efficiency was determined 74 %. Increasing the visible light intensity to 120 mW/cm2 resulted in a complete degradation. The coexistence of 10 % BiOBr and 5%Bi2S3 compounds on TiO2 not only increased the absorption edge to 600 nm and charge transportation but also improved photocatalytic properties of TiO2/BiOBr/Bi2S3/AC nanostructure as it could be an appropriate compound for water treatment.

Degradation of tricyclazole from aqueous solution and real wastewater by electron-beam irradiation

In this study, electron-beam (EB) irradiation was employed for the degradation of tricyclazole (TC) in an aqueous solution and real pesticide industry wastewater (RPW). Acute toxicity tests revealed that TC exhibits low toxicity against Daphnia magna, with LC50 values of 52.81 mg/L, 32.68 mg/L, 24.35 mg/L and 14.56 mg/L for TC at 24 h, 48 h, 72 h and 96 h, respectively. In contrast, RPW exhibited high toxicity against D. magna, with LC50 values of 0.194%, 0.157%, 0.141% and 0.136% at 24 h, 48 h, 72 h and 96 h, respectively. Results revealed that the high-efficiency removal of TC in an aqueous solution and RPW are achieved by employing EB. Approximately 96.5% of TC in the solution was decomposed under the optimum conditions of an absorbed dose of 3.5 kGy, a pH of 7.0, and an initial TC concentration of 4 mg/L and a H2O2concentration of 4 mM with an operating cost of ∼0.92 $/m3, while 99.2% TC and 82.8% TOC from real wastewater was eliminated at an absorbed dose of 4 kGy, and a H2O2 concentration of 5 mM, with an operating cost of 1.13 $/m3. The degradation of EB apparently followed first-order kinetics, with an R2 of ∼0.998. In real wastewater, the central composite design was employed to optimize the absorbed dose and H2O2 concentration and predict the TC and TOC removal efficiencies. Good regression coefficients (RTC2 = 0.775 and RTOC2= 0.783) of the model revealed fitted correlation between observed and predicted values. In addition, the major degradation pathways of TC were suggested by density functional theory and natural bond orbital calculations.

Novel Prussian blue analogues@MXene nanocomposite as heterogeneous activator of peroxymonosulfate for the degradation of coumarin: The nonnegligible role of Lewis-acid sites on MXene

In this study, with two dimensional MXene as the substrate, Prussian blue [email protected] composite ([email protected]) was fabricated and utilized as a heterogeneous catalyst for the oxidative degradation of coumarin (COU) based on peroxymonosulfate activation. The initial pH strongly affected the degradation process, and the alkaline pH was beneficial to the COU degradation than the acidic pH. The kinetic rate constants were determined to be 0.030, 0.055, 0.121 and 0.246 min-1at pHs of 3.0, 5.0, 6.6 and 10.0, respectively. The TOC removal efficiency achieved at pH 10.0 was 70.9% in 20 min reaction time. Radical scavengers tests showed that in the presence of 500 mM tert-butyl alcohol (TBA), the rate constant was gradually enhanced from 0.004 to 0.040 min−1 with increasing the solution pH from 3.0 to 10.0; while with the addition of 500 mM Methanol (Me), the rate constants were determined to be 0.002, 0.001, 0.002, and 0.002 min−1 at pHs of 3.0, 5.0, 6.6, and 10.0, respectively. Mechanism study indicated that the differences in COU degradation at different pHs could be mainly ascribed to the unsaturated Ti-C-O (Lewis-acid site) and terminal F-Ti on the catalyst surface. This work not only demonstrated that [email protected] was a promisingly effective catalyst for PMS activation for COU degradation, but also clearly spelled out the role of Lewis-acid sites of MXene in MXene-based catalysts.

Synergetic adsorption and Fenton-like degradation of tetracycline hydrochloride by magnetic spent bleaching earth carbon: Insights into performance and reaction mechanism

In this study, the synergetic adsorption and Fenton-like degradation of tetracycline hydrochloride (TCH) by magnetic spent bleaching earth carbon (Mag-SBE@C) with H2O2 were developed and performed, with 91.5% of TCH degradation efficiency and 42.1% of TOC removal efficiency. The effects of the reaction parameters (temperature, initial pH, catalyst dosage, molar ratio of TCH to H2O2) on TCH degradation in Mag-SBE@C/H2O2 system were studied. Under the optimal conditions (temperature 41.1 °C, initial pH 4.89 and molar ratio of H2O2 to TCH 114.435) forecasted by response surface methodology (RSM), high TCH degradation efficiency (99%) was achieved. Also, four cycling tests were performed to confirm the excellent stability and regeneration ability of Mag-SBE@C in presence of H2O2. In addition, the characteristics of Mag-SBE@C after reaction are analyzed in details via scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Brunner-Emmet-Teller (BET), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrum (FTIR) and X-ray diffraction (XRD), and it was found that Fe3O4 nanoparticles on Mag-SBE@C surface acted as co-catalyst and participated in degradation and improved reaction efficiency, while its properties were not greatly changed. The quenching experiments showed that hydroxyl radicals on Mag-SBE@C surface (OHadsorption) were dominant in Mag-SBE@C/H2O2 system. Meanwhile, three possible TCH degradation pathways were given based on the possible intermediates determined by liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-Q-TOF-MS/MS). Mag-SBE@C is an excellent heterogeneous Fenton-like catalyst, exhibiting greatly potential to antibiotics elimination.

Photocatalytic degradation of ciprofloxacin in water at nano-ZnO prepared by pulse alternating current electrochemical synthesis

Ciprofloxacin (CIP) is a broad spectrum synthetic antibiotic of the fluoroquinolone group frequently detected in hospital wastewater, sewage treatment plant effluent, and surface water. The current study investigates the CIP photocatalytic degradation at nano-ZnO synthesized by a novel large-scale and environmentally friendly electrochemical method using pulse alternating current. This method implies the use of LiCl, KCl, NaCl and Na2SO4 as the electrolytes without adding any organic additives or post annealing. The effect of electrolytic media on the morphological, structural, optical and electronic properties of the resulting nano-ZnO was evaluated. The highest CIP removal efficiency reached 93.6 % in 30 min and the TOC removal efficiency reached 51.0 % in 60 min under optimal conditions (5 mg L−1 initial CIP concentration, pH 6.5, catalyst dosage 0.5 g L−1, UV light intensity 2.0 mW cm−2) in the presence of ZnO nanoparticles prepared in LiCl. The efficiency values are higher than those of commercial ZnO due to the increased surface area and the improved separation of charge carriers. Reactive species study confirmed the main role of h+ in the photodegradation process. The photocatalytic performance of the synthesized ZnO samples suggests that these materials can be used for water treatment in environmental applications.

Heterogeneous catalytic degradation of nonylphenol using persulphate activated by natural pyrite: response surface methodology modelling and optimisation

ABSTRACT The degradation of nonylphenol polyethoxylates (NPEOs) was investigated by persulphate (PS) activated using naturally pyrite semi-conductor mineral (NP-SCM) in aqueous solutions. The effects of various factors including solution pH, NP-SCM dosage, NPEOs and PS concentration were examined through response surface methodology (RSM) and Box-Behnken design (BBD) technique. The properties of NP-SCM were characterised by FESEM, BET, XRD and EDX analyses. The results showed that the RSM model had a well correlation (R2 > 0.99) between the predicted data and the experimental findings of NPEOs degradation. In addition, under the optimum conditions (PS = 5.85 mM, pH = 3.0, NP-SCM = 0.85 g/L and NPEOs = 10 µM), the removal efficiency of NPEOs reached more than 99%. The maximum removal efficiency of COD and TOC was obtained 87% and 80% at 90 min reaction time, respectively. The negative effect of various competing ions on the removal of NPEOs was as phosphate>bicarbonate>copper>nitrate>calcium>ammonium. After five successive catalyst cycles reuse, the degradation efficiency was insignificantly decreased from 99.6% to 90.5%, which indicated the excellent potential reusability of NP-SCM catalyst. It can be concluded that NP-SCM along with PS, due to the generation of highly reactive oxidising species (SO4 ●-), its simplicity and easy separation of the catalyst, has a great potential for the degradation of NPEOs from aqueous solutions.

Treatment of textile industry wastewater by electro-Fenton process using graphite electrodes in batch and continuous mode

In this study, the effectiveness of electro-Fenton (EF) technology for the advanced treatment of biologically treated textile wastewater using graphite electrodes was investigated. The performance of the EF process was evaluated in terms of colour, COD and TOC removal. In batch system, the influence of process parameters such as wastewater pH, current intensity, reaction time, and Fe2+ concentration was investigated. Optimum operating conditions were determined as pH 3.0, current intensity of 0.55A, Fe2+ concentration of 2 mM. The use of EF process as a post treatment technology for the biologically treated textile wastewater has led to significant reduction in colour, COD, and TOC content of textile wastewater. In continuous system, 89 % colour, 93 % COD and 58 % TOC removal efficiencies were attained at pH 3, current intensity 1.65 A, Fe2+ of 2 mM and flow rate 25 mL.min−1. The corresponding average energy consumption, electrical energy efficiency and current efficiency were estimated as 16 kWhm−3, 17 kWhm−3order−1 and 0.300. The results showed that EF process with graphite anode and cathode is promising technology improving the wastewater quality for potential reuse.

Catalytic ozonation of norfloxacin using Co3O4/C composite derived from ZIF-67 as catalyst

In this study, Co3O4-carbon composite was synthesized by calcined metal organic framework (MOF) ZIF-67 and used as efficient catalysts for ozonation of norfloxacin (NOF). The MOF-derived Co3O4–C composite remained similar polyhedrons structure of ZIF-67, suggesting that Co3O4 was well-dispersed in Co3O4–C composite. Furthermore, a larger amount of surface carbon-oxygen functional groups were distributed on Co3O4–C composite, which resulted in the diversification of active sites for catalytic ozonation reaction. NOF degradation and mineralization could be effectively enhanced in Co3O4–C/O3 process. Moreover, NOF mineralization by catalytic ozonation strongly depended on the solution pH, while other operational conditions, such as O3 concentration and catalyst dosage had not obvious influence on it. Co3O4–C composite could significantly accelerate O3 decomposition to produce active free radicals (such as •OH), which enhanced the mineralization of NOF. The possible catalytic mechanism of Co3O4–C composite was proposed. Additionally, after five consecutive use of Co3O4–C composite in catalytic ozonation process, there was no obvious decrease in TOC removal efficiency, indicating a stable performance of Co3O4–C composite, which was suitable for the catalytic ozonation for wastewater treatment.

Employ of arbuscular mycorrhizal fungi for pharmaceuticals ibuprofen and diclofenac removal in mesocosm-scale constructed wetlands

This study investigated the effects of arbuscular mycorrhizal fungi (AMF) colonization on the growth of wetland plants (Glyceria maxima), and treatment performance in constructed wetlands (CWs) under the stress of pharmaceuticals ibuprofen (IBU) and diclofenac (DCF). Results showed that the growth of G. maxima was significantly increased by AMF colonization. AMF significantly increased the activities of antioxidant enzymes (peroxidase and superoxide dismutase) and soluble protein content in wetland plants, but the contents of malondialdehyde and O2•− were reduced. The removal efficiencies of TOC, PO43−-P, NH4+-N, and TN were increased in AMF+ treatments by 6%, 11%, 15% and 11%, respectively. AMF increased the removal efficiencies of IBU and DCF by 6–14% and 2–21%, respectively, and reduced the content of their metabolites (2-OH IBU, CA IBU and 4′-OH DCF) in the effluent. Besides, the presence of AMF increased the contents of IBU and DCF in plant roots, while decreased their transportation to shoots. AMF symbiosis decreased the contents of IBU metabolites (2-OH IBU and CA IBU) but increased the contents of DCF metabolite (4′-OH DCF) in the roots of the host plant. In conclusion, these results indicated that AMF plays a promising role in CWs for emerging pollutants removal.

Simultaneous removal of pyridine and denitrification in an integrated bioelectro-photocatalytic system utilizing N-doped graphene/α-Fe2O3 modified photoanode

In order to realize simultaneous removal of pyridine and denitrification, an integrated bioelectro-photocatalytic system (IBPS) equipped with N-doped graphene/α-Fe2O3 modified graphite felt (GF) photoanode and GF biocathode was constructed and operated in ON-OFF illumination mode. Compared to α-Fe2O3 modified GF electrode, N-doped graphene/α-Fe2O3 modified photoanode showed superior stability, photo-electrochemical and catalytic activity owing to the excellent electron transporting properties of N-doped graphene and unique structure of N-doped graphene/α-Fe2O3 composite. In IBPS, ammonia produced from pyridine photocatalytic degradation diffused from anode to biocathode through the cation-exchange membrane. Simultaneous nitrification and denitrification were realized in the biocathode chamber under limited dissolved oxygen. At the same time, the harvested photo-electrons derived from photoanode were delivered to the biocathode via an external circuit for enhanced denitrification. Complete removal of pyridine and high TOC removal efficiency of 85.90 ± 5.48% in the anode and complete denitrification in the biocathode after four ON-OFF cycles (96 h) reaction were achieved. Furthermore, the underlying mechanism for the enhanced removal of pyridine and denitrification was proposed preliminarily. This integrated reactor synergically utilized photoenergy, electrical energy and bioenergy for removal of pyridine and denitrification, showing a promising future in designing new systems for water environmental remediation from solar energy.

A microwave atmospheric plasma strategy for fast and efficient degradation of aqueous p-nitrophenol

Plasma technology has received intensive research interest in pollutants degradation. However, conventional plasma generator suffers from erosion of electrodes and consequent short life time and pollution. In this work, an electrodeless high-flow microwave atmospheric plasma jet is developed for fast degradation of p-nitrophenol. With the assistance of injection locking technology, stable plasma is managed to be generated by low-cost magnetron. 100% removal of 100 mg/L PNP is achieved after 12 min, with a TOC removal efficiency of 57.6%. The fast degradation is probably due to the high cross section (around 153 mm2) of plasma gas. Change in the removal efficiency are less than 4% and 5% as the pH of the solution changes from 2.02 to 12.07 and conductivity varies between 5.38 × 10−2 and 43.6 mS/cm, respectively. Moreover, optical emission spectroscopy spectra of the microwave plasma and a hydroxyl radical scavenger (t-butanol) are employed to identify the generated oxidizing species, which indicates that •OH is the key factor during the degradation process. The hydroxylated intermediates and organic acid transformed from PNP were revealed. Based on the examined intermediate products, the possible degradation mechanism and pathway are analyzed.

Catalytic ozonation for degradation of sulfamethazine using NiCo2O4 as catalyst

In this study, spinel NiCo2O4 was prepared, characterized, and used for catalytic ozonation of SMT. The performance of NiCo2O4 in SMT mineralization was systematically evaluated. The results showed that NiCo2O4 could significantly enhance the mineralization of SMT over a wide initial pH range of 3.0–9.0. The mineralization rate of SMT increased with the increase in the dosage of NiCo2O4 and O3 concentration, while the initial concentration of SMT (from 10 mg/L to 40 mg/L) had no obvious influence on the removal efficiency of TOC, indicating that the SMT mineralization was mainly affected by the mass transfer. Furthermore, according to the result of the determination of OH, NiCo2O4 could undoubtedly improve the generation of OH, the quenching test confirmed that OH played an important role in TOC removal in ozonation process. Moreover, the XPS spectra of as-prepared and used NiCo2O4 catalyst showed that Co ions might indirectly promote the catalytic ozonation process as the Lewis acid sites, while the Ni2+/Ni3+ cycle in the catalyst played a vital role in catalyzing ozone to generate free radicals and enhancing the mineralization capacity of NiCo2O4/O3 system.

Degradation of sulfamethoxazole by ozonation combined with ionizing radiation

In this study, the degradation and mineralization of sulfamethoxazole (SMX) by ozonation and ionizing radiation were investigated respectively, and the performance of the combined process of ozonation and ionizing radiation was evaluated. Results showed that complete degradation of SMX could be obtained by ozonation in 12 min or by ionizing radiation with the absorbed dose of 1.5 kGy. However, the mineralization of SMX was very limited in ozonation and ionizing radiation system, TOC removal efficiency was less than 15% and 27% in single-ozonation and single-radiation process, respectively. The combination of ozonation and radiation process obviously enhanced the mineralization of SMX, TOC removal efficiency increased to 65.7%. Moreover, the ozonation-radiation process also exhibited good performance in the mineralization of sulfamethazine (SMT) and sulfanilamide (SM), suggesting a good application prospect of the combined process in treating wastewater contaminated with antibiotics. In addition, some different intermediate products were identified during SMX degradation in ozonation process and ionizing radiation process by a high-performance liquid chromatography-mass spectrometry (LC-MS), and possible pathways of SMX degradation by ozonation and radiation were proposed.

Electrochemical oxidation of aniline using Ti/RuO2-SnO2 and Ti/RuO2-IrO2 as anode

Electrocatalytic properties of anode and the electrolyte composition are important parameters influence the degradation efficiency for aniline wastewater. Ti/RuO2-SnO2 and Ti/RuO2-IrO2 have been fabricated using thermal decomposition method and experiments in electrolyte containing 0.05 M Na2SO4, 0.05 M NaCl and 0.05 M Na2SO4+0.005 M FeSO4 at different current density were conducted to study the influence on aniline degradation. Linear sweep voltammetry (LSV) showed that Ti/RuO2-SnO2 had higher oxygen evolution potential and degrade aniline through electrochemical transformation and electrochemical combustion while Ti/RuO2-IrO2 degrade aniline mainly through electrochemical transformation. The study showed that Ti/RuO2-SnO2 had higher electrocatalytic activity towards the degradation of aniline than Ti/RuO2-IrO2 anode in 0.05 M Na2SO4 and in 0.05 M NaCl electrolyte. The maximum TOC removal efficiency for Ti/RuO2-SnO2 was 64.2% at 40 mA cm−2 in Na2SO4 electrolyte while the average MCE was 1.6% and the average ECTOC was 1.51 kWh (g TOC)−1. On the contrary, the maximum TOC removal efficiency for Ti/RuO2-IrO2 was 63.1% at 40 mA cm−2 in NaCl electrolyte while the average MCE was 1.6% and the average ECTOC was 1.95 kWh (g TOC)−1. The presence of Fe2+ in Na2SO4 electrolyte would decrease the TOC removal efficiency except at low current density (20 mA cm−2) for Ti/RuO2-SnO2. These results indicated that Ti/RuO2-SnO2 and Ti/RuO2-IrO2 anode were suitable in Na2SO4 and NaCl electrolyte, respectively, while the presence of Fe2+ would inhibit aniline degradation.

Elimination of pharmaceutical pollutants by solar photoelectro-Fenton process in a pilot plant

In this study, the simultaneous degradation of antibiotics (ampicillin, sulfamethazine, and tetracycline; and non-steroidal anti-inflammatories (diclofenac and salicylic acid)) including the total organic carbon abatement by solar photoelectro-Fenton process was assessed. Eight liters of solution containing the mixture of the five pharmaceuticals in 1mmolL-1 Fe2+, 0.05molL-1 Na2SO4 at pH3 and 35°C were electrolyzed applying different current densities (j = 10, 25, and 50mAcm-2) in a solar-electrochemical pilot plant. The pilot plant was equipped with an electrochemical filter press cell with a dimensionally stable anode (DSA type) and an air-diffusion cathode coupled to a solar photoreactor exposed directly to sunlight radiation. All pharmaceuticals were degraded during the first 10min. A TOC removal efficiency of 99.2% after 100min of treatment with an energy consumption of 534.23kWh (kgTOC)-1 and 7.15kWhm-3 was achieved. The pharmaceutical concentration decay followed a pseudo-first-order kinetics. The specific energy per unit of mass of ampicillin, diclofenac, salicylic acid, sulfamethazine, and tetracycline was obtained at 11.73, 19.56, 35.2, 11.73, and 39.32kWh (kgPD)-1 for ampicillin, diclofenac, salicylic acid, sulfamethazine, and tetracycline, respectively. With our results, we demonstrated that SPEF is an emerging technology for the treatment of this type of pollutants in short time.

Synthesis of CeOx@SiO2 with tandem effect of mass transfer and activation for enhancing sulfanilamide degradation with ozone

In this work, a hollow mesoporous CeOx@SiO2 was synthesized and used to promote sulfanilamide (SA) mineralization in ozonation. SA mineralization was promoted to 68.2% by O3/CeOx@SiO2 in 120 min, but only 30.0% in O3 process. O3/CeOx@SiO2 behaved the better at acidic and alkaline condition than that at neutral condition. CeOx@SiO2 had the great ability in enhancing O3 utility rate. Silanol (SiOH) in pore channel of SiO2 shell was non-reactive with O3 but could provide transmission way for O3 to reach the inner CeOx core. Lewis sites, oxygen vacancies and surface hydroxyl groups induced by CeOx favored for the activation of O3. The excess electron at oxygen vacancies would be transferred to the absorbed O3 molecular, which then generated reactive oxygen species (ROS) to mineralize SA. Hydroxyl radicals (OH) and superoxide radicals (O2−) were the main ROS, which were recorded by EPR. The interfacial electron transfer process was revealed by LSV and ESI characterizations. SA degradation intermediates were also identified by HPLC-MS and IC, a possible degradation pathway was proposed. Moreover, CeOx@SiO2 showed a good reusability, no obvious decline of TOC removal was found in four times’ uses. Water matrix would complete ROS with SA, which inhibited the SA removal of both O3 and O3/CeOx@SiO2 processes, but the better TOC removal efficiency was still obtained by O3/CeOx@SiO2 in actual water.

Efficient Technique for Simultaneous Lead Recovery and PbO₂/Ti Electrode Preparation for Electrocatalytic Degradation of Basic Red.

In order to achieve the effective removal of Pb2+ from low-concentration wastewater as well as the lead recovery for direct reuse simultaneously, a simple electrodeposition method was used in this study. In this process, synthetic lead wastewater with low concentration of 4, 8, 12 and 16 mg/L was treated, more than 67% lead was recovered from wastewater and a PbO₂/Ti electrode was fabricated in a simple reaction tank. The test results of characterizations confirmed that PbO₂ nanoeletrocatalyst was successfully deposited on a Ti substrate. Electrochemical activity tests indicated that PbO₂/Ti electrode had advantages of high oxygen evolution potential (1.90 V) and low electron transfer resistance. Furthermore, the results of electrocatalytic degradation experiments demonstrated that prepared PbO₂/Ti electrode had the superb decolorization and mineralization ability on Basic Red. After 120 min of electrolysis, the Basic Red removal efficiency and TOC removal efficiency could reach to 89.38% and 68.82%, respectively, which was 5.2 and 7.1 times higher than the Ti substrate alone. Besides, the calculated mineralization current efficiency for PbO₂/Ti electrode increased from 5.18% to 36.74% after PbO₂ depositing, and thus an economical benefit was obtained by more than 5 times energy saving. The influences of the applied current density, initial dye concentration, electrolyte concentration and solution pH on the oxidation efficiency were also investigated and optimized. The prepared PbO₂/Ti electrode also showed a great stability with high dye removal efficiency (above 85%) after 10 times repeated experiments. These results suggest that it is a promising technological process to remove and recover lead from low-concentration wastewater efficiently and reuse them as electrocatalyst for other organic wastewater treatments.