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Removal of monomeric siloxanes from water via adsorption poses a significant challenge, particularly during water reclamation in closed-volume systems. In this study, both faulted and faultless variants UTD-1 pure silica zeolites with a DON-type framework were considered for the removal of monomethylsilanetriol (MMST), dimethylsilanediol (DMSD), and trimethylsilanol (TMS), in single- and multi-component fashion. The results showed that UTD-1faulted exhibited the largest adsorption capacity for TMS, with a maximum adsorption uptake of 73.1 mg g−1 in the 1 to 140 mg L−1 aqueous concentration range. This is 7× larger than UTD-1faultless and at least one magnitude larger than other materials such as activated carbon. The interaction of TMS with UTD-1faulted is mainly with OH groups from siloxy-related faults present in the material, and multicomponent adsorption tests showed that TMS helps to drive the uptake of other siloxanes via co-adsorption. UTD-1 is a promising material platform for developing adsorption-based strategies for removing persistent monomeric siloxanes from aqueous environments.

The relationship between endemic sheep fluorosis and coal mining and combustion in Helan Mountain, Ningxia, China, is lacking clear research and understanding. A total of 137 samples of topsoil and grass were collected in this area and fluorine, sulfate, and pH levels were determined. The mean fluorine content in topsoil is 707 ± 126 μg g−1 (n = 77), which is significantly higher than that of standard Chinese topsoil. The mean fluorine content of pasture is 218 ± 42 μg g−1 (n = 28), which suggests that sheep fluorosis may be associated with high fluorine levels in topsoil and pasture. Sulfate content in topsoil is 1771 ± 130 μg g−1 (n = 77) and pH is 5.92 ± 0.82. The pH and sulfate content of acidic topsoil are positively correlated (r = 0.72), which implies that the acidity may be due to the presence of acidic sulfates, such as NaHSO4 or KHSO4. High fluorine, sulfate, and acidity may be connected with the long history of coal mining, coal use, and coal combustion, where deposition of fluoride results in coexistence with acidic sulfate.

Cheese making and vegetable processing are vital industries worldwide, but their operations generate billions of liters of wastewater annually that must be managed in an environmentally safe yet cost-effective manner. For small to medium sized facilities or those without access to wastewater treatment plants, land application systems are commonly utilized. These systems rely primarily on plant uptake and denitrification to remove nitrogen (N) from the effluent. Quantification of soil denitrification is difficult because of the challenges in differentiating between the N2 produced by microbial soil action and atmospheric N. At the behest of industry and regulators, we developed a full N mass balance for six industry facilities to evaluate their systems effectiveness in protecting local water resources. A fully automated acetylene inhibition technique (AIT) soil gas collection system was deployed at each site over two years. These data combined with effluent parameters, lysimeter and plant uptake data and continuously collected soil parameter data allowed mass balance calculation. A laboratory-based soil incubation study provided correction factors for known AIT limitations and evaluation over a greater temperature range. Lab study results indicate that the AIT underestimates system denitrification by 12.4× in the wetland-like cheese making treatment systems and 4.4× in the managed grassland vegetable processing treatment systems. While the wide variability between system performance limits method application at a single facility for short time periods, average values are indicative of general system design performance and utility in wastewater treatment when highly engineered options are unavailable or cost prohibitive.

Road dust and stormwater runoff are significant pathways for transporting microplastics (MPs) from land-based sources to the surrounding ecological compartments. The aim of this study is to understand the occurrence of MPs in both road dust and stormwater samples collected under various land uses, including residential, commercial and industrial areas, within Melbourne metropolitan city, Australia. This study also evaluated the ecological risk indices of MP polymers under different land uses. MP emission characteristics and loads (number- and mass-based) were estimated to investigate pollution risks. Higher quantities of MPs were detected in road dust and stormwater in industrial areas (2410 items per kg and 35 items per L) than in commercial (2130 items per kg and 27 items per L) and residential (1970 items per kg and 24 items per L) areas. Mass loads of MPs were also higher in industrial regions in road dust and stormwater samples. It was found that 200 μm to 2450 μm sized MPs were abundant in road dust, which was higher than the sizes of stormwater MPs (125 μm to 960 μm). The water forces in the drainage system could be the reason for the breakdown of larger MPs. Fragments and fibers were the dominant shapes of MPs in all the selected areas. Fourier transform infrared spectroscopy of representative samples identified several types of polymers, predominantly polypropylene, polyethylene, polyethylene terephthalate/polyester, polyvinyl chloride and polyethylene. The hazard index indicates that the ecological risks of MPs are higher in industrial areas than in other areas. This study revealed that MP emission via road dust was significantly higher due to traffic and industrial and human activities. This study has demonstrated that stormwater runoff is the primary corridor for transporting MPs from road dust to the aquatic environment of wetlands.

Sampling, separation, detection, and characterization of micro- and nanoplastic pollutants is a critical goal to assess their amount, fate, and the related hazards for ecosystems. There is still a major lack of understanding of the most relevant mechanisms of interaction and exchange of this class of pollutants with the environment and with organisms. In the last few years a number of studies highlighted the importance of the evaluation of the chemical species associated with the presence of microplastics in the environment, such as plasticizers, low-molecular weight degradation products, and different kinds of organic contaminants. In this work we combined microwave-assisted extraction and digestion, together with analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS), to quantify microplastics together with different classes of associated pollutants. This method was developed using mussels as a matrix and it can be potentially applied to characterize and quantify, together with microplastics, polymer additives (phthalate plasticizers, UV stabilizers, etc.), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and emerging contaminants like anti-inflammatory drugs. This method allowed the quantification of more than 40 different contaminants in a single chromatographic run, with recoveries higher that 87% in most cases and limits of detection/quantitation in the nanogram range. The method was also tested on a standard microplastic calibration mixture containing 11 different polymers, and recoveries higher than 84% were obtained in most cases.

Developing the diverse chemical properties and expanding the catalytic performance of boron nitride (BN) materials remains a formidable challenge although it has long been a hot topic of research. Optimizing the electronic configuration of BN is implemented by incorporating heteroatomic carbon, which endows modified BN with features in terms of visible-light response, highly efficient charge separation and available surface-active sites. In addition, it was also found that the introduction of carbon also enhanced the adsorption and activation of BN on reactant molecules using diffuse reflection infrared Fourier transformation spectroscopy (DRIFTS), temperature-programmed desorption (TPD) and electron paramagnetic resonance (EPR) spectroscopy. As expected, carbon-doped boron nitride (BCN) shows remarkable performance in the photocatalytic removal of hydrogen sulfide (H2S) and nitric oxide (NO). The optimized BCN sample exhibits 99% and 60% of the photocatalytic removal efficiency for 20 ppm H2S (Flow velocity, 20 mL min−1) and 1 ppm NO (Flow velocity, 500 mL min−1), respectively. This work provides insight into the design of functionalized BN and an exciting approach to handling low-concentration acidic gases.

A graphical abstract is available for this content

A graphical abstract is available for this content

Development of heterogeneous catalysts that are active in the visible light region is important for realizing the dream of using sunlight for effecting chemical transformations to achieve sustainability. In this work, conducting polymer (CP) and bismuth oxyiodide (BiOI) based Z-scheme nanocomposites were prepared at room temperature. The nanocomposite formation was confirmed by various analytical techniques. In comparison to pure BiOI and Fe-nPPy, the nanocomposite Fe-nPPy/BiOI-3 showed significantly enhanced activity for the photocatalytic degradation of crystal violet (CV) dye when exposed to visible light. Moreover, the photocatalyst was versatile for photocatalytic environmental remediation as it could also degrade pharmaceutical pollutant tetracycline (TC). The physical as well as optical properties of the prepared materials were thoroughly characterized. Proper alignment of band edge potential and better interfacial contact between Fe-nPPy and BiOI, reduces charge recombination in the nanocomposite and enable their better utilisation for the photocatalytic degradation reaction. Furthermore, the photogenerated electrons were found to be the primary reactive species responsible for the degradation process, as per radical trapping experiments.

MIL-88-A, an iron-based metal–organic framework (MOF), was synthesized and investigated for its potential as a mediator in a solar-powered system for the activation of persulfate (PS). Solar/MIL-88-A/PS and UVA/MIL-88-A/PS systems were evaluated for the degradation of naproxen (NAP) in water. Control experiments were conducted to study the activation of PS by MIL-88-A in the absence and presence of either UVA lamps or sunlight. Both systems were optimized and tested for their recyclability and matrix variations by varying water-quality parameters, including pH, salinity, bicarbonates, and phosphates. The results indicated that (i) 87% of NAP ([NAP]0 = 50 mg L−1) was degraded within a period of 100 min in UVA/MIL-88-A/PS system, whereas complete degradation occurred in 10–15 min in solar/MIL-88-A/PS system; (ii) MIL-88-A can be recycled over five cycles for PS activation without any regeneration process; and (iii) carbonates and phosphates have inhibitory effect on the degradation of NAP in both systems. The degradation mechanism was elucidated using EPR, TOF-SIMs, and HPLC-MS, which revealed that the degradation mechanism is based on oxidation by hydroxyl (HRs) and sulfate radicals (SRs). Three NAP degradation products were identified using an HPLC-QTOF high-resolution mass spectrometer.

This paper presents the use of four machine learning algorithms including Gaussian process regression (GPR), random forest (FR), extreme gradient boosting (XGB) and light gradient boosting machine (LightGBM) to predict the concentration of total suspended solids (TSS), chemical oxygen demand (COD), and biochemical oxygen demand (BOD) in the effluent of the Gaza wastewater treatment plant one day ahead. Data was collected from 360 wastewater samples taken from the Gaza wastewater treatment plant, and five input parameters were used in the proposed method: pHinf, temperature (Tempinf), BODinf, TSSinf, and CODinf. Four error measures were used to evaluate the prediction accuracy of the models. Results showed that the GPR model in the testing datasets is the best predictive model for predicting the effluent's TSS, COD and BOD with the best accuracy in relation to the correlation coefficient (CC), that is, (0.964–0.950–0.975) against RF (0.932–0.910–0.943), XGB (0.916–0.901–0.954), and LightGBM (0.890–0.892–0.883). The importance of input parameters was assessed, and temperature and pH were found to be the most important parameters in wastewater quality predictions using these four models. The study concluded that GPR is the most representative model. The model may help users in selecting optimal wastewater treatment based on original characteristics and standards.

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Anaerobic digestion (AD) is a complex process that can be severely impacted by a range of toxicants found in wastewater, leading to system failure. To prevent this, monitoring key process indicators is crucial, but current methods have limitations in terms of response time and reliability. To address this challenge, we propose an innovative solution for ex situ monitoring of biotoxicity in AD using a paper-microwell-based and smartphone-assisted colorimetric analytical device. This device utilizes resazurin reduction by anaerobic sludge as a biological indicator, which reflects the health of anaerobic microbial consortia with a short response time. The device is fabricated through plasma treatment of chromatography paper, integrated with resazurin, and requires no external power source. To evaluate the device's efficiency, we conducted tests to measure and differentiate the toxicity of three types of chlorophenols, namely pentachlorophenol, 2,4-dichlorophenol, and 4-chlorophenol, after loading them into AD for a duration of 30 min. This paper-microwell-based analytical device demonstrated its ability to identify the presence of toxicants and provide a quick response time, making it a promising technology for monitoring toxicity incidents in real-time in AD processes. With its low cost, portability, and reliability, this innovative technology has the potential to contribute to the prevention of system failure caused by toxicants in AD processes. The analytical greenness metric approach (AGREE) proposes this paper-based analytical device as a greener alternative for measuring anaerobic digestion activities compared to traditional methods such as biochemical methane potential and chemical oxygen demand.

With the advancement of technology, studies in the field of nanotechnology have attracted great interest in recent years. The fact that nanomaterials have superior advantages over micromaterials provides a wide range of uses. Green synthesis is an effective way to prepare nanomaterials with an easy, fast, and environmentally friendly method. Within the scope of the study, AgNPs were synthesized using basil extract and combined with chitosan/PVA as a support material. By using chitosan/PVA support materials, the surface area of AgNPs was increased and it was aimed to improve their properties. The synthesized AgNPs@chitosan/PVA nanocomposite was characterized using various methods. In the UV-Vis spectrum, an absorbance peak was observed at 430 nm for the AgNPs@chitosan/PVA nanocomposite, and the particle size was determined as 25.10 nm according to TEM results. In addition, the photocatalytic and antioxidant activities of AgNPs@chitosan/PVA nanocomposite were investigated. The antioxidant activity of the AgNPs@chitosan/PVA (100 μg mL−1) nanocomposite against DPPH and H2O2 was determined as 89.18% and 71.87%, respectively. The photocatalytic activity of the AgNPs@chitosan/PVA nanocomposite against methylene blue (MB), methylene red (MR), methylene orange (MO), safranin, and crystal violet (CV) dyes was 77%, 85%, 79%, 54%, and 9%, respectively. While the highest photocatalytic activity was observed against MR dye, very low photocatalytic activity was observed for CV. In light of the results obtained, it can be said that the AgNPs@chitosan/PVA nanocomposite has the potential to be used as an antioxidant agent and photocatalyst.

Extracting uranium (U(VI)) from seawater can effectively solve the shortage of uranium resources on land. The key to U(VI) extraction from seawater is preparing high performance U(VI) extraction materials. Although PAO based materials present outstanding performance in U(VI) extraction, their experimental adsorption capabilities are greatly restricted by its aggregation. To inhibit PAO aggregation, we used KMnO4 as a regulator to interfere with PAO aggregation in aqueous solutions, and the physicochemical properties of the obtained KMnO4@PAO were well characterized. Importantly, KMnO4@PAO also presents excellent photo-thermal conversion properties in various aqueous solutions, which are beneficial for U(VI) extraction. The adsorption properties of KMnO4@PAO for U(VI) under different solution conditions (pH, adsorption time, U(VI) ion concentration, and temperature) were studied by batch adsorption experiments. The results reveal that KMnO4@PAO presents excellent adsorption properties for U(VI), and its efficient photo-thermal conversion properties can increase solution temperature and U(VI) adsorption capability.

The demand for critical and rare earth elements is surging and coal combustion residue could be an alternate source of critical elements. Data on the concentration of critical and rare earth elements (REYs) in different size fractions of fly ash would help in segregation of the ash. This study was conducted with the objective of examining the possibility of separation of coal ash into a size fraction useful for element extraction and the rest for bulk uses like cement, concrete, landfill, roads, embankments, etc. The concentration of critical elements, their partitioning in different size ash particles (>500 to <25 μm), and their chemical association were determined for a coal fly ash sample from Talcher, India. The total REY concentration in the ash varied between 440 and 529 mg kg−1, wherein the contents were relatively higher for Nd (75–103 mg kg−1) followed by Ce (58.3–88.7 mg kg−1), La (41.6–80.3 mg kg−1), Sm (39.0–79.3 mg kg−1), and Y (38.4–49.3 mg kg−1). The REY outlook coefficient of the raw ash (1.03) is more than 0.7 and accordingly this fly ash can be considered as an interesting source of rare earth elements. This factor was further enhanced to 2.3 in the coarse ash particles of size > 250 μm. Sequential extraction showed that most of the rare and critical elements are associated with the alumino-silicate matrix. The Al2O3 content of this ash is relatively high (25%), so there is scope for co-extraction of Al along with the rare earth elements. The ash disposal and utilization policy should consider the separation and preservation of the coarse ash fraction (>250 μm) for the extraction of critical and rare earth elements.

Pharmaceutical pollutants are released into the environment due to their direct outflow from waste disposal, animal discharge, and drug manufacturing. The long-term health effects on humans and animals due to their biological activity are the negative impacts of pharmaceutical pollutants. Microbial degradation is an effective remediation strategy for removing harmful contaminants from contaminated zones by breaking down foreign substances into smaller useable materials. The novel aspect of the review deals with the advancements and kinetic prospects of the microbial degradation of pharmaceutical pollutants. This review illustrates the classifications, toxic effects on health, occurrences and sources of pharmaceutical pollutants. The interaction mechanism between microbes and pollutants and the molecular mechanism under aerobic and anaerobic conditions are clearly demonstrated in this review. This review discusses in depth the advancements in the field of microbial degradation, such as the utilization of genetically engineered microbes and enzyme immobilization techniques for enhancing the degradation of pollutants. The purpose of this review is to describe the microbial degradation kinetics in order to efficiently supervise the pharmaceutical-contaminated sites. Recent advancements and future prospects for the effective removal of pharmaceutical contaminants are also discussed in depth.

An integrated strategy combining 3D architecture design and chemical doping holds great promise for enhancing the performance of bio-based engineered carbon materials in environmental applications. This review paper critically examines the use of integrated hierarchical porous carbon derived from biomass (bio-based IHPC) as an engineered catalyst and adsorbent for environmental purposes. The hierarchically interconnected pore architectures can reduce the electrical resistance and shorten the diffusion pathway, which is beneficial for the transport of ions/molecules. Additionally, the high pore volume, large specific surface area, and abundant active sites contribute to the high capacity for ion and molecule capture. The bio-based IHPC with 3D interconnected hierarchical porous structures can be obtained through non-templating, hard-templating and self-templating strategies. Chemical doping can further create functional groups and active sites on the bio-based IHPC surface, resulting in an abundance of reaction and interaction with pollutants. In particular, the surface properties of bio-based IHPCs can be further modified by heteroatom doping or metal (hydr)oxide coating. The review demonstrates the efficiency of bio-based IHPC as an engineered catalyst and adsorbent in various environmental applications. These applications include the removal of toxic trace elements and organic pollutants, carbon capture, enhancement of anaerobic digestion processes, antimicrobial treatment, and oil–water separation. The paper thoroughly discusses the influence mechanisms of pore architectures and chemical doping on the performance of bio-based IHPC in these applications. Finally, the paper concludes by presenting promising research directions for the preparation and application of bio-based IHPC.

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