Journal of hazardous materials letters最新文献

With the decommissioning of nuclear facilities, an increasing amount of radioactive graphite needs to be treated safely and effectively. In this work, microwave sintering technology was initially applied to treat simulated graphite waste. The effects of microwaves on the phase composition and microstructure of graphite were investigated. Combined with the mass loss results and fitting results of the phase, the mechanism for simulated graphite waste treatment via microwave sintering was obtained. According to the results, there are three stages regarding the effect of microwave sintering on the microstructure of graphite waste. This work reveals the potential application of microwave sintering technology in the treatment of graphite waste and its treatment mechanism.

Facing the ongoing coronavirus infectious disease-2019 (COVID-19) pandemic, many studies focus on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in indoor environment, on solid surface or in wastewater. It remains unclear whether SARS-CoV-2 can spill over into outdoor environments and impose transmission risks to surrounding people and communities. In this study, we investigated the presence of SARS-CoV-2 by measuring viral RNA in 118 samples from outdoor environment of three hospitals in Wuhan. We detected SARS-CoV-2 in soils (205–550 copies/g), aerosols (285−1,130 copies/m³) and wastewaters (255−18,744 copies/L) in locations close to hospital departments receiving COVID-19 patients or in wastewater treatment sectors. These findings revealed a significant viral spillover in hospital outdoor environments that was possibly caused by respiratory droplets from patients or aerosolized particles from wastewater containing SARS-CoV-2. In contrast, SARS-CoV-2 was not detected in other areas or on surfaces with regular implemented disinfection. Soils may behave as viral warehouse through deposition and serve as a secondary source spreading SARS-CoV-2 for a prolonged time. For the first time, our findings demonstrate that there are high-risk areas out of expectation in hospital outdoor environments to spread SARS-CoV-2, calling for sealing of wastewater treatment unit and complete sanitation to prevent COVID-19 transmission risks.

This study, which investigated the sonodegradation of selected pharmaceutical active compounds (PhACs) (amitriptyline (AMT) and ibuprofen (IBP)) with MXene, was carried out in an aqueous solution. To investigate the practicality of the degradation process, the experiments were conducted in various water quality conditions, including pH, temperature, natural organic matter, and ionic strength. Based on the experimental results, the produced hydrogen peroxide, which could be a representative of the produced OH radicals, was a vital factor that affected the degradation performance of both PhACs. To confirm the importance of OH radicals, the effect of a OH radical promoter (H₂O₂) and scavenger (t-BuOH) was also studied. In addition, the synergism between ultrasonication (US) and MXene was evaluated with the rate constants of US only, MXene only, and a US/MXene combined system. Mineralization of the PhACs was also investigated, and removal of AMT was higher than that of IBP, which could be attributed to the physicochemical properties of the compounds and enhanced adsorption by the well-dispersed MXene. Overall, utilization of MXene by means of ultrasonication could enhance the removal performance of PhACs in water.

Fixed bed adsorption of toxic metal ions such as chromium is a research area of current interest. Mathematical models are routinely used to summarize breakthrough results of metal ions, which often display varying degrees of curve asymmetry. This work introduces the Weibull function as a simple model for correlating asymmetric breakthrough curves of chromium. The Weibull function is similar to the widely used Bohart-Adams model in several aspects. For example, they both produce sigmoid or S-shaped curves. Their simple mathematical forms can be linearized and linear regression can then be used to estimate their parameters. However, the Weibull function, unlike the Bohart-Adams model, can track the trajectory of asymmetric breakthrough data. Applying the Weibull function to published breakthrough data of chromium, this article illustrates its outright superiority versus the Bohart-Adams model in representing highly asymmetric data. Both equations provide satisfactory fits to breakthrough data exhibiting a moderate degree of curve asymmetry.

Per- and polyfluoroalkyl substances (PFAS) represent a family of emerging persistent organic pollutants. Cost-effective remediation of PFAS contamination via chemical or biochemical degradation is challenging due to their extremely high stability. This study reports the removal of two representative PFAS species, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), from water by adsorption using aluminum-based water treatment residuals (Al-WTR), a non-hazardous waste generated during the process of drinking water treatment by alum salts. Rapid adsorption of PFOA and PFOS onto Al-WTR followed a pseudo 2^nd order kinetic pattern. Lower pH facilitated the adsorption process with a faster adsorption rate and greater adsorption capacity. At pH 3.0 and an initial concentration of 1.0 mg/L, 97.4 % of PFOA and 99.5 % of PFOS were adsorbed onto Al-WTR. Adsorption isotherm modeling showed that the maximum adsorption capacities of PFOA and PFOS on Al-WTR at pH 3.0 were 0.232 and 0.316 mg/g, respectively. Desorption tests indicated that the adsorption by Al-WTR was irreversible, making Al-WTR an excellent candidate for treating PFOA and PFOS in solution. The highly encouraging results of this preliminary study indicate that Al-WTR may be a promising, viable, and cost-effective PFOA/PFOS treatment option for water reuse, industrial wastewater treatment, and groundwater remediation.

Due to an assumed lack of anionic binding sites (most plastics are non-polar), scientists long considered virgin particulate plastics inert towards metal ions. However, we proved significant metal sorption to microplastics at neutral pH and release in a solution mimicking gastrointestinal chemistry serving as a proof-of-principle for environmental and human bioavailability. Competitive ion-exchange incubation experiments comprised 55 metals and metalloids. Fast kinetics were observed with 45 %–75 % of As, Be, Bi, Cr, Fe, In, Pb, Th, Sn and the rare-earth element ions being sorbed after 1 h. The investigated metal and metalloid cations showed significant differences in the extent of sorption, based upon which a distinct categorization was possible. Microplastics are not only a potential danger for aquatic and human life, but - as demonstrated in this paper - also serve as a Trojan Horse for dissolved metal cations. The corresponding effects on aquatic and human health will gain higher importance in the near future due to the predicted increases of marine plastic litter and microplastic sorbents.

Fluoride contamination in drinking water is a global issue. Frequent over-exposure to fluoride causes several health problems such as fluorosis, neurological, thyroid, osteoporosis, etc. The guideline values prescribed by the WHO and other nationals for fluoride in drinking water are reasonable but mostly relevant to fluorosis. However, these guideline values cannot be satisfied in some regions due to economic and financial shortcomings. Several fluorosis management techniques were suggested to address excess fluoride in drinking water, but each have specific drawbacks. Defluoridation techniques like the Nalgonda technique, reverse osmosis (RO), and adsorption using activated alumina have found to be promising to reduce fluoride concentration within the prescribed limits, and RO water is most widely used for drinking in fluorosis affected regions. However, these techniques are still associated with certain drawbacks, and prior research on this theme has focused on one dimension of removing excess fluoride from water. Hence, it is essential to understand the basic problems associated with fluoride contamination, such as sources of fluoride exposure, adverse health effects and defluoridation techniques feasibility. Furthermore, perception of the effect of co-existing ions with fluoride in drinking water is crucial in deciding fluoride toxicity level and developing efficient strategies for fluorosis mitigation.

Waste generated from HIV viral load (VL) testing contains potentially hazardous guanidinium thiocyanate (GTC). GTC is toxic to humans and can pollute waters and harm aquatic life if not disposed of appropriately. We assessed gaps in waste management (WM) policies, regulations and practices through a self-assessment scorecard and an online survey questionnaire among 11 African countries participating in a laboratory systems strengthening community of practice and receiving technical assistance to scale-up VL testing. We identified solutions from national stakeholders, technical agencies, and manufacturers to inform interventions for improving WM. Nine of 11 countries did not have WM policies/guidelines in place. Most Countries reported disposing liquid chemical waste into the sewer. Nine countries prioritised the development of policies as a multi-sectoral approach in the short term. High-temperature incineration through cement factory kilns was identified as an effective, inexpensive and high-capacity disposal option for GTC-containing waste in the short term. A long-term consideration with funding from governments and donors were infrastructural investments for conventional high-temperature incineration where cement factory kilns are unavailable/inaccessible. Adequate WM of GTC-containing waste through available funding could provide the necessary impetus to establish comprehensive WM systems addressing all types of healthcare waste through a multisectoral approach.

This study investigated the mechanisms of removal of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) using polyelectrolyte (PE) functionalized ultrafiltration (UF) membranes, performed through a fluidic method of layer-by-layer (LbL) deposition of polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) multilayer coatings. The effects of source water composition (humic acids [HA] and cations [Ca²⁺ and Mg²⁺]) on PFOS and PFOA removal efficiency by the functionalized membrane were determined. PAH/PAA modification resulted in approximately 38 % and 9.2 % reduction in membrane molecular weight cut-off (MWCO) and porosity, respectively, leading to approximately 30 % increase in the removal of PFOS and PFOA primarily due to size exclusion. The presence of only HA led to 10–12 % higher removal of PFOS/A when compared to DI water; however, an increase in HA concentration did not further influence their removal efficiency. The coexistence of cations and HA resulted in significantly higher removal of PFOS and PFOA (up to 23 % higher for PFOS). Further enhancement of PFOS removal (14 % higher) was observed when cation concentrations were doubled, attributable to the interactions of PFOS/A with the source water components and the functionalized membrane, resulting in enhanced size and charge exclusion of macromolecular complexes including PFOS-cation-PFOS, PFOS-cation-HA, and PFOA-cation-HA.

Antimony (Sb) and cadmium (Cd) coexisted in urban contaminated soil due to textile printing and dyeing waste water, but the environmental risks and ecotoxicological effects they caused are poorly understood. In this study, earthworm Eisenia fetida was exposed into soil spiked with Sb, Cd and their mixture, and multiple biomarker responses (protein, malonaldehyde (MDA), metallothionein (MT), reactive oxygen species (ROS), catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and glutathione S-transferasesase (GST)) were measured to evaluate biological health status and joint effect via Biomarker rResponse Index (BRI) and Effect Addition Index (EAI). The results showed that earthworm could not accumulate Sb effectively, but Cd accumulation by earthworm indicated a well dose-response relationship between issue content and treatment level. Secondly, the protein content was overall decreased, and the contents of MDA, MT and ROS as well as the activities of SOD, POD, CAT, GST and ROS were increased, suggesting membrane lipid peroxidation and waken-up antioxidant capacity, among which GST was the most sensitive. Furthermore, severe alterations for health status were always found except under the antimony dosage of 5 mg/kg, and earthworm health status was more sensitive in presence of single Cd. According to EAI, a clear joint effect of antagonism was observed at whole range of combined treatment levels. This is a key study providing biomarker responses of soil Sb and evaluating the joint effect of Sb and Cd at different contents using earthworm Eisenia fetida, BRI and EAI.