Journal of hazardous materials letters最新文献

Microplastics have become ubiquitous on the planet and are considered one of the biggest threats to life on earth. Several recent studies have addressed the serious risks that microplastics can pose to human health. In this study, the microplastic content and spatial variations in number, size, colour, and polymers from a highly urbanized cosmopolitan, urban, and rural coastal locations of the northwest Indian coast were documented using yellow clams. The mean incidence of microplastics across all the stations among the clams is found to be one of the highest ever reported worldwide, which is 35.93 MPs items/g in soft tissue parts and 91.42 MPs items/individual. The clams were found to have a higher microplastic diversity integrated index (MDII) and Microplastic index (MPI). The majority of the microplastics observed were fibres and fragments, belonged to the size range of 1–100 µm (51.36%), and were identified as HDPE, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyamide, and polypropylene. The clam condition index (CI) was recorded high at the rural coast with lower population and lowest at the megacity having greater population which may indicate the negative effect of MPs on clams growth.

Reductive water treatment using hydrated electrons ($e_{\mathrm{aq}}^{-}$) is a promising technology to destruct perfluoroalkyl substances; however, it faces challenges of slow reaction kinetics, undesirable chemical addition, and high energy consumption. Herein, we developed a hydrogen (H₂)-polarized water photolysis system using vacuum UV (VUV) light at 185 nm for reductive destruction of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). The 185-nm photons directly photolyzed H₂O and OH^- into HO·, H·, and $e_{\mathrm{aq}}^{-}$. H₂ elevated the quasi steady-state concentration of $e_{\mathrm{aq}}^{-}$ 18 times in untuned VUV systems through eliminating the scavenging effect of dissolved oxygen and converting hydroxyl radicals (HO·/O·^-) into $e_{\mathrm{aq}}^{-}$. The polarization effect of H₂ increased the degradation of PFOA from 10 % to 95 % and the defluorination from 17 % to 94 % and led to 87 % of defluorination for PFOS. The pH impacted VUV photon adsorption between H₂O and OH^- and shifted the equilibrium between H· and $e_{\mathrm{aq}}^{-}$, which led to an optimal pH of 10.3 for PFOA destruction. The presence of chloride and sulfate enhanced the production of $e_{\mathrm{aq}}^{-}$ and promoted PFOA destruction. H₂-polarized VUV water photolysis systems produced high levels of $e_{\mathrm{aq}}^{-}$ from clean water constituents and significantly reduced energy consumption for PFAS treatment under mild alkaline conditions.

One of the greatest environmental concerns in the world is thought to be the effluents from the textile industry. The use of synthetic dyes in textiles makes the traditional method of treating textile effluents more difficult. Microorganisms can be used to remediate the damage that textile dyes do to the environment. In this investigation, two bacterial strains with the capacity of degrading dye were isolated from textile waste and identified as Pseudomonas sp. (Accession no. NR 117,678.1) and Bacillus sp. (Accession no: NR148248.1) through morphological, biochemical, and molecular test. The cytotoxicity of this wastewater on Artemia salina and phytotoxicity on Triticum aestivum were also investigated using brine shrimp lethality assay and plant growth analysis, respectively. Wheat seed germination was adversely affected by wastewater containing dyes, but subsequently germination was enhanced when the wastewater was treated by the isolated strains. Pseudomonas sp. degraded pink and green dyes more effectively than Bacillus sp., according to results of a comparison of the two bacteria's dye-degrading capacities using the spectrophotometric method. The dye degrading capacity of the bacteria was validated by the HPLC analysis. Therefore, both Pseudomonas species and Bacillus species could be used as efficient bacteria in the large-scale treatment of textile effluents.

Reductive dechlorination is a core pathway of chlorination in an anaerobic environment, which can be carried out by fermentative, methanogenic, iron and sulfate-reducing microorganisms. The present review showed the different metabolic ways of microbes with the emphasis on the anaerobic microbial dechlorination (including chemical, biological and nanotechnology-based strategies), that have been employed to mitigate the chlorinated pollutants. Chemical and nanomaterial science has made substantial advancement in several aspects of dechlorination over the past two decades, providing information about the process and the outcome of the reaction. However, these chemical processes are expensive to start with and pose ecological hazards. So, extensive research has been done to come up with eco-friendly biological alternatives). Under anaerobic conditions, dehalorespiring bacteria are capable of dechlorinating chloroethenes by mediating a stepwise replacement of chlorine with hydrogen resulting in the sequential conversion of perchloroethylene (PCE) to trichloroethylene (TCE), dichloroethylene (DCE) isomers, vinyl chloride (VC), and finally, ethane. Among many dehalorespiring bacterial isolates, only a few strains of the genus Dehalococcoides completely converted the chloroethenes to nontoxic ethane. In the paper we will, therefore, focus on this Dehalococcoides spp. Several factors influence the dechlorination activity between different dehalogenating bacteria. The vcrA and bvcA genes dechlorinate VC into ethene, which are essential for complete dechlorination. These pathways offer understanding of potential bioremediation of chlorinated aliphatic or aromatic compounds by Dehalococcoides with the likelihood of highly effective bioremediation.

Microbial electrochemical system (MES) technology has been widely investigated for organic degradation. However, the removal of recalcitrant organic contaminants containing halogen-, nitro-, or azo-groups remains a great challenge. Integrating the cathodic and anodic processes in an MES is able to improve or complete the mineralization of the target halogen-, nitro- and azo-organics via a sequential reductive and oxidative process. In this way, a cathode is used to reduce the toxic target organics, while an anode is to oxidize the residual organics from the reduction process and at the same time generate electrons to support the reduction process. This paper has provided a concise review about the sequential cathode-anode contaminant degradation in an MES and its specific mechanisms. Potential strategies to improve the MES degradation performance were discussed, mainly including the application and development of the biocatalyzed cathode as well as the optimization of the anodic operating condition and the improvement of anodic bacteria and electrode material. Perspectives on future directions were proposed and the key challenges were identified as the competitive or inhibitive influence of other compounds that could coexist in real wastewater on the target contaminants.

Mercury is a global pollutant, very dangerous for the aquatic ecosystems and for human health. The sources of mercury in the environment are either anthropogenic or natural. However, historical mining activities and current anthropogenic activities, have led to a significant increase of its level in the environment. Its removal by efficient and cost-effective technologies, is of the utmost importance in order to help restore it back towards natural levels. Here we show that a novel cellulose citrate biopolymer, produced by the reaction of cellulose and citric acid, is an efficient adsorbent of inorganic mercury with a distribution constant close to 10⁵ l/g and an estimated record high maximum adsorption capacity of 1600 mg/g. Moreover, due to the large fraction of citrate moieties on its surface, its adsorption selectivity toward inorganic mercury, is the highest after that for Pb(II), among a series of divalent heavy metals, in different aqueous matrices. Finally, cellulose citrate can be reused for several adsorption cycles by a simple regeneration process without significant adsorption performance loss.

This work aims to study the catalytic performance of Cu/Al₂O₃ catalysts in the catalytic reaction of oxidation of phenol. The addition of La and Mn to Al₂O₃ support and the calcination temperature influence on the catalytic performance and Cu leaching were studied. The addition of either La or Mn to the support triggered less Cu leaching compared to the unmodified support. The catalysts modified with Mn and calcined at 650ºC and 900 °C yielded low Cu leaching values and high phenol conversions at 120 min of reaction, achieving total consumption of H₂O₂. The catalysts prepared in the same way but modified with La and calcined at 900 °C, achieved 100% phenol conversion and higher TOC conversion. Copper leaching was higher when the support was modified with La, but improved when compared to the unmodified support, suggesting that the presence of Mn allowed a better anchoring of Cu on the support. However, this was not beneficial for the reaction since a certain amount of Cu in the homogeneous phase was required for the reaction to start. Cu-La-Al₂O₃ showed stability after consecutive reaction cycles with the corresponding calcinations in each cycle.