Construction of novel Ag/AgI/Bi4Ti3O12 plasmonic heterojunction: A study focusing on the performance and mechanism of photocatalytic removal of tetracycline.

As a result of the insufficient absorption of visible light, the application of Bi4Ti3O12 in the field of photocatalysis is limited. Ag/AgI was uniformly modified on the surface of the nanoflower bulb of Bi4Ti3O12 by simple precipitation method and photodeposition. The fabricated Ag/AgI/Bi4Ti3O12 obtained an ultra-high tetracycline (TC) removal rate under visible light irradiation. And the synergetic effects caused by the surface plasmon resonance (SPR) effect of Ag, the photosensitivity of AgI and the p-n heterojunction are the key to improving the photocatalytic performance of materials. Besides, four plausible photodegradation pathways of TC were proposed and its intermediates were evaluated for toxicity, showing a significant decrease in toxicity after photoreaction.

Mussel-inspired self-healing hydrogel based on gelatin and oxidized tannic acid for pH-responsive controlled drug release.

A series of mussel-inspired pH-responsive self-healing hydrogels based on gelatin crosslinked by oxidized tannic acid (GLT-OTAs) were prepared and used as controlled drug delivery systems (CDDS). An antiphlogistic drug, indomethacin (IDMC) was used as model drug to be immobilized into the hydrogels. The obtained hydrogel samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical stability, biocompatibility and self-healing property of the hydrogels were estimated, respectively. Swelling and drug release behaviors of these hydrogels were measured in phosphate buffered saline (PBS) with pH 7.4 (simulated intestinal fluid) and HCl solution with pH 1.2 (simulated gastric fluid) at 37 °C. Effect of the OTA content on the structures and characteristics of all samples was discussed. FTIR spectra revealed the covalent cross-linking between gelatin and OTA induced by Michael addition and Schiff base reaction. Both XRD and FTIR all showed the drug (IDMC) was loaded successfully and existed steadily. GLT-OTA hydrogels had satisfactory biocompatibility, superior self-healing. Results also illustrated that the mechanical strength, internal structure, the swelling and drug release behaviors of the GLT-OTAs hydrogel were greatly affected by the OTA content. With increasing the OTA content, the mechanical stability of GLT-OTAs hydrogel became better and better, and their internal structure became more and more compact. The swelling degree (SD) and cumulative drug release of all hydrogel samples tended to decrease with increasing OTA content and both had obvious pH responsiveness. For each hydrogel sample, the cumulative drug release in PBS at pH 7.4 was greater than that in HCl solution at pH 1.2. These results indicated that the obtained GLT-OTAs hydrogel had promising potential to be used as effective pH-responsive and self-healing drug delivery materials.

Novel La3+/Sm3+ co-doped Bi5O7I with efficient visible-light photocatalytic activity for advanced treatment of wastewater: Internal mechanism, TC degradation pathway, and toxicity analysis.

Controlling semiconductor photocatalysts by doping rare-earth ions is an effective strategy to improve photocatalytic performance. Simple solvothermal and calcination methods were used to prepare La3+ and Sm3+ modified Bi5O7I nanomaterials. Some characterizations such as XRD, XPS, SEM, TEM, UV-vis, etc. were carried out to explore its structural composition and photoelectrochemical properties. The photocatalytic activity was investigated by simulating the degradation of TC and RhB under visible-light irradiation. The degradation results showed that the photocatalytic efficiency of 4S4L-Bi5O7I was the best among the samples with the 100% degradation rate of TC (Tetracycline hydrochloride) and 93% of RhB (Rhodamine B). The capture experiment and ESR test proved that the active substances that play a role in the photocatalytic degradation of pollutants were ·O2-, 1O2 and h+, and on this basis, the possible degradation mechanism was proposed. The final results showed that La/Sm co-doping expanded the light absorption range of Bi5O7I and improved the charge separation efficiency and the specific surface area. Besides, the surface defects were formed on the surface of Bi5O7I due to ion-doping, which could catch e- to promote the separation and transfer of carriers and improve the photocatalytic activity. LC-MS was used to analyze the possible degradation pathways of TC. And the toxicity of TC was also analyzed via T.E.S.T and Toxtree. The results showed comprehensive toxicity of TC was decreased by 4S4L-Bi5O7I so that the overall water pollution was reduced. This work can provide a reference for the subsequent development of bismuth-based photocatalysts.

Er3+/Sm3+ co-doped Bi2O2CO3 in photocatalytic water treatment: Immobilization, acute toxicity, sterilization, and catalytic oxidation activity.

Defect construction and rare earth doping are the linchpins to completing the target of partial electronic regulation. In Er3+/Sm3+ co-doping Bi2O2CO3, rare earth doping resulted in the exposure of {001} crystal plane in Bi2O2CO3 and cause surface defects and electron traps, achieving wide light response capability and fast carrier separation. Furthermore, a potential TC degradation route was acknowledged derived from LC-MS. Then, the median lethal concentration LC50 (96 h) is 80 ppm, probing the 2E2SBOC photocatalyst has low toxicity in actual wastewater. Combining with immobilization technology, not only does it have little impact on the organisms in the wastewater, but it is easy to recycle after degradation. In terms of new water disinfection technology, bacterial experiments in natural waters proved that 2E2SBOC has a potential disinfection system, which promotes the exposure of more active sites during degradation. This effective project offers a novel perspective for the development and application of rare-earth-doped photocatalysts.

Construction of Z-scheme Ag-AgBr/Bi2O2CO3/CNT heterojunctions with remarkable photocatalytic performance using carbon nanotubes as efficient electronic mediators.

It is a useful strategy to use a solid electronic mediator with good conductivity to assist the separation of semiconductor photo-induced electron-hole pairs and the redox of semiconductor materials. In order to construct a photocatalyst for more efficient photocatalytic degradation of antibiotics, a simple hydrothermal and precipitation method was used to construct the Ag-AgBr/Bi2O2CO3/CNT Z-scheme heterojunction by using carbon nanotubes (CNTs) as electronic mediators. Compared with the pristine AgBr, Bi2O2CO3, Bi2O2CO3/CNT, the 30%Ag-AgBr/Bi2O2CO3/CNT photocatalyst has better photocatalytic activity under visible light irradiation, showing the best degradation ability to tetracycline (TC). Meanwhile, the photocatalytic properties of 30%Ag-AgBr/Bi2O2CO3/CNT in different pH and inorganic ions were studied. Finally, the degradation pathway and catalytic mechanism of 30%Ag-AgBr/Bi2O2CO3/CNT photocatalytic degradation of TC were also argued. The construction of the Z-scheme electron transport pathway, in which CNTs were used as electronic mediators, and the SPR effect of Ag and Bi metal, which enable the effective separation and transfer of photo-generated electron-hole pairs, are responsible for the significant improvement in photocatalytic performance. It opens up new possibilities for designing and developing high-efficiency photocatalysts with CNTs as the electronic mediator.

Facile construction for new core-shell Z-scheme photocatalyst GO/AgI/Bi2O3 with enhanced visible-light photocatalytic activity.

Heterojunction formation and morphology control have always been regarded as effective ways to improve the performance of visible-light-driven photocatalysts. In this study, a new facile strategy was applied to synthesize the Z-scheme GO/AgI/Bi2O3 heterojunction, where polyvinyl pyrrolidone (PVP) and γ-methacryloxypropyl trimethoxy silane (KH-570) were used to modulate the morphologies. Methyl orange and tetracycline hydrochloride were chosen as target contaminants to evaluate the photocatalytic properties of samples and the results revealed that 2% GO/AgI/Bi2O3 exhibited the best photocatalytic performance under visible-light irradiation. The enhanced photocatalytic activity can mainly attribute to Z-scheme heterojunction formed by the deposing of AgI and GO as well as the sufficient heterogeneous interfaces resulted from the improved morphology, which have effectively promoted the separation and transfer of electron-hole pairs. To deeply realize the enhanced performance of GO/AgI/Bi2O3 photocatalysts, the reaction kinetics, trapping experiments and photocatalytic mechanism were deduced.

Emission characteristics and potential toxicity of polycyclic aromatic hydrocarbons in particulate matter from the prebaked anode industry.

The emission factors (EFs) and source profiles of polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM10 and PM2.5) from the prebaked anode industry were studied to fill the knowledge gap and provide data for emission inventory and source resolution. In 2018, three prebaked anode plants were selected in Central China, each having one calcining chimney as well as one baking chimney, and then 92 samples were collected from the stack gas of the six chimneys. The results of the study are as follows. (1) PM10 and PM2.5 from the prebaked anode industry contained 37-42% water-soluble ions, 16-20% elements, 11-17% organic carbon, and 9.2-14% elemental carbon. (2) The EFs for PAHs of PM10 and PM2.5 were 1146.1 ± 899.7 and 866.2 ± 1179.8 mg/(t aluminum produced), respectively. The EF for BaP was seven times lower than that given by the European Environment Agency (EEA), whereas those of BbF, BkF, and IcdP were 2-13 times higher than those given by the EEA. (3) Seven diagnostic ratios for PAHs, including Ant/(Ant+Phe), Flua/(Flua+Pyr), BaA/(BaA + Chr), IcdP/(IcdP+BghiP), Flu/(Flu+Pyr), Phe/Ant and BaA/Chr were discussed. Just by diagnostic ratio, it is hard to precisely distinguish between calcining and baking in prebaked industry. (4) The toxic equivalence of PMs in the baking stack gas in the prebaked anode industry was five times higher than that in the calcining stack gas, and PM2.5 showed higher potential toxicity risk than PM10.

[Heavy Metal Pollution Characteristics and Ecological and Health Risk Assessment of Atmospheric PM2.5 in a Living Area of Zhengzhou City].

To study the pollution characteristics of atmospheric heavy metal elements in a living area of Zhengzhou City, assess the potential ecological risks, and determine risks to resident health in this city, the Wuhan Tianhong TH-16A Airborne Particles Intelligent Sampler was used to collect atmospheric PM2.5 in Zhengzhou City. The mass concentrations of 17 metal elements were analyzed by ambient air determination of inorganic elements by ambient particle matter wavelength dispersive X-ray fluorescence spectrometry. The source of heavy metals was analyzed by the enrichment factor method and principal component analysis. The ecological risk index method and the US Environmental Protection Agency's health risk assessment method were used to evaluate the potential ecological risks and residents' health risks from Cr, Cd, Cu, Zn, Ni, Pb, As, and other elements. The results showed that metals with higher enrichment factor values were Cd, Sb, Pb, and As, and Cd had the highest enrichment factor value. The sources of metal elements in a living area of Zhengzhou City were mainly crust/burning coal, fuel, garbage burning, metallurgical dust, and vehicle emission. The single factor potential ecological hazard index values of Cd, Pb, Zn, As, Cu, Ni, and Cr were 70420.2, 255.3, 204.6, 71.5, 36.9, 24.0, and 5.1, respectively. Cd, As, and Cr in a living area of Zhengzhou City posed a cancer risk, and Cd was the most harmful. Mn had a non-carcinogenic risk.

[Emission Characteristics Analysis and Health Risk Assessment of Unorganized VOCs in the Carbon Industry, Zhengzhou].

The three typical carbon enterprises in Zhengzhou were selected as research targets, and the emission characteristics of volatile organic compounds (VOCs) and their ozone formation potential (OFP) in different functional areas were studied. The US Environmental Protection Agency (EPA) health risk assessment model was used to evaluate the health risks of VOCs emitted by the carbon industry. The results showed that the concentration of VOCs in the production areas of the three research enterprises was between 89.77-964.60 µg·m-3, and the management area was between 51.46-121.59 µg·m-3. Naphthalene and carbon disulfide were at the highest concentrations in the carbon plants. The ozone formation potential of VOCs in the production area was between 75.42-1416.73 µg·m-3, and in the management area was between 65.32-202.42 µg·m-3, mainly from the contribution of aromatic hydrocarbons and olefins. The carcinogenic health risk (Risk) of VOCs in the production area was 3.5×10-5-2.8×10-3, and in the management area was 2.0×10-5-9.4×10-5, which was higher than the maximum acceptable level recommended by the EPA (10-6). The non-carcinogenic health risk index (HI) of the VOCs in the production area was 3.2-1.4×102, and in the management area was 4.3×10-1-3.8, except for the management area of the first enterprise, which was greater than 1, which may expose the workers. These health factors cause cancer and non-carcinogenic hazards.

[Health Benefit Evaluation for PM10 and PM2.5 Pollution Control in Zhengzhou, China, 2014-2016].

Based on the annual average concentration values, the health effects and health benefits as well as 95% confidence intervals of PM10 and PM2.5 pollution control from 2014 to 2016 in Zhengzhou were evaluated by applying the Poisson regression relative risk model. Results showed that the health benefits of PM10 pollution control were 18.18 billion RMB (15.04, 21.12), 24.25 billion RMB (20.25, 27.94), and 20.62 billion RMB (17.33, 23.92), which accounted for 2.7%, 3.3%, and 2.5% of the GDP of Zhengzhou, respectively, in 2014-2016. The health benefits of PM2.5 pollution control were 17.88 billion RMB (14.37, 21.16), 21.65 billion RMB (17.46, 25.53), and 17.25 billion RMB (13.78, 20.55), which accounted for 2.6%, 3.0%, and 2.1% of the GDP of Zhengzhou, respectively, in 2014-2016. After the PM10 and PM2.5 pollution was controlled, the number of urban beneficiaries was higher than that of rural areas, and acute bronchitis beneficiaries were higher than the beneficiaries of other health end-points. For chronic bronchitis, adults benefited more than children, while the opposite occurred for asthma. In this study, chronic bronchitis had the highest health benefit, followed by asthma, and outpatient and inpatient setting had the lower health benefits.

[Characteristics and Source Analysis of Water-Soluble Ions in PM2.5 in Zhengzhou].

In order to explore the pollution characteristics of water-soluble ions in PM2.5 in Zhengzhou, high time resolution and continuous observation of water-soluble inorganic ions in PM2.5 was conducted from December 1, 2017, to November 30, 2018, in Zhengzhou. The results showed that during the observation period, the average concentration of total water-soluble ions in Zhengzhou was 42.7 µg·m-3. The order of mass concentration of each ion, from large to small, was as follows:NO3-(17.7 µg·m-3), SO42-(10.2 µg·m-3), NH4+(9.0 µg·m-3), Cl-(2.3 µg·m-3), K+(1.3 µg·m-3), Na+(1.3 µg·m-3), Ca2+(0.8 µg·m-3), and Mg2+(0.1 µg·m-3). The mass concentration of total water-soluble ions was the highest in winter, slightly higher in autumn than in spring, and lowest in summer. The diurnal variation in single peak distribution was observed across the whole year in spring, summer, and autumn, while there was no significant diurnal variation in winter. The mass concentration of secondary inorganic ions (SO42-, NO3-, and NH4+) accounted for 43.8% of PM2.5, mainly in the form of (NH4)2SO4 and NH4NO3. There was a large degree of secondary transformation throughout the observation period; relative humidity had a significant influence on the sulfur oxidation rate, and temperature had a significant influence on the nitrogen oxidation rate. During the observation period, there was a good correlation between secondary ions, and K+ showed a good correlation with Mg2+ and Cl-. The main source of the secondary ions was the secondary conversion of gaseous pollutants. Mg2+ and Ca2+ were derived from soil dust and construction dust. K+ was one of the main biomarkers of biomass combustion. Na+ was mainly derived from sea salt and soil dust, and Cl- was derived not only from sea salt but also biomass and fossil fuel combustion. The results of principal component analysis showed that the water-soluble ions in PM2.5 in Zhengzhou were mainly affected by secondary transformation, combustion sources, and dust emission from soil or building construction.

[Emission Characteristics and List of Inorganic Elements in Fine Particles of Typical Industrial Kilns in Zhengzhou City].

Samples of particulate matter from flue gas emissions of typical brick, cement, and firebrick industrial kilns in Zhengzhou City were collected by dilution channel systems. Cr, Mn, Fe, Co, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Ni, Cu, Zn, Ga, As, Se, Sr, Cd, Sb, Sn, Ba, and Pb were analyzed. The emission factors (EFs) and emissions of inorganic elements of PM2.5 from kilns flue gases of three industries in Zhengzhou City during 2016 were calculated. A grid list of 1 km×1 km was also established. The results show that the highest concentration of total inorganic elements was in the firebrick industry, corresponding to(609.97±490.97) µg·m-3. The concentration of inorganic elements in the three industries accounted for 34%-54%, 27%-42%, and 23%-53% of PM2.5. The inorganic elements emitted from industrial kilns in brick and cement industries were mainly crust elements, and the highest concentration elements were Cl and Al. The inorganic elements emitted by industrial furnaces in the firebrick industry were mainly heavy metals, and the highest concentration element was Pb. The coefficient of divergence (CD) of inorganic elements in brick and cement industry was 0.389, that is slightly different. The CD between cement and refractory industry was 0.732, which represents a significant difference between inorganic element emissions. In 2016, the emissions of Pb, S, Zn, Cl, K, As, Fe, Si, Cr, Al, Na, and Ca in PM2.5 from major industrial furnaces in Zhengzhou City were 919.0, 793.1, 124.7, 378.6, 82.6, 12.2, 60.4, 145.4, 7.4, 86.6, 15.8, and 111.4 kg·a-1, respectively. Heavy metal emission in the Xinmi area was the highest, representing a high health risk.

Constructing a new Z-scheme multi-heterojunction photocataslyts Ag-AgI/BiOI-Bi2O3 with enhanced photocatalytic activity.

The series Ag-AgI/BiOI-Bi2O3 visible-light-driven photocataslyts were successfully synthesized by solvothermal method. The as-synthesized samples were systematically characterized by XRD, SEM, TEM, EDS, BET, XPS, FR-IR, UV-vis DRS, photoelectrochemical measurements and EPR. The formation mechanism of the new composite photocataslyts was investigated and the simulate formation process had been illustrated. The photocatalytic properties of the samples were evaluated by degradation of methyl orange under visible-light irradiation. The results shown that the 30% Ag-AgI/BiOI-Bi2O3 photocataslyts possessed the best photocatalytic activity and the kinetics reaction models were followed pseudo-first-order kinetics. The enhanced photocatalytic performance could be attributed to the effective separation and transfer of electron-hole pairs resulting by the deposing of Ag-AgI nanoparticles and Bi2O3. The photocatalytic mechanism was deduced by trapping experiments and EPR, and the results demonstrated that h+, OH, O2- radicals played different roles in the degradation. Furthermore, a new Z-scheme multi-heterojunction mechanism was proposed basing on the results of trapping experiments and EPR.

Size-fractionated particulate elements in an inland city of China: Deposition flux in human respiratory, health risks, source apportionment, and dry deposition.

Size-resolved samples were collected using a 14-stage impactor during four seasons in Zhengzhou and analyzed for 26 elements to calculate the health risks from atmospheric particle-bound metals. High concentrations of heavy metals were observed in ultrafine (10.2 (Ni)-66.9 (Cd) ng m-3) or submicrometer (11.4 (Ni)-134 (Pb) ng m-3) mode in winter. Two size-dependent models were used to estimate the deposition of inhaled toxic metals in various regions of the human respiratory system. Results show that heavy metals deposited in the alveolar region ranged from 7.6 (As)-375 (Al) ng m-3 and were almost concentrated in ultrafine and fine modes. Cd (2.2-8.6) may cause accumulative non-carcinogenic health effects on children, and Cr (1.0 × 10-4-2.2 × 10-4) may lead to carcinogenic health risks for nearby residents around the sampling site. The major sources by principal component analysis that contributed to Cr and Cd in ultrafine and fine particles were coal combustion, vehicular and industrial emissions. The atmospheric dry deposition fluxes of Cr and Cd were between 0.7 and 1.9 µg m-2 day-1 calculated by a multi-step method. From the environmental and public health perspective, environmental agencies must control the emission of heavy metals in the atmosphere.

Insight into the formation of secondary inorganic aerosol based on high-time-resolution data during haze episodes and snowfall periods in Zhengzhou, China.

Episodic haze is frequently observed in Zhengzhou, China. Such haze typically contains secondary inorganic aerosols. In this paper, we explore the formation mechanisms of sulfate, nitrate, and ammonium (SNA) in Zhengzhou from January 3 to 25, 2018 based on the results of a series of online instruments and a size-segregated filter sampler. Our results document the remarkable contributions of SNA to winter haze episodes in Zhengzhou, where they account for about 50% of PM2.5 mass concentration. SNA were mainly concentrated in droplet-mode particles, which increased remarkably with the aggravation of the haze episode. In addition, KNO3 and NaNO3 were formed in droplet-mode particles and coarse-mode particles respectively with increasing PM2.5 concentration. The atmosphere during the observation period was ammonia-rich, and the aerosol was acidic under high PM2.5 concentration. Homogeneous reactions dominated the formation of nitrate. HONO photolysis played a more important role in the origin of OH radicals when O3 decreased during haze episode. Under high relative humidity (RH), nitrate formation was influenced by heterogeneous hydrolysis reactions of N2O5. Sulfates were mainly formed through aqueous-phase reactions, especially when the RH was higher than 60%. Under these conditions, there were amounts of liquid water content existed in aerosols. Finally, we observed enhanced conversion of SO2 and NO2 during snowfall periods. This effect may be attributable to the higher RH and O3 levels despite the unfavorable effects of wet deposition and low concentrations of gaseous precursors.

A research on shape-controllable synthesis of Ag3PO4/AgBr and its degradation of ciprofloxacin.

Antibiotic ciprofloxacin is one of the commonly used broad spectrum fluoroquinolone human and veterinary drugs. Because of the overuse of human beings, the presence of ciprofloxacin has been detected in a variety of environmental matrices. To solve this problem, a facile, environmentally-friendly Ag3PO4/AgBr composite photocatalyst was synthesized by a simple precipitation method at room temperature in the presence of cetyltrimethyl ammonium bromide (CTAB). CTAB was served as surfactant and the source of bromide ions. The as-prepared Ag3PO4/AgBr microspheres were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The results revealed that the Ag3PO4/AgBr sample (synthesized with CTAB, 0.8 g) exhibited the highest photocatalytic activity to the photodegradation rate of 96.36%. Moreover, mechanism detection experiment indicated that h+ was the major active species in the degradation process. So the enhanced photocatalytic activity of Ag3PO4/AgBr composites is attributed to its excellent separation of photogenerated electron-hole pairs through Ag3PO4/AgBr heterojunction. Also, Ag3PO4/AgBr heterojunction has a lower band gap compared to pure Ag3PO4 and pure AgBr, so higher efficiency of light harvesting is equipped.

[Size Distribution Characteristics of Water-Soluble Inorganic Ions During Summer and Autumn in Zhengzhou].

To study the compositional characteristics of atmospheric particulates with different particle sizes in the central city of Zhengzhou, China, a Tisch graded impact sampler was used to sample atmospheric particulates in summer and autumn. The mass concentrations of water-soluble inorganic ions, including anions (Cl-, F-, NO3-, and SO42-) and cations (Na+, Ca2+, NH4+, K+, and Mg2+) were measured by ion chromatography, and the online ion chromatography-based analyzer MARGA monitored the real-time concentration of particulate nitrate. The results showed that the average concentration of water-soluble ions in Zhengzhou City was (70.9±52.1) µg·m-3 during the sampling period, and the order of water-soluble ion mass concentrations was NO3- > SO42- > NH4+ > Ca2+ > Na+ > Cl- > Mg2+ > K+ > F-; NO3-, SO42-, and NH4+ accounted for 79.9% of total water-soluble ions. The NO3- concentration was mainly concentrated in the 0.65-3.3 µm particle size segment, despite the SO42- concentration being concentrated in the ≤ 1.1 µm particle size segment in autumn or summer. Both NO3- and SO42- had a bimodal distribution in summer and autumn and were mainly distributed as fine particles. NH4+ showed seasonal variation with a bimodal distribution in summer and a unimodal distribution in autumn. Zhengzhou City had serious ozone pollution in summer, and O3 and NO3- showed the "staggered peak" phenomenon, indicating photochemical reactions in the atmosphere. In autumn, water-soluble inorganic ion concentration in particulate matter was high, and the ratio of[NO3-]/[SO42-] was higher than 0.5. The mobile source is an important source of particles. NOR and SOR peaks were on the 1.1-2.1 µm particle size segment in summer, whereas those in the 0.65-1.1 µm particle size segment occurred in autumn. The sulfur gas-to-grain conversion in summer was larger than that of nitrogen, contrary to the result in autumn.

Efficient photocatalytic degradation of tetracycline hydrochloride by Ag3PO4 under visible-light irradiation.

A facile, environmental-friendly Ag3PO4-PN photocatalyst was synthesized by a simple precipitation method at room temperature in the presence of ammonia and polyvinyl pyrrolidone (PVP). As-synthesized samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). The enhancement of photocatalytic efficiency of Ag3PO4-PN is strongly dependent on the excellent photo-absorption capacity, sharp edges and corners, and synergistic effect of PVP and NH3·H2O. The effects of catalyst dosage, TC concentration and solution pH were explored with tetracycline hydrochloride (TC) as target contamination. The mineralization was evaluated by total organic carbon (TOC) analysis and determination of the concentration of inorganic ions such as NO3 (-) and Cl(-). Radical detection experiment indicated the h(+) and ·O(2-) are major active species in the degradation of TC by Ag3PO4-PN. Moreover, photocatalyst stability and regeneration experiments exhibited the favorable stability and rejuvenation ability, suggesting a promising prospect of practical application of Ag3PO4 in the wastewater treatment.

Efficient visible-light photocatalytic degradation of sulfadiazine sodium with hierarchical Bi7O9I3under solar irradiation.

Bi7O9I3, a kind of visible-light-responsive photocatalyst, with hierarchical micro/nano-architecture was successfully synthesized by oil-bath heating method, with ethylene glycol as solvent, and applied to degrade sulfonamide antibiotics. The as-prepared product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflection spectra and scanning electron microscopy (SEM). XRD and XPS tests confirmed that the product was indeed Bi7O9I3. The result of SEM observation shows that the as-synthesized Bi7O9I3 consists of a large number of micro-sheets with parallel rectangle structure. The optical test exhibited strong photoabsorption in visible light irradiation, with 617 nm of absorption edges. Moreover, the difference in the photocatalytic efficiency of as-prepared Bi7O9I3 at different seasons of a whole year was investigated in this study. The chemical oxygen demand removal efficiency and concentration of NO(3)(-) and SO(4)(2-) of solution after reaction were also researched to confirm whether degradation of the pollutant was complete; the results indicated a high mineralization capacity of Bi7O9I3. The as-synthesized Bi7O9I3exhibits an excellent oxidizing capacity of sulfadiazine sodium and favorable stability during the photocatalytic reaction.