Hazardous Materials

Enhanced diuron remediation by microorganism-immobilized silkworm excrement composites and their impact on soil microbial communities Publication date: 15 August 2019 Source: Journal of Hazardous Materials, Volume 376 Author(s): Jie Liu, Menrang Yang, Yutai Wang, Liwen Qu, Guohua Zhong Abstract In response to the potential threats stemming from the constantly increasing consumption of herbicides, bioremediation offers a beneficial technology for reducing the widespread herbicide contamination. In order to facilitate the in-situ degradation of diuron, Arthrobacter globiformis D47 is captured onto a biocompatible carrier to assemble the microorganism-immobilized silkworm excrement (MSE) composites. By characterization, bacterial cells are intensively entrapped in/onto the carriers, showing high survival and stable catalytic degradation of target pollutants. Meanwhile, MES composites display excellent adaptiveness and feasibility under different conditions, and the average half-life of diuron is shortened to 7.69 d in sugarcane field where diuron is regularly sprayed for weed management. Importantly, we assess that the use of MSE may generally boost the overall xenobiotic-degrading ability, likely due to the slight alternation of the diversity and composition of soil microbial communities. Taking together, the presented MSE provides an attractive in situ approach for the efficient diuron removal as well as for the more feasible utilization of various pollutant-degrading microorganisms. Graphical abstract

Study on the effects of oxygen-containing functional groups on Hg0 adsorption in simulated flue gas by XAFS and XPS analysis Publication date: 15 August 2019 Source: Journal of Hazardous Materials, Volume 376 Author(s): Jinjing Luo, Qiang Niu, Mingchang Jin, Yinan Cao, Lurong Ye, Rupeng Du Abstract The effect of physicochemical properties of activated carbon on adsorption of elemental mercury (Hg0) was investigated on a series of modified activated carbons. Heat treatment and benzoic acid impregnation were conducted to vary the oxygen functional groups on carbon surface. Hg0 adsorption experiments were run in a fixed-bed reactor at 140 °C. Surface characteristics of carbon samples were studied by N2 adsorption, Boehm titration, X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), respectively. The predominant mechanism of Hg0 removal was the formation of chemical bonds between Hg and various functional groups. Both XPS and XAFS analysis revealed that mercury bound on carbon surface was mainly in oxidation state. Under N2 atmosphere, the absorbed Hg was found as Hg2+, and coordinated to O atom. With the existence of HCl in simulated flue gas, Hg0 was bonded on Cl sites and HgCl2 was assumed to be the dominated form.

Carbon dots sensitized 2D-2D heterojunction of BiVO4/Bi3TaO7 for visible light photocatalytic removal towards the broad-spectrum antibiotics Publication date: 15 August 2019 Source: Journal of Hazardous Materials, Volume 376 Author(s): Shukun Le, Wenjing Li, Yuanjiang Wang, Xue Jiang, Xiaoxue Yang, Xiaojing Wang Abstract Focused on the removal of the complicated residual antibiotic in aqueous environment, in this work, a novel carbon dots (C-dots) sensitized 2D-2D heterojunction of BiVO4/Bi3TaO7 were assembled through a simple hydrothermal process. The characteristic by TEM, SEM, and XPS confirmed C-dots evenly anchored on the surface of BiVO4/Bi3TaO7 heterojunction. The as-prepared C-dots/BiVO4/Bi3TaO7 showed superior performance for the degradation of the various antibiotics under visible light illumination. When the concentration of C-dots in the composite is 3 wt.%, the photodegraded rates are obtained to be 91.7%, 89.3%, 87.1%, for tetracycline (TC), amoxicillin (AMX) and ciprofloxacin (CIP), respectively, without significant deactivation during consecutive ten recycle experiments. Furthermore, by assessing the antibiotics mixture solution of TC, AMX and CIP, it is proposed that the prepared samples are potentially effective for the wastewater effluents. A probable mechanism was reasonably proposed. The improved photocatalytic activities could be attributed to the unique construction of the C-dots mediated heterojunction, which could expedite electron migration, improve light harvesting capacity and enhance charge separation efficiency. The present investigation may provide a new perspective to design C-dots mediated heterojunction which could be a potential visible-light-driven photocatalysts for the better practical applications in remediation of broad-spectrum antibiotic residues. Graphical abstract

Removal and simultaneous reduction of Cr(VI) by organo-Fe(III) composites produced during coprecipitation and coagulation processes Publication date: 15 August 2019 Source: Journal of Hazardous Materials, Volume 376 Author(s): Kai-Yue Chen, Yu-Min Tzou, Ya-Ting Chan, Jeng-Jzung Wu, Heng-Yi Teah, Yu-Ting Liu Abstract Composites formed during the coprecipitation and/or coagulation of ubiquitous dissolved organic matter (DOM) and Fe in natural and waste water systems might be potential scavengers for Cr(VI) in terms of sorption and reduction. Our objective here was to determine sorption and simultaneous reduction of Cr(VI) on organo-Fe(III) composites (OFC) in relation coprecipitated pH and C/(C + Fe) ratios. Results showed the greatest Cr sorption of 51.8 mg g−1 on the OFC sample that was precipitated at pH 3 and contained the C/(C + Fe) molar ratio of 0.71. Wherein the Cr(VI) removal subsequent to the coprecipitation was dominated by the sorption on Fe hydroxides. Although amounts of total sorbed Cr decreased with increasing C/(C + Fe) molar ratio, the reverse trend on Cr(VI) reducibility compensated the Cr(VI) removal capability of OFC samples. With C/(C + Fe) molar ratios ≥ 0.89, the increasing amounts of coprecipitated organic matter that homogeneously distributed with Fe domains on OFC surfaces could trigger a significantly pronounced Cr reduction. Collectively, our results suggested an alternative method for Cr(VI) remediation by manipulating C/Fe ratios in suspensions. After the sorption of most Cr(VI) on Fe hydroxides, increasing C/Fe ratio in systems could further improve the Cr(VI) removal efficiency by the reduction of remaining Cr(VI) to Cr(III). Graphical abstract

Use of a floating adsorbent to remove dyes from water: A novel efficient surface separation method Publication date: 5 August 2019 Source: Journal of Hazardous Materials, Volume 375 Author(s): Yanyan An, Huaili Zheng, Xinyu Zheng, Qiang Sun, Yuhao Zhou Abstract In this study, our group grafted 2-acrylamido-2-methylpropane sulfonic acid (AMPS) onto the surface of hollow glass microspheres (HGM) and successfully prepared AMPS grafted floating adsorbent (AFA). The prepared AFA carries a large amount of negative charges, and the adsorptions of cationic dyes are achieved under the action of strong electrostatic interaction. Furthermore, due to the unique shell structure of AFA, it has a stable self-floating ability, which may change the traditional separation method to make the adsorbent easier to enrich and separate from water surface. Characterizations of AFA by scanning electron microscope, energy dispersive spectrometry, X-ray photoelectron spectroscopy. Fourier transform infrared spectra, Brunauer-Emmett-Teller surface areas, thermogravimetric analysis, and X-ray diffractometer shows the successful grafting of AMPS. Adsorption experiments confirmed that the adsorption capacities of AFA for methylene blue, malachite green, basic fuchsin and crystal violet under optimum conditions were 436.8 mg g−1, 637.6 mg g−1, 457.8 mg g−1, and 399.4 mg g−1, respectively. At the same time, AFA has excellent recyclability, and its adsorption capacity can be maintained after 6 cycles of reuse. Graphical abstract

Use 3-D tomography to reveal structural modification of bentonite-enriched clay by nonionic surfactants: Application of organo-clay composites to detoxify aflatoxin B1 in chickens Publication date: 5 August 2019 Source: Journal of Hazardous Materials, Volume 375 Author(s): Yu-Min Tzou, Ya-Ting Chan, Shuen-Ei Chen, Chun-Chieh Wang, Po-Neng Chiang, Heng Yi Teah, Jui-Ting Hung, Jeng-Jzung Wu, Yu-Ting Liu Abstract Although nonionic surfactants are relatively eco-friendly compared with cationic and anionic surfactants, few studies have investigated their application in modified clay. Herein we prepared organo-clay composites (OCCs) by mixing bentonite-enriched clay (BEC) with nonionic surfactants (Brij 30 and Igepal CO-890) and determined if these modifications would enable chickens to detoxify aflatoxin B1 (AFB1). For the first time, in situ three-dimensional (3-D) microstructures of modified BEC was characterized in suspension using transmission X-ray microscopy. Although X-ray diffraction patterns indicated the expansion in the spacing between planes of atoms (basal spacing) of surfactant-modified BEC, 3-D images indicated shrinkage in its microscale porous framework with increasing surfactant additions from 1 to 30 wt%. Such declining trends in porous dimensions caused by the dehydration in interlayer galleries of clays positively correlated with sorption amounts of AFB1 on OCCs. After chickens had consumed amended feeds for 11 weeks, AFB1 concentrations in liver, kidney, and plasma were significantly lower than in the control treatment. Thus, we suggest using BEC with 1 wt% surfactant addition, an amendment to chicken feeds, to detoxify AFB1. Modifying BEC with nonionic surfactants show the promise in mitigating AFB1 accumulation in chickens, which should improve food safety and reduce environmental contamination. Graphical abstract

Co-transport of Pb(II) and oxygen-content-controllable graphene oxide from electron-beam-irradiated graphite in saturated porous media Publication date: 5 August 2019 Source: Journal of Hazardous Materials, Volume 375 Author(s): Yanji Jiang, Xianqiang Yin, Duo Guan, Tao Jing, Huimin Sun, Nong Wang, Jing Bai Abstract It is essential to investigate the role of the surface oxygen content of graphene oxide (GO) in transport processes. In this study, GO was prepared using flake graphite with different radiation doses. The effects of the flow rate and ionic strength (IS) on the migration and co-transport of GO and Pb(II) ions were investigated via laboratory packed-column experiments. The experimental results showed that the mobility of GO in saturated porous media decreased with increasing flow rate. Further, the mobility of GO with a radiation dose of 18 kGy was lower than that of GOs with other radiation doses for an IS below 0.01 M. Regarding the co-transport of irradiated GO and Pb(II) in porous media, the greater the radiation dose, the stronger was the ability of GO to promote Pb(II) transport. The surface oxygen content promoted the ability of GO to remove Pb(II). However, radiation doses exceeding a certain range inhibited the release of Pb(II). The transport of GO in saturated porous media was successfully simulated with the advection–dispersion–reaction (ADR) equation. This study is expected to provide a new perspective on the potential risks of GO due to surface changes during its transport in the environment. Graphical abstract

Development of a model (SWNano) to assess the fate and transport of TiO2 engineered nanoparticles in sewer networks Publication date: 5 August 2019 Source: Journal of Hazardous Materials, Volume 375 Author(s): Ki-Eun Kim, Yu Sik Hwang, Min-Hee Jang, Jee Hey Song, Hee Seok Kim, Dong Soo Lee Abstract A new model, SWNano (Sewer-Water Nano), has been developed in the present study that quantitatively simulates the spatio-temporal changes in the concentrations of TiO2 ENPs of dispersed and aggregated forms in the sewage water and sediment of a sewer network. As a brief example of SWNano applications, a small section of the entire sewer network of Seoul, Korea, was chosen to study where the sewage water was experimentally characterized. The predictions of SWNano present important findings that i) heteroaggregation is the most significant process following the advective transport among the fate and transport processes in the sewer pipes, ii) the heteroaggregation of TiO2 ENPs with SPMs in the sewage water can substantially (a few % to more than 50%) reduce the freely dispersed TiO2 ENPs depending on the magnitude of attachment efficiency, and iii) accurate determination of attachment efficiency is of critical importance in predicting the quantity of individual forms of ENPs exiting the sewer system. The predictions strongly suggest that the fate and transport of TiO2ENPs in the sewer networks be taken into account to improve the assessment of exposure to TiO2 ENPs in the aquatic ecosystems, which warrants further development and use of models like SWNano. Graphical abstract

Industrial textile effluent treatment and antibacterial effectiveness of Zea mays L. Dry husk mediated bio-synthesized copper oxide nanoparticles Publication date: 5 August 2019 Source: Journal of Hazardous Materials, Volume 375 Author(s): Assumpta Chinwe Nwanya, Lovasoa Christine Razanamahandry, A.K.H. Bashir, Chinwe O. Ikpo, Stephen C. Nwanya, Subelia Botha, S.K.O. Ntwampe, Fabian I. Ezema, Emmanuel I. Iwuoha, Malik Maaza Abstract Zea mays L. dry husk extract was used to bio synthesize copper oxide nanoparticles. Red coloured cubic Cu2O nanoparticles were obtained for the first time via this simple, eco- friendly, green synthesis route. The Cu2O nanoparticles were thermally oxidized to pure monoclinic CuO nanoparticles at 600 °C. The phases of the copper oxides were confirmed from the x-ray diffraction (XRD) studies. The nanoparticle sizes as obtained from high resolution transmission electron microscope (HRTEM) analysis range from 10 to 26 nm, 36–73 nm and 30−90 nm for the unannealed Cu2O, 300 °C and 600 °C annealed CuO respectively. The values of the bandgap energies obtained from diffuse reflectance of the nanoparticles are 2.0, 1.30 and 1.42 eV respectively for the unannealed, 300 °C, and 600 °C annealed copper oxide nanoparticles. The 600 °C annealed copper oxide nanoparticles showed 91% and 90% degradation ability for methylene blue dye (BM) and textile effluent (TE) respectively under visible light irradiation. While CuO_300 is more effective to inhibit the growth of Escherichia coli 518,133 and Staphylococcus aureus 9144, Cu2O is better for Pseudomonas aeruginosa and Bacillus licheniformis. The results confirm the photo-catalytic and anti-microbial effectiveness of the copper oxide nanoparticles.

Valorization of glycerol/ethanol-rich wastewater to bioflocculants: recovery, properties, and performance Publication date: 5 August 2019 Source: Journal of Hazardous Materials, Volume 375 Author(s): Victor Ajao, Siti Millah, Maria Cristina Gagliano, Harry Bruning, Huub Rijnaarts, Hardy Temmink Abstract Microbial extracellular polymeric substances (EPS) were produced in two membrane bioreactors, each separately treating fresh and saline synthetic wastewater (consisting of glycerol and ethanol), with the purpose of applying them as sustainable bioflocculants. The reactors were operated under nitrogen-rich (COD/N ratios of 5 and 20) and limited (COD/N ratios of 60 and 100) conditions. Under both conditions, high COD removal efficiencies of 87–96% were achieved. However, nitrogen limitation enhanced EPS production, particularly the polysaccharide fraction. The maximum EPS recovery (g EPS−COD/g CODinfluent) from the fresh wastewater was 54% and 36% recovery was obtained from the saline (30 g NaCl/L) wastewater. The biopolymers had molecular weights up to 2.1 MDa and anionic charge densities of 2.3–4.7 meq/g at pH 7. Using kaolin clay suspensions, high flocculation efficiencies of 85–92% turbidity removal were achieved at EPS dosages below 0.5 mg/g clay. Interestingly, EPS produced under saline conditions proved to be better flocculants in a saline environment than the corresponding freshwater EPS in the same environment. The results demonstrate the potential of glycerol/ethanol-rich wastewater, namely biodiesel/ethanol industrial wastewater, as suitable substrates to produce EPS as effective bioflocculants. Graphical abstract

ALEXANDROS SFAKIANAKIS ANAPAFSEOS 5 AGIOS NIKOLAOS CRETE 72100 GREECE +306932607174 +302841026182