Mixed Pollutants Research Articles

Vertical MOF film supported on an organic–inorganic mixed substrate for complex wastewater purification

Flexible metal–organic framework (MOF) films are greatly desired for the separation of hazardous molecules and ions from wastewater. The current MOF films are usually horizontally deposited on the substrates, and thus restricted by brittleness, low exposure of surface area, as well as poor separation functions. Here, an organic–inorganic mixed substrate is firstly fabricated by growing hydroxyapatite (HA) nanowire arrays on the cellulose fiber (CF). Subsequently, MIL-100(Fe) nanocrystals are assembled on the surfaces of HA nanowire arrays through a layer-by-layer manner, leading to a unique vertical MOF film. The resulting vertical MOF films show competitive advantages over the horizontal counterparts: (i) they show excellent flexibility and they are tolerant to serious physical damage; (ii) they have multiple separation functions including ion exchange of HA, excellent adsorption of MOFs, and strong electrostatic interaction of CF; and (iii) the agglomeration of MIL-100(Fe) nanocrystals is effectively suppressed. Therefore, the average roughness, specific surface area, and average pore size of films are optimized. As a result, the vertical MOF films show universal separation of positively/negatively-charged dyes and Pb2+ ion, with high removal rates of > 94 %. More appealing, the mixed pollutants in the complex wastewater can be one-step separated through the vertical MOF films, with high removal rates of > 96 %.

Assembling fixed-biofilm reactor with modified basalt fiber and modified wild jujube seed biochar for concurrent removal of nitrate, tetracycline and cadmium: Performance and microflora response

Mixed pollution of nitrate, tetracycline (TC) and cadmium (Cd2+) induced by improper discharge of various wastewater from industry and agriculture has attracted extensive attention. A novel biocarrier (MBF@FMJSB) assembled with modified basalt fiber and modified wild jujube seed biochar (FMJSB) was used to construct fixed-biofilm reactor (FBR) for concurrent removal of nitrate, TC, and Cd2+. The removal efficiencies of nitrate, TC, and Cd2+ of the bioreactor were 79.34%, 85.45%, and 88.02%, respectively, when HRT was 6.0 h, C/N ratio was 1.5, influent nitrate concentration was 25 mg L−1, pH was 6.5, and TC and Cd2+ concentrations was 0.6 and 1 mg L−1. The addition of FMJSB was not only beneficial for bacteria to resist the stress of TC and Cd2+, but also contributed to the removal of TC and Cd2+ pollutants. In addition, microbial metabolism was a key pathway for pollutant removal in FBR. Microflora with Zoogloea as a core genus can dynamically regulate the community structure and expression of microbial metabolism related genes to adapt to TC and Cd2+ stresses. This study was valuable for the treatment of wastewater containing mixed pollutants.

Antifouling multi-functional membrane for oil/dye wastewater treatment: Regeneration while treating mixed pollutants

Treatment of insoluble oils or soluble organic dyes in wastewater by membrane separation is considered to be one of the most effective strategies. However, simultaneously removing oils and dyes from wastewater is challenging. In this study, hydroxyl iron oxide was grown on PVDF membranes by in situ self-assembly and in situ self-growth strategies using proanthocyanidins as a bridge. The PVDF-PC-FeOOH membrane possesses excellent wettability and photo-Fenton catalytic properties (all types of underwater oil contact angles are larger than 150°, and the degradation efficiency of methylene blue within 20 min is greater than 70%). The emulsion separation flux and efficiency can reach 976.1 L·m-2h−1 and 99.7%, respectively. In addition, the photo-Fenton catalytic degradation process was discussed. The regeneration rate of the membrane is over 90%. The flux can be stabilized over a period of time in a continuous filtration process of 60 min (flux over 158.7 L·m-2h−1). Simultaneous removal of mixed pollutants and regeneration of the membrane is achieved in a single step. In multi-component oily wastewater, the membrane has selective adsorption capacity for cationic dyes, and the removal rate can achieve 98.6%. The strategy provided in the present study enhances the value of membranes for practical applications in the field concerning the filtration of oily wastewater and selective separation of dyes in the dyeing and printing industry.

Carbon black nanoparticles and cadmium co-exposure aggravates bronchial epithelial cells inflammation via autophagy-lysosome pathway

Carbon black nanoparticles (CBNPs) and cadmium (Cd) are major components of various air pollutants and cigarette smoke. Autophagy and inflammation both play critical roles in understanding the toxicity of particles and their components, as well as maintaining body homeostasis. However, the effects and mechanisms of CBNPs and Cd (CBNPs-Cd) co-exposure on the human respiratory system remain unclear. In this study, a CBNPs-Cd exposure model was constructed to explore the respiratory toxicity and combined mechanism of these chemicals on the autophagy-lysosome pathway in the context of respiratory inflammation. Co-exposure of CBNPs and Cd significantly increased the number of autophagosomes and lysosomes in human bronchial epithelial cells (16HBE) and mouse lung tissues compared to the control group, as well as the groups exposed to CBNPs and Cd alone. Autophagic markers, LC3II and P62 proteins, were up-regulated in 16HBE cells and mouse lung tissues after CBNPs-Cd co-exposure. However, treatment with Cq inhibitor (an indicator of lysosomal acid environment) resulted in a substantial decreased co-localization fluorescence of LC3 and lysosomes in the CBNPs-Cd combination group compared with the CBNPs-Cd single and control groups. No difference in LAMP1 protein expression was observed among the exposed groups. Adding 3 MA alleviated inflammatory responses, while applying the Baf-A1 inhibitor aggravated inflammation both in vitro and in vivo following CBNPs-Cd co-exposure. Factorial analysis showed no interaction between CBNPs and Cd in their effects on 16HBE cells. We demonstrated that co-exposure to CBNPs-Cd increases the synthesis of autophagosomes and regulates the acidic environment of lysosomes, thereby inhibiting autophagy-lysosome fusion and enhancing the inflammatory response in both 16HBE cells and mouse lung. These findings provide evidence for a comprehensive understanding of the interaction between CBNPs and Cd in mixed pollutants, as well as for the prevention and control of occupational exposure to these two chemicals.

Effects of plasticizer on removal of antibiotics and antibiotic resistance genes from agricultural soils via soil microbial fuel cells

Soil microbial fuel cells (MFCs), a novel ecosystem technology, have recently been intensively studied for antibiotic-polluted soils. However, actual agricultural soils are always contaminated by mixed pollutants, especially plasticizers from extensively used agricultural plastic films. The aim of this study is to investigate the effect of di-2-ethylhexyl phthalate (DEHP, a representative plasticizer in soil) on the removal of sulfadiazine (SDZ, a frequently detected antibiotic in natural environments), antibiotic resistance genes (ARGs), and the microbial community in soil MFCs. Our results confirmed that soil MFCs maintained a good antibiotic removal ability even under the influence of residual DEHP and achieved a higher removal performance at higher DEHP concentrations due to enhanced power generation. Specifically, a higher DEHP concentration had a favorable effect on antibiotic removal in soil MFCs because the biodegradation efficiency was improved in both the upper (i.e., to 0.268 ± 0.021 mg kg−1 from 4.867 ± 0.221 mg kg−1) and lower layers (i.e., to 0.293 ± 0.047 mg kg−1 from 4.867 ± 0.221 mg kg−1) of polluted soils. Moreover, a high DEHP concentration significantly promoted the abundance of bacteria associated with electricity generation compared with a lower DEHP concentration, resulting in the promotion of extracellular electron transfer, and enhancing SDZ degradation. The increased ARG abundance may have been caused by the enrichment of ARG potential hosts brought about by high DEHP concentrations, likely due to the increased conjugative transfer rates of the RP4 plasmid due to decreased membrane permeability and an increased reactive oxygen species content. The results revealed the ecological risk of residual DEHP in soil that promotes ARG transmission in soil MFCs, although it has the potential to reduce SDZ toxicity through horizontal gene transfer. We also highlight concerns regarding the management of antibiotics and plasticizers in soil. The negative effects of plasticizers on antibiotic removal should be carefully evaluated when using soil MFCs for the in situ remediation of antibiotic-contaminated soil.

Synergetic removal of Cr(VI) and dibutyl phthalate mixed pollutants on MoS2 sheet inserted in TiO2 nanotube under visible light

The challenge of developing stable and efficient photocatalysts for the simultaneous removal of heavy metals and organic pollution persists. Herein, molybdenum sulfide (MoS2) sheet inserted in porous-walled titanium dioxide nanotube arrays (TNTAs) with Z-scheme heterojunctions were synthesized via anodic oxidation and hydrothermal methods. The MoS2@p-TNTAs possess a robust response to visible light, with a large specific surface area and tight inter-semiconductor bonding. Notably, MoS2@p-TNTAs exhibited superior removal efficiencies in treating Cr(VI)-DBP mixed pollutants solution compared to individual pollutants. The degradation kinetic constants of Cr(VI) and DBP in the mixed pollutants were 8.3 and 3.3 times higher than those of single pollutants, respectively. The photodegradation efficiency of MoS2@p-TNTAs for DBP has consistently remained above 85 % even after undergoing 20 cycles, while the morphological structure remained stable, demonstrating outstanding structural stability and reusability. Mechanistic analysis revealed that the composites with Z-scheme heterojunctions exhibit a robust redox capability, while DBP and Cr were synergistically removed by consuming holes and electrons, respectively. Consequently, this study offers valuable insights into the potential application of TNTAs in wastewater treatment.

Self-regulated S-scheme heterojunction for synergistic removal of tetracycline and hexavalent chromium: Synergistic mechanism of trivalent chromium

The limitation of conventional photocatalysts in simultaneously removing Tetracycline (TC), hexavalent chromium (Cr (VI)) and trivalent chromium (Cr (III)) were addressed in mixed pollution treatment. The S-scheme heterojunction of titanate nanotubes/Bi2WO6 (TNTs/BWO) was successfully constructed to achieve efficient removal of TC, Cr (VI), and Cr (III). The theoretical calculations (DFT) demonstrated that TNTs’ ion exchange properties led to the partial replacement of interlayer Na+ by Cr (III), optimizing the S-scheme heterojunction during the photocatalytic reaction. Experimental results revealed that the coexistence of TC, Cr (VI), and Cr (III) had a mutual promotion effect, as evidenced by the apparent rate constant of Cr (VI) reaching 0.7 min−1, which was 87.5 times higher than that of the single pollutant system, while maintaining a high apparent rate constant for TC. The likely intermediate products, degradation pathways, and photocatalytic mechanism were also elucidated using DFT molecular orbitals and Fukui index analysis. This work provides new insights and strategies for simultaneously removing pollutants and contributes to wastewater purification.

Synergistic effects on the degradation of a mixture of pharmaceutical pollutants in aqueous solution, raw sewage, and hospital wastewater using UV light-assisted Fenton process

The widespread pharmaceutical pollutants enter the aquatic environment through wastewater, and it poses a threat to aquatic organisms and human health. Advanced oxidation process (AOPs) is one of the widely used treatment methods for the degradation of pharmaceutical pollutants by utilizing Ultraviolet light (UV), iron (Fe2+), and hydrogen peroxide (H2O2). This study investigates the application of AOP (UV/Fe2+/H2O2) for the degradation kinetics of mixed pollutants (amoxicillin, acetaminophen, and ciprofloxacin), mineralization, and degradation products. The sources for these pollutants are hospitals, households, manufacturing industries, etc. The effects of degradation were evaluated by varying pH, Fe2+, H2O2, the mixed pollutants, and time respectively. The results revealed that the optimal conditions were observed at UV light 15 W, mixed pollutant 5 mg/L, Fe2+ 0.04 mM, H2O2 3 mM, and time 10 min. The maximum degradation was achieved at >99 % in the mixed pollutants with the kinetics in the order of ACET > CIP > AMX. The maximum mineralization was observed at 68 % and transformation products were identified using LC-ESI-MS. In addition, the process performance of the UV/Fe2+/H2O2 method was assessed by applying optimum conditions in real wastewater (raw sewage and hospital wastewater). The study revealed that the UV/Fe2+/H2O2 method had a high performance in the removal of multiple pollutants in real wastewater.

The Aerosol Optical Characteristics in Different Dust Events Based on a 532 nm and 355 nm Polarization Lidar in Beijing

Extreme weather events are happening more frequently as a result of global climate change. Dust storms broke out in the spring of 2017 in China and drastically impacted the local air quality. In this study, a variety of data, including aerosol vertical profiles, surface particle concentration, meteorological parameters, and MODIS–derived aerosol optical depth, as well as backward trajectory analysis, were employed to analyze two dust events from April to May in Beijing. The dust plumes were mainly concentrated below 0.8 km, with peak PM10 values of 1000 μg·m−3 and 300 μg·m−3 in the two cases. The aerosols showed different vertical distribution characteristics. The pure dust in case 1 from 4 to 5 May 2017 had a longer duration (2 days) and presented a larger aerosol extinction coefficient (2.27 km−1 at 355 nm and 1.25 km−1 at 532 nm) than that of the mixed dust in case 2 on 17 April 2017 (2.01 km−1 at 355 nm and 1.33 km−1 at 532 nm). The particle depolarization ratio (PDR) remained constant (0.24 ± 0.03 in case 1) from the surface to 0.8 km in height. In contrast, the PDR profile in the mixed dust (case 2) layer was split into two regions—large values exceeding 0.15 above 0.6 km and small values of 0.11 ± 0.03 below 0.6 km. The influence of meteorological information on aerosol distribution was also investigated, and wind was predominant through the observing period. The pure dust in case 1 was mainly from Mongolia, with strong northwest winds, while the near-surface mixed pollution was caused by the combination of long-transported sand and local emission. Furthermore, lidar-derived profiles of dust mass concentrations in the two cases were presented. This study reveals the vertical characteristics of dust aerosols in the production and dissipation of localized dust events and confirms the efficacy of thorough observations with multiple approaches from the ground to space to monitor dust events in real time.

Research on degradation mechanism of trichlorobenzene and Hg0 by nonthermal plasma catalysis

Aiming at mercury and dioxin in fire coal gas as research objects, nonthermal plasma (NTP) catalytic technology was used to investigate the degradation effect of operating condition parameters on mixed pollutants in mixed flue gas condition, and to explore the synergistic degradation of Hg0 and TCB (1, 2, 3-trichlorobenzene, TCB) under mixed flue gas conditions. The research results showed that the conversion efficiency of mercury and TCB increased with the additional output of voltage, and decreased with the increase of the gas flow rate. Under optimal reaction conditions: voltage = 17 kV, frequency = 300 Hz, gas flow rate = 2 l min−1, the conversion efficiency of Hg0 and TCB reached the highest 91.4% and 84.98%, respectively. In the NTP catalytic system, active free radicals played an important role in the synergistic conversion of mercury and TCB, which have a competitive effect, to make the conversion efficiency of mixed pollutants lower than a single substance. In the mixed flue gas condition, the mixed gas has an inhibitory effect on the synergistic conversion of mercury and TCB. Kinetic modeling of NTP catalytic synergistic reaction was established. Under three conditions of TCB, mercury and TCB, mixed simulated flue gas, the NTP catalytic technology showed a quasi-first-order kinetic reaction for the degradation of TCB. According to the synergistic effect of NTP and composites, the transformation and degradation of TCB mainly included two processes: TCB and ring opening, and Hg0 was finally oxidized to Hg2+.

The impact of different aerosol layering conditions on the high-resolution MODIS/MAIAC AOD retrieval bias: The uncertainty analysis

The Eastern Mediterranean/Middle East (EMME) region belongs to one of the most polluted and vulnerable to climate change related areas in the world. To monitor these changes, comprehensive set of measurements need to be conducted. Ground-level monitoring sites provide continuous measurements, yet their spatial coverage in EMME is very limited. Satellite data largely expand spatial coverage, however, retrieval accuracy over arid regions with bright surface background, mixed with urban and industrial sources, remains challenging. In this study, we analyzed the agreement between aerosol optical depth (AOD) data from the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm at 1-km spatial resolution and corresponding ground-based Aerosol Robotic Network (AERONET) measurements, using data from September 2019 to October 2022 in Tel Aviv, Israel. We identified all overestimation and underestimation MAIAC AOD measurements, relative to AERONET, and used multiwavelength polarization lidar observations of vertical aerosol profiles to characterize these conditions. Our findings suggest that under clear atmospheric conditions (AOD¡0.12), MAIAC overestimation prevails, while under dusty (AOD¿0.3), and partially cloudy conditions, MAIAC underestimation prevails. We found that dust component (high particle depolarization ratio, and low Angstrom exponent) is often presented in cases of underestimation, while a single layer overestimation cases typically related to anthropogenic pollution. The two-layers overestimation cases tend to have marine aerosols at the bottom and mixed pollution sources at the top. Our study highlights the importance of studying the different layering conditions that largely bias the MAIAC AOD retrieval accuracy. This knowledge is highly important since AOD is widely used as input variable in numerous modeling studies and air quality applications and rarely prepossessed for such a bias.

Boosted Tetracycline and Cr(VI) Simultaneous Cleanup over Z-Scheme WO3/CoO p-n Heterojunction with 0D/3D Structure under Visible Light.

In this study, a Z-Scheme WO3/CoO p-n heterojunction with a 0D/3D structure was designed and prepared via a simple solvothermal approach to remove the combined pollution of tetracycline and heavy metal Cr(VI) in water. The 0D WO3 nanoparticles adhered to the surface of the 3D octahedral CoO to facilitate the construction of Z-scheme p-n heterojunctions, which could avoid the deactivation of the monomeric material due to agglomeration, extend the optical response range, and separate the photogenerated electronhole pairs. The degradation efficiency of mixed pollutants after a 70 min reaction was significantly higher than that of monomeric TC and Cr(VI). Among them, a 70% WO3/CoO heterojunction had the best photocatalytic degradation effect on the mixture of TC and Cr(VI) pollutants, and the removing rate was 95.35% and 70.2%, respectively. Meanwhile, after five cycles, the removal rate of the mixed pollutants by the 70% WO3/CoO remained almost unchanged, indicating that the Z-scheme WO3/CoO p-n heterojunction has good stability. In addition, for an active component capture experiment, ESR and LC-MS were employed to reveal the possible Z-scheme pathway under the built-in electric field of the p-n heterojunction and photocatalytic removing mechanism of TC and Cr(VI). These results offer a promising idea for the treatment of the combined pollution of antibiotics and heavy metals by a Z-scheme WO3/CoO p-n heterojunction photocatalyst, and have broad application prospects: boosted tetracycline and Cr(VI) simultaneous cleanup over a Z-scheme WO3/CoO p-n heterojunction with a 0D/3D structure under visible light.

Coalescence of As(II) with •OH: The pivot for co-processing of As(III) and butyl xanthate

Although water metalloid pollution is widely studied, the effect of the combined pollution of organic matter and metalloids in mining water and, especially, the possible interaction mechanisms between metalloids and flotation reagents, are both poorly understood. Existence of mixed pollution of metalloids and organic compounds tends to cause more serious harm to natural organisms. In this study, a synergistic removal of arsenite (As(III)) and butyl xanthate (Bx) in an advanced oxidation system was reported using biochar-based catalyst loaded with nano-zero-valent iron from an inexpensive iron source (iron slag) to activate peroxodisulfate. The removal efficiencies were improved by 30 % in the co-existence of As(III) and Bx compared to those of the single pollutant. The theoretical calculations, especially frontier molecular orbital theory, revealed the generation of [AsO2-OH]•− by the combination of As(II) with •OH. This [AsO2-OH]•− participated in the oxidative degradation of Bx with high activity and combined with the sulfur falling off Bx after the reaction to form a novel Fe-As-S complex as indicated by X-ray absorption +fine structure analysis. Overall, this study reports the generation of low-valent arsenic active substances of [AsO2-OH]•− and their effect on the removal of organic pollution containing S atoms in advanced oxidation systems under typical mining water conditions with the coexistence of As(III) and expands the understanding and application of traditional free radicals.

Competitive coordination initiated one-pot synthesis of core–shell Bi-MOF@BiOX (X = I, Br and Cl) heterostructures for photocatalytic elimination of mixed pollutants

Core-shell Bi-MOF@BiOX (X = I, Br and Cl) hybrids were fabricated by a one-pot solvothermal strategy via regulating the concentration and type of halogen ions in the Bi-based CAU-17 synthesis. By virtue of the competitive coordination effect to Bi3+ between CAU-17 and BiOX, CAU-17 was converted into another Bi-MOF with similar structures and compositions. Moreover, Bi3+ plays the role of “bridge” and endows an intimate interface contact between BiOX and the Bi-MOF, which immensely expedites the charge and mass transportation. The obtained Bi-MOF@BiOX hierarchical heterostructures were applied to photocatalytic elimination of solo and mixed pollutants (Cr(VI)/tetracycline and Cr(VI)/o-nitrophenol), and exhibited favorable performances. Choosing Bi-MOF@BiOI as a typical example, the corresponding performances for Cr(VI) reduction, tetracycline and o-nitrophenol degradation in their solo systems are 14, 10, 8 times higher than those of CAU-17, and 13, 7, 5 times higher than those of BiOI under visible light, respectively. Of note, the above photocatalytic performances could be further improved in the coexisting environment of Cr(VI) and tetracycline or o-nitrophenol, which is attributed to the elevated charge separation efficiency caused by the timely consumption of photo-excited electrons and holes. This work gives some insights into the delicate design of MOF photocatalysts and their applications in environmental restoration.

Synergetic removal of mixed pollutants over cerium oxide/red phosphorus heterojunction composite

CeO2/hydrothermally treated red phosphorus (HRP) heterojunction composite was formed to address the easy recombination of carriers. The results of the composition proportion optimization revealed that the 5%CeO2/HRP composite (weight proportion of CeO2 about 5wt%) showed the best photocatalytic degradation performance for Rhodamine B (RhB). The rate constant value of 5%CeO2/HRP was 0.071 min−1, which was 2.0 and 35.5 times more than that of pure HRP and CeO2. In addition, the introduction of the heavy metal Cr(VI) to form a mixed heavy metal-organic pollutant solution significantly improved the removal of RhB due to the simultaneous removal of the two target pollutants could improve the utilization efficiency of photogenerated carriers. Mechanistic investigations proved that the heterojunction could be decreased the recombination ratio of photogenerated electron-hole pairs in single semiconductors, thereby enhancing its photocatalytic activity. This research not only offered a novel method for designing heterojunction photocatalytic materials, but also provided a fresh perspective on the treatment of mixed pollutants.

Progress of synthetic cyclodextrins-based materials as effective adsorbents of the common water pollutants: Comprehensive review

Recently, cyclodextrin (CD)-based adsorbents have received significant attention for water-pollutant removal owing to their excellent properties, such as rapid adsorption kinetics, easy regeneration, and high mechanical stability. This review systematically covers the current methods for preparing CD-based adsorbents, including crosslinking, immobilization (grafting), self-assembly, molecular imprinting, and ionic imprinting. The characterization of CD-based adsorbents using FTIR, SEM, and BET analysis is also discussed. Furthermore, the use of CD-based adsorbents for the adsorption of specific pollutants, such as heavy metals, dyes, endocrine-disrupting chemicals, pharmaceuticals, and other organic pollutants, is highlighted by introducing the adsorption properties and mechanisms. Compared with native cyclodextrins, modified cyclodextrins facilitate the separation of the adsorbent from the aqueous phase, thus enhancing the application of CD-based adsorbents in practical applications. Most of the reported CD-based adsorbents demonstrate high efficiency for the adsorption of different pollutants. Moreover, the interior hydrophobic cavity of CDs predominantly contributes to capturing organic pollutants, particularly endocrine-disrupting chemicals. The performance of crosslinked and immobilized CD-based adsorbents for the simultaneous removal of mixed pollutants is excellent. Most CD-based adsorbents can be easily regenerated using a suitable desorption eluent. The challenges and limitations associated with CD-based adsorbents are presented, along with possible solutions and developments for highly efficient CD-based adsorbents that can be applied in practical wastewater treatment.

MoS2 grown on hollow carbon nanospheres as photoanode for improved photoelectrocatalytic degradation of Bisphenol A

Photoelectrocatalytic (PEC) technology capable of fully mineralizing hazardous substances is a promising strategy to address growing environmental problems. Herein, MoS2 nanosheets grown on nitrogen doped hollow carbon spheres (MoS2–NHCS) composites was prepared, and then bonded on a foamed nickel matrix by electrodeposition as photoanode for PEC degradation of Bisphenol A (BPA). Due to the integrated synergistic effect of unique composites structure and photocatalysis/electrocatalysis, the separation efficiency and survival life of photogenerated carriers were improved, and then accelerated the degradation of pollutants. The maximum reaction rate constant was 7.30 × 10−3 min−1. Photoelectrochemical characterization and key influencing parameters were discussed to clarify the relations between structure and function. The activity loss of MoS2–NHCS photoanode after four cycles was less than 10%, showing the long-term stability of BPA removal. The radicals quenching results revealed that this composite system was dominated by •OH together with moiety contributed by h+ and O2•-. Based on the detection results of intermediates, a possible decomposition pathway of BPA was proposed. The mixed pollution experiments suggested that the synergistic effect between organic matter and heavy metal greatly increased the treatment load of this composite electrode, providing a new idea for the study of practical wastewater treatment by the PEC system.

The Source Apportionment of Heavy Metals in Surface Dust in the Main District Bus Stops of Tianshui City Based on the Positive Matrix Factorization Model and Geo-Statistics

For the pollution assessment and quantitative source apportionment of heavy metals in surface dust, a total of 52 surface dust samples were collected from bus stops in Tianshui City. The geoaccumulation index (Igeo) and potential ecological risk index (RI) were used to analyze the pollution levels caused by heavy metals. The Positive Matrix Factorization (PMF) of the receptor modeling and geo-statistics were employed to analyze the source of the heavy metals. The results were as follows. ① Except for Mn, Co and V, the mean concentrations of other heavy metals have exceeded the local background value of Gansu. The percentage of excessive concentrations of Cu, Zn, Sr, Ba and Pb in the samples was 100%, and that of Cr, Ni and As were 96.15%, 94.23%, and 96.15%, respectively. ② Semivariogram model fitting showed that the block-based coefficients of Cu, Zn, Sr, Ba, Pb, Cr, Ni, and As were between 0.25 and 0.75, indicating that they were mainly affected by human factors. The high values of Pb, Zn, Ni and As were mainly distributed in the eastern part of the study area, and the high values of Cu, Sr, Ba and Cr were distributed in a spot-like pattern in the study area. ③ The Igeo results showed that As, Cu, Zn, and Pb were the main contamination factors, and the optimized RI showed that the heavy metals were the overall ecological risk of intensity, among which Pb, As and Cu were the main ecological factors and should be taken as the priority control objects. ④ Based on the PMF, there are four main sources of eleven heavy metals. V, Mn, and Co were attributed to natural sources, accounting for 18.33%; Cu, Sr, and Ba were from mixed sources of pollution from transportation and industrial alloy manufacturing, accounting for 26.99%; Cr and Ni were from sources of construction waste pollution, accounting for 17.17%, As, Zn and Pb were mainly produced by coal-traffic mixed pollution emissions, accounting for 37.52%. Overall, the study area was dominated by coal-traffic emissions.

Spatial and temporal distribution characteristics of antibiotics and heavy metals in the Yitong River basin and ecological risk assessment

Due to rapid socioeconomic development, antibiotic pollution and heavy metal pollution are receiving increasing amounts of attention. Both antibiotics and heavy metals in the environment are persistent and toxic, and the interactions between the pollutants create potential long-term hazards for the ecological environment and human health as mixed pollutants. In this study, the surface water of the Yitong River in Changchun was used as the research object, and the hazards associated with antibiotics and heavy metals in the surface water were assessed by analyzing the spatial and temporal distribution characteristics of antibiotics and heavy metals and by using ecological risk assessment and human health risk assessment models. The results showed that ofloxacin (OFL) and norfloxacin (NOR) varied seasonally according to the seasonal climate, with total concentrations ranging from 17.65 to 902.47 ng/L and ND to 260.49 ng/L for OFL and NOR, respectively, and from 8.30 to 120.40 μg/L, 1.52 to 113.41 μg/L and 0.03 to 0.04 μg/L for copper (Cu), zinc (Zn) and cadmium (Cd), respectively. In terms of spatial distribution, the concentration of antibiotics in the urban sections, which had intensive human activities, was higher than that in the suburban sections, while the concentration of heavy metals in the suburban sections, which had intensive agricultural operations, was greater than that in the urban section. Ecological risk evaluation showed that NOR and OFL were present in the water bodies at a high-risk level, Cd was at a low pollution level, and the heavy metal Cd was the primary pollutant associated with health risks toward for adults and children, and it was mainly at a medium risk level. Additionally, both antibiotics and heavy metals posed higher health risks for children than for adults.

Insight into the superior piezophotocatalytic performance of BaTiO3//ZnO Janus nanofibrous heterostructures in the treatment of multi-pollutants from water

Piezophotocatalytic technology has emerged as a promising wastewater treatment approach recently. A novel piezoelectric material, the flexible bamboo-like BaTiO3//ZnO Janus nanofibers membrane (BTO//ZO JNM), was fabricated via side-by-side electrospinning. The as-prepared BTO//ZO JNM exhibited superior durability and universal applicability in the removal of bisphenol A, congo red, methylene blue and tetracycline hydrochloride under stir and light irradiation. The removal of these pollutions reached 94.75%, 93.45%, 99.06% and 97.65% within 60 min, respectively. The adsorption of Ni2+ and Cu2+ and their effects on catalytic degradation were also studied. Importantly, owing to the significantly raising macroscopic polarization, BTO//ZO JNM possessed higher degradation efficiency than that of uniaxial blend nanofibrous membrane, which was illustrated by COMSOL simulation. An in-depth understanding of piezophotocatalysis mechanism was speculated through construction-performance relationships of Janus heterojunction. This BTO//ZO JNM process will provide a new strategy for the development of piezoelectric materials for the treatment of mixed pollutants.