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The presence of pesticide residues has become one of the main risk factors affecting the safety and quality of agro-food. In this study, a multi-residue method for the analysis of 284 pesticides in five local fruit cultivars in Shanghai was developed based on ultrahigh-performance liquid chromatography-quadrupole time-of-fight mass spectrometry (UPLC-QTOF/MS). The limits of determination and the limits of quantitation of pesticides were 0.6–10 and 2–30 µg/kg, respectively. A total of 44, 10, 10, 18, and 7 pesticides were detected in strawberries, watermelons, melons, peaches, and grapes, respectively. The pesticide levels in 95.0% of the samples were below the maximum residual limits (MRLs) prescribed by China, and in 66.2% of the samples below the EU MRLs. The dietary risk assessment study showed big differences in the chronic and acute exposure risk values among different Chinese consumer groups. Through fruit consumption, children/females showed higher exposure risks than adults/males. But both the risk values were less than 100%, indicating that potential dietary risk induced by the pesticides was not significant for Chinese consumers. Nevertheless, certain measures are needed for both growers and government in order to decrease the MRL-exceeding rate of pesticide residues and ensure the quality and safety of fruits for consumers.

Soil fumigation using 1,3-dichloropropene (1,3-D) and chloropicrin (CP) is an important strategy for agriculture production; however, excessive emissions can cause air pollution and possible human exposure. In this study, solar light-driven CuInS2/ZnS:Al-TiO2 photocatalytic film was prepared through spin-coating on the flexible polyethylene terephthalate (PET) substrate of 0.1 mm. Using the photocatalytic film, degradation of 1,3-D was inhibited in the Pci-clor 60 formulation of 1,3-D and CP. However, the degradation of CP was accelerated in this formulation, and the half-life was shortened from 0.66 to 0.40 h. Emissions of 1,3-D from soil to the air were reduced by 97.30%, 97.17%, 47.10%, and 7.88%, for treatments of D + Film, D + C + Film, D + PET, and D, respectively. The efficiencies for reducing 1,3-D emission were significantly improved by about 1.1 and 11.3 times using the film, compared with using the PET alone and no film, respectively. Furthermore, fumigation effects on nematodes could still achieve higher than 90%. The findings provided a basis for the practical application of quantum dot films to reduce soil fumigants emissions by photocatalytic degradation.

Granulation of biochar-based fertilizer is one potential method to reduce transportation costs, provide for enhanced handling, and decrease the loss of fertilizer during soil application. This study aimed to synthesize binder-free biogas residue biochar-based fertilizer (RBF) pellets and investigate their physical properties and slow-release potential. Results showed that the physical properties and forming quality of the pellets reached the best when the moisture content was 7.84%, the diameter was 7 mm, the compression speed was 49.54 mm/min, and the molding pressure was 7.5 MPa. Sustained-release kinetic analysis and characterization results identified that the RBF had excellent nitrogen (N), phosphorus (P), and potassium (K) sustained release properties. The sustained release of nutrients gradually increased with the drying temperature, and the sustained-release effect of P was the best, followed by that of N and K. Therefore, RBF pellets may be applied as a green slow-release fertilizer in agricultural production. Physical, chemical, and slow-release properties could be improved by optimizing the drying and granulation process parameters, thus providing a new idea for the combination of kitchen waste recycling and sustainable agricultural development.

The disposal of large amounts of biogas residue from anaerobically digested waste is a burden on environment protection. Porous biochars (BCs) were synthesized from biogas residue at three pyrolysis temperatures (300 °C, 550 °C, and 800 °C) and used to catalyze H2O2 for the degradation of benzene, toluene, ethylbenzene, xylene isomers (ortho, para, and meta), and styrene (BTEXS) to develop a new use for biogas residues. The prepared BCs were characterized through scanning electron microscopy, Brunauer–Emmett–Teller method, Fourier transform infrared spectrometry, and X-ray photoelectron spectroscopy. Results showed that BC800/H2O2 had the highest BTEXS degradation performance over 6 h. The degradation kinetic data were most consistent with the pseudo-second-order model. The different catalytic effect of the three BCs pyrolyzed at different temperatures were attributed to the dominant active sites (C–O/C–OH/C=C/C=O groups, pyridinic N, and graphitic N) that induced the production of reactive oxygen species (ROS). ROS-quenching experiments indicated that the degradation of BTEXS by BC300/H2O2, BC550/H2O2, and BC800/H2O2 involved ∙OH, ∙O2−, and 1O2. ∙OH was the dominant ROS in BC300/H2O2 and BC550/H2O2, and 1O2 was the dominant ROS in BC800/H2O2. Our findings provided new insight into the different catalytic mechanisms for BC production at different pyrolysis temperatures and demonstrated that a porous BC catalyst with high utilization value could be prepared from biogas residue and could hold considerable potential for application in BTEXS treatment in the future.

A colorimetric method is described for detection of the antibiotic ciprofloxacin (CIP) in aqueous solutions based on an unmodified CIP-aptamer and gold nanoparticles (AuNPs), which are regarded as a probe and an indicator, respectively. In the absence of CIP, aptamers can hybridize with poly dimethyl diallyl ammonium chloride (PDDA) to form a 'duplex' structure through electrostatic interactions, and AuNPs remain dispersed in solution, leading to a red solution and an obvious absorption peak at 520 nm. Contrarily, the CIP-aptamer can specifically bind to CIP after the introduction of CIP into the solution. Then PDDA is thus free to aggregate AuNPs. The solution turns blue from red accordingly, presenting a strong absorption at 650 nm. Hence, the concentration of CIP can be quantified through the changes of the absorption. This sensitive and selective colorimetric method for CIP detection has a good linear response (R = 0.9935) in the 20 to 300 nM CIP concentration range, with a limit of detection (LOD) of 0.215 nM. Importantly, the proposed aptasensor demonstrates great application potential in CIP determination in aqueous samples.

An efficient iron-manganese modified biochar (FMBC) was successfully synthesized as a heterogeneous Fenton-like catalyst through easy post-modification and applied for degradation of benzene, toluene, ethylbenzene, xylene isomers (ortho, para, and meta), and styrene (BTEXS) in the presence of H2O2. The catalyst was characterized by Brunauer–Emmett–Teller method, scanning electron microscopy, and X-ray photoelectron spectrometry. The effects of H2O2 concentration, FMBC dose, and initial pH on BTEXS degradation were also investigated. Results showed that degradation efficiency of FMBC for individual BTEXS varied from 83.05% to 94.12% in 3 h. Kinetic analysis showed that a first-order kinetic model with respect to BTEXS concentration could be used to explain the BTEXS degradation for FMBC/H2O2 system. The degradation reaction was more suitable in a wide pH range (3–10) than those in previous studies, thereby overcoming the low-efficiency problem of conventional Fenton reaction at high pH. Moreover, the doses of FMBC and H2O2 are a crucial factor affecting BTEXS degradation. Radical scavenger experiments revealed that ∙OH, ∙O2−, and 1O2 participated in the degradation process, and ∙OH was the major contributor. The synthesized catalyst is durable with stable BTEXS removal efficiency after seven consecutive cycles. The removal efficiency of BTEXS by FMBC in produced water reached 93.23% in 12 h, indicating FMBC has practical value.

Growth of metal oxide layers on quantum dots (QDs) has been regarded as a good way to improve the photostability of QDs. However, direct growth of metal oxides on individual QD remains a great challenge. Here we report a novel approach to rapidly anchor metal oxides on QD surfaces through a sacrificial oxidation of a self-metal source strategy. As typical core/shell QDs, CdSe/CdS or aluminum doped CdSe/CdS (CdSe/CdS:Al) QDs were chosen and treated with peroxide (benzoyl peroxide). Self-metal sources (cadmium or/and aluminum) can be easily sacrificially oxidized, leading to the quick growth of cadmium oxide (CdO) or aluminum/cadmium hybrid oxides (Al2O3/CdO) on the surface of individual QD for improved photostability. Compared with CdO, Al2O3 possesses excellent barrier properties against moisture and oxygen. Therefore, CdSe/CdS QDs with the protection of an Al2O3/CdO hybrid layer show much superior photostability. Under strong illumination with blue light, the QDs coated with the Al2O3/CdO hybrid layer retained 100% of the original photoluminescence intensity after 70 h, while that of the untreated CdSe/CdS:Al, the treated CdSe/CdS and the CdSe/CdS QDs dropped to 65%, 45%, and 5%, respectively. Furthermore, we demonstrate that this method can be extended to other metal-doped QD systems, even including some inactive metals difficult to be oxidized spontaneously in an ambient atmosphere, which provides a new way to stabilize QDs for diverse optoelectronic applications.

Reducing the emissions of soil fumigants such as 1,3-dichloropropene (1,3-D) is essential to protecting air quality. Although biochar is useful in reducing such emissions, biochar-adsorbed fumigants may desorb and cause secondary air pollution. This study investigated the degradation of 1,3-D on iron (Fe)-impregnated biochar (FBC) amended with urea-hydrogen peroxide (UHP). The results indicated the degradation rate of trans-1,3-D on FBC-UHP was 54-fold higher than that on pristine biochar (PBC). Electron paramagnetic resonance (EPR) combined with other characterization methods revealed that the presence of semiquinone-type radicals in FBC effectively accelerated the Fe(III)/Fe(II) cycleto maintain enough Fe(IIII) for UHP activation and ·OH generation. ·OH, rather than ·O2-, was the dominant active oxidant. Soil column tests showed that application of FBC to the soil surface reduced cumulative 1,3-D emissions from 34.80 % (bare soil) to 0.81%. After the column experiment, the mixing of the FBC with UHP resulted in the residual cis-isomers decreasing from 32.5% to 10.5%. Greenhouse bioassays showed that mixing post-1,3-D degradation FBC-UHP with soil significantly promoted lettuce growth relative to PBC. The findings of this study provide a new approach for biochar application, especially for the emission reduction of hazardous volatile organic compounds from soil.

Biochar improves soil fertility and promotes long-term terrestrial carbon sequestration. However, biochar seems not to be stable enough due to physical, chemical and biological reactions. In this study, a novel, stable, and magnesium (Mg)-impregnated biochar was prepared from cow dung and applied to decrease P leaching from soil. XPS, FTIR, XRD, SEM and EDS were used to evaluate the effect of modification and phosphorus(P) sorption on the oxidation resistance of biochar. The results showed that the oxidation resistance of the Mg-impregnated biochar was improved by the formation of MgO on its surface. The soil column experiment indicated that the Mg-impregnated -biochar decreased P loss from leaching by 89.25%. In addition, the available P content of the soil surface layer under Mg-impregnated biochar treatment increased by 3.5-fold relative to that under the control treatment. P sorption also enhanced the oxidation resistance of biochar. The relative contents of CO, CO, and COOH on the surface of P-laden biochar was 20.97% and was lower than those on the surface of biochar without P sorption (33.15%). Oxidation resistance was enhanced by the formation of new MgP crystals, which prevented the oxidation of CC, CC, and CH into CO, CO, and COOH, respectively, by acting as a physical barrier between the biochar surface and oxygen. The results of XRD, SEM and EDS provided evidence for the formation of MgP crystals. Overall, results indicated that the Mg-impregnated biochar can reduce P leaching loss from soil and has enhanced stability.

An effective engineered biochar was investigated by pyrolyzing cow dung for phosphorus (P) adsorption from water solutions and by reusing the biochar as slow-release fertilizer in soil. Response surface methodology (RSM) was employed to optimize the adsorption conditions. Six variables were screened using the Plackett-Burman design. Adsorbent dose, initial P concentration, and pyrolysis temperature were the most important variables. A significant interactive effect was observed between adsorbent dose and initial P concentration. Under the optimized conditions, the adsorption capacity of the engineered biochar reached 345 mg g−1, which was significantly higher than those previously obtained under the same initial P concentrations. The scanning electron microscopy with energy dispersive spectrometry analysis proved the formation of crystals on the surface of the engineered biochar. Results of X-ray diffraction and X-ray photoelectron spectroscopy indicated that P adsorption was controlled by a precipitation mechanism. Amendment of P-laden engineered biochar into the soil planted with lettuce significantly improved soil available P, organic carbon content, soil moisture, and pH. As a result, seed germination, crop growth, crop yields and P concentration of lettuce were promoted. These results suggested that RSM optimization increased the P adsorption capacity of the engineered biochar. Moreover, the P-laden engineered biochar derived from cow dung can be reused as soil amendment to serve as slow-release P fertilizer.

The biochar-induced catalytic degradation of contaminants produced by environmentally persistent free radicals (EPFRs) has attracted considerable attention; however, its mechanism and influential factors are poorly understood. In this study, the catalytic characteristics of rice husk-derived biochars pyrolyzed at different temperatures (300 °C to 700 °C, R-300 to R-700, respectively.) were investigated during soil fumigant 1,3-dichloropropene (1,3-D) degradation. Results showed that the degradation rate of 1,3-D initially decreased from 0.00152 h−1 on R-300 to 0.00073 h−1 on R-500 and subsequently increased from 0.00073 h−1 on R-500 to 0.00305 h−1 on R-700 with increasing biochar pyrolysis temperature. A U-shaped relationship was observed between biochar pyrolysis temperature and 1,3-D degradation rate. Three degradation intermediates were identified based on the National Institute of Standards and Technology database information acquired through headspace GC–MS technologies. The catalytic efficiency of biochar improved with increasing moisture content or degradation temperature. When the biochar moisture content increased from 0% to 80%, the degradation efficiency of cis- and trans-isomers on R-500 increased from 6.27% to 35.45% and from 8.48% to 36.36%. When the degradation temperature increased from 20 °C to 40 °C, the degradation efficiency of cis- and trans-isomers on R-500 increased from 37.50% to 49.80% and from 35.90% to 53.48%. The different effects of 1,3-D degradation rate on different biochars were attributed to the pyrolysis temperature-induced changes in the biochar pore structures, changes in the pH of biochar reaction solutions, and changes in EPFR-induced hydroxyl radicals. These results suggested that the characteristics of biochar render it suitable for the degradation of organic pollutants.

A fluorometric method is described for the determination of ofloxacin (OFL). It is based on the use of the fluorescent intercalator SYBR Green I (SG-I). The OFL-aptamer has G-quadruplex structures and can be recognized by SG-I. It results in strong fluorescence of SG-I. If OFL is present, OFL will bind to its aptamer to form stable complexes. This induces the despiralization of partial dsDNA regions, leads to changes in the structure of the aptamer. Thus, SG-I is released from the OFL-aptamer into solution. Hence, the fluorescence of SG-I drops. Fluorescence decreases linearly in the 1.1 to 200 nM OFL concentration range, and the limit of detection is 0.34 nM. The method shows good selectivity to much interference including analogues, hormones, pesticides. It is also effortless and fast with the times of measurement of40 min. In addition, good recoveries of 91.3-119.0% were found for tap water, river water and artificial urine spiked with OFL with relative standard deviation (RSD) of ≤11.6%. Graphical abstract A sensitive fluorometric method is developed for ofloxacin (OFL) detection in aqueous samples based on the fluorescence intensity change of SYBR Green I (SG-I) with or without OFL.

Emissions of volatile soil fumigant 1,3-dichloropropene (1,3-D) from soil to air are a significant concern in relation to air quality, and cost-effective strategies to reduce such emissions are urgently required by growers to help them comply with increasingly stringent regulations. In this work, application of a rice husk-derived biochar to the surface of a sandy loam soil chamber reduced soil-air emissions of 1,3-D from 42% in a control (no biochar) to 8% due to adsorption onto the biochar. This adsorbed 1,3-D showed a potential for re-volatilization into air and solubilization into the soil-liquid phase. Biochar at the soil surface also reduced soil-gas concentrations in the upper soil; based on the determination of concentration-time values, this may limit 1,3-D-induced nematode control in the upper soil. In batch studies, the mixing of biochar into the soil severely limited nematode control; 1,3-D application rates around four times greater than the maximum permissible limit would be required to give nematode control under such conditions. Therefore, the use of biochar as a surface amendment, while showing an emission reduction benefit, may limit pest control during subsequent fumigations if, as seems probable, it is plowed into the soil.

This paper proposes a colorimetric aptasensor for the detection of testosterone (TES) in environmental water, using TES-specific aptamer (apT5) as a sensing probe, gold nanoparticles (AuNPs) as indicator, and hexadecyltrimethylammonium bromide (CTAB) as inducer, respectively. Based on competition between TES and CTAB for apT5, the aptamer can form an aptamer–TES complex, leaving CTAB free to aggregate AuNPs in the presence of TES. Dispersed and aggregated AuNPs have different absorption wavelengths and the signal of absorption intensity is associated with the concentration of TES, so TES can be detected quantitatively based on the signal absorption intensity. This sensitive aptasensor for TES detection has a wide linear range (R=0.998) from 1.91–800nM and a limit of detection (LOD) of 1.91nM. In addition, this aptasensor has high selectivity over some interferents. The method detects TES in tap water samples with recoveries in the range of 98.9–102.6% (RSD ≤ 7.35%). This biosensor presents a good and potential application to rapidly detect TES in actual environmental water samples.

Spraying pesticides is an essential measure for crop protection in agricultural production process. However, the large organic solvents and surfactants usage of common pesticide formulations have caused concern about environmental pollution. In recent years, unmanned aerial vehicle (UAV) spraying has gained more and more attention because of its ability to reduce the usage of pesticide and replace traditional human-powered spraying equipment. Nevertheless, the potential pollution hazard, spray drift and loss of current pesticide formulations in actual aerial spraying also remain challenging to date. Based on the requirement of appropriative pesticide formulation for UAV spraying, a novel oil-in-water microemulsion of thiamethoxam and acetamiprid without any organic solvents was investigated in this study. Complex emulsifiers were proposed to increase the solubility of pesticides in water, which could avoid the addition of unnecessary organic solvents in microemulsions. The physicochemical properties and application performance of the microemulsions were determined using visual observation, Turbiscan technique, laser particle size, indoor spraying experiments, high-performance liquid chromatography with ultraviolet detection and transmission electron microscopy. The optimal microemulsion with the formulation of 10 % sodium dodecyl sulfate and 10 % fatty alcohol polyoxyethylene ether sulfate consisted of small particles with a mean diameter of 1.9 nm, and exhibited good stability, improved wettability, anti evaporation, and spraying performance with deposition coverage rate of 16.2 %. This study expanded the possibility of the preparation and development of environmentally friendly pesticide formulations applicable for UAV agricultural spraying.

Glutathione S-transferases (GSTs) are a multifunctional protein superfamily that can catalyze the detoxification processes in an organism. In the present study, we determined the structure and function of GSTs in Chinese mitten crab (Eriocheir sinensis) by gene cloning, expression, and enzyme activity in order to investigate the metabolic detoxification of GSTs in the hepatopancreas and muscles under three pesticide (trichlorfon, β-cypermethrin and avermectin) stresses. Multiple sequence alignment analysis showed that all the three Es-GST genes possessed N-terminal, and C-terminal domain as well as G-binding sites, while Es-GST2 and Es-GST3 contained Mu-type GST-specific Mu-loop structures. Phylogenetic tree analysis revealed that the three Es-GSTs belonged to the Mu-type GST of crustaceans. The quantitative real-time PCR revealed that the three Es-GSTS were expressed in 9 tissues of Eriocheir sinensis, with highest expression in hepatopancreas and muscle. The expression of the three Es-GSTS significantly increased in the hepatopancreas and muscle under the three pesticide stresses compared to the control group, and a steady increase in GST activity was observed. The study showed that the three Es-GSTs belong to the Mu-type GST of the crustaceans and might play an important role in the metabolic detoxification in Eriocheir sinensis.

The conversion of waste biomass into biochar is considered as a waste disposal alternative, especially because biochar is a low-cost adsorbent for soil contaminants. However, a risk of desorption of contaminants from biochar may lead to secondary pollution. This study investigated the degradation behavior of soil fumigant, 1,3-dichloropropne (1,3-D), on cow manure-derived biochar (CMB) pyrolyzed at five different temperatures from 300 to 700 °C (termed as C-300 to C-700). Results showed that 1,3-D degradation rate was U-shape related to biochar pyrolysis temperature. Four degradation byproducts (NH2CH2CH2CH3OH, CH3CH2NH2, NH2COCONH2, OHCH2COOH) were identified by headspace GC–MS. When biochar humidity improved from 0 to 50% or incubation temperature increased from 20 to 40 °C, the degradation of cis-1,3-D on C-300 improved 24.26% and 35.48%, respectively. The OH concentrations, detected by the terephthalic acid method, were considerably higher for C-300 than that for C-700. Pyrolysis temperature (300–700 ° C) governed biochar physicochemical properties and further affected 1,3-D degradation mechanisms (pH-controlled substitution or OH-restricted oxidation reaction). All these findings showed that CMB can adsorb and degrade 1,3-D, thereby reduce its desorption risk, indicative of the conversion of cow manure into biochar as an effective waste management practice.

A colorimetric method is presented for the determination of the antibiotic ofloxacin (OFL) in aqueous solution. It is based on the use of an aptamer and gold nanoparticles (AuNPs). In the absence of OFL, the AuNPs are wrapped by the aptamer and maintain dispersed even at the high NaCl concentrations. The solution with colloidally dispersed AuNPs remains red and has an absorption peak at 520 nm. In the presence of OFL, it will bind to the aptamer which is then released from the AuNPs. Hence, AuNPs will aggregate in the salt solution, and color gradually turns to blue, with a new absorption peak at 650 nm. This convenient and specific colorimetric assay for OFL has a linear response in the 20 to 400 nM OFL concentration range and a 3.4 nM detection limit. The method has a large application potential for OFL detection in environmental and biological samples. Graphical abstract Schematic of a sensitive and simple colorimetric aptasensor for ofloxacin (OFL) detection in tap water and synthesic urine. The assay is based on the salt-induced aggregation of gold nanoparticles which results in a color change from red to purple.

A novel and improved protocol was developed to prepare CuInS2/ZnS:Al-sensitized TiO2 (CIS/ZnS:Al–TiO2) nanocomposites for 1,3-dichloropropene (1,3-D) photodegradation. Response surface methodology was employed to model and optimize the operational parameters of this protocol. The CIS/ZnS:Al quantum dot (QDs) content, ZnS:Al coating time, and TGA/TiO2 molar ratio were chosen as independent variables at three levels by using the Box–Behnken design; their combined effects on the 1,3-D degradation efficiency were investigated. The synthesized CIS/ZnS:Al QDs and CIS/ZnS:Al–TiO2 nanocomposites were characterized by their photoluminescence intensity, UV-vis absorption spectra, X-ray diffraction, and transmission electron microscopy. Based on the experimental results, an empirical expression was established and subsequently applied to predict the 1,3-D degradation efficiency with the prepared photocatalysts. The predicted degradation efficiencies matched well with the experimental values (R2, 0.9874). The ANOVA results showed that the significance of the parameters was ZnS:Al coating time > QDs content > TGA/TiO2 molar ratio. The 3D response surface plots indicated that the optimum synthesis parameters were a CIS/ZnS:Al QDs content of 23%, a coating time of 418 min, and a molar ratio of 1.6. The 1,3-D degradation efficiency with the optimized photocatalyst reached 92% under an irradiation time of 5 h. The photodegradation kinetics of 1,3-D was well fitted with a pseudo-first-order kinetic equation. The experimental design and theoretical prediction methods in this work are of great significance in the design and development of high-performance CIS/ZnS:Al–TiO2 nanocomposites.

This paper proposes a fluorescent aptasensor for the detection of carbendazim (CBZ) in aqueous solution using CBZ-specific aptamer as sensing probe, gold nanoparticles (AuNPs) and Rhodamine B (RhoB) as indicator, respectively. In the absence of CBZ, CBZ aptamer could wrap AuNPs and maintained it dispersed in NaCl solution basically. Contrarily, the aptamer could specifically combine with CBZ and form a stable aptamer-CBZ complex, leaving AuNPs exposed to be aggregated by NaCl solution. The dispersed AuNPs could efficiently quench the fluorescence of RhoB, but those aggregated AuNPs have poor capability to impair the fluorescent indicator. Thus, the concentration of CBZ could be detected quantitatively through the distinction of the fluorescence intensity. This convenient fluorescent assay for CBZ had a wide linear range from 2.33 to 800 nM and a 2.33 nM limit of detection (LOD). Furthermore, it had high selectivity over pesticides, antibiotics, metal ions and other disrupting chemicals. As for application, the method could determine CBZ in water samples with recoveries in the range of 96.3–111.2%. This fluorescent aptasensor possessed great potential application for CBZ detection in actual aquatic environment.

Semiconductor quantum dots (QDs) are suitable light absorbers for photocatalysis because of their unique properties. However, QDs generally suffer from poor photochemical stability against air, limiting their applications in photocatalysis. In this study, a stable solar-light-driven QDs-containing photocatalytic film was developed to facilitate photocatalytic degradation of the soil fumigant 1,3-dichloropropene (1,3-D). Highly stable CuInS2/ZnS:Al core/shell QDs (CIS/ZnS:Al QDs) were synthesized by doping Al into the ZnS shell and controlling ZnS:Al shell thickness; the CIS/ZnS:Al QDs were subsequently combined with TiO2 to form a CIS/ZnS:Al-TiO2 photocatalyst. The optimized ZnS:Al shell thickness for 1,3-D photodegradation was approximately 1.3 nm, which guaranteed and balanced the good photocatalytic activity and stability of the CIS/ZnS:Al-TiO2 photocatalyst. The photodegradation efficiency of 1,3-D can be maintained up to more than 80% after five cycles during recycling experiment. When CIS/ZnS:Al-TiO2 was deposited as photocatalytic film on a flexible polyethylene terephthalate substrate, over 99% of cis-1,3-D and 98% of trans-1,3-D were depleted as they passed through the film during 15 h of irradiation under natural solar light. This study demonstrated that the stable CIS/ZnS:Al-TiO2 photocatalyst both in powder and film form is a promising agent for photodegradation and emission reduction of soil fumigants.

Biochar has been explored as a cost-effective sorbent of contaminants, such as soil fumigant. However, contaminant-loaded biochar probably becomes a source of secondary air pollution. In this study, biochars developed from cow manure and rice husk at 300°C or 700°C were used to investigate the catalytic degradation of the soil fumigant 1,3-dichloropropene (1,3-D) in aqueous biochar slurry. Results showed that the adsorption of 1,3-D on the biochars was influenced by Langmuir surface monolayer adsorption. The maximum adsorption capacity of cow manure was greater than that of rice husk at the same pyrolysis temperature. Batch experiments revealed that 1,3-D degradation was improved in aqueous biochar slurry. The most rapid 1,3-D degradation occurred on cow manure-derived biochar produced at 300°C (C-300), with t1/2=3.47days. The degradation efficiency of 1,3-D on C-300 was 95.52%. Environmentally persistent free radicals (EPFRs) in biochars were detected via electron paramagnetic resonance (EPR) techniques. Dissolved organic matter (DOM) and hydroxyl radical (·OH) in biochars were detected by using a fluorescence spectrophotometer coupled with a terephthalic acid trapping method. The improvement of 1,3-D degradation efficiency may be attributed to EPFRs and DOM in aqueous biochar slurry. Our results may pose implications in the development of effective reduction strategies for soil fumigant emission with biochar.

The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperature has great influence on the adsorption of H2S. At the different pyrolysis temperature, the H2S removal efficiency of rice hull-derived biochar was different. The adsorption capacities of biochar were 2.09 mg·g(-1), 2.65 mg·g(-1), 16.30 mg·g(-1), 20.80 mg·g(-1), and 382.70 mg·g(-1), which their pyrolysis temperatures were 100 °C, 200 °C, 300 °C, 400 °C and 500 °C respectively. Based on the Yoon-Nelson model, it analyzed the mass transfer mechanism of hydrogen sulfide adsorption by biochar.The paper focuses on the biochar derived from rice hull-removed hydrogen sulfide (H2S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperatures have great influence on the adsorption of H2S. At the different pyrolysis temperatures, the H2S removal efficiency of rice hull-derived biohar was different. The adsorption capacities of biochar were 2.09, 2.65, 16.30, 20.80, and 382.70 mg·g(-1), and their pyrolysis temperatures were 100, 200, 300, 400, and 500 °C, respectively. Based on the Yoon-Nelson model, the mass transfer mechanism of hydrogen sulfide adsorption by biochar was analyzed.

The disposal of a large amount of biogas residue from anaerobically digested food waste is a burden for biogas production. The aim of this work was to investigate biogas residue as a potential feedstock, by preparing biochar at a broad pyrolysis temperature range of 400&ndash, 900 &deg, C. The properties required for phosphorus recovery and soil amendment application were evaluated. Biogas residue collected from an urban food waste treatment plant was pyrolyzed in a laboratory scale reactor. It was found that by increasing the pyrolysis temperature, the yield of biochar decreased and the pH, electrical conductivity and Brunauer&ndash, Emmett&ndash, Teller surface area increased. The amount of phosphorus adsorbed onto the biogas residue-derived biochar (BRB) at 900 &deg, C was larger than that of other kinds of biochar. The kinetics of phosphorus (P) adsorption on BRB could be described by the pseudo-second-order equation. The pot experiments showed that the resulting biochar is beneficial for the growth of cabbage. Overall, turning solid residue from the anaerobic digestion of food waste for biogas production into biochar shows good prospects as a means of solving the disposal problem, while creating new markets for food waste biogas residue.

Single-layer metallic rings are the effective structure cell which are widely used to design single-band and multiband perfect metamaterial absorbers owning to their electromagnetic resonance. However, the absorbers based on the single-layer metallic rings have a common shortcoming, that is the narrow absorption bandwidth. To overcome the limitations, here we proposed a single-layer, flexible and broadband terahertz metamaterial absorber, which consists of four sub-cells with multiple metal rings and a metal ground plane separated by a dielectric layer. By enhancing the coupling response between adjacent metallic rings and merging the adjacent resonant peaks of multi-resonators, we experimentally observed broadband characteristics at the terahertz band. The average absorption of 88% from 0.63 to 1.34 THz and the relative absorption bandwidth of 95% at the incident angle of 15o for TE polarization. Correspondingly, for TM polarization the absorption of more than 80% from 0.61 to 1.1 THz with the relative absorption bandwidth of 80% were also observed. The results went far beyond the previous single-layer absorbers based on metal rings and were much better than the fractal-cross structure reported recently [Kenney et al., ACS Photonics 4, 2604 (2017)]. We had reason to believe that the presented terahertz metamaterial absorber with broad absorption bandwidth and simple structure can find important applications in communication, stealth, energy harvesting systems and so on.

During soil fumigation, it is ideal to mitigate soil fumigant emissions, ensure pest control efficacy, and speed up the recovery of the soil microorganism population established postapplication. However, no current fumigant emission reduction strategy can meet all these requirements. In the present study, replicated soil columns were used to study the effect of biochar derived from rice husk (BR) and green waste (BG) applied to the soil surface on 1,3-dichloropropene (1,3-D) and chloropicrin (CP) emissions and soil gas distribution, and on microorganism population re-establishment. Relative to fumigated bare soil (no emission reduction strategy), high-density polyethylene (HDPE), and ammonium thiosulfate (ATS) treatments, BR gave dramatic emission reductions for both fumigants with no obvious emission peak, whereas BG was very effective only for 1,3-D. With BR application, the concentration of fumigant in the soil gas was higher than in the bare soil and ATS treatment. After the soil column experiment, mixing the BR with the fumigated soil resulted in higher soil respiration rates than were observed for HDPE and ATS treatments. Therefore, biochar amendment to the soil surface may be an effective strategy for fumigant emission reduction and the recovery of soil microorganism populations established postapplication.

Although the deuterium and helium have almost the same mass, a Penning Optical Gas Analyzer (POGA) system on the basis of the spectroscopic method and Penning discharging has been designed on EAST, since 2014. The POGA system was developed successfully in 2015, it was the first time that EAST could detect helium partial pressure in deuterium plasma (wall conditioning and plasma operation scenario). With dedicated calibration and proper adjustment of the parameters, the minimum concentration of helium in deuterium gas can be measured as about 0.5% instead of 1% on the other tokamak devices. Moreover, the He and D2 partial pressures are measured simultaneously. At present, the measurable range of deuterium partial pressure is 1 × 10−7 mbar to 1 × 10−5 mbar, meanwhile the range of helium is 1 × 10−8 mbar to 1 × 10−5 mbar. The measurable range can be modified by means of the adjustment of POGA system's parameters. It is possible to detect the interesting part of the gas with a time resolution of less than 5 ms (the 200 ms because of conductance of transfer pipe at present). The POGA system was routinely employed to wall conditioning and helium enrichment investigation in 2015. Last but not the least, the low temperature plasma of POGA is generated by normal penning gauge Pfeiffer IKR gauge instead of Alcatel CF2P, which has been suspended for a few years and was used for almost all the POGA systems in the world.