Hazardous Materials

Influence of red mud on mechanical and durability performance of self-compacting concrete Publication date: 5 November 2019 Source: Journal of Hazardous Materials, Volume 379 Author(s): W.C. Tang, Z. Wang, S.W. Donne, M. Forghani, Y. Liu Abstract Red mud is a hazardous waste material produced during alkaline leaching of bauxite in the Bayer process. This study proposed the use of red mud to replace fly ash in self-compacting concrete (SCC) and the influences of red mud on fresh and hardened properties, and durability performances of SCC were studied. The fresh concrete results show that red mud had a slight negative impact on the fresh properties of SCC. The hardened concrete results show that the mechanical strength of concrete increased with increasing of red mud content. The half-cell potential test results indicated that red mud had a significant effect on restraining the corrosion process in SCC. Compared to the control sample, the red mud samples suffered less corrosion. Cracks associated with corrosion of reinforcement were observed in RMC0 and RMC100 samples after 28 day accelerated corrosion test. The ICP-MS results showed that there's no significant difference in metal elements among the solutions regardless the red mud content in concrete.The relative corrosion rate test results suggested that red mud can suppress the corrosion current. The SCC samples consisting 75% red mud performed the best resistance to corrosion according to the results of half-cell potentials and mass loss of rebar.

Butylated hydroxyanisole isomers induce distinct adipogenesis in 3T3-L1 cells Publication date: 5 November 2019 Source: Journal of Hazardous Materials, Volume 379 Author(s): Zhendong Sun, Xiaoxi Yang, Qian S Liu, Chuanhai Li, Qunfang Zhou, Heidelore Fiedler, Chunyang Liao, Jianqing Zhang, Guibin Jiang Abstract Butylated hydroxyanisole (BHA) isomers, as the widely used anthropogenic antioxidants in food, have been revealed to induce endocrine disrupting effects, while the mechanism how BHA isomers regulate the lipogenic differentiation remains to be elucidated. Using 3T3-L1 differentiation model, the effects of BHA isomers, including 2-tert-butyl-4-hydroxyanisole (2-BHA), 3-tert-butyl-4-hydroxyanisole (3-BHA) and their mixture (BHA), on adipogenesis were tested. The results showed that 3-BHA and BHA promoted adipocyte differentiation and enhanced the cellular lipid accumulation through the regulation of the transcriptional and protein levels of the adipogenetic biomarkers, while 2-BHA had no effect. The effective window for 3-BHA induced lipogenesis was the first four days during 3T3-L1 differentiation. BHA isomers showed no binding affinities for peroxisome proliferator activated receptor γ (PPARγ). Instead, the upstream of PPARγ signaling pathway, i.e. the phosphorylation of cAMP-response element binding protein (CREB), upregulation of CAAT/enhancer-binding proteins β (C/EBPβ) and elevated cell proliferation during postconfluent mitosis stage were induced by 3-BHA exposure. Altogether, this study revealed the adipogenic effect of 3-BHA through interference with the upstream events of the PPARγ signaling pathway. The authorized usage of BHA as food additives and its occurrence in human sera can potentially contribute to the incidence of obesity, which is of high concern. Graphical abstract

Porous NiFe-oxide nanocubes derived from prussian blue analogue as efficient adsorbents for the removal of toxic metal ions and organic dyes Publication date: 5 November 2019 Source: Journal of Hazardous Materials, Volume 379 Author(s): Yi Xie, Changlun Chen, Xirui Lu, Fen Luo, Chengming Wang, Ahmed Alsaedi, Tasawar Hayat Abstract A novel porous NiFe-oxide nanocubes (NiFe NCs) binary material was successfully fabricated via a facile and scalable tactic, which involved a morphology-inherited heat treating of Ni3[Fe(CN)6]2·xH2O prussian blue analogue nanocubes as self-sacrificial templates. Consequently, it was demonstrated that the NiFe NCs consisted of primary nanostructure units and interconnected pores, with an average size of ˜80 nm. When employed as adsorbents, the as-prepared NiFe NCs displayed remarkable adsorption capacities for heavy metal ions (232.3 mg g−1 for As(V) and 350.71 mg g−1 for Cr(VI)) and organic dyes (284.99 mg g−1 for XO and 31.97 mg g−1for CR at 298 K). The resulting NiFe NCs further revealed efficient regeneration and reusability even after five consecutive adsorption/desorption cycles. The microscopic spectrum analysis demonstrated that the interaction between As(V) and NiFe NCs was mainly ascribed to the metal-oxide bonds (MO) and hydroxyl groups (OH), while Cr(VI) adsorption was in conjunction with the reduction reaction of Cr(VI) to Cr(III). Furthermore, the adsorption of organic dyes on NiFe NCs depended on the pore structure and molecule sizes of the organic dye molecules. These findings make cost-efficient NiFe NCs materials a powerful candidate for remediating water contaminated with inorganic and organic contaminants. Graphical abstract

Experimental study on thermal structure inside flame front with a melting layer for downward flame spread of XPS foam Publication date: 5 November 2019 Source: Journal of Hazardous Materials, Volume 379 Author(s): Shengfeng Luo, Qiyuan Xie, LiangJun Da, Rong Qiu Abstract Thermal structure inside flame front during downward flame spread was experimentally measured for XPS foam with thicknesses of 1.6, 2.4, 3.4, and 4.4 cm. The temperature distribution and temperature gradient in the condensed phase, as well as the shape of the molten liquid, were obtained by 2-D heat transfer equations and experimental measurement. The results show that both the temperature and its temperature gradient decrease from the sample surface to the inside of the condensed phase, which results in the inclination of the melting interface. The molten layer is the thinnest near the sample surface and thicker inside the condensed phase. The adhering of the molten liquid to the wall greatly increases the thickness of the molten layer near the back wall, and the higher the thickness, the more molten material adheres to the wall. Finally, there is a relatively flat solid-liquid interface near the sample surface and a large inclined solid-liquid interface near the back of the sample, especially for the thicker samples of 3.4cm and 4.4cm. It is indicated that the distribution of the molten layer in the direction perpendicular to the plane of the XPS sheet is a significant factor for dripping and collapsing.

Electrochemical degradation of oxalic acid over highly reactive nano-textured γ- and α-MnO2/carbon electrode fabricated by KMnO4 reduction on loofah sponge-derived active carbon Publication date: 5 November 2019 Source: Journal of Hazardous Materials, Volume 379 Author(s): Yu-Jen Shih, Chin-Pao Huang, Ya-Han Chan, Yao-Hui Huang Abstract Manganese dioxide incorporated activated carbon (MnO2/AC) was synthesized and used to electrochemically degrade oxalic acid in aqueous solutions. The highly porous carbon provided reactive sites for the electro-sorption of oxalic acid and MnO2, with a specific polymorphism efficiently mediating the electron transfer between the electrode and organic pollutants. The activated carbon, made from the pyrolysis of dry loofah sponge using ZnCl2 as activating agent, exhibited a high double-layer capacitance dependent upon the heating temperature (100 F/g at 800 °C). The γ-MnO2 was in-situ deposited over the microporous structure of activated carbon through the redox reaction between KMnO4 and carbon. Simple further calcination converted γ-MnO2 to α-MnO2 nano-whisker at temperatures above 500 °C. Cyclic voltammetry showed that oxalic acid significantly improved the anodic current of the Mn(III)/Mn(IV) redox couple on the MnO2/AC electrode at an electrode potential around + 0.6 V (vs. Ag/AgCl). About 95% of oxalic acid degradation was achieved at pH < 4; meanwhile, 80% of the mineralization (total organic carbon removal) was attained independent of pH. Calcination converted γ-MnO2 to α-MnO2 which had higher electrochemical stability and inhibited the dissolution of Mn(II) from the electrode. Graphical abstract

Promoting Fe3+/Fe2+ cycling under visible light by synergistic interactions between P25 and small amount of Fenton reagents Publication date: 5 November 2019 Source: Journal of Hazardous Materials, Volume 379 Author(s): Lijie Xu, Liang Meng, Xiaoxiao Zhang, Xiang Mei, Xuewen Guo, Wei Li, Ping Wang, Lu Gan Abstract Merits of adding P25 to homogeneous photo-Fenton-like process (ph-F) were evaluated under visible light using Bisphenol A (BPA) as a model pollutant. Interactions between P25 and Fe3+/H2O2 were emphasized. Results show that adsorption of Fe(III) on P25 produced redshift of light absorption, and interactions between P25 and H2O2 promoted photoelectron generation, effectively introducing visible light into ph-F. The visible-light-driven ph-F demonstrated adequate performance at high Fe3+/H2O2 dosage, while P25 addition showed significant acceleration of BPA degradation with saving amount of Fe3+/H2O2. The mechanism was confirmed to be enhanced Fe3+/Fe2+ cycling by photo-electrons, particularly pronounced at low [Fe(III)]. Additionally, H2O2 was utilized more efficiently in P25-ph-F than that in ph-F by diminishing the radical scavenging role of H2O2 at lower [Fe(III)]. Kinetics and ESR analysis supported this mechanism. Compared to ph-F, the P25-ph-F process also demonstrated stronger potentials in degrading BPA at high concentrations and better mineralization capability with reduced Fe3+/H2O2 reagents. The sustainability of P25-ph-F was also examined in regard to its advantage under sunlight and the strong recyclable and reusable capability. BPA decomposition was dominated by •OH attack at both the aromatic ring and the connecting carbon, and P25-ph-F was more competent in transforming the primary intermediates than ph-F. Graphical abstract

Influence of dissolved organic matter components on arsenate adsorption/desorption by TiO2 Publication date: 15 October 2019 Source: Journal of Hazardous Materials, Volume 378 Author(s): Meijie Ren, Guangfei Qu, Heng Li, Ping Ning Abstract The influences of different dissolved organic matter (DOM) components and ionic matters on As(V) adsorption/desorption behavior on the TiO2 surface were investigated. The results demonstrated that the characteristics and involving order of DOM significantly affected the As(V) adsorption/desorption behavior. The presence of DOM decreased the As(V) adsorption quantity. Fulvic acid (FA) exhibited the most negative effect, and followed by the order of alginate ≈ BSA > SDBS. The precomplexation DOM prevented more As(V) adsorption. While, the presence of DOM caused more As(V) release when the surrounding changed and FA exhibited the strongest effect. The results indicated that the site competition and electrostatic repulsion were the major mechanisms to resist As(V) adsorption. The presence of Fe3+ and Ca2+ increased As(V) adsorption by bridge effect, while PO43− and CO32− decreased As(V) adsorption owing to the competition. Graphical abstract

Biodegradability and ecological impacts of polyethylene-based mulching film at agricultural environment Publication date: 15 October 2019 Source: Journal of Hazardous Materials, Volume 378 Author(s): Lijun Hou, Jiao Xi, Xiaotian Chen, Xuewen Li, Wen Ma, Jike Lu, Jing Xu, Yan Bing Lin Abstract Discarded Polyethylene (PE) mulches have posed a persistent pollution in the agricultural field. Although PE degraded by microbes has been reported, the effect on in situ soil environment is not completely understood. To determine the biodegradability and ecological impacts of PE-based mulches, we tested the biodegradation related properties of screened strains and analyzed change in soil quality and microbial community after covering with different mulches. Strain Bacillus aryabhattai 5-3 showed 3.85 ± 0.50% gravimetric weight loss after a 30 days incubation with PE-based mulch as the sole carbon source; Considerable pits and vast cavities were found on the surface using AFM and SEM. The hydrophobicity of mulch sheet was decreased to 68.9 ± 0.8°, FTIR identified that new oxidized groups were formed on the surfaces of incubated mulch. Additionally, the fluctuations of microbial communities indicate that synthetic mulch could replace the current commercial product to minimise agricultural pollution. Graphical abstract

Adsorptive removal of nitroimidazole antibiotics from water using porous carbons derived from melamine-loaded MAF-6 Publication date: 15 October 2019 Source: Journal of Hazardous Materials, Volume 378 Author(s): Mithun Sarker, Subin Shin, Sung Hwa Jhung Abstract Nitrogen-containing carbons were obtained via pyrolysis of melamine-loaded metal azolate frameworks (named mela@MAF-6), a sub-class of metal organic frameworks. The porosity and defect concentration of the obtained carbons (named as CDM@M-6) were dependent on the quantity of melamine loaded in the mela@MAF-6. The CDM@M-6 s were applied for the adsorptive removal of nitroimidazole antibiotics (NIABs) from water; the performance of CDM@M-6, particularly CDM(0.25)@M-6, was outstanding for the elimination of NIABs such as dimetridazole (DMZ), metronidazole (MNZ), and menidazole (MZ)) from water. The adsorption capacity of CDM(0.25)@M-6 for DMZ, MNZ, and MZ was higher than that of any adsorbent reported so far. The highest adsorptive performance of CDM(0.25)@M-6 for DMZ (Q0: 621 mg/g) and MNZ (Q0: 702 mg/g) was explained by hydrogen bonding, where CDM@M-6 and DMZ/MNZ acted as a H-donor and H-acceptor, respectively. In addition, CDM(0.25)@M-6 could be regenerated via ethanol washing and reused for next cycles without any severe decrease in performance. Therefore, CDM@M-6 is recommended as a suitable adsorbent for the elimination of NIABs from water. Graphical abstract

Assessment of harmfulness and biological effect of carbon fiber dust generated during new carbon fiber recycling method Publication date: 15 October 2019 Source: Journal of Hazardous Materials, Volume 378 Author(s): Akihiro Moriyama, Takema Hasegawa, Chisato Nagaya, Kazuhiro Hamada, Takehiro Himaki, Mami Murakami, Masanori Horie, Junko Takahashi, Hitoshi Iwahashi, Hiroshi Moritomi Abstract Concern over the effects of nanomaterials on human health has risen due to the dramatic advances in the development of various technologies based on nanomaterials. Gifu Prefecture and Gifu University are developing technologies for recycling used carbon fiber because the waste disposal process is highly cost and energy intensive. However, generation of carbon fiber dust during the recycling process is a serious issue, especially in the occupational environment. Recycling requires carbonization by partial firing treatment at 500℃ followed by firing treatment at 440℃: these processes produce dust as a by-product. It is important to study the influence of carbon fibers on human health at a molecular level. In this study, three types of carbon fibers - before recycling, after carbonization, and after firing were evaluated for their toxic effects on mice. During the breeding period, no loss in body weight was confirmed. Further, by staining the lung tissue sections, it was found that pulmonary fibrosis did not occur. We found that these carbon fibers might not possess severe toxicity. However, we also found that the toxicity varies according to firing treatment. Furthermore, we found that firing treatment reduces the potential hazard to human health.

Alexandros Sfakianakis
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