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Oil adsorption sponges have attracted great attention in the field of oil-water mixture treatment, due to their low cost, high porosity, flexible design, and three dimensional skeleton structures. However, the hydrophilic-oleophilic of commercial sponge limits its application for oil-water treatment. To improve the adsorption performance and simplify the oil recovery process, various modification methods have been studied recently. Herein, we discuss the fabrication of hydrophobic/oleophilic sponges and summarize the recently reported modify materials onto sponges. Furthermore, some additional material properties are also presented, which make sponges superior capacity for addressing oil spills under extreme conditions. In addition, some oil collecting devices based on sponges, which are used to facilitate the oil collecting processes, are also shown. Meanwhile, the outlooks and challenges are also offered for future applications of sponges in the remediation of oil spill.

Heavy metal contamination of soil has become a serious global issue because of their persistence in the environment and the non-biodegradable nature leading to their accumulation to toxic levels. In order to achieve early warning and prevent soil quality from deteriorating, it is necessary to select suitable indices to diagnose heavy metal pollution. Microbiological indices for monitoring soil pollution by heavy metals are gaining attention. However, the related researches are scattered, and critical review is imperative. This review is mainly to provide readers with an in-depth understanding of the merits and limitations of microbiological indices for heavy metals contaminated and remediated soils. Microbiological indicators include microbial abundance, community diversity and structure, functional activity. The changes of different microbiological indices and the mechanism of microbial response to heavy metal stress in soils are comprehensively summarized. Furthermore, research gaps and future directions of the microbial ecotoxicological diagnosis of soil contamination by heavy metals are also proposed and discussed.

Chitosan-stabilized FeS magnetic (MC-FeS) composites were successfully prepared to address the easily oxidization of FeS and enhance Cr(VI) removal from water. Results showed that the MC-FeS composites enhanced the Cr(VI) removal capacity as compared to bare FeS. Further investigation using X-ray photoelectron spectroscopy showed that FeOOH, S8, Cr2O3, Cr2S3, and a Fe(III)-Cr(III) complex were apparently introduced by Cr(VI), Fe(II), and S(−II), respectively. The sorption kinetics could be interpreted using a pseudo-second-order kinetic model, whereas the isotherms were simulated using the Redlich‒Peterson isotherm model indicating Cr(VI) removal by MC-FeS composites was a hybrid chemical reaction‒sorption process. In addition, the MC-FeS composite presented high stability against aging and performed well in a long-term reaction system and typical natural water environment. The effective performance of MC-FeS composites shows their great potential in wastewater remediation contaminated by heavy metals.

In this study, magnetic graphene oxide modified zeolite (Cu-Z-GO-M) composites with two different ratios of GO to zeolite (named Cu-Z-GO-M 1:2 and Cu-Z-GO-M 1:1) were synthesized by solid-state dispersion (SSD) method. The properties of zeolite-based composites were characterized by SEM, XRD, FTIR, XPS, and magnetization curves. In order to understand the pollutant removal performance of the as-prepared composites, methylene blue (MB) was used as the target pollutant in adsorption experiments. The removal efficiency of MB onto Cu-Z-GO-M composite was enhanced obviously with pH > 9. The adsorption capacities of MB onto Cu-Z-GO-M 1:1 were 82.147, 89.315, 97.346 mg/g at 298, 308, and 318 K, respectively. The removal ability of MB increased with the increase of GO content in modified composites. The adsorption behavior can be well described using a pseudo-second-order kinetic and Freundlich isotherm model. The thermodynamic analysis indicated the MB adsorption by Cu-Z-GO-M was a spontaneous and endothermic reaction. The results showed that the prepared Cu-Z-GO-M composite could be a promising adsorbent with good adsorption capacity and reusability for MB removal from wastewater.

Oil spills result in severe environmental pollution and inflict serious ecological damage, which makes the development of facile, low-cost, high-capacity, and sustainable oil absorbents to be a task of high practical significance. In this study, a kaolin-modified hydrophobic melamine sponge (K-MS) was prepared via simple soaking method, which can be applied to clean up oil spills and organic solvents leaks. The properties of the K-MS were characterized by a range of instrumental techniques. The addition of fluorizated kaolin not only endowed commercially available melamine sponge hydrophobic properties and enhanced its adsorption capacity to various oils and organic solvents. The K-MS exhibited the high adsorption capacity (up to 87–194 g/g) and excellent recyclability (>90%). The equilibrium adsorption time was fast within 1 s for diesel. Moreover, the as-prepared sponge adsorption performance was examined in harsh environment, which has remarkable chemical stability and compressive properties. Thus, this study presents a low-cost facile strategy to produce promising absorbent for large-scale oil and organic solvents cleanups and recovery. Furthermore, this approach can be extended to a series of clay minerals in rich source, thus could open up new prospects for design hydrophobic materials to address oil pollution.

In this work, the immobilization of silver nanoparticles on lignosulfonate functionalized kaolin composite (LS-kaolin-Ag) was fabricated by a facile reduction method without additional reductant and stabilizer. Transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy (FTIR) were used to confirm the successful preparation of LS-kaolin-Ag composite. The catalytic reduction tests on both cationic dye rhodamine B and anionic dye Congo red indicated the high catalytic activities of this as-prepared LS-kaolin-Ag composite. Meanwhile, this catalyst showed good recyclability for dye decolorization with just a little decrease of conversion percent in five successive reactions. These results suggest that LS-kaolin-Ag composite as an efficient and cost-effective catalyst shows great application potential for the decolorization of various organic dyes.

To explore the approach for further enhancing the dye removal performance of polydopamine (PDA) coated materials, a novel composite of PDA-kaolin with reduced graphene oxide hybridization (PDA-rGO-kaolin) was synthesized and selected as a model adsorbent for methylene blue (MB) removal. The BET characteristic analysis showed that the introduction of rGO significantly increased the surface area of PDA-kaolin by 3.1 times. A series of comparative experiments on PDA-kaolin and PDA-rGO-kaolin towards MB removal in various conditions were carried out. Adsorption experiment indicated that PDA-rGO-kaolin was more satisfactory for MB removal. Kinetic analysis showed that the adsorption followed a pseudo-second-order kinetic model. The adsorption behavior could be better described by Langmuir isotherm model. Compared with PDA-kaolin, PDA-rGO-kaolin showed higher maximum adsorption capacity towards MB (39.663 mg/g). Furthermore, the adsorption of MB molecules on adsorbents was spontaneous and endothermic process according to thermodynamic experiment. Moreover, PDA-rGO-kaolin showed a good regeneration performance for MB removal. These results show that the introduction of graphene is a feasible and efficient method to improve the adsorption performance of PDA coated kaolin composite.

This study presents a one-step synthetic approach for magnetic biochar (MBC) photo-degradation of diethyl phthalate (DEP). The results showed that MBC exhibited better catalytic property for DEP degradation than BC, and its catalytic performance was influenced by the amount of Fe doping. Electron paramagnetic resonance (EPR), quenching experiments, and chemical probe studies confirmed the presence of persistent free radicals (PFRs), hydroxyl radicals (·OH), and superoxide anion radical (·O2-) in both of BC and MBC. Solar light promoted the formation of PFRs in BC system, which transferred electrons to oxygen to form ·O2-, thus yielding ·OH. On the other hand, electron transfer occurred between PFRs and Fe3+ for MBC, Fe2+ played an important role in activation of O2 and ·O2- production. Subsequently, photo-Fenton reaction was primarily responsible for ·OH formation. This work compared the different generation pathways for ROS between BC and MBC and provides new insight into the possible mediatory roles of BC in O2 activation under solar light by transition metals.

As an aliphatic amino acid, cysteine (CYS) is diffuse in the living cells of plants and animals. However, little is known of its role in the reactivity of nano-sized zero-valent iron (NZVI) in the degradation of pollutants. This study shows that the introduction of CYS to the NZVI system can help improve the efficiency of reduction, with 30% more efficient degradation and a reaction rate constant nine times higher when nitrobenzene (NB) is used as probe compound. The rates of degradation of NB were positively correlated with the range of concentrations of CYS from 0 to 10 mmol/L. The introduction of CYS increased the maximum concentration of Fe(III) by 12 times and that of Fe(II) by four times in this system. A comparison of systems featuring only CYS or Fe(II) showed that the direct reduction of NB was not the main factor influencing its CYS-stimulated removal. The reduction in the concentration of CYS was accompanied by the generation of cystine (CY, the oxidized form of cysteine), and both eventually became stable. The introduction of CY also enhanced NB degradation due to NZVI, accompanied by the regeneration of CYS. This supports the claim that CYS can accelerate electron transfer from NZVI to NB, thus enhancing the efficiency of degradation of NB.

Quinclorac (3,7-dichloroquinoline-8-carboxylic acid, QNC) is a highly selective auxin herbicide that is typically applied to paddy rice fields. Its residue is a serious problem in crop rotations. In this study, Oryza sativa L. seedlings was used as a model plant to explore its biochemical response to abiotic stress caused by QNC and nZVI coexposure, as well as the interactions between QNC and nZVI treatments. Exposure to 5 and 10 mg/L QNC reduced the fresh biomass by 26.6% and 33.9%, respectively, compared to the control. The presence of 50 and 250 mg/L nZVI alleviated the QNC toxicity, but the nZVI toxicity was aggravated by the coexist of QNC. Root length was enhanced upon exposure to low or medium doses of both QNC and nZVI, whereas root length was inhibited under high-dose coexposure. Both nZVI and QNC, either alone or in combination, significantly inhibited the biosynthesis of chlorophyll, and the inhibition rate increased with elevated nZVI and QNC concentration. It was indicated that nZVI or QNC can affect the plant photosynthesis, and there was a significant interaction between the two treatments. Effects of QNC on the antioxidant response of Oryza sativa L. differed in the shoots and roots; generally, the introduction of 50 and 250 mg/L nZVI alleviated the oxidative stress (POD in shoots, SOD and MDA in roots) induced by QNC. However, 750 mg/kg nZVI seriously damaged Oryza sativa L. seedlings, which likely resulted from active iron deficiency. QNC could be removed from the culture solution by nZVI; as a result, nZVI suppressed QNC uptake by 20%–30%.

Carbon nanotubes can interact with proteins or enzymes upon penetration into cell membranes of living organisms that may affect the protein-protein interactions in vivo. Here, three structural models composed of four-chain esterase from Hungatella hathewayi with and without pristine or carboxylated single-walled carbon nanotube (SWCNT) are constructed to investigate the changes in protein-protein interactions and SWCNT orientations by molecular dynamics simulations. The results show that the protein-protein interact very tightly to protect them from the separation by the carboxylated or pristine SWCNTs, as shown by the calculations of binding affinity and the distances between the centers of mass of different protein chains. Both pristine and carboxylated SWCNTs cause structural changes in the esterase. In addition, functionalization (e.g., carboxylation) can regulate the SWCNT orientation when positioned near the esterase.

In this work, a facile and cost-effective method was reported to fabricate a novel, robust, and superhydrophobic kaolinite modified graphene oxide-melamine sponge (K-GOMS). The GO sheets were used to increase the roughness of the sponge smooth surface. The hydrophobic kaolinite adhered on GO sheets significantly enhanced the superhydrophobicity of the K-GOMS surface with a water contact angle of 152.3°. Several organic solvents and oils were selected to test the adsorption performance of the obtained adsorbents. The results revealed that the superhydrophobic K-GOMS exhibited not only superior adsorption capacity for various organic solvents and oils, from 60 to 113 times of its own weight, but also outstanding recyclability with an adsorption capacity retention higher than 94% after 30 cycles of diesel oil adsorption, and excellent environmental tolerance in wide range of pH values and temperatures. Therefore, this study provides an effective way for constructing facile, low-cost, and large-scale production of superhydrophobic adsorbents for oil-water separation.

An observer-based dc voltage droop and current feed-forward control for a dc microgrid has been proposed in this paper. With the proposed control scheme, dynamic response of dc voltage control can be improved effectively through using an observer. Moreover, the feedback current for dc voltage droop and the feed-forward current are both obtained from the observer without additional current measurement. Furthermore, system stability analysis shows that, the propose method has enhanced robustness and stability when compared to the traditional droop method under variations of system parameters, such as loads, cable impedances, and droop control gains. In a droop controlled dc microgrid, there exists a trade-off between the load demand sharing accuracy (which needs a high droop gain) and stability (which limits the droop gain). With the above mentioned advantages, the proposed method can effectively address this trade-off in such a system. The effectiveness of the proposed method is verified by experiments in a laboratory dc microgrid with two boost dc–dc converters based distributed generations and a buck type constant power dc load.

Toxicity effects of silver nanoparticles (AgNPs) on the freshwater bivalve Corbicula fluminea (C. fluminea) were investigated through experiments. In this study, C. fluminea promoted the sedimentation of AgNPs and affected the fate and transformation of AgNPs. A series of biomarkers of C. fluminea in vivo were evaluated after 14 days exposure to various doses (0–2 mg L−1) of polyvinyl pyrrolidone (PVP) coated AgNPs. The levels of antioxidants increased obviously in 2 mg L−1 AgNPs treatments to protect C. fluminea from oxidative damage. Glutathione peroxidase (GPx) and glutathione (GSH) played important roles in tissues detoxification in 0.1 and 0.5 mg L−1 exposure, respectively. The biological behaviors (feeding rate, ammonia excretion rate) were inhibited at 0.1 mg L−1, inducted at 0.5 mg L−1, and inhibited again at 2 mg L-1 AgNPs, which indicated that AgNPs influenced the physiological metabolism of C. fluminea. Ag contents in tissue and shell of C. fluminea were much higher than blank groups. In addition, in vivo tissues were more sensitive to low AgNPs concentration compared with shells, indicating that C. fluminea could be used as a good indicator for AgNPs freshwater pollution. No Ag was detected in feces probably implying that nanoparticles had long gut retention time in C. fluminea. Overall, this study reveals the interactions between AgNPs and C. fluminea and provides important implications about the fate and toxicity of AgNPs in natural aquatic environment.

In this study, graphene oxide modified kaolin (GO-kaolin) composites (named 2% GK, 5% GK, and 10% GK) were synthesized by a facile method. Characterization results indicated the successful modification of GO on kaolin surface. To understand the dye removal performance of kaolin with GO modification, batch adsorption experiments were carried out using methylene blue (MB) as a model dye pollutant in various experimental conditions The adsorption results showed that the increase of GO content in modified kaolin composite could effectively enhance the removal of MB from aqueous solution in each experiment condition, which was attributed to the increase of special surface area and active adsorption sites. Kinetic analysis of MB adsorption by GO-kaolin samples was shown a better fitting to pseudo-second-order kinetic models. The adsorption isotherm data were better fitted to Langmuir isotherm models. The values of thermodynamics constants suggested that the adsorption reaction was endothermic in nature. Furthermore, adsorption process of MB on kaolin was changed after the introduction of GO. An excellent regeneration performance of 10% GK was observed via the regeneration experiment. The results show that kaolin modified with suitable GO content is a high-efficiency and reusable adsorbent in the removal of MB from wastewater.

In this work, P. chrysogenum strain F1-ferrihydrite composites (PFC) were applied to the bioremediation of polluted mimic wastewater with high concentration (50–500 mg/L) of arsenic. An interesting phenomenon was discovered that the PFC was formed in situ in the process of removal of As(III), which can greatly improve their practical application in separation and reutilization. The results showed that optimum removal efficiency achieved 81.23% for As(III) at an initial concentration of 100 mg/L that also could be up to 75.00% at 200 mg/L with composite sorbent PFC. According to the adsorption isotherms and kinetics experiments, the adsorption reaction included both physical adsorption and chemical adsorption. The formation of composite PFC significantly promoted the sorption of As(III) ion between biomass and ferrihydrite from aqueous. The adsorption rates and capacities for arsenic were both enhanced markedly than biomass and ferrihydrite individually as well. Adsorption-desorption experiment indicated PFC maintained to a dominant with 74.47% of removal efficiency over 3 cycles. This research demonstrated that PFC has great potential in removing high concentration of As(III) from wastewater.

The Mg/Al layered double hydroxide (Mg/Al-LDH) intercalated with the [Formula: see text] (MoS4-LDH) impregnated into poly(acrylamide-co-sodium acrylate) (PP) was synthesized as layered double hydroxides-PP (LDHS-PP), whose characterization, adsorption properties and mechanisms were investigated. The maximum adsorption capacity (qm) for Cd(II) was ∼2789.58 mg/g by 1% LDHS-PP, while it was ∼1893.09 mg/g by PP, which indicated that the MoS4-LDH greatly improved the Cd(II) uptake for PP in aqueous solution. In strongly acidic conditions (∼pH 3.0), there was still a good removal efficiency of about 45.65% by the 1% LDHS-PP, while that of PP was almost zero. At pH 5.0 the removal efficiency increased to 85.17% by the 1% LDHS-PP. The sorption kinetics for the 1% LDHS-PP was described well by a pseudo-second-order kinetic model. X-ray photoelectron spectrometry (XPS) and elemental distribution maps further confirmed the presence of MoS4-LDH in the PP and most of the Cd(II) chemisorption based on the Cd-S bonding. Due to its high removal efficiency and acid resistance, LDHS-PP is a promising in-situ fixation agent for the remediation of agricultural soil polluted with Cd(II) at low pH.

Potential transformations of silver nanoparticles (AgNPs) upon interaction with naturally ubiquitous organic ligands in aquatic environments influence their transport, persistence, bioavailability, and subsequent toxicity to organisms. In this study, differential behaviors of AgNPs and silver ions (Ag+) towards cysteine (Cys), an amino acid representative of thiol ligands that easily coordinate to Ag+ and graft to nanoparticle surfaces, were investigated in the aspects of bioremediation and their toxicity to Phanerochaete chrysosporium. Total Ag removal, 2,4-dichlorophenol (2,4-DCP) degradation, extracellular protein secretion, and cellular viability were enhanced to some extent after supplement of various concentrations of cysteine under stress of AgNPs and Ag+. However, an obvious decrease in total Ag uptake was observed after 5–50 μM cysteine addition in the groups treated with 10 μM AgNPs and 1 μM Ag+, especially at a Cys:Ag molar ratio of 5. More stabilization in uptake pattern at this ratio was detected under Ag+ exposure than that under AgNP exposure. Furthermore, in the absence of cysteine, all Ag+ treatments stimulated the generation of reactive oxygen species (ROS) more significantly than high-dose AgNPs did. However, cysteine supply under AgNP/Ag+ stress aggravated ROS levels, albeit alleviated at 100 μM Ag+, indicating that the toxicity profiles of AgNPs and Ag+ to P. chrysosporium could be exacerbated or marginally mitigated by cysteine. The results obtained were possibly associated with the lability and bioavailability of AgNP/Ag+-cysteine complexes.

Three-dimensional graphene based materials (3D GBMs) as emerging materials have been widely used in various fields. This mini-review selectively highlights the recent research progress in the application of 3D GBMs in organic dyes removal. In particularly, the application potential, catalytic performance, and degradation mechanisms of the 3D GBMs are summarized in this mini-review. The factors affecting the degradation capacity of 3D GBMs are discussed briefly. Furthermore, the possible ongoing researches on 3D GBMs are also put forward. We deem that this mini-review will provide a valuable insight into the design and application of 3D GBMs in environmental field.

In this study, graphene wrapped Fe-doped TiO2 (G-TiO2-Fe) spheres were prepared through a simple hydrothermal process. The structural, optical and photocatalytic properties of synthesized composite were characterized by field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), Raman Microprobe (Raman), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance spectrophotometer (DRS). The G-TiO2-Fe composite showed a significant red-shift in light response edge as compared with TiO2. Meanwhile, the band gap exhibited an obvious decline from 3.24 to 2.99 eV. The photocatalytic capacity of G-TiO2-Fe was further evaluated by methylene blue (MB) degradation experiments, and the results indicated that the optimized G-TiO2-Fe exhibited a remarkable increase in photocatalytic activity. The superior photocatalytic performance of the novel material could be ascribed to the synthetic effects of doped Fe and wrapped graphene shells. The unique geometrical configuration and constructive component which modified the TiO2 electronic structure will largely improve the electron transporting efficiency and restrain the electron-hole recombination.

This study investigated the influence of silver ions (Ag + ) on the cytotoxicity of silver nanoparticles (AgNPs) in Phanerochaete chrysosporium and noted the degree of extracellular secretions in response to the toxicant's stress. Oxalate production was elicited with moderate concentrations of 2,4-dichlorophenol (2,4-DCP) and AgNPs reaching a plateau at 10 mg/L and 10 μM, respectively. Increased oxalate accumulation was accompanied by higher activities of manganese peroxidase (MnP) and lignin peroxidase (LiP). However, the secretion of oxalate, MnP and LiP was significantly inhibited owing to Ag + incorporation into AgNP solution. Production of extracellular polymeric substances (EPS) significantly elevated with an increase in 2,4-DCP concentrations; however, after 24 h of exposure to 100 mg/L 2,4-DCP, an obvious decrease in EPS occurred, indicating that part of EPS could be consumed as carbon and energy sources to ameliorate biological tolerance to toxic stress. Furthermore, AgNP-induced “particle-specific” cytotoxicity was substantially enhanced with additional Ag + as evidenced by its significant negative impact on cellular growth, plasma membrane integrity, and morphological preservation compared with AgNPs at equal Ag concentration.

Although humic acid (HA) plays an important role in the fate and transport of nanoparticles in subsurface environments, the roles of specific fractions of HA in the transport of nanoparticles are still not well understood. In this study, quantum dots (QDs) with carboxyl and amino modifications (QD–COOH and QD–NH2) were used as typical nanoparticles to understand the effects of molecular weight (MW) fractionated humic acid (Mf-HA) on the transport and retention behaviour of nanoparticles. Transport experiments on QDs were performed both in the absence and presence of pristine- and Mf-HA in both NaCl and CaCl2 solutions at pH 7.0. The Mf-HA had distinct effects on the transport and retention behavior of QDs, which were highly dependent on the MW of the Mf-HA. In addition, the surface coating of the QDs and cation types also showed significant effects on the transport behavior of QDs. In NaCl solution, the transport of QD–NH2 was dramatically enhanced in the presence of pristine- and Mf-HA, and the high MW Mf-HA (>100 kDa and 30–100 kDa) could enhance the mobility of the QDs more significantly than the low MW Mf-HA (10–30 kDa, 3–10 kDa, and

The extensive use of neonicotinoid pesticides in the past two decades caused serious impacts on many kinds of living beings. Therefore, it has been strongly suggested to detoxify and eliminate neonicotinoids’ residual levels in environment. Here, the degradation and detoxification of thiamethoxam (THX) by white-rot fungus Phanerochaete chrysosporium was conducted. Results shown that P. chrysosporium can tolerate THX and degraded 49% of THX after incubation for 15 days, and then 98% for 25 days at the initial concentration of 10 mg/L, which indicates the excellent degradation ability of this fungus to THX. Based on the by-products identified, THX underwent dechlorination, nitrate reduction, and C–N cleavage between the 2-chlorothiazole ring and oxadiazine. (Z)-N-(3-methyl-1,3,5-oxadiazinan-4-ylidene)nitramide and 3-methyl-1,3,5-oxadiazinan-4-imine were identified as the main metabolites. The impacts of THX and its corresponding degradation intermediates on the growth of E. coil and Microcystis aeruginosa as well as the germination of rape and cabbage demonstrated that P. chrysosporium effectively degrades THX into metabolites and reduces its biotoxicity. The present work demonstrates that P. chrysosporium can be effectively used for degradation and detoxification of THX.

Being that the influence of organic ligands on contaminant removal by nanoscale zero valent iron (nZVI) has been explored in quite a few studies, there is little information on reaction mechanisms of the ZVI-ligand system under different aeration conditions. The degradation of nitrobenzene (NB) by nZVI-oxalic acids (OA) was investigated under N2, O2 and without aeration conditions. From the findings, it was evident that OA dramatically improved NB degradation by nZVI with all of the aeration conditions. Approximately 100% of NB was degraded by nZVI-OA+N2 system after 60 min of reaction, followed in effectiveness by nZVI-OA+ without aeration (95%) as well as nZVI-OA+O2 (85%). Operation parameters including OA concentration and pH had significant effect on the removal of NB in the nZVI-OA system. 3 mM OA concentration and pH 3.0 were found to be favourable. The Fe2+, total dissolved iron concentrations, pH and ORP values in the nZVI-OA systems had also been monitored. Intermediates and trapping experiments showed that reduction played a fundamental role in the NB degradation by nZVI-OA under N2 or without aeration conditions. The formation of Fe(OA)0 and Fe(OA)22− complexes had lower standard ORP, which could improve the strength of reductant in the systems, and thus resulting in an increased degradation efficiency of NB by nZVI-OA+N2. Under O2 aeration condition, the NB degradation process could be regarded as an oxidation. In the meantime, OA promoted the production of reactive oxidants species by speeding up the oxidation rates of Fe2+ by O2 and H2O2. Summarily, the improved reactivity of nZVI was largely as a result of the strong complexation ability of OA.

The growing potential of quantum dots (QDs) in biomedical applications has raised considerable concerns regarding their toxicological impact. Consequently, there has been a need to understand the underlying toxicity mechanism of QDs. In this work, we comprehensively investigated the bioaccumulation and toxicity of three CdSe/ZnS QDs (COOH CdSe/ZnS 525, NH2 CdSe/ZnS 525, and NH2 CdSe/ZnS 625) in Phanerochaete chrysosporium (P. chrysosporium) using confocal laser scanning microscopy, reactive oxygen species (ROS) measurements, and cell viability assays. Confocal laser scanning microscopy analytical results indicated that all the CdSe/ZnS QDs, with the concentration ranging from 10 to 80nM, could accumulate largely in the hyphae and induce the generation of ROS, showing a direct toxicity to P. chrysosporium. And the bioaccumulation and toxicity of CdSe/ZnS QDs presented dose-dependent and time-dependent effects on P. chrysosporium. Furthermore, the CdSe/ZnS QDs-induced cytotoxicity was also related to their physicochemical properties, including particle size and surface charges: NH2 CdSe/ZnS 525 with small size was more cytotoxic as compared to NH2 CdSe/ZnS 625 with large size, and the smaller negative charged NH2 CdSe/ZnS 525 resulted in greater cytotoxicity than the larger negative charged COOH CdSe/ZnS 525. The obtained results provide valuable information for exploring and understanding of toxicity mechanism of QDs in living cells.

Red mud and compost are two inexpensive and effective materials available for the in situ treatment of soil contaminated with heavy metals. In order to investigate the specific process involved, a detailed analysis of the synergistic effects of combined red mud and compost was carried out. The efficiency of three different treatment systems, namely compost (C), red mud (R), and a mixture of compost and red mud (R + C), on the movability, ecological risk, and biological effective Cu, Zn, Cd, and Pb over time of incubation in agricultural soil was evaluated. Results showed that the pH, water extractable organic carbon (WEOC) and total organic carbon (TOC) showed significant changes after addition of these amendment materials to the target soil. The combination of red mud and compost mixture as amendment material (R + C) resulted in the largest reduction in efficiency of the available heavy metals. In addition, the microbial biomass in the treated soil increased after addition of the amendment materials, highest increase was observed with R + C. The results indicate that these amendment materials, especially R + C could lower the ecological risk of heavy metals in soil.

In the present study, Ag nanoparticles loaded on polydopamine coated magnetic biochar (MC-PDA-Ag) catalyst was prepared by in-situ reduction approach. The morphology, composition, and structure of MC-PDA-Ag were characterized by the transmission electron microscopy (TEM), the scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). Catalytic reduction tests confirmed that MC-PDA-Ag catalyst showed excellent catalytic performance on the model dyes (MB, RhB, and MO) in the presence of NaBH4. The reduction efficiency of MB exceeded 90% by MC-PDA-Ag even under different initial pH (3–11) and different NaNO3 concentrations (0–0.5 M) within 5 min, indicating that the MC-PDA-Ag catalyst has potential strong universal adaptability in dye wastewater treatment. Furthermore, no significant decrease in catalytic ability was observed after 5 recycles, and the catalyst could be separated by an external magnet, indicating that this as-prepared catalyst exhibited high reusability and easy separability. These results suggest that MC-PDA-Ag composite catalyst can be used as an efficient catalyst for the reduction of organic dyes, and shows great potential application in wastewater treatment.

The traditional high-salinity organic wastewater treatment process is cumbersome and costly, and involves an independent process for removing pollutants and salinity. A flow-through coupled system of electro-Fenton and electrosorption processes was designed in this work. The simultaneous purification and desalination of high concentration wastewater were effectively achieved through the cooperation of various electrochemical reactions, which avoids the complex processes of desalination and dilution in advance when treating high-salinity organic wastewater, and the removal performance was improved. The influence of key parameters, including voltage, initial pH, plate spacing, H2O2 concentration, and flow rate, were systematically investigated. The findings show that actual wastewater passing through the coupled system promptly turns to clean water with significantly decreased COD, TN, and salinity, with removal efficiencies reaching 96.5%, 98.2%, and 46.2%, respectively, under the optimal conditions (voltage intensity 1.5 V, initial pH 4, plate spacing 1 cm, flow rate 40 mL/min, H2O2 concentration 50 mM). The reaction mechanism study suggested that both the Fenton reaction, direct electron transfer, and indirect oxidation by active chlorine contributed to the removal of COD and TN, while the decrease in salinity mainly occurred in the process of electrosorption. Moreover, the regeneration of the ACF and the operational stability of the coupled system were good after five cycles. The economic analysis indicated that the cost of the flow-through coupled system was only $1.18/m3, which has important benefits.

A novel composite of carbon disulfide-modified magnetic ion-imprinted chitosan-Fe(III), i.e., MMIC-Fe(III) composite, was prepared as an efficient adsorbent for the simultaneous removal of tetracycline (TC) and Cd(II). This adsorbent showed excellent performance in removing TC and Cd(II) due to its rapid kinetics, high adsorption capacity, good reusability, and was well suited for use with real water samples. Kinetics studies demonstrated that the adsorption proceeded according to a pseudo-second order model. The adsorption isotherms were well described by the Langmuir model, with maximum adsorption capacity for TC and Cd(II) being 516.29 and 194.31 mg/g, respectively. The synergistic effect of TC and Cd(II) adsorption might be due to the formation of TC-Cd(II) complex bridging the adsorbate and adsorbent. These properties demonstrate the potential application of MMIC-Fe(III) for the simultaneous removal of TC and Cd(II), and may provide some information for the synergistic removal of antibiotics and heavy metals from aquatic environments.

The growing potential of quantum dots (QDs) in biological and biomedical applications has raised considerable concern due to their toxicological impact. Consequently, it is urgent to elucidate the underlying toxicity mechanism of QDs. In this work, we comprehensively investigated the cellular uptake of four CdSe/ZnS QDs (COOH CdSe/ZnS 525, COOH CdSe/ZnS 625, NH2 CdSe/ZnS 525, and NH2 CdSe/ZnS 625) and induced physiological responses in Phanerochaete chrysosporium (P. chrysosporium) through inductively coupled plasma optical emission spectroscopy, confocal laser scanning microscopy, and the determination of malondialdehyde content, superoxide level, superoxide dismutase activity, catalase activity and glutathione level. The results showed that the four CdSe/ZnS QDs accumulated largely in the hyphae and caused oxidative stress to P. chrysosporium in the tested concentration range (10–80 nM). Furthermore, the cellular uptake and cytotoxicity were related to the physicochemical properties of the QDs, such as particle size and surface charges. Negatively charged CdSe/ZnS QDs with small size could be more easily ingested by P. chrysosporium than large ones; thus small size CdSe/ZnS QDs were more cytotoxic to P. chrysosporium. On the other hand, small negatively charged CdSe/ZnS QDs resulted in greater cytotoxicity than large negatively charged CdSe/ZnS QDs. The obtained results offer valuable information for revealing the toxicity mechanism of QDs in living cells.

The phytogenic algicide sanguinarine shows strong inhibitory effects on some bloom-forming cyanobacteria and exhibits great potential in cyanobacterial bloom mitigation. To evaluate the possible ecological effects of sanguinarine on microalgae, the effects and possible mechanisms of sanguinarine on the competition between bloom-forming cyanobacterium Raphidiopsis raciborskii (formerly named Cylindrospermopsis raciborskii) and green alga Scenedesmus obliquus were investigated through co-culture competition test and comparative toxicological study including growth characteristics, chlorophyll fluorescence transients, activities of antioxidant enzymes, and lipid peroxidation. The results of Raphidiopsis-Scenedesmus co-culture competition test showed that sanguinarine decreased the competition ability of R. raciborskii, which benefitted S. obliquus in winning the competition. Toxicological studies have shown that sanguinarine exhibited high inhibitory effects on the growth and photosynthesis of R. raciborskii but no obvious toxicity on S. obliquus at concentrations of no more than 80 μg L−1. Oxidative damage partially contributed but was not the primary mechanism for the toxicity of sanguinarine on R. raciborskii. The results presented in this study indicate that sanguinarine may be a good algicidal candidate in mitigation of Raphidiopsis-based water bloom.

Due to the increase in oil spill accidents and discharge of oily wastewater, it is urgent to develop functional materials to separate oil from oil/water mixtures. In this work, the kaolin-coated meshes were fabricated by a facile coating method to construct a micro-hierarchical surface and controllable pore size for the separation of various oil/water mixtures. The obtained meshes exhibits super-hydrophilicity, underwater super-oleophobicity with underwater oil contact angle >150° and outstanding oil/water separation efficiency above 99% and flux up to 190 L m−2 h−1 under gravity force. Moreover, the mesh still maintained high stability and good separation efficiency under corrosive condition and recycling. Furthermore, the mesh can also remove water from the water-in-oil emulsion. Results from this study are meaningful for the development of low-cost, and eco-friendly materials with high efficiency and mechanical robustness for oily wastewater treatment and open a new way for high-increment utilization of kaolin mineral.

Phthalate esters (PAEs) are one of the most frequently detected organic pollutants in soils. In this work, the adsorption behaviors of di-ethyl phthalate (DEP) and dibutyl phthalate (DBP) on soils, humins (HM) and Clay organo-mineral complexes (Clay-OM) from four regions in China, Changchun (CC), Cangzhou (CZ), Yinchuan (YC), and Changsha (CS) were studied. The surface and structural properties of these sorbents were characterized using Brunauer-Emmett-Teller specific surface area, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and 13C nuclear magnetic resonance methods. The results showed that the CC soil has the largest pore volume (PV) and specific surface area (SSA). PV, SSA, and aliphatic carbon content of the samples ranked as Clay-OM > HM > soil. Adsorption experiments indicated that the Clay-OM exhibited the strongest adsorption affinity for both DBP and DEP, followed by HM, and then the soil samples. Furthermore, DEP and DBP adsorption amounts on the samples declined as follows: CC > CS > CZ > YC. To illustrate the dominant mechanisms for PAEs adsorption onto soil, the soil organic carbon content normalized adsorption coefficient (LogKoc) was correlated with several possible parameters using multiple parameter linear regression and significance testing. The R2 values of the DBP and DEP in multi-regression equations were 0.825 and 0.741 respectively, and the significance test suggested that pore structure and specific surface area had crucial influences on the adsorption progress.

In this study, influences of cations (Na+, K+, Ca2+, and Mg2+), anions (NO3-, Cl-, and SO42-), and humic acid (HA) on the antimicrobial efficacy of silver nanoparticles (AgNPs)/Ag+ against Phanerochaete chrysosporium were investigated by observing cell viability and total Ag uptake. K+ enhanced the antimicrobial toxicity of AgNPs on P. chrysosporium, while divalent cations decreased the toxicity considerably, with preference of Ca2+ over Mg2+. Impact caused by a combination of monovalent and divalent electrolytes was mainly controlled by divalent cations. Compared to AgNPs, however, Ag+ with the same total Ag content exhibited stronger antimicrobial efficacy towards P. chrysosporium, regardless of the type of electrolytes. Furthermore, HA addition induced greater microbial activity under AgNP stress, possibly originating from stronger affinity of AgNPs over Ag+ to organic matters. The obtained results suggested that antimicrobial efficacy of AgNPs was closely related to water chemistry: addition of divalent electrolytes and HA reduced the opportunities directly for AgNP contact and interaction with cells through formation of aggregates, complexes, and surface coatings, leading to significant toxicity reduction; however, in monovalent electrolytes, the dominating mode of action of AgNPs could be toxic effects of the released Ag+ on microorganisms due to nanoparticle dissolution.

In this study, interaction of oxytetracycline (OTC) onto nano-hydroxyapatite (nHAP) was evaluated as affected by pH and metal ions. Results showed that the adsorption process of OTC was highly pH- and metallic species-dependent. The amount of sorbed OTC at four pH were in the order of pH 8.0 > pH 10.0 > pH 5.5 > pH 3.0 and reached equilibrium around 120 min, indicating adsorption affinity of four species to nHAP followed the order of OTC− > OTC2− > OTC± > OTC+. Adding metal ions greatly increased the distribution coefficient (Kd) of OTC between adsorbents and aqueous phases, following the order of Fe3+ > Cu2+ > Pb2+ > Cd2+ = Ca2+ in the pH range of 3.0–10.0. Moreover, the co-adsorption behavior of OTC and heavy metals onto nHAP was also explored at pH 5.5 for the first time. OTC adsorption was significantly enhanced with the co-existence of 0.25 mmol/L Cu2+ or Pb2+. Inversely, the presence of 0.25 mmol/L OTC slightly led to the improvement of Cu2+ adsorption and depression of Pb2+ adsorption, yet Pb2+ adsorption was obviously promoted with the co-existence of 0.1 mmol/L OTC. Meanwhile, adsorption of OTC and Cd2+ showed unapparent variation in single or binary systems. The bridging effect involving metal ions, O- and N- containing groups in OTC molecules, and CaOH or POH sites of nHAP resulted in the formation of ternary complexes which were responsible for the promotion of their adsorption, while dissolution-precipitation was another key mechanism with the co-existence of Pb2+.

Hydrogen sulfide (H2S), an important cellular signaling molecule, plays vital roles in mediating responses to biotic/abiotic stresses. Influences of H2S on metal removal, cell viability, and antioxidant response of Phanerochaete chrysosporium upon exposure to heavy metals and silver nanoparticles (AgNPs) in the present study were investigated. An enhancement in Pb(ΙΙ) removal with an increase in concentration of the H2S donor sodium hydrosulfide (NaHS) was observed, and the maximum removal efficiencies increased by 31% and 17% under 100 and 200 mg/L Pb(ΙΙ) exposure, respectively, in the presence of 500 μM NaHS. Application of 500 μM NaHS increased the cell viability by 15%–39% under Pb(II) stress (10–200 mg/L) with relative to the untreated control. Increase in total Ag uptake and cell survival was also elicited by NaHS in a concentration-dependent manner under AgNP stress. Meanwhile, activities of superoxide dismutase and catalase were significantly enhanced with the introduction of NaHS under stresses of Pb(II), Cd(II), Cu(II), Zn(II), Ni(II), and AgNPs. The inhibition in lipid peroxidation and oxidative stress was observed in P. chrysosporium cells exposed to these toxicants following NaHS pretreatment, which could be attributed to the upregulation in antioxidant enzymes. The results obtained suggest that H2S can alleviate heavy metals and AgNP-induced toxicity to P. chrysosporium and improve the removal efficiency of these toxicants from wastewater.

In this work, silver nanoparticles supported on polydopamine-kaolin composite (PDA-kaolin-Ag) was fabricated by an in-situ reduction method with PDA as both reductant and stabilizer. The morphology, composition, and structure of PDA-kaolin-Ag composite were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalytic reduction tests confirmed the importance of PDA modification and high catalytic activities of this as-prepared PDA-kaolin-Ag composite towards a model dye Rhodamine B. The catalytic reduction processes followed pseudo-first order kinetics. Meanwhile, this catalyst showed excellent stability and recyclability for dye decoloration. Furthermore, this composite also exhibited good catalytic performance on methylene blue, methyl orange, and Congo red. These results suggest that PDA-kaolin-Ag composites can be used as efficient and cost-effective catalyst for the decoloration of various organic dyes.

Antioxidative response of Phanerochaete chrysosporium induced by silver nanoparticles (AgNPs) and their toxicity mechanisms were comprehensively investigated in a complex system with 2,4-dichlorophenol (2,4-DCP) and Ag+. Malondialdehyde content was elevated by 2,4-DCP, AgNPs, and/or Ag+ in concentration- and time-dependent manners within 24 h, indicating an increase in lipid peroxidation. However, beyond 48 h of exposure, lipid peroxidation was alleviated by upregulation of intracellular protein production and enhancement in the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Comparatively, POD played more major roles in cell protection against oxidative damage. Furthermore, the dynamic change in reactive oxygen species (ROS) level was parallel to that of oxidized glutathione (GSSG), and ROS levels correlated well with GSSG contents (R2 = 0.953) after exposure to AgNPs for 24 h. This finding suggested that elimination of oxidative stress resulted in depletion of reduced glutathione. Coupled with the analyses of anoxidative responses of P. chrysosporium under the single and combined treatments of AgNPs and Ag+, HAADF-STEM, SEM, and EDX demonstrated that AgNP-induced cytotoxicity could originate from the original AgNPs, rather than dissolved Ag+ or the biosynthesized AgNPs.

The adsorption capacity of calcium alginate (Ca-alginate) beads was evaluated by measuring the removal of three organic compounds with different charges (malachite green, p-chlophenol and methyl orange). The diffusion was investigated in Ca-alginate hydrogel as a function of solute charge. It was found that an increased electrostatic attraction between the hydrogel and solute would improve the mobility of solute and hence enhance its adsorption efficiency. The degradation kinetics of charged pollutants by Ca-alginate with NZVI entrapped (NZVI-alginate) beads was compared to that of bare NZVI and the data followed a pseudo-first-order kinetic model. Negatively charged Ca-alginate hydrogel strongly adsorbed positively charged pollutant, which led to an enhancement in degradation rate. However, the degradation efficiency of neutral and negatively charged pollutants by NZVI-alginate was comparable with that by bare NZVI. Thus, the degradation ability of NZVI-alginate was related with the diffusion and adsorption behavior of solutes in Ca-alginate hydrogel. The experimental results showed that the free calcium ions containing in Ca-alginate had a significant impact on the adsorption and degradation behaviors of positively charged pollutant, but those of neutral and negatively charged pollutants were only moderately affected. With the dispersity of NZVI particles in beads (1:1-1:4, w/w) increasing, the degradation efficiency of malachite green was improved, whereas further increase of NZVI dispersity (1:6, w/w) brought about a depressed degradation.

This study investigated the performance of immobilized Phanerochaete chrysosporium loaded with nitrogen-doped TiO2 nanoparticles in the treatment of raw landfill leachate with a very low biodegradability ratio (BOD5/COD) of 0.09. The effects of various operating parameters, such as initial chemical oxygen demand (COD) concentration, pH, temperature, and biosorbent dosage, were evaluated with respect to the removal efficiency of total organic carbon (TOC) and ammonia nitrogen (NH3-N). For the immobilized biosorbents, an optimum pH of 6.0 for TOC and 7.0 for NH3-N were found suitable for TOC and NH3-N removal at temperature of 37°C, respectively. The most superior removal efficiencies of TOC and NH3-N of landfill leachate were over 75% and 74% in 72 h at an initial COD concentration of 200 mg L(-1), respectively. In addition, heavy metals were partly removed by the immobilized biosorbents during the process of landfill leachate treatment. The species and mass percentage of organic compounds in landfill leachate after the treatment were found to have considerably declined according to the gas chromatography coupled with mass spectrometry (GC-MS) system. These results indicate that the immobilized P. chrysosporium loaded with nitrogen-doped TiO2 nanoparticles could be a convenient and efficient method for the treatment of landfill leachate.

Due to the wide use of silver nanoparticles (AgNPs) in various fields, it is crucial to explore the potential negative impacts on the aquatic environment of AgNPs entering into the environment in different ways. In this study, comparative experiments were conducted to investigate the toxicological impacts of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) with two kinds of dosing regimens, continuous and one-time pulsed dosing, in different exposure media (deionized water and XiangJiang River water). There were a number of quite different experimental results (including 100% mortality of zebrafish, decline in the activity of enzymes, and lowest number and length of adventitious roots) in the one-time pulsed dosing regimen at high PVP-AgNP concentration exposure (HOE) compared to the three other treatments. Meanwhile, we determined that the concentration of leached silver ions from PVP-AgNPs was too low to play a role in zebrafish death. Those results showed that HOE led to a range of dramatic ecosystem impacts which were more destructive than those of other treatments. Moreover, compared with the continuous dosing regimen, despite the fact that higher toxicity was observed for HOE, there was little difference in the removal of total silver from the aquatic environment for the different dosing regimens. No obvious differences in ecological impacts were observed between different water columns under low concentration exposure. Overall, this work highlighted the fact that the toxicity of AgNPs was impacted by different dosing regimens in different exposure media, which may be helpful for assessments of ecological impacts on aquatic environments.

In this study, the dibutyl phthalate (DBP) binding properties of a DBP-tolerant bacterium (B. cepacia) were characterized in terms of adsorption kinetics and isotherm. Living and nonliving cells both exhibited rapid removal of DBP, achieving more than 80% of maximum sorption within 30 min of contact and reached the equilibrium after 3 h. The adsorption isotherms were well fitted with the Sips model and the nonliving cells have greater biosorption capacity and affinity for DBP than the living cells. Furthermore, the absence of an active mechanism dependent on metabolism implied that the DBP bioaccumulation by living cells was mainly attribute to passive surface binding. The optimum pH for DBP adsorption by living and nonliving cells were both observed to be 6.0. The biosorptive mechanism of DBP binding by B. cepacia was further confirmed by FTIR analysis and various chemical treatments. FTIR results indicated that the phosphate and CH2 groups on B. cepacia were the main bounding sites for DBP. Furthermore, 2.28, 2.15, 1.93 and 0.87 g of pretreated cells were obtained from 2.40 g of native cells via extracellular polymeric substances (EPS), superficial layer-capsule, lipids components and cell membrane removal treatments, respectively. Total binding amount of DBP on the native cells, EPS-removed cells, capsule-removed cells, lipids-extracted cells and membrane-removed cells were 26.69, 24.84, 24.93, 16.11 and 10.80 mg, respectively, suggesting that the cell wall lipids, proteins or peptidoglycan might play important roles in the sorption of DBP by B. cepacia. The information could be applied in understanding on the mobility, transport and ultimate fate of PAEs in soil and related environment.

The toxicity of silver nanoparticles (AgNPs) is widely exploited, but their hormesis effect has, so far, received little attention. This study reports the hormesis effect at low AgNPs concentrations of 0.34 mg L−1, with a 29.9% increase in bacterial viability compared with the control. Cysteine can induce a hormesis effect at a higher concentration. 12.5 mg L−1 cysteine induced a hormesis effect in the AgNP concentration range of 1.7–5.1 mg L−1. Results suggest that this cysteine-induced hormesis effect is concentration-dependent; the concentration that make sulfuration rate (ns/nAg) of 6.15 shows strong excitation to cells.

Remediating uranium contamination is of worldwide interest because of the increasing release of uranium from mining and processing, nuclear power leaks, depleted uranium components in weapons production and disposal, and phosphate fertilizer in agriculture activities. Iron-based technologies are attractive because they are highly efficient, inexpensive, and readily available. This paper provides an overview of the current literature that addresses the application of iron-based technologies in the remediation of sites with elevated uranium levels. The application of iron-based materials, the current remediation technologies and mechanisms, and the effectiveness and environmental safety considerations of these approaches were discussed. Because uranium can be reduced and reoxidized in the environment, the review also proposes strategies for long-term in situ remediation of uranium. Unfortunately, iron-based materials (nanoscale zerovalent iron and iron oxides) can be toxic to microorganisms. As such, further studies exploring the links among the fates, ecological impacts, and other environmentally relevant factors are needed to better understand the constraints on using iron-based technologies for remediation.

Despite the increasing knowledge on the discharge of silver nanoparticles (AgNPs) into the environment and their potential toxicity to microorganisms, the interaction of AgNPs with heavy metals remains poorly understood. This study focused on the effect of AgNPs on heavy metal concentration and form in sediment contaminated with heavy metals from the Xiangjiang River. The results showed that the concentration of Cu, Zn, Pb and Cd decreased and then increased with a change in form. The changes in form and concentrations of heavy metals in pore water suggested that Cu and Zn were more likely to be affected compared to Pb and Cd. The concentrations of Hg in sediment pore water in three AgNPs-dosed containers, increased greatly until they reached their peaks at 4.468 ± 0.133, 4.589 ± 0.235, and 5.083 ± 0.084 μg L(-1) in Bare AgNPs, Citrate AgNPs and Tween 80 AgNPs, respectively. The measurements of Hg concentrations in the sediment pore water, combined with SEM and EDX analysis, demonstrated that added AgNPs stabilized in pore water and formed an amalgam with Hg(0), which can affect Hg transportation over long distance.

Due to the particular activation and inhibition behavior of silver nanoparticles (AgNPs) on microbes at various concentrations, it’s crucial to exploit the special concentration effect in environment. Here, we studied the viability variation of Phanerochaete chrysosporium (P. chrysosporium) under exposure to citrate-coated AgNPs (Citrate-AgNPs) in the presence of different sulfide sources (an inorganic sulfide, NaHS and an organic sulfide, thioacetamide (TAA)). The results indicated that both NaHS and TAA can promote activation of P. chrysosporium by Citrate-AgNPs at a higher concentration, which was initial at toxic level. Treatment with various concentrations of Citrate-AgNPs (0–9 mg/L) demonstrated a maximum activation concentration (MAC) at 3 mg/L. With the increase in sulfide concentration, MAC transferred to higher concentration significantly, indicating the obvious “toxicity to activation” transformation at a higher concentration. Ag+ testing exhibited that variations in sulfide-induced Ag+ concentration (3−7 μg/L Ag+) accounted for the “toxicity to activation” transformation. In addition, the similar results were observed on antibacterial application using Escherichia coli as the model species. Based on the research results, the application of this transformation in improving antibacterial activity was proposed. Therefore, the antibacterial activity of AgNPs can be controlled, even at concentration, via adjusting for the sulfide concentration.

With the rapid development of AC/DC hybrid microgrids and the widespread use of distributed power resources, planning strategies for microgrids with high-density distributed power generation have become an urgent problem. Because current research on microgrid planning has not considered line factors, this paper analyses the planning of an AC/DC hybrid microgrid based on an AC microgrid. The capacity and siting of the distributed power resources are optimized, taking into account the influence of the line investment cost and the interactive power upper limit on the planning results. In the proposed model, the objective is aimed at minimizing the sum of investment cost, load-loss economic cost, and system losses, taking into consideration power balance constraints and feeder number constraints. The commercial solver CPLEX is applied to attain the optimal distributed power capacity and site. The theoretical results are verified by an actual system.

Graphene has been employed as an excellent support for metal nanomaterials because of its unique structural and physicochemical properties. Silver nanoparticles (AgNPs) with exceptional properties have received considerable attention in various fields; however, particle aggregation limits its application. Therefore, the combination of AgNPs and graphene based nanocomposites (Ag-graphene based nanocomposites) has been widely explored to improve their properties and applications. Excitingly, enhanced antimicrobial, catalytic, and surface enhanced Raman scattering properties are obtained after their combination. In order to have a comprehensive knowledge of these nanocomposites, this Review highlights the chemical and biological synthesis of Ag-graphene nanocomposites. In particular, their applications as antimicrobial agents, catalysts, and sensors in biomedicine, agricultural protection, and environmental remediation and detection are covered. Meanwhile, the factors that influence the synthesis and applications are also briefly discussed. Furthermore, several important issues on the challenges and new directions are also provided for further development of these nanocomposites.

Cyanobacterial blooms result in high level of cyanobacterial extracellular polymeric substances (EPS) in water. The effects of bloom-forming cyanobacterial EPS on the distribution of Cd(II) in the interface between sediment and water is unknown. Clay is a main component in sediment. The effects of EPS, originated from a typical bloom-forming cyanobacterium Microcystis aeruginosa, on the adsorption and desorption characteristics of Cd(II) by kaolinite were investigated in this study. Results of XRD analysis indicated that cyanobacterial EPS bound on the surface of kaolinite. The composite of kaolinite + EPS showed higher adsorption capacity toward Cd(II) than pure kaolinite, and hydroxyl groups were involved in the adsorption processes. The data for the adsorption of Cd(II) by kaolinite are well fitted by both Langmuir model and Freundlich model, whereas only Freundlich model well describes the adsorption data of Cd(II) by the composite of kaolinite + EPS. The adsorption of Cd(II) onto kaolinite was an exothermic process, but it became an endothermic process after EPS incorporation. Results of desorption showed that EPS incorporation increased the adsorption of kaolinite toward Cd(II) through physical adsorption, ion exchange and complexation.