Journal of hazardous materials letters最新文献

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.

Breakpoint chlorination, an important chemical process relevant to chlorine-based advanced oxidation processes for potable reuse and to traditional water treatment, was investigated for its oxidative capacity, generation of reactive species, and potential impacts on organic contaminant degradation. This work describes a newly recognized HO^• radical generation pathway during breakpoint chlorination that may play an important role in water treatment and examines the behavior of the HO^• radical and other related reactive species and their potential formation pathways. Experimental data showed that the removal of 1,4-dioxane (1,4-D) positively correlated with chlorine-to-ammonia molar ratio until a molar ratio of ~1.5–2.0 was reached, above which removal efficiency rapidly decreased. Peroxynitrite (ONOO^–) and peroxynitrous acid (ONOOH) are proposed as important radical sources that lead to the formation of HO^• in the breakpoint process. This is supported by application of tert-butanol as a selective HO^• scavenger and the observation that the amendment of reaction solutions with carbonate species suppressed oxidative capacity to a much greater extent than expected based solely on scavenging of HO^• by H₂CO₃ * /CO₂ and HCO₃^– (apparently due to selective scavenging of ONOOH/ONOO^– by dissolved CO₂). These experiments also provided evidence that reactive species other than HO^• contributed to 1,4-D oxidation. The results of this study suggest that breakpoint chlorination can lead to significant degradation of organic contaminants via ONOOH/ONOO^–-mediated formation of HO^• and other reactive species and may potentially be optimized for enhanced removal of recalcitrant organic contaminants in the context of water reuse, though with due caution to the potential for enhancement of nitrogenous and other disinfection byproduct formation under such conditions.

In recent decades, antibiotic resistance (AR) has become a public health concern fuelled by increasing antibiotic consumption in many societies. Aquatic environments play a crucial role in AR development and spread where they receive antibiotics, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from a number of sources such as agriculture, aquaculture and wastewater treatment plants. Modelling is an increasingly important approach to understanding AR in aquatic environments and helps identify resistance patterns of emerging concern, evaluate fate and transport, and assess infection risks as well as look into their management in the future. However, current water quality models need to be improved to deal with the development and spread of AR. Prioritising the development of fate and transport models for AR could provide insights into bacterial evolution and help manage environmental pollution. This article provides a conceptual water quality modelling framework through a concise review of methods and approaches that can be used to model and evaluate AR in aquatic environments at the watershed scale. The key steps that need to build a framework include identifying sources and loadings, modelling the fate and transport of ARB and quantifying associated risks to humans and animals. Developing modelling scenarios and management strategies based on the framework could also contribute to achieving Sustainable Development Goals 3 (good health and well-being) and 6 (clean water and sanitation).

Environmental biomarkers represent an emerging tool in environmental monitoring by measuring variations in cellular or molecular exposure to chemical pollutants. Carbonic anhydrase, a widespread enzyme in organisms, has the potential to be utilized as a biomarker because of its sensitive activity to chemical pollutants. Here, we report the first extracellular carbonic anhydrase (EcaA) from cyanobacteria as a biomarker for monitoring antibiotics. A recombinant microbial factory that is capable of heterologously overexpressing EcaA was constructed, and the purified enzyme exhibited superior performance in monitoring various antibiotics in vitro. The IC₅₀ values of the four selected antibiotics, ciprofloxacin, spectinomycin, tetracycline and ampicillin, were 1.45 ± 0.61, 10.40 ± 0.34, 18.92 ± 2.42 and 59.73 ± 2.56 μM, respectively. The feasibility of EcaA as a biomarker for monitoring antibiotics in vivo was also confirmed. Growth of wild-type cyanobacteria was more inhibited by ciprofloxacin and tetracycline than an EcaA-null mutant, demonstrating that EcaA responded physiologically to the two antibiotics, thus causing growth defects. Our results enable advanced development and optimization of carbonic anhydrase as a biomarker to monitor antibiotics in vitro and in vivo.

Hurricanes and extreme stormwater events can transport fecal contaminants and a wide range of bacterial pathogens to receiving rivers and streams, threatening public health. This study investigated the impact of flooding on bacterial diversity and the occurrence of fecal and potential bacterial pathogens in Texas Rivers over a short (3 weeks and 3 months) and long time (12 months) after Hurricane Harvey. Water samples were collected from 8 sampling sites of Guadalupe and San Antonio Rivers during three sampling events and bacterial community structure was evaluated using next-generation sequencing (NGS). Results showed that Proteobacteria, Actinobacteria, Bacteroidetes, and Cyanobacteria were the predominant phyla in the water samples. Hierarchal cluster analysis and principal coordinate analysis indicated that bacterial community structure was significantly different in the water samples collected from flooded and non-flooded sites. At genus level, eight fecal-associated and twelve potentially pathogenic bacterial genera were detected in water samples, mainly from flooded sites collected during short-term sampling events. Overall, results suggest that NGS-based microbial water quality monitoring of environmental samples after flooding events could provide critical information about the wide range of pathogens, which can be further assessed by specific methods to identify the risk of exposure.

Chemical warfare agents (CWAs) pose a significant threat to humans because of their high toxicity. Zirconium-based metal–organic frameworks (Zr-MOFs) are promising candidates for the purification and detoxification of CWAs. In this study, we prepared a Zr₆O₄(OH)₈(H₂O)₄(abtc)₂ denoted to Zr-abtc (abtc = 3,3′,5,5′-azobenzene-tetracarboxylate) under eco-friendly hydrothermal reflux conditions and investigated its detoxification performance. Dimethyl methylphosphonate (DMMP) was used as a simulant of a nerve agent to evaluate the adsorption performance of Zr–abtc. The Zr–abtc MOF was constructed from an 8-connected Zr₆ cluster [Zr₆(µ₃-O)₄(µ₃-OH)₄] with abtc as a linker, resulting in the generation of abundant surface hydroxyl groups, high porosity, and remarkable structural robustness under high moisture and high temperature conditions. The results of the breakthrough (BT) test of DMMP under dry and humid conditions reveal that Zr–abtc displays high DMMP adsorption performance with the adsorption capacity of 1.74 and 1.60 mmol/g under dry and humid condition, respectively. The high performance of Zr–abtc can be attributed to not only the strong interaction between the surface hydroxyl group of Zr–abtc MOF and DMMP but also the catalytic activity of the surface hydroxyl group to form the decomposed product of DMMP, as demonstrated using Fourier transform infrared spectroscopy (FTIR).

Historical use of per- and polyfluoroalkyl substances (PFAS) at firefighting training grounds (FTGs) has prompted questions regarding possible PFAS retention within concrete and subsequent releases to the environment. This investigation seeks to better understand the release of five PFAS from concrete cores collected from a legacy FTG. The vertical profile of cores were assessed, then surface ponding and rainfall simulations were conducted on the cores. Perfluorooctane sulfonate (PFOS) had the highest concentrations in both the core (up to 10,000 μg kg⁻¹) and in ponded water on their surface (up to 100 μg L⁻¹), followed by 6:2 fluorotelomer sulfonate (6:2 FTS) and perfluorohexane sulfonate (PFHxS). The maximum concentrations of PFAS in runoff water of five rainfall simulations were similar, suggesting recurring release of PFAS from AFFF impacted concrete, which could be sustained by upward transport of PFAS in the concrete subsurface layers through a potential “wicking” effect. The estimated mass of PFAS released during a simulated rainfall of 60 mm was approximately 1% of the total PFAS mass estimated within the top 1 cm of the concrete core. The results of the study suggest that concrete at FTGs may present an ongoing secondary source of PFAS in runoff water events.

Plastic waste is the biggest global problem in present times due to its constant bioaccumulation in the environment. During the last year, 367 Mt of plastics were produced in the world, of which 28.6 Mt correspond to polyurethane waste. Polyurethanes can be found in products such as adhesives, preservatives, and foams, and are often difficult to recycle. The fragmentation of plastic waste in the environment generates microplastics causing a long-term effect on our ecosystem. In search of its solution via bioremediation using enzymes, in our present study cutinase enzyme has been chosen, as it appears to be a novel candidate due to the wide variety of substrates it hydrolyzes and its presence in different microorganisms. According to physiochemical characteristics, it was found that microbial cutinase enzymes are majorly made up of aliphatic amino acids. A higher aliphatic index (more than 80) indicates the great thermostability of the enzyme. Moreover, the enzyme is found to be hydrophilic and structurally stable. The negative GRAVY value of the enzyme confirmed its stable interaction with water. It was also observed that all chosen protein models had an average of 91.10 % amino acids in the favorable regions of the Ramachandran plot. The studied microbial cutinase enzymes from both fungi Humicola insolens and actinobacterium Thermobifida fusca successfully coupled with the polyurethane resin monomers. The main interactions were found in the catalytic triad with bonds close to the urethane bonds of the ligand, in addition to having an average binding energy of − 6 kJ/mol. The interaction between the cutinases with the PUR resin as a ligand was found to be evident from our study with stable binding energies, which makes microbial cutinases potential enzymes for polyurethane waste bioremediation processes.