Journal of hazardous materials letters最新文献

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.

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.

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.

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.

Effective removal of contaminants of emerging concern (CECs) from water via adsorption requires adsorbent materials that showcase a synergistic combination of textural properties, hydrophobicity, and specific surface interactions. In this work, we present a hierarchical composite prepared on the basis of in-situ or confined growth of a faujasite zeolite (FAU) within the voids of a 3D mesoporous ordered carbon (3DOm). This adsorbent was tested for the removal of several CECs (i.e., caffeine, carbamazepine, naproxen and metabolites clofibric acid, 10,11-epoxy-carbamazepine, o-desmethyl naproxen, paraxanthine, and salicylic acid) from water at ambient conditions. Upon inclusion of copper(II) extra-framework cations, the hierarchical composite (Cu-3DOm-FAU) excelled at adsorbing ionic CECs and offered similar uptake capacity toward neutral parent compounds in both single- and multi-component fashion and while covering a μg L⁻¹ - mg L⁻¹ concentration range. Compared to other adsorbents reported so far in the literature, the Cu-3DOm-FAU composite adsorption capacities were larger, in many cases by at least one order of magnitude. Given the substantial thermal stability of the composite, regeneration could be accomplished via thermal cycling also depending on the type of CEC involved.

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.

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.

Microplastics contamination has been widely reported in filter feeders yet the < 1 μm size fraction has been largely ignored. In attempt to characterize this sub 1 μm size fraction and better understand the size distribution of microplastics contamination in filter feeders, field deployed oysters were characterised using a combination of size fractionation combined with pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) as well as Fourier Transform-Infrared Spectroscopy (μFT-IR). Sequential filtration followed by Py-GC/MS identified the 1–22 μm fraction to contain the highest total plastic mass concentration (Ʃ31 mg/g), followed by the <1 μm fraction (Ʃ7.7 mg/g) and the >22 μm fraction (Ʃ0.1 mg/g). μFT-IR identified 0.2 particles/g tissue but was limited to particles >150 μm in size. Our results clearly show that an important size fraction of microplastics is being overlooked in almost all studies published to date that rely on FTIR for polymer identification.

Disinfection by-products (DBPs) are important environmental contaminants that have documented human health issues from many epidemiologic studies. Unlike classical contaminants, they are not manufactured, but form during drinking water treatment. As a result, they can be difficult to identify because most are not present in the mass spectral library databases. This perspective article presents lessons learned over the years for tackling unknown DBPs, many of which can also be applied to the identification of other unknown environmental contaminants. These lessons include: the importance of high resolution mass spectrometry, confirming tentative identifications with authentic chemical standards, considering possible isomers with unknown identification, and using multiple analytical techniques to enable a more complete picture of unknowns; understanding that features are not chemical structures; recognizing when the structure you identified in a solvent extract may not be the original form of the chemical in water; how some of our best discoveries are by accident; and finally, the “so what” question—is the compound you identified a concern?