Mechanisms of cetyltrimethyl ammonium chloride-induced toxicity to photosystem II oxygen evolution complex of Chlorella vulgaris F1068 Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Na Liu, Han Zhang, Jinfeng Zhao, Yin Xu, Fei Ge Abstract Microalgae photosynthesis is sensitive to coexisted contaminates in aquatic environment, thereby causes adverse effect on algal growth and nutrients uptake. Here, we investigated the photosynthetic toxicity mechanism of cetyltrimethyl ammonium chloride (CTAC)-induced on a green microalga Chlorella vulgaris F1068 (C. vulgaris F1068). Results showed that CTAC reduced the algal growth rate, nutrients removal efficiency and weakened the photosynthetic performance. Meanwhile, the efficiency of oxygen evolution complex (OEC) and oxygen evolvement rates stressed by CTAC were significantly declined to 90.48% and 58.48% of the control (without CTAC), respectively. In addition, atomic force microscopy (AFM) detected the damage of PSII-OEC morphology and structure by CTAC. Furthermore, proteomic analysis showed that 41% of proteins were in the chloroplast thylakoid membranes which function in photosynthesis. The activity of oxygen-evolving enhancer protein 2 (OEE2 or PsbP) involved in electron transfer was significantly inhibited by CTAC, which down-regulated 15.14-fold in the presence of 0.6 mg/L CTAC. These results indicated that photosynthetic inhibition of CTAC mainly occurred in the PSII-OEC. This study provided a new perspective of the photosynthetic response in evaluation of environmental bioimpacts of surfactants on microalgae. Graphical abstract

Littered cigarette butt as a well-known hazardous waste: A comprehensive systematic review Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Javad Torkashvand, Mahdi Farzadkia, Hamid Reza Sobhi, Ali Esrafili Abstract Most of cigarettes used in the world have filters. Following smoking, the cigarette butts (CBs) are often littered as wastes in the environment. CBs generally contain several toxic substances that are trapped in the cigarette filter. Filters are made of non-biodegradable materials and remain in the environment for a long time. Within this study, it is attempted to systematically review the articles on CBs and find out the answers to the problems associated with the factors including quantity, distribution, origin and toxicity of CBs in the environment. It is estimated that approximately 5.5 trillion cigarettes are being produced annually in the world and the CB wastes would reach 1.2 million tons and increase by 50% until 2025. CBs contain thousands of dangerous chemicals such as arsenic, benzene, hydrogen cyanide, PAHs, pyridine, heavy metals and so forth. It is also believed that eachCB can pollute 1000 liters of water. Given the inadequacy of mechanical equipment as well as the cost of collecting these wastes, there should be a special focus on these items as follows: producing cigarettes with degradable filters, reducing the rate of smoking in the world, reducing the toxic and chemical substances in the process of plant growth, processing and production of cigarettes, training people to discard CBs properly, putting legal and financial pressures on cigarettes production, and the last but not least, providing effective solutions for collecting CBs.

Research of the thermal decomposition mechanism and pyrolysis pathways from macromonomer to small molecule of waste printed circuit board Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Ruitong Gao, Lu Zhan, Jie Guo, Zhenming Xu Abstract Pyrolysis is an important pre-treatment technology for pyrometallurgy, which could reduce pollution and recover materials from waste printed circuit boards (WPCBs). However, present studies on mechanism of pyrolysis were insufficient, which results in the unclear of controlling reaction rate and inhibiting side reaction. To further develop pyrolysis technology, the in-depth research on the pyrolysis mechanism is necessary. In this study, we investigated the thermal decomposition process and pyrolysis pathways from macromonomers to products of WPCBs. The results showed that HBr was produced at the initial stage of pyrolysis. Then, the resin body depolymerized into macromonomers, followed by random rupture and free radical reactions to form pyrolysis products. Besides, possible mechanism for bisphenol A thermal decomposing was analyzed by bond energy. The results suggested that methyl groups in bisphenol A would be preferentially removed because of low bond energy. The six possible pathways may occur simultaneously when energy sufficient. Moreover, the mechanism function was determined by Škvára-Šesták method as: G(α)=-ln1-α2, which indicated pyrolysis reaction agreed with the model of random nucleation followed by random growth. This study provided the theoretical basis for pollution control, process optimization and reactor design of WPCBs pyrolysis. Graphical abstract

Occurrence and distribution of clinical and veterinary antibiotics in the faeces of a Chinese population Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Qing Wang, Yu-Jing Duan, Shao-Peng Wang, Li-Tao Wang, Ze-Lin Hou, Yu-Xiao Cui, Jie Hou, Ranjit Das, Da-Qing Mao, Yi Luo Abstract Antibiotics ingested in the human gut may create selective pressure to change the composition of the gut microbiota, which could adversely effect the immune system of the host. However, the occurrence and distribution of antibiotics in the human gut remains unclear. A total population of 180 individuals, across three Chinses regions with different economic development levels, including children, adults, and elders, were sampled in 2017. A total of 19 representative antibiotics, including both clinical and veterinary antibiotics, were investigated in human faeces. While clinical use and prescriptions were the main exposure pathways for children, environmental media were the exposure pathway to adults. In addition, significant differences (P < 0.05) in antibiotic residues in human faeces were observed amongst various economic development levels, where human faeces from underdeveloped areas were mostly associated with higher levels of antibiotics. This study first to investigate the occurrence and distribution of typical antibiotics in the faeces of a Chinese population and thereby provide a reference for the intensive study of the effects and mechanisms of antibiotics on human gut microbiota. Graphical abstract

Is color a matter of concern during microplastic exposure to Scenedesmus obliquus and Daphnia magna? Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Qiqing Chen, Yue Li, Bowen Li Abstract Toxicities of microplastics (MPs) on aquatic organisms have been widely investigated often by using white or transparent MPs. However, various colored MPs scatter in the real aquatic environment. Here we investigated four colored MPs’ effects on Scenedesmus obliquus algal growth first. Under the light condition, algal growth increased initially due to hormesis stimulation and then decreased gradually at higher MP concentrations. Green colored MPs exhibited the lowest inhibition effect, probably due to their resemblance to algae; white MPs inhibited the algal growth significantly, which was attributed to the presence of ethanol. Turbulence condition seemed to diminish algal growth differences among groups, but it led to slight oxidative stress. Furthermore, we also tested MP effects on Daphnia magna feeding ability. Results indicated that daphnids were probably not able to distinguish colored MPs from algae. But their algae ingestion amounts increased when MPs reached to 40% of algal cells, probably because daphnids could widen their filtering gapes when food quality decreases. However, this phenomenon did not last until the 3rd day, as the agglomeration of MPs and algae made them settle down. Overall, our results highlighted the color may alter some MP effects and is necessary to be considered in (eco)toxicological studies. Graphical abstract

Novel immobilized ternary photocatalytic polymer film based airlift reactor for efficient degradation of complex phthalocyanine dye wastewater Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Suman Das, Hari Mahalingam Abstract Reduced graphene oxide (rGO) as well as graphitic carbon nitride (g-C3N4) catalysts were synthesized and a physical admixture of rGO and g-C3N4 along with TiO2 in the ratio of 1:1:1 by weight was immobilized in a polystyrene film using the facile solvent casting method. An internal loop airlift reactor with a working volume of 1.2 litres incorporating the prepared polymer-based photocatalytic film was designed and tested for the photocatalytic degradation of remazol turquoise blue dye synthetic wastewater. The reactor parameters affecting the photocatalytic activity such as airflow rate and Di/Do (ratio of draft tube diameter to outer tube diameter) were evaluated. The successful operation of the reactor obtained using the ternary immobilized catalyst mixture film gave 92.25% total organic carbon reduction and 94% decolourization within 140 min, compared to 91% decolourization by the slurry form within 40 min. Complete and quicker decolourization of the dye was also demonstrated under the influence of O3 or H2O2. The immobilized catalyst was successfully reused four times. The ternary catalyst admixture employed in this work and the unique design of the photocatalytic reactor helps to increase the degradation rate of toxic textile effluents thus making it suitable for larger scales of treatment. Graphical abstract

Arsenic adsorption mechanism on palm oil fuel ash (POFA) powder suspension Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Mohamad Sukri Mohamad Yusof, Mohd Hafiz Dzarfan Othman, Roswanira Abdul Wahab, Khairulazhar Jumbri, Fazira Ilyana Abdul Razak, Tonni Agustiono Kurniawan, Rozaimi Abu Samah, Azeman Mustafa, Mukhlis Abdul Rahman, Juhana Jaafar, Ahmad Fauzi Ismail Abstract The contribution of palm oil fuel ash (POFA), an agricultural waste as a low cost adsorbent for the removal of arsenite (As(III)) and arsenate (As(V)) was explored. Investigation on the adsorbency characteristics of POFA suspension revealed that the surface area, particle size, composition, and crystallinity of the SiO2 rich mullite structure were the crucial factors in ensuring a high adsorption capacity of the ions. Maximum adsorption capacities of As(III) and As(V) at 91.2 and 99.4 mg g−1, respectively, were obtained when POFA of 30 μm particle size was employed at pH 3 with the highest calcination temperature at 1150 °C. An optimum dosage of 1.0 g of dried POFA powder successfully removed 48.7% and 50.2% of As(III) and As(V), respectively. Molecular modeling using the density functional theory consequently identified the energy for the proposed reaction routes between the SiO− and As+ species. The high stability of the POFA suspension in water in conjunction with good adsorption capacity of As(III) and As(V) seen in this study, thus envisages its feasibility as a potential alternative absorbent for the remediation of water polluted with heavy metals. Graphical abstract

Targeting the miR-122/PKM2 autophagy axis relieves arsenic stress Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Yu Wang, Hongjing Zhao, Menghao Guo, Dongxue Fei, Lina Zhang, Mingwei Xing Abstract Arsenic (As) is a natural hepatotoxicity inducer that is found ubiquitously in foods and environmental media. We found that arsenite exposure elicits autophagy in vivo and vitro, the specific role and regulatory mechanism of which are yet clear. MicroRNAs (miRNAs) are short noncoding RNAs that function in the posttranscriptional regulation of gene expression. Here, we report that miR-122, the most enriched constitutive miRNA in the liver, induced cell protective autophagy in arsenite-exposed hepatocytes. Arsenite exposure elevated miRNA-122 level and decreased the level of its target gene, PKM2. Under arsenic stress, overexpression of miR-122 significantly induced cell protective autophagy, characterized by lipidation of LC3-II and a corresponding consumption of p62. Conversely, autophagy inhibition by miR-122 knockdown was reversed by si-PKM2 cotransfection. We also found that miR-122 knockdown positively regulated the PI3K/Akt/mTOR pathway, and this phenomenon was reversed by cotransfecting cells with si-PKM2. Taken together, our findings show that the miR-122/PKM2 autophagy axis protects hepatocytes from arsenite stress via the PI3K/Akt/mTOR pathway; thus, miR-122 may be a potential candidate in the treatment of arseniasis. Graphical abstract

Molecularly imprinted carbon nanosheets supported TiO2: Strong selectivity and synergic adsorption-photocatalysis for antibiotics removal Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Lulu Li, Xuyang Zheng, Yinghua Chi, Yao Wang, Xiang Sun, Qinyan Yue, Baoyu Gao, Shiping Xu Abstract In order to achieve strong specific recognition and remarkable synergy between adsorption and photocatalysis, carbon nanosheets supported TiO2 (CT) was designed and embellished by molecular imprinting technology with ciprofloxacin (CIP) as template. The molecular imprinted CT (CT-MI) product exhibited remarkable synergy of adsorption-photocatalysis and high selectivity in both aspects, benefitted from specific recognition of imprinted layer, strong carbon adsorption and electroconductivity, and enhanced photocatalysis. Compared to the competitive pollutant, sulfamethoxazole (SMZ) in this study, selectivity coefficient was 7.2 for adsorption and 3.2 for photocatalysis, respectively. This is superior to most of the imprinted photocatalysts reported in the literature. In addition, effect of mass ratio between TiO2 matrix to imprinted polymers, as well as water quality and composition, to the performance of final product was studied and favorable conditions were proposed. Electron transfer mode, selective recognition mode, and antibiotics degradation mechanism and pathways were also illustrated based on trapping experiments and HPLC-MS technology etc. This study confirmed that alliance between molecular imprinting, carbon nanosheets and well dispersed photocatalyst possessed broad prospect of applications in specific recognition and selective degradation of a highly toxic pollutant in a variety of mixed systems. Graphical abstract

Novel Fe-doped CePO4 catalyst for selective catalytic reduction of NO with NH3: The role of Fe3+ ions Publication date: 5 February 2020 Source: Journal of Hazardous Materials, Volume 383 Author(s): Yiqing Zeng, Wang Song, Yanan Wang, Shule Zhang, Tianxiao Wang, Qin Zhong Abstract Novel Fe-doped CePO4 (FexCe1-x) catalyst was firstly successfully synthesized via a simple co-precipitation method and demonstrated excellent NH3-SCR performance in comparison with FePO4 and CePO4. In order to study the promoting effects of Fe3+ ion on the NH3-SCR activity of CePO4 catalyst, various characterizations were conducted. It was found that NH3 capacity of FexCe1-x catalyst was controlled by P sites and depended on their specific surface area. Interestingly, Fe species in FexCe1-x were not a Lewis acid site for NH3 adsorption, but it could promote the activation of NH3. More importantly, Fe3+ doping could induce the redox equilibrium of Fe3+ + Ce3+ ⇆ Fe2+ + Ce4+, which significantly improved redox properties of CePO4 catalyst. Accordingly, improved catalytic activity of FexCe1-x catalysts could be attributed to the collective effects of the higher surface area, better redox properties and easily activated NH3. Among them, superior redox property of FexCe1-x catalysts was the main reason boosting their high catalytic activity. Finally, the reaction process analyzed by in situ DRIFT proposed that the NH3-SCR reaction over CePO4 and FexCe1-x occurred mainly via Eley-Rideal mechanism. We anticipated this work could promote the development of novel NH3-SCR catalyst. Graphical abstract