Residential Wastewater Research Articles

High efficiency separation of bastnaesite (REFCO3) and monazite (REPO4) in mixed rare earth concentrate by heating under N2 and leaching with HCl/AlCl3

Bayan Obo mixed rare earth (RE) concentrate is one of the most significant rare earth mineral resources worldwide. However, the concentrated sulfuric acid roasting method, which is commonly used to treat ores, generates pollutants such as waste gas, wastewater, and leach residue, resulting in the squandering of the associated resources. This paper introduces a green process involving selective mineral phase transformation (MPT) by heating, followed by leaching to separate bastnaesite and monazite in a mixed RE concentrate to facilitate their subsequent decomposition or extraction. The effects of the MPT conditions on rare earth extraction were investigated. During the MPT process, bastnasite decomposed into REOF, which is more easily leached, whereas monazite remained unchanged. Under suitable conditions, the leaching efficiency of REOF reached 93.7%, while that of monazite (REPO4) was only 3.2%. Furthermore, the content of monazite in the leach residue was 91.2%. Compared to the mixed RE concentrate, numerous cracks and pores were generated on the surface and inside the MPT products. Furthermore, the total pore volume and specific surface area significantly increased, which made the reaction between the MPT products and hydrochloric acid more efficient. Thus, the MPT process facilitated the leaching of bastnasite and its separation from monazite.

Selected Micropollutant Removal from Municipal Wastewater

Micropollutants belong to various groups of chemicals. One of the most diverse and large group of them are pharmaceuticals. The presence of pharmaceutical residues in wastewater poses a significant challenge to water quality and environmental health. This paper provides an overview of recent advancements in the removal of pharmaceuticals from water, focusing on various treatment processes and their effectiveness in eliminating micropollutants. Through a review of the literature, including studies on ozonation, UV irradiation, sulfate radical-based technologies, and photocatalytic processes, insights into degradation mechanisms and optimal conditions for their removal are synthesized. Additionally, with new legislation mandating the monitoring of selected micropollutants and the implementation of quaternary treatment in wastewater treatment plants, the paper discusses prospects for future research and recommendations for effective pharmaceutical removal. Key actions include conducting comprehensive laboratory and pilot trials, implementing quaternary treatment of wastewater, continuously monitoring water quality, investing in research and development, and promoting collaboration and knowledge sharing among stakeholders. By embracing these strategies, we can work towards safeguarding water resources and protecting public health from the adverse effects of pharmaceutical contamination.

Using Quantitative Microbial Risk Assessment (QMRA) of SARS-CoV-2 to understand possible exposure to health risks in selected wastewater treatment plants located in the Eastern region of South Africa

In the past two years, Covid-19 has emerged as the most severe and pressing public health issue, causing a great deal of damage to societal and economic welfare, as well as causing illness and mortality. The operators in wastewater treatment plants (WWTPs), particularly those employed in rural communities, appear to often exhibit a lack of adherence to proper safety protocols by not utilizing sufficient protective equipment while handling unprocessed sewage samples throughout the different phases of wastewater treatment and disposal. This study aimed at examining the potential health risk of infection among WWTP operators, as a result of unintentional ingestion of wastewater during routine duties in facilities that receive influent containing Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) from various areas. This study examined the prevalence of SARS-CoV-2 in grab samples of untreated wastewater samples using the real-time quantitative polymerase chain reaction (RT-qPCR) technique and quantitative microbial risk assessment (QMRA) model was employed on three probable exposure of SARS-CoV-2 scenarios that are expressed as moderate, aggressive and extreme (2 mL, 10 mL, 20 mL) to evaluate the probability of infection to WWTP workers based on the 6 h that the workers spent in WWTPs performing their daily activities which exposed them to potential health risk of various pathogens. At the highest SARS-CoV-2 genome of 266.23 × 102 gc/mL, the findings indicated that there was no statistically significant difference in the probability of infections with respect to seasonal differences because the P(i) value was greater than 0.05 (p > 0.05). Overall, P(i) was highly significant across all volumetric scenarios in the study with p value that was p < 0.001. The probability of getting infected during the different seasons is assumed to be low since there was no statistically difference in P(i) with respect to season however it can be assumed that there is a high chance of getting infected regardless of volumetric intake. Our study suggests that the risk of accidental occupational exposure to SARS-CoV-2 in raw wastewater is negligible to workers whereby workers would perform their daily activities without wearing protective gear. Nevertheless, the importance and work of WWTPs by workers should not be overlooked. Regardless of the situation, it is widely recognized that residential wastewater poses a potential risk of infection due to the presence of several enteric pathogens, therefore, it is crucial to ensure that those who are occupationally exposed to untreated wastewater are well equipped with suitable personal protective equipment (PPE).

Sequential co-processing of olive mill wastewater and organic residues by anaerobic co-digestion and pyrolysis for the generation of bioadsorbent and low-cost media for microalgae cultivation

This investigation aims to evaluate the co-valorization of olive mill wastewater with other organic residues involving acid pretreatment, co-digestion, pyrolysis, and microalgae cultivation. Phosphoric acid pretreatment (5%, 60°C for 1 h) was used to solubilize the organic matter in a mixture of coffee grounds, orange peel, olive mill wastewater, and cardboard. The acidic treatment led to the production of 328 Nml of biogas/gVS, while the untreated mixture provided 257 Nml of biogas/gVS. The solid digestates were subjected to pyrolysis (500°C for 1 h), providing a biochar yield of approximately 44% for both digestates. Adsorption tests using methylene blue revealed an adsorption capacity of the biochar generated from the digestate of the acid pre-treated mixture of 4 mg/g, which was higher than that of the biochar from the untreated mixture (3.5 mg/g). The liquid digestates were also used as growth media for microalgae. Compared to the reference media (BG11), the use of the digestates-based media resulted in a lower growth rate (0.04 d-1) and biomass (247 mg/L) but significantly higher lipid content (49%). The study shows, therefore, that the use of acid pretreatment had a positive effect on biogas production (solubilization of sugars), on the adsorption efficiency of the biochar (improvement of the porosity of the material), and on the production of lipids from the microalgae which can be destined to biodiesel.

Pharmaceutical Contaminants in Wastewater and Receiving Water Bodies of South Africa: A Review of Sources, Pathways, Occurrence, Effects, and Geographical Distribution

The focus of this review article was to outline the sources, pathways, effects, occurrence, and spatial distribution of the most prescribed pharmaceuticals in wastewater and receiving waters of South Africa. Google Scholar, Web of Science, and Scopus were used to gather data from different regions. A zone-wise classification method was used to determine the spatial distribution and data deficiencies in different regions of South Africa. This review revealed that over 100 pharmaceutical compounds have been reported in South Africa’s various water sources and wastewater, with most studies and highest concentrations being documented in Gauteng and Kwa-Zulu Natal. The pharmaceutical concentration in water samples ranged from ng/L to µg/L. Aspirin, ketoprofen, diclofenac, ibuprofen, naproxen, erythromycin, tetracycline, sulfamethoxazole, acetaminophen, streptomycin, ciprofloxacin, ampicillin, carbamazepine, atenolol, pindolol, efavirenz, and zidovudine residues were among the frequently detected pharmaceutical residues in water bodies and wastewaters of South Africa. Based on the spatial distribution data, Gauteng has the highest number of pharmaceuticals (108) detected in waste and surface water, with the Northern Cape having no monitoring evidence. Therefore, to precisely ascertain the geographical distribution of pharmaceutical contaminants in South Africa, this review recommends that further research be carried out to track their occurrence in aquatic environments and WWTP, especially in isolated regions like Limpopo.

Antibiotic consumption and antibiotics occurrence into the environment: a case study of hospital in Metro, Lampung

Increased antibiotic consumption has exposed bacterial communities and environmental ecosystems to large amounts of antibiotic residues derived from the excretion of irrationally consumed antibiotics. This study provides an overview of antibiotic consumption patterns in hospital inpatients and the distribution of residues released into the environment. Medical record data was used to calculate the amount of consumption from hospital inpatients, and based on the type of antibiotics that have a DU90% value, ecotoxicological risk calculations were carried out to estimate the level of danger that occurs in the environment. A total of 27 types of antibiotics were prescribed, with a total consumption of 20504.42 Kg/year. Antibiotics such as ceftriaxone, cefixime, cefadroxil, and levofloxacin are the most widely used antibiotics based on medical record data. The results of estimating the release of antibiotic residues in wastewater obtained ecotoxicological risk values for algae, invertebrates, and fish greater than one (RQs&gt;1). This condition indicates an ecotoxicological risk at the health facility site due to the release of antibiotic residues into the river water body from the WWTP outlet. The release of antibiotic residues into the water can result in ecosystem damage and pollution of the aquatic environment.

Contamination Characteristics and Ecological Risk of Antibiotics in Contaminated Sites of Typical Pharmaceutical Factories in China

To understand the contamination characteristics and ecological risk of antibiotics in contaminated fields of pharmaceutical plants， samples of the surface soil， soil column， wastewater treatment process water， ground water， and residue dregs were collected from two typical antibiotic pharmaceutical plants in South and North China. A total of 87 commonly used antibiotics were quantified using ultrasound extraction-solid phase extraction and ultra-high performance liquid chromatography-mass spectrometry. The results showed that a total of 31 antibiotics of five classes were detected in all types of samples， and the maximum concentrations at each sampling point in the surface soil， soil column， residue dregs， wastewater treatment process water， and groundwater were 420 ng·g-1， 595 ng·g-1， 139 ng·g-1， 1 151 ng·L-1， and 6.65 ng·L-1， respectively. Most of the antibiotics were found in the surface soil， showing a decreasing trend with the depth of the soil column. The ecological risk assessment indicated that sulfamethazine， sulfaquinoxaline， tetracycline， chlorotetracycline， and D-sorbitol were at higher risk. Improving the efficiency of antibiotic removal from pharmaceutical wastewater and preventing production shop leaks are effective measures of controlling antibiotic contamination into and around fields in pharmaceutical plants.

A novel synchronous fluorescence spectrometry combined with fluorescence sensitization for the highly sensitive and simultaneous detection of enoxacin, ofloxacin and tetracycline hydrochloride residues in wastewater

The synergistic effect of sodium dodecyl sulfate (SDS) and Mg2+ could significantly enhance the fluorescence intensity of enoxacin (ENO) at λex/λem = 269.2 nm/385.6 nm, ofloxacin (OFL) at λex/λem = 290.8 nm/466.2 nm and tetracycline hydrochloride (TCH) at λex/λem = 372.6 nm/514.8 nm. Moreover, when the wavelength difference (Δλ) was chosen 135 nm, the synchronous fluorescence spectra of the three antibiotic complexes could be well separated and the interference of the samples matrix were eliminated primely. Therefore, only one synchronous fluorescence scan was needed to simultaneously determine the three antibiotics. Based on these facts, a synchronous fluorescence spectrometry combining fluorescence sensitization for highly sensitive and selective determination of ENO, OFL and TCH residues in wastewater was developed for the first time. The experimental results showed that the concentrations of ENO, OFL and TCH in the range of 0.5–550 ng mL−1, 1–1500 ng mL−1 and 10–5500 ng mL−1 showed a good linear relationship with fluorescence intensity. The limits of detection were 0.0599 ng mL−1, 0.115 ng mL−1 and 0.151 ng mL−1, respectively. The recoveries of the actual sample were 87.50%–99.99 %, 93.00%–98.50 % and 85.70%–98.42 %, respectively. Overall, the novel synchronous fluorescence spectrometry established in the experiment has the advantages of high sensitivity, good selectivity, fast detection speed and high accuracy. It has been successfully applied to the detection of residual amounts of ENO, OFL and TCH in wastewater with satisfactory results.

Multimedia fate simulation of mercury in a coastal urban area based on the fugacity/aquivalence method

Due to intensive industrial production and living activities, urban areas are the main anthropogenic mercury (Hg) emission sources. After entering the environment through exhaust gases, wastewater or waste residues, Hg can migrate and transform among different environmental compartments in various species, such as elemental mercury (Hg0), divalent mercury (Hg2+) and methylmercury (MeHg). Studies have yet to report on the multimedia behaviors of Hg in urban areas due to the complexity of the processes involved. In this study, the atmospheric Hg emission in Dalian, a coastal city in Northeast China, was estimated by an anthropogenic emission inventory, and a Level III multimedia model was constructed based on the fugacity/aquivalence method to simulate the fate of Hg in air, water, soil, sediment, vegetation and film. The total annual atmospheric emission was 9.91 t, of which coal combustion and non-coal sources accounted for 70.1 % and 29.9 %, respectively. Atmospheric emission and advection were dominated by Hg0, and aquatic emission and advection were dominated by Hg2+. The migration of air–vegetation, vegetation–soil and soil–air were three important pathways of Hg in urban areas. The model was validated by collecting local soil and vegetation samples and regional air, seawater and sediment monitoring data. The scenario simulation indicated that the local load would decrease to different extents with a 21.0 % reduction in atmospheric Hg emission by implementing the “coal-to-gas” measures. Our developed model can characterize the fate of Hg in coastal urban areas and provide a reference for control strategies.

New insights into rare earth element-induced microalgae lipid accumulation: Implication for biodiesel production and adsorption mechanism

A coupling technology for lipid production and adsorption of rare earth elements (REEs) using microalgae was studied in this work. The microalgae cell growth, lipid production, biochemical parameters and lipid profiles were investigated under different REEs (Ce3+, Gd3+and La3+). The results showed that the maximum lipid production was achieved at different concentrations of REEs, with lipid productivities of 300.44, 386.84 and 292.19 mg L−1 d−1 under treatment conditions of 100 μg L−1 Ce3+, 250 μg L−1 Gd3+ and 1 mg L−1 La3+, respectively. Moreover, the adsorption efficiency of Ce3+, Gd3+ and La3+exceeded 96.58 %, 93.06 % and 91.3 % at concentrations of 25–1000 μg L−1, 100–500 μg L−1 and 0.25–1 mg L−1, respectively. In addition, algal cells were able to adsorb 66.2 % of 100 μg L−1 Ce3+, 48.4 % of 250 μg L−1 Gd3+ and 59.9 % of 1 mg L−1 La3+. The combination of extracellular polysaccharide and algal cell wall could adsorb 25.2 % of 100 μg L−1 Ce3+, 44.5 % of 250 μg L−1 Gd3+ and 30.5 % of 1 mg L−1 La3+, respectively. These findings indicated that microalgae predominantly adsorbed REEs through the intracellular pathway. This study elucidates the mechanism of effective lipid accumulation and adsorption of REEs by microalgae under REEs stress conditions. It establishes a theoretical foundation for the efficient microalgae lipid production and REEs recovery from wastewater or waste residues containing REEs.

Differential capacity of phragmites ecotypes in remediation of inorganic contaminants in coastal ecosystems: Implications for climate change

Remediating inorganic pollutants is an important part of protecting coastal ecosystems, which are especially at risk from the effects of climate change. Different Phragmites karka (Retz) Trin. ex Steud ecotypes were gathered from a variety of environments, and their abilities to remove inorganic contaminants from coastal wetlands were assessed. The goal is to learn how these ecotypes process innovation might help reduce the negative impacts of climate change on coastal environments. The Phragmites karka ecotype E1, found in a coastal environment in Ichkera that was impacted by residential wastewater, has higher biomass production and photosynthetic pigment content than the Phragmites karka ecotypes E2 (Kalsh) and E3 (Gatwala). Osmoprotectant accumulation was similar across ecotypes, suggesting that all were able to successfully adapt to polluted marine environments. The levels of both total soluble sugars and proteins were highest in E2. The amount of glycine betaine (GB) rose across the board, with the highest levels being found in the E3 ecotype. The study also demonstrated that differing coastal habitats significantly influenced the antioxidant activity of all ecotypes, with E1 displaying the lowest superoxide dismutase (SOD) activity, while E2 exhibited the lowest peroxidase (POD) and catalase (CAT) activities. Significant morphological changes were evident in E3, such as an expansion of the phloem, vascular bundle, and metaxylem cell areas. When compared to the E3 ecotype, the E1 and E2 ecotypes showed striking improvements across the board in leaf anatomy. Mechanistic links between architectural and physio-biochemical alterations are crucial to the ecological survival of different ecotypes of Phragmites karka in coastal environments affected by climate change. Their robustness and capacity to reduce pollution can help coastal ecosystems endure in the face of persistent climate change.

Microbial functional heterogeneity induced in a petroleum-polluted soil profile

Microbial taxonomic diversity declines with increasing stress caused by petroleum pollution. However, few studies have tested whether functional diversities vary similarly to taxonomic diversity along the stress gradient. Here, we investigated soil microbial communities in a petrochemically polluted site in China. Total petroleum hydrocarbon (TPH) concentrations were higher in the middle (2–3 m) and deep soil layer (3–5 m) than in the surface soil layer (0–2 m). Accordingly, microbial taxonomic α-diversity was decreased by 44% (p < 0.001) in the middle and deep soil layers, compared to the surface soil layer. In contrast, functional α-diversity decreased by 3% (p < 0.001), showing a much better buffering capacity to environmental stress. Differences in microbial taxonomic and functional β-diversities were enlarged in the middle and deep soil layers, extending the Anna Karenina Principle (AKP) that a community adapts to stressful environments in its own way. Consistent with the stress gradient hypothesis, we revealed a higher degree of network connectivity among microbial species and genes in the middle and deep soil layers compared to the surface soil layer. Together, we demonstrate that microbial functionality is more tolerant to stress than taxonomy, both of which were amenable to AKP and the stress gradient hypothesis.

Magnetic r‐graphene oxide‐doped tin‐lanthanum intercalated thiosulfate layered double hydroxide as a new nanocomposite sorbent for the extraction of tetracycline and oxytetracycline residues in pharmaceutical wastewater

AbstractA new analytical method combining magnetic micro‐solid phase extraction (μ‐SPE) in tandem with high‐performance liquid chromatography‐ultraviolet (HPLC‐UV) analysis was developed and used for the simultaneous extraction/preconcentration of tetracycline (TC) and oxytetracycline (OTC) residues in drug manufacturing effluents. The μ‐SPE conducted by the introduction of iron oxide reduced‐graphene oxide (MrGO) doped tin‐lanthanium intercalated with thiosulfate ions to produce magnetic LDH (MrGO/Sn‐La‐S). The adsorbent was synthesized and characterized using x‐ray diffraction, Fourier transform infrared, scanning electron microscopy, energy‐dispersive x‐ray, elemental mapping, transmission electron microscopy, x‐ray photoelectron spectroscopy, and value stream mapping techniques. The effective parameters, including the extraction and desorption steps, were investigated and optimized. Under optimized conditions, the limits of detection (LOD) for TC and OTC were obtained as 5.42 and 3.31 μg.L−1, respectively, while the linearity was in the range of 10.0–500.0 μg.L−1 for both antibiotics with satisfactory determination coefficients (R2) of 0.9811 and 0.9846 for TC and OTC, respectively. The recovery percentages for the analytes in real samples were achieved in the ranges of 89.2%–101.6% and 91.0%–101.3% for TC and OTC antibiotics, respectively. All these features proved the potential of the developed method and adsorbent for real world applications.

Cytochrome P450 for environmental remediation:catalytic mechanism, engineering strategies and future prospects.

Environmental pollution is a global concern. Various organic compounds are released into the environment through wastewater, waste gas, and waste residue, ultimately accumulating in the environment and the food chain. This poses a significant threat to both human health and ecology. Currently, a growing body of research has demonstrated that microorganisms employ their Cytochrome P450 (CYP450) system for biodegradation, offering a crucial approach for eliminating these pollutants in environmental remediation. CYP450, a ubiquitous catalyst in nature, includes a vast array of family members distributed widely across various organisms, including bacteria, fungi, and mammals. These enzymes participate in the metabolism of diverse organic compounds. Furthermore, the rapid advancements in enzyme and protein engineering have led to increased utilization of engineered CYP450s in environmental remediation, enhancing their efficiency in pollutant removal. This article presents an overview of the current understanding of various members of the CYP450 superfamily involved in transforming organic pollutants and the engineering of biodegrading CYP450s. Additionally, it explores the catalytic mechanisms, current practical applications of CYP450-based systems, their potential applications, and the prospects in bioremediation.

In silico ecotoxicity assessment of pharmaceutical residues in wastewater following oxidative treatment

Advanced oxidation processes such as thermal plasma activation and UV-C/H2O2 treatment are considered as applications for the degradation of pharmaceutical residues in wastewater complementary to conventional wastewater treatment. It is supposed that direct oxidative treatment can lower the toxicity of hospital sewage water (HSW).The aim of this study was to predict the ecotoxicity for three aquatic species before and after oxidative treatment of 10 quantified pharmaceuticals in hospital sewage water. With the application of oxidative chemistry, pharmaceuticals are degraded into transformation products before reaching complete mineralization. To estimate the potential ecotoxicity for fish, Daphnia and green algae ECOSAR quantitative structure-activity relationship software was used. Structure information from pristine pharmaceuticals and their oxidative transformation products were calculated separately and in a mixture computed to determine the risk quotient (RQ).Calculated mixture toxicities for 10 compounds found in untreated HSW resulted in moderate-high RQ predictions for all three aquatic species. Compared to untreated HSW, 30-min treatment with thermal plasma activation or UV-C/H2O2 resulted in lowered RQs. For the expected transformation products originating from fluoxetine, cyclophosphamide and acetaminophen increased RQs were predicted. Prolongation of thermal plasma oxidation up to 120 min predicted low-moderate toxicity in all target species. It is anticipated that further degradation of oxidative transformation products will end in less toxic aliphatic and carboxylic acid products. Predicted RQs after UV-C/H2O2 treatment turned out to be still moderate-high.In conclusion, in silico extrapolation of experimental findings can provide useful predicted estimates of mixture toxicity. However due to the complex composition of wastewater this in silico approach is a first step to screen for ecotoxicity. It is recommendable to confirm these predictions with ecotoxic bioassays.

A comparative study of two types of anode electrodes in a microbial fuel cell for producing bioelectricity from residential wastewater

The increasing of population growth is positively correlated with the energy demand which leads to fossil fuel depletion. New renewable energy is one of the solutions to address the future energy crisis. Microbial fuel cell (MFC) is one of the renewable energy sources since this device is able to convert chemical energy into electrical energy by using microorganisms. Many researchers have studied MFCs from wastewater as a medium for producing electricity through MFC systems. MFC performance depends on microbe metabolism, membrane, and electrodes. This study compared bioelectricity generation on a Batch System of Microbial Fuel Cell from residential wastewater using two types of anode electrodes (zinc plate and graphite rod). The consortium of indigenous wastewater bacteria has been used for MFC. An artificial membrane was made in the laboratory derived from the chitosan-jelly combination. Chitosan was extracted from crustacean shells. The research was conducted in the laboratory by directly measuring the voltage on the MFC system for three (3) days. This research reveals that the MFCs with zinc plate anode electrodes generated higher voltage throughout the days evaluated, with peaks of 970 mV. Meanwhile, MFC with graphite rod anode resulted in 880 mV maximum. This research finding of MFCs with zinc plate as electrode materials could be the key to sustainable bioelectricity generation from wastewater.

Overlooked abiotic humification for kanamycin removal in kanamycin fermentation waste by tea polyphenols: New, environmentally friendly and specific

Kanamycin, a typical aminoglycoside antibiotic, is mainly used for the treatment of diseases in humans or animals, while the related antibiotic pollution has been regarded as a serious issue. In this study, a green novel approach to remove kanamycin was established, specifically, kanamycin was specifically removed through abiotic humification process with tea polyphenols (TPs) as the polyphenol donor. The results demonstrated that the kanamycin could be effectively removed by TPs under alkaline conditions, with a 99.9 % highest removal efficiency. Among the three factors (pH, temperature and MnO2 dosage) selected in this study, pH was the most critical factor, with an increase in reaction pH (>6.0) leading to a higher kanamycin removal efficiency, and the temperature and MnO2 dosage ranked as the second and third important factor. Furthermore, kanamycin was mainly removed by being transformed into humic-like acid (HLA) product, and the product antimicrobial activity could be significantly reduced (≥27). Finally, satisfying removal efficiency of kanamycin were observed during the application of TPs in kanamycin fermentation wastewater and kanamycin mycelial residue (KMR), with the highest kanamycin removal efficiency was 99.9 %, and 99.6 %, respectively. This study could also offer insights for the removal of other pollutants containing primary amine or polyphenols.

Composite super-adsorbents of chitosan/activated carbon for the removal of nonsteroidal anti-inflammatory drug from wastewaters

Pharmaceutical residues in wastewater are an environmental concern with implications on human health and aquatic ecosystems. To solve this problem, this study proposes a more sustainable approach using chitosan-based adsorbents combined with activated carbon (AC) for the removal of pharmaceutical waste from wastewater. Chitosan (Cs), a biodegradable polysaccharide, offers unique properties for contaminant adsorption and activated carbon offers a large specific surface area. The synergistic effect of these two super-absorbents is examined for the removal of diclofenac, a widely used drug. The effectiveness of these adsorbents was evaluated, considering factors such as pH, contact time, and temperature. The results showed that Cs/AC beads with a 2:1 ratio had the highest adsorption capacity (165.33 mg/g at 323 K), the results fitted better to Langmuir model, and adsorption followed a pseudo-second-order kinetic model. Thermodynamic analysis indicated that the adsorption process was chemisorption, with a strong interaction between diclofenac and adsorbents. Regeneration studies showed that Cs/AC composites can be regenerated up to ten cycles, showing a small reduction in their efficiency. Overall, the chitosan/activated carbon approach shows promising prospects as an effective and environmentally friendly method for the removal of pharmaceutical residues from wastewater.

Cross-linking copolymerization on magnetic microspheres surface induced neodymium ion imprinting for high capacity and high selectivity removal of Nd3+ from aqueous solution

The development of reliable ways to recover rare earth metals can avoid the loss of valuable resources in tailings, industrial wastewater and process residues. In this study, 2-acetamidoacrylic acid, which has a strong coordination ability for Nd3+, was selected as the functional monomer through theoretical simulation (DFT calculation) and experimental study (fluorescence burst method). Meanwhile, Nd3+ was used as template ion, N-isopropylacrylamide as an ionic cross-linker, ethylene glycol dimethacrylate was used as cross-linking agent, Fe3O4@SiO2 was used as carrier, and ion imprinted polymer containing Nd3+ vacancy (Nd(III)-V/MIIP) was synthesized by surface imprinting technique. The Nd(III)-V/MIIP prepared by this method can selectively adsorb Nd3+ in various metal ion solutions, and the adsorption capacity was increased by about 40 % compared with that of the MNIP adsorbent without Nd3+ vacancies, with a distribution system of 624.93 mL/g. The Nd(III)-V/MIIP can effectively solve the problem of the difficult separation of the rare earth ions from each other. Based on the results of XPS, DFT, HOMO and LUMO, it can be inferred that −COO− coordination on AAA, where the −COO− is coordinated to Nd3+ with a binding energy of -26.58 eV, which allows selective adsorption of Nd3+ ions in the complex water system.

Detection of 4-aminothiophenol with core-shell structured Ag@ZnS as a surface enhanced Raman scattering substrate

4-Aminothiophenol (4-ATP, a toxic pesticide intermediate) residues in waste water endanger water ecology and human health. Therefore, the development of reliable surface-enhanced Raman scattering (SERS) substrate is a promising strategy for monitoring and preventing 4-ATP pollution. In this work, a core-shell structured Ag@ZnS hybrid, consisting of Ag nano-core and ZnS nano-shell, was fabricated and employed as a SERS substrate to detect 4-ATP. Owing to the specific core-shell structure, epy as-prepared Ag@ZnS substrate is stable against oxidation and spontaneous agglomeration of Ag NPs, enjoying good stability and uniform hot spots. Moreover, the formation of heterostructure between Ag-core and ZnS-shell offered a remarkable chemical enhancement for the Raman signals. The optimized Ag@ZnS substrate showed high sensitivity for rhodamine 6 G (R6G, 10−9 M) and methylene blue (10−8 M) probes, as well as 4-ATP (10−8 M) target analyte. Likewise, the superior reproducibility (RSD<5.50 %, n = 16) and good stability (79.5 % of initial strength after 28 days) for 4-ATP makes this substrate a good candidate for actual determination of trace 4-ATP. This work proposes a strategy to fabricate a reliable SERS substrate with high sensitivity and superior reproducibility, and the designed Ag@ZnS substrate may be applicable to monitor 4-ATP residues in wastewater.