l-Cysteine and barium titanate co-modified enteromorpha biochar as effective peroxymonosulfate activator for atrazine treatment.

In this study, pyrolysis and hydrothermal methods were used for Enteromorpha biochar that was co-modified with l-cysteine and barium titanate (LBCBa). It has great environmental tolerance and can remove 93.0 % of atrazine (ATZ, 10 mg·L-1) within 60 mins of ultrasonic treatment. The enhanced hydrophilicity, electron-donating capability, and piezoelectricity of LBCBa are considered to induce excellent performance. The apparent reaction rate of the LBCBa-2/PMS/ATZ system with ultrasonic was 2.87 times that without ultrasonic. The density functional theory points out that, introducing l-cysteine to carbon edges improves the adsorption of ATZ and peroxymonosulfate (PMS), making PMS easier to activate. This work offered unique insights for fabricating effective catalysts and demonstrated the combination of hydrophilic functional groups and piezoelectricity in improving catalytic performance and stability.

Engineered hydrochar from waste reed straw for peroxymonosulfate activation to degrade quinclorac and improve solanaceae plants growth.

Hydrochar from agricultural wastes is regarded as a prospective and low-cost material to activate peroxymonosulfate (PMS) for degrading pollutants. Herein, a novel in-situ N-doped hydrochar composite (RHCM4) was synthesized using montmorillonite and waste reed straw rich in nitrogen as pyrolysis catalyst and carbon source, respectively. The fabricated RHCM4 possessed excellent PMS activation performance for decomposing quinclorac (QC), a refractory herbicide, with a high removal efficiency of 100.0% and mineralization efficiency of 75.1%. The quenching experiments and electron spin resonance (ESR) detection disclosed free radicals (•OH, •SO4-, and •O2-) and non-radicals (1O2) took part in the QC degradation process. Additionally, the catalytic mechanisms were analyzed in depth with the aid of various characterizations. Moreover, the QC degradation intermediates and pathways were clarified by density functional theory calculations and HPLC-MS. Importantly, phytotoxicity experiments showed that RHCM4/PMS could efficaciously mitigate the injury of QC to Solanaceae crops (pepper, tomato, and tobacco). These findings give a new idea for enhancing the catalytic activity of hydrochar from agricultural wastes and broaden its application in the field of agricultural environment.

Piezoelectricity ameliorates high-valent iron oxo species production in peroxymonosulfate activation for refractory atrazine remediation.

Over the past few years, high-valent iron oxo species (Fe(IV)) have shown considerable promise. However, an improved solution is needed for the bottleneck of unsatisfactory electron transfer efficiency in Fe-based catalyst/PMS systems. In this study, Enteromorpha-derived biochar was pyrolyzed with iron and barium titanate (FeBCBa). Under ultrasonic treatment, it removes 94.5% of atrazine (10 mg/L) within 60 min, and is environmentally friendly. BaTiO3's piezoelectricity enhances Fe(IV) production in FeBCBa, resulting in superior performance. In the ultrasonic condition, the apparent reaction rate was 1.42 times higher than in the non-ultrasonic condition. Using density functional theory calculations, it can be shown that due to the Fe dopant, electrons in ATZ's LUMO are more easily transferred to the catalyst's HOMO, which is beneficial for ATZ removal. The results of this study provide new guidance for constructing stable and efficient catalysts for environmental remediation.

Heavy metal content and health risk assessment of atmospheric particles in China: A meta-analysis.

In recent decades, China has devoted significant attention to the heavy metals pollution in particulate matter. However, the majority of studies have only focused on the field monitoring in relatively remote areas, which may not be representative of air quality across the country. This study reevaluated the characteristics, temporal and spatial changes, and health concerns associated with heavy metal pollution in atmospheric particulates on a national scale by coupling Meta-analysis and Monte Carlo simulation analysis. In terms of spatial distribution, the heavy metals pollution levels in the northern coast and northeastern regions are relatively high, whereas it is low along the middle Yellow River, middle Yangtze River, as well as Southwest. With the exception of Cu, the distribution of all elements in PM2.5 steadily decreased over time Moreover, PM10 and PM2.5 performed similar where Cd and Ni both first increased followed by a decline while, Cr displayed a decrease before it showed an increment. And since the implementation of prevention and control policies about the atmospheric release, the focus of industrial emission has gradually shifted from energy production and processing to living products manufacturing. Moreover, the carcinogenic risk was shown to be Cr > As, Pb > Ni, Cd, while the non-carcinogenic risk was as follows: As, Ni > Cr, Cd. Among all contaminants, Cd, As, and Cr in PM2.5 and PM10 exceeded the WHO standard in the cities with worst air quality. It was observed that As posed the largest non-carcinogenic risk to adults while, Cr caused the most carcinogenic risk to adults and children, where the carcinogenic risk of children remains higher than that of adults. Therefore, the findings of this study may offer data support to the China's heavy metal pollution standards in airborne particles and offer theoretical data support for pollution management.

Environmental-friendly hydrochar-montmorillonite composite for efficient catalytic degradation of dicamba and alleviating its damage to crops.

In recent years, carbon-based materials catalyzing peroxymonosulfate (PMS) for green degradation of persistent organic pollutants have attracted increasing attention. However, PMS activation by hydrochar composite (e.g. hydrochar-montomorillonite) has rarely been investigated. Herein, a simple preparation, low-cost and eco-friendly catalyst of hydrochar-montmorillonite composite (HC-Mt) was prepared to firstly catalyze PMS for the degradation of dicamba (DIC). The as-prepared HC-Mt showed a remarkably better catalyzing performance for PMS than pure hydrochar (HC) due to its good physicochemical characteristics and abundant oxygen-containing groups. Furthermore, the electron spin resonance (ESR) and quenching tests revealed that active species such as SO4-, OH and O2- all participated in the degradation process. DIC sites on C6, Cl 10, and O15 exhibited higher reactivity according to the density functional theory (DFT) calculation, which were easily attacked by active species. The DIC degradation mainly occurred via hydroxyl substitution, decarboxylation, oxidation and ring-cleavage and finally most of the intermediates were mineralized into CO2 and H2O. Finally, the phytotoxicity assessment was measured by the germination growth situation of tobacco and mung beans in the presence of DIC (with or without treatment by HC-Mt/PMS). The result showed that HC-Mt/PMS could significantly reduce the phytotoxicity of DIC to crops, suggesting that catalyzing PMS using HC-Mt was environmentally friendly. Therefore, this work did not only provide a novel catalyzing PMS strategy using hydrochar composite for wastewater treatment, but also give a new idea for herbicide phytotoxicity management.

Ultrafast photodegradation of nitenpyram by Ag/Ag3PO4/Zn-Al LDH composites activated by persulfate system: Removal efficiency, degradation pathway and reaction mechanism.

In this study, an investigation is conducted into the degradation of nitenpyram (NTP) using highly efficient APMMO/PDS/Vis system. As photocatalysts, silver phosphate (AP) and calcined Zn-Al layered double hydroxides (MMO) exhibit high efficiency in achieving charge separation. Besides, the injection of electrons into peroxydisulfate (PDS) from the APMMO can contribute to obtaining the species in the active state with higher efficiency. Based on the APMMO/PDS/Vis system, 50 mg/L of nitenpyram (NTP, 50 mL) can be completely removed in 60 min using 0.8 g/L photocatalyst and 0.2 g/L PDS under the optimum condition and visible light (780 nm > λ > 420 nm). Meanwhile, as demonstrated under visible light within 30 min, an ultrahigh degradation efficiency can be achieved by NTP based on APMMO1/PDS/Vis system. Besides, the electron paramagnetic resonance (EPR) technique and radical quenching experiments suggested 1O2, h+, SO4-•, •O2-, and •OH are all contributory to the removal of pollutants. Given the outcomes achieved by LC/MS system and mass spectrometry, the primary degradation intermediates of NTP end up being converted into photodegradation products (such as 2-Chloropyridine, 6-Chloropurine Riboside and dl-Leucine). Additionally, there are three potential photodegradation pathways to NTP degradation have been deployed. Moreover, the NTP light degradation occurring in APMMO1/PDS/Vis system is competent under the three types of real water sample. Accordingly, the high-efficiency APMMO1/PDS/Vis system is fit for use in water pollution control for agricultural productions.

Montmorillonite-supported nanoscale zero-valent iron for thiamethoxam removal: response surface optimization and degradation pathway.

As a highly efficient insecticide, thiamethoxam was widely used in the world. However, it was bioaccumulative and toxic to aquatic organisms that must be removed from water. In this work, nanoscale zero-valent iron particles loaded on montmorillonite (nZVI/Mt) were successfully synthesized for effective removal of thiamethoxam. The properties of nZVI/Mt for the removal of thiamethoxam were investigated, and the reaction conditions were optimized through response surface methodology. Furthermore, the degradation products were analyzed by liquid chromatography-mass spectrometry (LC/MS). The results demonstrated that the reaction activity of nZVI was enhanced because the agglomeration and oxidation of nZVI particles were effectively inhibited by using montmorillonite as a support. The significance of the effects of each factor on the removal of thiamethoxam was determined to be in the order of pH Ëƒ temperature Ëƒ reaction time Ëƒ nZVI/Mt dosage. The optimal conditions were as follows: a dosage of nZVI/Mt of 2 g/L, a reaction time of 2 h, a reaction temperature of 35 °C, and a solution pH of 3. The removal efficiency of thiamethoxam (C0 = 20 mg/L) was observed to be as high as 94.29% under the optimal conditions, which was close to the value of 94.47% that was predicted using the mathematical model, indicating that the model could accurately predict the removal efficiency of thiamethoxam. The degradation mechanism involved the -NO2 group on the thiamethoxam molecule was reduced and eliminated by nZVI/Mt.

Chiral pharmaceuticals: Environment sources, potential human health impacts, remediation technologies and future perspective.

Chiral pharmaceuticals (CPs), including non-steroid anti-inflammatory drugs (NSAIDs), ß-blockers and some herbicide and pesticides, are widely used in aquaculture, clinical treatment and many other fields. However, people are increasingly concerned about such ubiquitous pollutants, which can frequently be detected in contaminated soil and water. In large part, the significant sources of chiral pharmaceuticals stem from industrial processes, such as the direct discharge of untreated or incompletely treated wastewaters containing chiral pharmaceuticals, incorrect storage and use, animal wastes and biosolids. The main ways for human exposure to chiral pharmaceuticals are the disease treatment process and chiral pharmaceuticals contaminants. According to the results of a series of toxic studies, some diseases, even cancers, may be associated with exposure to certain chiral pharmaceuticals. Therefore, the treatment of chiral pharmaceuticals has become an important issue. The current advanced remediation techniques for chiral pharmaceuticals include the conventional method (sorption and sonolysis), biotransformation (an aerobic granular sludge-sequencing batch reactor and constructed wetland system) and advanced oxidation processes (ozonation and photocatalysis). Herein, in this review, we summarize the current status and sources of chiral pharmaceuticals, potential effects on human health, as well as the superiority, disadvantages and prospects of current advanced remediation technologies. Moreover, we also anticipate the prospect of the future research needed for chiral pharmaceuticals pollutant remediation.

Highly effective antibacterial activity by the synergistic effect of three dimensional ordered mesoporous carbon-lysozyme composite.

Aiming at developing a safe and efficient alternative to traditional drinking water disinfection, this work successfully synthesized a novel antibacterial material with high surface area, ultra large pore size and tunable loading of immobilized lysozyme. The immobilized enzymes exhibit high antibacterial efficacy without forming carcinogenic disinfection byproducts. Critical immobilization parameters were optimized to keep the activity of the immobilized enzyme at a high level. The immobilization of lysozymes on 3DOm COOH could be confirmed by the characterizations of transmission electron microscopy, X-ray diffraction and Zeta-Potential. In addition, the structural stability of lysozymes on 3DOm COOH were studied by Fourier transform infrared spectroscopy. The antibacterial performance of 3DOm COOH-Lyz were specifically investigated based on the disinfection efficacy of Staphylococcus aureus in water. The results revealed that the immobilization capacity and relative activity of immobilized lysozyme were 814mg/g carrier and 80%, respectively, under the optimal immobilization conditions. And the antibacterial material with the initial mass ratio of lysozyme and 3DOm COOH as 3:1 exhibited maximum bacteria removal efficiency (98.1%) at pH 5. Moreover, the reusability test indicated that 3DOm COOH-Lyz has certain operational stability, and remains 82% bacterial removal efficiency even in the fifth cycle, which provides a promising application for safe and efficient drinking water disinfection in small-scale and emergency water treatment.

pH-dependent degradation of p-nitrophenol by sulfidated nanoscale zerovalent iron under aerobic or anoxic conditions.

Sulfidated nanoscale zerovalent iron (S-NZVI) is attracting considerable attention due to its easy production and high reactivity to pollutants. We studied the reactivity of optimized S-NZVI (Fe/S molar ratio 6.9), comparing with pristine nanoscale zerovalent iron (NZVI), at various pH solutions (6.77-9.11) towards p-nitrophenol (PNP) under aerobic and anoxic conditions. Studies showed that the optimized extent of sulfidation could utterly enhance PNP degradation compared to NZVI. Batch experiments indicated that in anoxic S-NZVI systems the degradation rate constant increased with increasing pH up to 7.60, and then declined. However, in aerobic S-NZVI, and in anoxic or aerobic NZVI systems, it decreased as pH increased. It was manifested that anoxic S-NZVI systems preferred to weaker alkaline solutions, whereas aerobic S-NZVI systems performed better in acidic solutions. The highest TOC removal efficiency of PNP (17.59%) was achieved in the aerobic S-NZVI system at pH 6.77, revealing that oxygen improved the degradation of PNP by excessive amounts of hydroxyl radicals in slightly acidic conditions, and the TOC removal efficiency was supposed to be further improved in moderate acidic solutions. Acetic acid, a nontoxic ring opening by-product, confirms that the S-NZVI system could be a promising process for industrial wastewater containing sulfide ions.

Rapid adsorption of 2,4-dichlorophenoxyacetic acid by iron oxide nanoparticles-doped carboxylic ordered mesoporous carbon.

The ordered mesoporous carbon composite functionalized with carboxylate groups and iron oxide nanoparticles (Fe/OMC) was successfully prepared and used to adsorb 2,4-dichlorophenoxyacetic acid (2,4-D) from wastewater. The resultant adsorbent possessed high degree of order, large specific surface area and pore volume, and good magnetic properties. The increase in initial pollutant concentration and contact time would make the adsorption capacity increase, but the pH and temperature are inversely proportional to 2,4-D uptake. The equilibrium of adsorption was reached within 120 min, and the equilibrated adsorption capacity increased from 99.38 to 310.78 mg/g with the increase of initial concentration of 2,4-D from 100 to 500 mg/L. Notablely, the adsorption capacity reached 97% of the maximum within the first 5 min. The kinetics and isotherm study showed that the pseudo-second-order kinetic and Langmuir isotherm models could well fit the adsorption data. These results indicate that Fe/OMC has a good potential for the rapid adsorption of 2,4-D and prevention of its further diffusion.