Πέμπτη, 14 Μαρτίου 2019

Hazardous Materials

Oxidation of 2,6-di-tert-butylphenol with tert-butyl hydroperoxide catalyzed by iron porphyrin tetrasulfonate, iron porphyrin tetracarboxylate and their supported analogues in a water-methanol mixture

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Yasemin Çimen Mutlu, Tuğçe Günay Semerci, Hayrettin Türk

Abstract

In this study, two water-soluble iron porphyrins bearing sulfonate and carboxylate functionalities (FePTS and FePTC, respectively) and their supported analogues were used as catalysts for the oxidation of 2,6-di-tert-butylphenol (DTBP) in a water-methanol mixture. tert-Butyl hydroperoxide (TBHP) was the oxidant and the volume ratio of water to methanol in the mixture was 1–8. The major products of the DTBP oxidation were 3,3ʹ,5,5ʹ-tetra-tert-butyl-4,4ʹ-diphenoquinone (DPQ) and 4,4′-dihydroxy-3,3′,5,5′-tetra-tert- butylbiphenyl (H2DPQ). Also 2,6-di-tert-butyl-1,4-benzoquinone (BQ) was the minor product of the oxidation. The results showed that FePTC was more catalytically active than FePTS in the oxidation and gave the highest TON and TOF values in comparison to those for metalloporphyrin and metallophthalocyanine based catalysts in the DTBP oxidation given in the literature. In addition, the ecotoxicity tests of the DTBP oxidation mixtures before and after oxidative catalytic treatment toward Artemia salina were performed. It was found that the toxicity of the catalytically treated DTBP mixture containing residual DTBP and products was lower than the catalytically untreated DTBP mixture.



Degradation of antibiotics in multi-component systems with novel ternary AgBr/Ag3PO4@natural hematite heterojunction photocatalyst under simulated solar light

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Liwei Chen, Shengjiong Yang, Yang Huang, Baogang Zhang, Fuxing Kang, Dahu Ding, Tianming Cai

Abstract

Abatement of antibiotics from aquatic systems is of great importance but remains a challenge. Herein, we prepared ternary AgBr/Ag3PO4@natural hematite (AgBr/Ag3PO4@NH) heterojunction composite via a simple route for the photocatalytic degradation of antibiotic pollutants. By adjusting the dose of Ag species, four products with different Ag content (denoted as Ag0.5BrPFe, Ag1BrPFe, Ag1.5BrPFe, and Ag2BrPFe) were developed. Among them, Ag1.5BrPFe exhibited the best photocatalytic activity. Four antibiotics (i.e. ciprofloxacin (CIP), norfloxacin (NOR), sulfadiazine (SDZ), and tetracycline (TTC)) could be degraded with synthesized Ag1.5BrPFe in multi-component systems. Water matrix indexes including solution pH, coexisting anions, humic acids exhibited distinct effects on the degradation process. The results revealed that the degradation process was accelerated at acidic conditions while depressed at basic conditions. Superoxide radical and hole were detected by in situ electron spin resonance technique and played the dominant roles. The degradation pathway TTC was tentatively established followed with the identification of the degradation intermediates and computational analysis. This work would shed light on the photocatalytic degradation mechanism of organic pollutants by the AgBr/Ag3PO4@NH composite.

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Considerations for emission monitoring and liner analysis of thermally manufactured sewer cured-in-place-pipes (CIPP)

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Kyungyeon Ra, Seyedeh Mahboobeh Teimouri Sendesi, Md. Nuruddin, Nadezhda N. Zyaykina, Emily N. Conkling, Brandon E. Boor, Chad T. Jafvert, John A. Howarter, Jeffrey P. Youngblood, Andrew J. Whelton

Abstract

Cured-in-place-pipes (CIPP) are plastic liners chemically manufactured inside existing damaged sewer pipes. They are gaining popularity in North America, Africa, Asia, Europe, and Oceania. Volatile and semi-volatile organic compound (VOC/SVOC) emissions from storm sewer CIPP installations were investigated at a dedicated outdoor research site. Tedlar bag, sorbent tube, and photoionization detector (PID) air sampling was conducted for five steam-CIPP installations and was coupled with composite characterizations. New CIPPs contained up to 2.21 wt% volatile material and only 6–31% chemical mass extracted per CIPP was identified. Each 6.1 m [20 ft] liner contained an estimated 5–10 kg [11–22 lbs] of residual chemical. Extracted chemicals included hazardous air pollutants and suspected and known carcinogens that were not reported by others. These included monomers, monomer oxidation products, antioxidants, initiator degradation products, and a plasticizer. PID signals did not accurately represent styrene air concentration differing sometimes by 10s- to 1000s-fold. Multiple VOCs found in air samples likely affected PID responses. Styrene (>86.4 ppmv) and methylene chloride (>1.56 ppmv) air concentrations were likely greater onsite and phenol was also detected. Additional studies are needed to examine pollutant emissions so process monitoring can be improved, and environment impacts and associated human exposures can be minimized.



Single component phosphamide-based intumescent flame retardant with potential reactivity towards low flammability and smoke epoxy resins

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Rong-Kun Jian, Yuan-Fang Ai, Long Xia, Li-Jing Zhao, Hai-Bo Zhao

Abstract

To develop a low flammability and smoke epoxy resin, benzothiazole-based phosphamide (DOP-ABZ) was prepared through the reaction of 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphinane-2-oxide (DOP) and 2-aminobenzothiazole (ABZ). Intumescent flame-retardant (IFR) epoxy thermosets (EP) with different loadings of DOP-ABZ were prepared according to the assigned curing procedure. The thermal stability of IFR-EP decreased as compared to that of EP, but the flame retardancy of IFR-EP were greatly improved. EP/20 wt% DOP-ABZ passed UL-94 V-0 rating and got a high LOI value of 28.3%. Meanwhile, cone calorimeter tests showed that the heat release rate greatly decreased from 1139.7 kW/m2 of EP to 238.9 kW/m2, and the productions of smoke/toxic gases including CO and CO2 were also remarkably reduced. Furthermore, the mechanical strength of EP/17.5 wt% DOP-ABZ was enhanced to some extent, i.e. tensile strength increased from 71 MPa of EP to 81 MPa, flexural strength from 98 to 119 MPa, and impact strength from 22 to 32 kJ/m2. Finally, the flame-retardant mechanism was disclosed that DOP-ABZ produced phosphorus-containing acids so as to dehydrate and carbonize epoxy macromolecules leading to the formation of graphitized chars. Meanwhile, the nitrogen/sulfur-containing intermediates simultaneously released noncombustible gases to expand the as-formed char, and then interrupt the combustion reaction.

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Nano-ZnO impairs anti-predation capacity of marine mussels under seawater acidification

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Yueyong Shang, Xinghuo Wang, Hui Kong, Wei Huang, Menghong Hu, Youji Wang

Abstract

Artificial nanoparticles and ocean acidification (OA) caused by the rapid increase of CO2 absorbed by the ocean are both ecologically hazardous to marine organisms. The combined effects of the two environmental stressors on the anti-predation ability of marine mussels were studied. Mytilus coruscus was exposed to three different gradient concentrations of nano-ZnO (0, 2.5, 10 mg/L) in combination of two pH levels (7.7 and 8.1). The crab Charybdis japonica was used as its predator. During the experiment, anti-predator indexes, including number of byssus threads (NBT), shell-closing strength (SCS), diameter of byssus thread (BTD), length of byssus thread (BTL), cumulative length of byssus thread (CBTL) and cumulative volume of byssus thread (CBTV) were studied. The results showed that predator induced the anti-predation responses in M. coruscus, and NBT, SCS, BTL, CBTL and CBTV were significantly increased. Under the conditions of pH 7.7 and 10 mg/L nano-ZnO, NBT, SCS, BTD, BTL, CBTL, and CBTV were significantly reduced. What's more, significant interactions among pH, nano-ZnO and predator were observed in CBTL and CBTV. Therefore, the joint treatment of nano-ZnO and low pH reduces the adhesion strength of byssus thread and may increase the probability of mussels being preyed.

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New insights on the understanding of the high adsorption of bisphenol compounds on reduced graphene oxide at high pH values via charge assisted hydrogen bond

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Peng Wang, Di Zhang, Huan Tang, Hao Li, Bo Pan

Abstract

The adsorption characteristics and mechanisms of ionic organic compounds dependent on their dissociation species are still unclear, which hindered the understanding of their environmental behavior and risks. This study compared the sorption of four bisphenol compounds (BCs) on graphite adsorbents, with a specific emphasis on the roles of charge assisted hydrogen bond (CAHB). The negative correlations between the localized orbital locator integrated π over plane index and the single point adsorption coefficient Kd of the four BCs indicated that π–π interaction was an important mechanism for BCs adsorption on graphite adsorbents. Based on the speciation distribution calculation and the modeling of pH-dependent adsorption, the apparent adsorption coefficient of different species were obtained. Except for bisphenol S, the KdHA− of BC monovalent anions was 2.6 times to one order magnitude higher than that of the neutral species. According to the density functional theory (DFT) calculation, strong CAHB is expected between BC monovalent anions and graphite adsorbents, indicating that CAHB overcame the enhanced electrostatic repulsion and became the dominant adsorption mechanism. This study highlighted the importance of CAHB in the adsorption of ionic organic compounds on carbonaceous materials, which should be carefully taken into consideration for their environmental fate studies.

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Rapid microwave-assisted bio-synthesized silver/Dandelion catalyst with superior catalytic performance for dyes degradation

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Xiaoxu Lai, Ronghui Guo, Hongyan Xiao, Jianwu Lan, Shouxiang Jiang, Ce Cui, Erhui Ren

Abstract

Silver nanoparticles were synthesized under microwave irradiation, a facile and efficient way, using dandelion extract as reducing and capping agents. The as-synthesized silver nanoparticles/Dandelion compounds (AgNPs/Dandelion) were characterized by field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), Zeta potential and ultraviolet visible (UV–vis) spectroscopy. The catalytic degradation activity of AgNPs/Dandelion for Methyl orange (MO) and Rhodamine B (RhB) in the presence of NaBH4 were recorded by UV–vis spectroscopy. AgNPs/Dandelion exhibit excellent catalytic degradation activity for RhB and MO with rate constants of 0.1038 s−1 and 0.0393 s−1, respectively.



KOH-super activated carbon from biomass waste: Insights into the paracetamol adsorption mechanism and thermal regeneration cycles

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Lucas Spessato, Karen C. Bedin, André L. Cazetta, Isis P.A.F. Souza, Vitor A. Duarte, Lucas H.S. Crespo, Marcela C. Silva, Rodrigo M. Pontes, Vitor C. Almeida

Abstract

A super activated carbon (SAC) was produced by KOH-activation of a biomass waste for paracetamol (PCT) adsorption from aqueous solution and for adsorption-thermal regeneration cycles. The SAC and the regenerated SAC after five adsorption-regeneration cycles (RSAC-5th) were fully characterized by several techniques. The N2 physisorption showed that the SBET values of the SAC and RSAC-5th are remarkably different, being 2794 m² g−1 and 889 m² g−1, respectively. The XPS analysis demonstrated that the SAC surface is composed by oxygen containing-groups, whilst the RSAC-5th also presents nitrogen ones, provenient from the PCT molecules. The adsorption studies revealed that the maximum adsorption capacity (Qm) for the SAC (356.22 mg g−1) is higher than that for RSAC-5th (113.69 mg g−1). Also, the results demonstrated that the PCT adsorption is governed by both physisorption and chemisorption and the ab initio calculations showed the chemisorption mainly occurs in carboxylic groups.

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Identification of the cytochrome P450 involved in the degradation of neonicotinoid insecticide acetamiprid in Phanerochaete chrysosporium

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Jianqiao Wang, Haruka Ohno, Yuuri Ide, Hirofumi Ichinose, Toshio Mori, Hirokazu Kawagishi, Hirofumi Hirai

Abstract

We previously reported that cytochrome P450 s play critical roles in neonicotinoid insecticide biodegradation by white-rot fungi. Here, we investigated the biodegradation of acetamiprid (ACET) by Phanerochaete chrysosporium to identify the cytochrome P450 involved in this degradation process. During a 20-day incubation period, P. chrysosporium degraded 21% and 51% of ACET in ligninolytic and nonligninolytic media, respectively. The degradation rate of ACET was markedly decreased by the addition of cytochrome P450 inhibitors. Recombinant cytochrome P450s in P. chrysosporium (PcCYP) were heterologously expressed in Saccharomyces cerevisiae strain AH22, and the PcCYP involved in ACET degradation was identified. The results showed that CYP5147A3 can degrade ACET, and two ACET metabolites, N'-cyano-N-methyl acetamidine and 6-chloro-3-pyridinemethanol, were identified. To the best of our knowledge, this study provides the first characterization of the fungal cytochrome P450 that is responsible for the degradation and detoxification of ACET.



Mechanically robust high flux graphene oxide - nanocellulose membranes for dye removal from water

Publication date: 5 June 2019

Source: Journal of Hazardous Materials, Volume 371

Author(s): Peng Liu, Chuantao Zhu, Aji P. Mathew

Abstract

Ultrathin graphene oxide (GO) layer was fabricated on cellulose nanofiber (CNF) membrane to achieve robust crosslinker free layered membrane with synergistic water flux and separation performance. Unlike pristine cellulosic or GO membranes, GO-CNF hybrid membranes exhibited significantly improved mechanical stability in both dry and wet states. All membranes showed negative surface zeta potential. GO: CNF membrane (1:100) exhibited significantly high water flux (18,123 ± 574 Lm−2 h−1 bar−1); higher than that of CNF membrane or the hydrophilic commercial reference membrane with comparable pore structure (Nylon 66, 0.2 μm). We hypothyse that a unique surface structure of "standing inserted GO nanosheets" observed at low concentrations of GO contributes enormously to its ultrafast water permeability through creation of numerous water transport nanochannels. The aniosptropic layered membranes exhibited >90% rejection of positively and negatively charged dyes through a combination of electrostatic interaction, hydrophobic interactions and molecular size exclusion. Construction of an ultrathin GO layer on CNF offers a unique and efficient way to prepare highly functional, economical and scalable water purification membranes having significant advantage with respect to flux, mechanical stability and rejection of dyes compared to isotropic membrane with GO nanosheets randomly dispersed in the cellulose nanofibrous network.

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