Contaminants In Wastewater Research Articles

Effect of additives on the photocatalytic degradation of malachite green using NiS:Tb3+ nanoparticle and their photoluminescence properties

The contamination of wastewater with synthetic dyes presents a critical challenge, highlighting the need for advanced technologies and approaches to effectively manage, treat, and remediate polluted wastewater and mitigate its adverse environmental and health impacts. This study focuses on the photocatalytic degradation of malachite green dye, a widely used synthetic dye, using nickel sulfide nanoparticles doped with Tb3+ ions. The objective is to explore the potential of this approach in breaking down the dye into harmless components, thereby reducing its toxicological impacts on the environment and human health. The catalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible spectroscopy (UV). The effects of pH levels and various additives, including transition metals, inorganic oxidants, and inorganic anions, on the degradation process were systematically examined. The results demonstrate a high degradation efficiency of 94 % within 90 min, highlighting the efficacy of the photocatalytic process. Notably, adding transition-metal ions and inorganic oxidants enhanced the degradation rate, whereas inorganic anions had an inhibitory effect. Furthermore, an artificial neural network (ANN) model was developed to predict the degradation rate, demonstrating a strong correlation between experimental data and predicted values. This study provides valuable insights into optimizing photocatalytic degradation processes. It showcases the potential of ANN modelling in predicting the photocatalytic activity of nickel sulfide nanoparticles doped Tb3+ in the presence of various additives.

Vermifiltration for removal of emerging contaminant EDTA (ethylenediaminetetraacetic acid). Kinetics models for adsorption, bio- and vermidegradation

Vermifiltration is a sustainable technology that combines the action of microorganisms and earthworms to remove contaminants in wastewater. In this work, vermifiltration was used to remove the emerging contaminant, EDTA, from simulated greywater. Three types of filters were designed: Azide Filter (AF) to evaluate the adsorption process, Bio filter (BF), to evaluate adsorption plus the action of the microorganisms, and Vermi Filter (VF), to assess the previously described processes and the action of the earthworms. Each filter was filled with gravel, sand and an active layer, and VF was inoculated with 60 Eisenia fetida. The filters were operated on a batch system with recycling. Different regimes were observed: an initial rapid decrease of EDTA concentration by adsorption; a lag phase, which lasted from 7 to 18 days, and a final EDTA decrease due to biological or vermi degradation. A mathematical model was developed performing the EDTA mass balance in the system and considering a first order kinetic rate for EDTA removal. Experimental data was fitted by the model, determining kinetic constants for adsorption or degradation process, kads and kd respectively. The kads values were similar for all filters, whereas VF showed a kd 53 % higher than that of BF and AF. Earthworms survival was 85 % and, although the biomass was significantly reduced (64.8 %), there was cocoons and juveniles. Bioassays with Lactuca sativa showed no phytotoxicity of the treated wastewaters. All the systems were efficient but the VF was faster, supporting that vermifiltration is a suitable technology for treating EDTA greywater.

Superior Singlet Oxygen Electrosynthesis via Neighboring Dual Molecular Oxygen Coactivation for Selective Tetracycline Detoxification.

Oxygen (O2) electroreduction offers a green approach for singlet oxygen (1O2) synthesis in wastewater contaminants detoxification. However, traditional single O2 activation on single-metal catalytic sites seriously suffers from the kinetically-unfavorable desorption of adsorbed superoxide species (•O2 -*/•OOH*). Here, we demonstrate a novel dual O2 coactivation pathway on shortened Fe1-OV-Ti sites for superior 1O2 electrosynthesis through a rapid disproportionate process between surface-confined •O2 -*/•OOH*. Theoretical calculations combined with in situ electrochemical spectroscopies demonstrated that the shortened distance between Fe single atom and adjacent unsaturated Ti atom facilitates the direct recombination of surface-confined Fe-•OOH and Ti-•OO- to yield 1O2, bypassing the formidable •O2 -*/•OOH* desorption process. Impressively, Fe1-OV-Ti could realize an excellent 1O2 electrosynthesis rate of 54.5 μmol L-1 min-1 with an outstanding 1O2 selectivity of 97.6 % under neutral condition, surpassing that of Fe1-O-Ti (27.1 μmol L-1 min-1, 91.7 %). Using tetracycline (TC) as a model pollutant, the resulting Fe1-OV-Ti electrode achieved nearly 100 % degradation in 120 min at -0.6 V, meanwhile preventing the generation of toxic intermediates. This study provides a new 1O2 electrosynthesis strategy by controlling the distance of adjacent catalytic sites for the coactivation of dual molecular oxygen.

Layer-by-layer adsorption behavior of Cr(VI) on MoS2@Mt induced by sulfamethoxazole

Hexavalent chromium (Cr(VI)) contamination in wastewater is a serious environmental threat. Cr(VI) removal is often interfered by antibiotics in wastewater, however, the underlying mechanism remains unclear. Here, molybdenum disulfide/montmorillonite (MoS2@Mt) composites were prepared and used for Cr(VI) removal to reveal the adsorption behavior of Cr(VI) on MoS2@Mt induced by sulfamethoxazole. The induction effect of the typical antibiotic sulfamethoxazole (SMX) was investigated. The adsorption capacity of MoS2@Mt was maximum at pH 2 and decreased with increasing pH. The performance results showed that SMX promoted Cr(VI) removal, with a maximum increase of 14.80 % in removal efficiency. Cr(VI) adsorption on MoS2@Mt followed the Langmuir model, whereas it was more consistent with the Freundlich model in the presence of SMX. This suggested that SMX induced a monolayer to multilayer shift in Cr(VI) adsorption. XPS results indicated that Cr(VI) removal pathways included Cr(VI) adsorption, chemical reduction of Cr(VI) to trivalent chromium (Cr(III)), and Cr(III) chelation. In particular, electrostatic pulling, coordinated adsorption, and hydrogen bond attraction contributed to Cr(VI) adsorption. Mechanism investigation suggested that Cr(VI) or SMX absorbed on the material surface continued to absorb SMX or Cr(VI) by electrostatic attraction, resulting in layer-by-layer adsorption behavior, which facilitated Cr(VI) removal. In actual wastewater treatment, MoS2@Mt reduced Cr(VI) concentrations (0.15–5 mg/L) to below the World Health Organization standard of 0.05 mg/L in the presence of 0.32 mg/L SMX. Overall, this study revealed the mechanism of SMX-induced Cr(VI) adsorption behavior, which favors the elimination of Cr(VI) from real complex wastewater.

Sequestration of Dyes from Water into Poly(α-Olefins) Using Polyisobutylene Sequestering Agents

Trace concentrations of dyes are often present in textile wastewater streams and present a serious environmental problem. Thus, these dyes must be removed from wastewater either by degradation or sequestration prior to discharge of the wastewater into the environment. Existing processes to remove these wastewater contaminants include the use of solid sorbents to sequester dyes or the use of biochemical or chemical methods of dye degradation. However, these processes typically generate their own waste products, are not necessarily rapid because of the low dye concentration, and often use expensive or non-recyclable sequestrants or reagents. This paper describes a simple, recyclable, liquid–liquid extraction scheme where ionic dyes can be sequestered into poly(α-olefin) (PAO) solvent systems. The partitioning of anionic and cationic dyes from water into PAOs is facilitated by ionic PAO-phase anchored sequestering agents that are readily prepared from commercially available vinyl-terminated polyisobutylene (PIB). This is accomplished by a sequence of reactions involving hydroboration/oxidation, conversion of an alcohol into an iodide, and conversion of the resulting primary alkyl iodide into a cationic nitrogen derivative. The products of this synthetic sequence are cationic nitrogen iodide salts which serve as anionic sequestrants that are soluble in PAO. These studies showed that the resulting series of cationic PIB-bound cationic sequestering agents facilitated efficient extraction of anionic, azo, phthalein, and sulfonephthalein dyes from water into a hydrocarbon PAO phase. Since the hydrocarbon PAO phase is completely immiscible with water and the PIB derivatives are also insoluble in water, neither the sequestration solvent nor the sequestrants contaminate wastewater. The effectiveness and efficiency of these sequestrations were assayed by UV–visible spectroscopy. These spectroscopic studies showed that extraction efficiencies were in most cases >99%. These studies also involved procedures that allowed for the regeneration and recycling of these PAO sequestration systems. This allowed us to recycle the PAO solvent system for at least 10 sequential batch extractions where we sequestered sodium salts of methyl red and 4′,5′-dichlorofluorescein dyes from water with extraction efficiencies of >99%. These studies also showed that a PIB-bound derivative of the sodium salt of 1,1,1-trifluoromethylpentane-2,4-dione could be prepared from a PIB-bound carboxylic acid ester by a Claisen-like reaction and that the sodium salt of this β-diketone could be used to sequester cationic dyes from water. This PIB-bound anion rapidly and efficiently extracted >99% of methylene blue, malachite green, and safranine O from water based on UV–visible and 1H NMR spectroscopic assays.

Study of machine learning on the photocatalytic activity of a novel nanozeolite for the application in the Rhodamine B dye degradation

Contamination of wastewater with organic dyes has caused a serious threat to humans and aquatic life due to the hazardous effect of these contaminants. In this context, the present work aims to carry out a Machine Learning (ML) study to evaluate the photocatalytic activity of a nanozeolite (nANA) in the degradation of Rhodamine B (RhB) dye. Three machine learning algorithms (Random Forest, Artificial Neural Network and Xtreme Gradient Boosting) were used in the regression model development. The dataset used in the machine learning and data correlation was generated by Central Composite Rotational Design (CCRD 2²). Regarding the machine learning study, the ANN with structure 3:6:1 showed the best performance as a predictive model (R² = 0.98 and 0.9 for training and testing, RMSE < 5.0), resulting in the 50.37 ± 1.01 % RhB removal at pH 5.7, [RhB] = 200 mg L−1 and [nANA] = 2.75 g L−1 after 180 min under visible light. Feature importance revealed that all parameters (pH, [RhB], [nANA]) were relevant to the response. Therefore, this work confirms the potentiality of machine learning algorithms to develop predictive models as well as a good starting point for the scale-up of advanced oxidation processes.

Supercritical water valorization of a model wastewater containing anxiolytic and antidepressant drugs: Experimental and thermodynamic assessment

This study presents a continuous hydrothermal process based on the supercritical water (ScW) technology for the treatment of pharmaceutical contaminants in wastewater. Using a simulated wastewater as feedstock, which was prepared with 5 psychoactive drugs (sertraline, paroxetine, zolpidem, escitalopram, and clonazepam), the impact of temperature, feed flow rate, and concentration of H2O2 in the degradation of organic matter was investigated. Thermodynamic aspects of the process were also assessed. The optimal conditions of treatment were at a temperature of 692.8 °C, feed flow rate of 6.6 mL/min, and H2O2 concentration in terms of oxidant coefficient (Ox. C.) of 1.03. Under these conditions, the experimental test achieved a total organic carbon removal efficiency (%RTOC) of 85.9 ± 0.5 %. Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) concentrations decreased from 559.0 and 1118.4 mg/L to 66.0 and 152.5 mg/L, respectively. The liquid phase was also assessed by toxicity assays against Artemia salina microcrustaceans. For the gaseous phase, hydrogen was identified as the main component (57.7 %). Additionally, an assessment of the energy efficiency of the process scale-up was investigated. The ScW process showed a promising potential for large-scale continuous operations as an energy-efficient solution for wastewater treatment and valorization due to the concomitant production of H2-rich gas.

Fate of emerging contaminants in the soil-plant system: a study on durum wheat irrigated with treated municipal wastewater

IntroductionEmerging contaminants in irrigation wastewater can cause bioaccumulation in crops, posing health risks to humans and other living organisms. The extent to which different emerging contaminants (ECs) are taken up by plants varies depending on the physicochemical properties of the contaminants and the type of crops grown.MethodsThis study investigated the fate of emerging contaminants (ECs), particularly pharmaceuticals, in durum wheat grown on soils irrigated with treated wastewater in southern Italy. The experiment was conducted in lysimeters irrigated with wastewater during previous crop cycles, assessing the presence and distribution of ECs in both soil and plant tissues. Three different levels of exposure to ECs were compared: freshwater irrigation (FW), wastewater treated to European average contaminant levels (TWWx1), and a triple dose of contaminants (TWWx3).ResultsThe behavior of 12 different ECs in the plant-soil complex was analyzed and found variable. Fluconazole and carbamazepine were found to have higher uptake concentrations in the plant, with accumulation observed in the plant and grain, especially in the TWWx3 treatment. However, some ECs (such as Sulfamethoxazole, Trimethoprim, Ketoprofen, Diclofenac, Metoprolol, and Naproxen) showed high uncertainties in their fate, probably due to degradation in soil and influential crop parameters.DiscussionThe results of this study contribute to the argument that the reuse of treated wastewater for irrigation, if properly monitored, can be a safe approach in agriculture and can support policymakers in developing future legislative frameworks for sustainable water management.

Synthesis of amidoxime adsorbent prepared by radiation grafting on upcycled low-density polyethylene sheet for removal of heavy metals from wastewater

The issue of discharging waste, especially heavy metals from industrial activities into the environment, not only adversely impacts environmental quality but also has impacts on communities and human health. Removal and reduction of heavy metal contamination in rivers and wastewater are, therefore, critical initiatives that require significant attention. This work studied the removal of heavy metals, including Zn(II), Cu(II), As(III), and Pb(II) by utilizing an upcycled amidoxime low-density polyethylene sheet (AO-sheet). The synthesized AO-sheet was analyzed for various physical properties, including scanning electron microscope, energy-dispersive x-ray spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. For the batch adsorption experiment, parameters affecting adsorption capacity were studied: initial concentration, submerging time, and pH. Adsorption isotherms were also studied. The results of the heavy metal adsorption study showed that the initial concentration was the most significant parameter; the higher the initial concentration, the greater the adsorption capacity. The adsorption capacity of Zn(II) and Pb(II) increased with submersion time, which achieved 21.07 and 0.855 mg/g-adsorbent, respectively, after four weeks of submersion under the highest initial concentration studied. The adsorption capacity of Cu(II) was 7.98 mg/g-adsorbent after two weeks of optimal adsorption duration under the highest initial concentration studied. The adsorption capacity of As(II) was 1.07 mg/g-adsorbent after one week of optimal submersion time under the highest initial concentration studied. Moreover, the appropriate pH range for effective adsorption of Zn(II), Cu(II), and Pb(II) was identified as 8–9, while for As(III), it was 6–8, with an adsorption duration of 0.43 weeks (3 days). From the Langmuir isotherm, it was found that the adsorption of this work was characterized by monolayer adsorption. The results demonstrate that the AO-sheet can be effectively used to remove heavy metals from wastewater. Its potential for reusability was up to 8 cycles, with the Zn(II) adsorption capacity being reduced to about 20.37%.

Novel MoS2-In2O3-WS2 (2D/3D/2D) ternary heterostructure nanocomposite material: Efficient photocatalytic degradation of antimicrobial agents under visible-light

Fabrication of ternary composited photocatalytic nanomaterials with strong interaction is vital to deriving the fast charge separation for efficient photodegradation of organic contaminants in wastewater under visible light. In this work, novel ternary 2D/3D/2D MoS2-In2O3-WS2 multi-nanostructures were synthesized using facile hydrothermal processes. XRD, FTIR, and XPS results confirmed the phase, functional groups, and element composition of pure MoS2, MoS2-In2O3, and MoS2-In2O3-WS2 hybrids. UV-DRS spectra of the MoS2-In2O3-WS2 ternary hybrid indicate maximum absorption in the visible light range with a band-gap energy value of 2.4 eV. The surface of the 2D WS2 nanosheet structure tightly blends and densely disperses 2D MoS2 nanosheets and 3D In2O3 nanocubes. This confirmed the formation of the MoS2-In2O3-WS2 ternary hybrid in the form of 2D/3D/2D multi-nanostructures, which is also indicated from SEM and HR-TEM images. The synthesized MoS2-In2O3-WS2 ternary hybrid showed maximum photocatalytic activity under visible-light for antimicrobial agents such as triclosan (TCS) and trichlorocarban (TCC). The photocatalytic activity of TCS was revealed to be 95% at 90 min, while that of TCC was 93% at 100 min. The reusability and stability tests of the prepared MoS2-In2O3-WS2 ternary hybrid after four consecutive photocatalytic cycles were analyzed by FTIR and SEM, which indicated that the prepared ternary hybrid was very stable. Overall results suggested that the developed MoS2-In2O3-WS2 (2D/3D/2D) multi-nanostructures are environmentally friendly and low-cost nanocomposites as a potential photocatalyst for the removal of antimicrobial agents from wastewater.

Production of magnetic photocatalysts from TiO2, Fe(NO3)3 and sucrose and their application for the degradation of model organic contaminants

AbstractBACKGROUNDPhotocatalysis is an efficient method for the removal of organic contaminants in wastewater. In this study, different magnetic photocatalysts for the degradation of organic compounds were prepared.RESULTSTi/C/Fe photocatalysts were prepared by supporting TiO2 (20, 40 and 60% w/w) on a carbon/iron oxide (C/Fe) magnetic carrier. Characterization via Raman spectroscopy, X‐ray diffractometry, thermal analysis, X‐ray fluorescence, scanning electron microscopy and energy‐dispersive X‐ray spectroscopy/elemental mapping and magnetic property analysis by vibrating‐sample magnetometry confirmed the presence of TiO2, Fe3O4, Fe3C and char in the photocatalysts as well as their magnetic properties. The results of specific surface area analysis showed that the C/Fe support had a surface area of 183 m2 g−1 and that this area decreased with an increasing amount of supported TiO2, reaching up to 129 m2 g−1. Diffuse reflectance spectroscopy characterization revealed that the bandgap values obtained for the photocatalysts (Ti/C/Fe) were lower than 3.2 eV. The prepared photocatalysts showed high efficiency in degrading the contaminants Remazol Black (RB5) (99%), paracetamol (77%) and phenol (90%). Recovery and reuse experiments using RB5 showed that after the fourth reaction, the photocatalytic efficiency was reduced by 50%, and the recovery reached up to 70%. Sedimentation kinetics showed that while only 6% of the TiO2 was deposited, up to 89% of the photocatalysts were deposited.CONCLUSIONSThese results indicate that the photocatalysts showed excellent photocatalytic efficiency for different contaminants and can be easily and quickly separated from the reaction medium by magnetic separation. © 2024 Society of Chemical Industry (SCI).

Superoxide radicals mediated by high-spin Fe catalysis for organic wastewater treatment

Water resources are indispensable basic resources and important environmental carriers; the presence of organic contaminants in wastewater poses considerable risks to the health of both humans and ecosystems. Although the Fenton-like reactions using H2O2 as the oxidant to destroy organic pollutants are attractive, there are still challenges in improving reaction activity under neutral or even alkaline conditions. Herein, we designed a H2O2 activation pathway with O2•- as the main active species and elucidated that the spin interaction between Fe sites and coordinated O atoms effectively promotes the generation of the key intermediate Fe-*OOH. Furthermore, we successfully captured and analyzed the Fe-*OOH intermediate by in situ Raman spectroscopy. When applying FBOB to a continuous-flow reactor, CIP removal efficiency remained at around 90% within 600 min of continuous operation, achieving excellent efficiency, stability, and pH tolerance in removing pollutants.

Nitrogen and Phosphorus Discharges from Cargo Ships’ Black and Grey Waters—A Case Study of a Baltic Sea Port

Shipping is a vital component of global trade. However, shipping activities have negative environmental impacts, including emissions to air and water. The Baltic Sea is severely affected by eutrophication, mainly due to nutrient inputs, especially nitrogen and phosphorus. Understanding the contributions of various nutrient sources is essential for informed environmental regulation. The aim of this research is to quantify the nutrient content of black and grey water discharged from cargo ships in the Baltic Sea in order to assess their contribution to the total nutrient load. Specifically, this research examines the nitrogen and phosphorus loadings from ships calling the port of HaminaKotka and addresses key questions regarding nutrient generation, discharge proportions, emission shares by ship type, and their importance compared to other sources. Using a methodology based on ship data and nutrient production estimates, this study found that 2545 cargo ships generated a total of 781 kg of nitrogen and 134 kg of phosphorus in their effluents during their voyages to the port in 2021. However, only a small fraction (0.5%) of the cargo ships discharged their wastewater at port reception facilities. This study concludes that nutrient discharges from cargo ships’ wastewaters are relatively small, contributing less than 0.06% phosphorus and 0.01% nitrogen to the total load in the area. This result indicates that the impact of cargo ships’ wastewater on the eutrophication of the Baltic Sea is smaller than previously thought. The methodology used in this study can be applied in other ports and regions to assess nutrient discharges from cargo ships’ wastewaters on a wider scale. Further research is recommended to assess the effectiveness of on-board treatment systems, the impact of other contaminants in wastewater, and the development of port reception facilities to facilitate proper wastewater management in the maritime trade.

Adsorption of cationic dye onto Raphanus seeds: optimization, adsorption kinetics, thermodynamic studies

Dyes are one of the common contaminants in industrial wastewater. Adsorption is the most widely method which used to treat dye-contaminated water due to their easy use, cost-effectiveness, and their efficiency was high. The aim of this study is the investigating of the utilization of the activated carbon which prepared from Raphanus seeds solid residual (ACRS) as a low cost adsorbent for removing of cationic Methylene Blue dye (MB)from wastewater. measuring the surface area using BET methods and SEM. The FT‒IR and XRD was measured. Different variables (e.g.: initial concentration of the dye, pH, contact time, and dosage) have been studied. Process has been systematically investigated experimentally at (25 ± 1 °C). The % removal of MB reached 99.4% after 90-min MB adsorption (40 mg/L) was observed within 5 min of contact time for the Raphanus seeds solid residual (ACRS) dosage of 4 g/L. MB initial concentration (10 ppm) Raphanus seeds solid residual (ACRS) effectively adsorbed MB (> 99%) over a widely range of pH (from pH 2 to pH 8). However, a swift decline in removal was observed when the pH was set at 7. The results of the adsorption kinetics analysis indicate a strong correlation with the pseudo-second-order model, as evidenced by the high regression coefficients. However, the adsorption capacity diminished with a rise in temperature. Thermodynamic calculations of (MB) onto Raphanus seeds solid residual (ACRS) is an exothermic reaction. The results have been indicated that the effectiveness of MB removal by activated carbon prepared from Raphanus seeds solid residual is favorable under neutral conditions, Raphanus seeds solid residual (ACRS) can be considered an efficient, environmentally friendly, readily available, and economical adsorbent that could treat industrial wastewater contaminated with cationic textile dyes. The objective of the experiments was to investigate the impact of various factors on the response of a process or formulation. To accomplish this goal, response surface methodology (RSM) has employed as a statistical model. RSM is an efficient and effective method for optimizing processes through the use of a quadratic polynomial model. The utilization of RSM allows for a reduction in the number of experiments needed, thus minimizing the associated costs of extensive analysis. This method has been done using Box–Behnken Design (BBD) to optimize % removal of MB. The optimal conditions as obtained from the RSM is pH 7,contact time 120 min, initial concentration 10 ppm, ACRS dosage 1 g, adsorption temperature 45 °C.

Applications of Escherichia Coli Esterases for Bioremediation and Treatment of Wastewater Organic Chemical Pollutants

This study used computational techniques, including 3D enzyme structural modeling and molecular docking, to gain insight into the bioremediation of organic wastewater contaminants using E. coli esterase enzymes. Furthermore, a total of 24 wastewater organic chemicals belonging to different categories, such as pharmaceuticals, artificial sweeteners, pesticides/herbicides, endocrine disrupting chemicals, and persistent organic pollutants, were identified through the toxicology database. Comparative genetics and reported literature. Furthermore, 3D PDB and AlphaFold structures of 194 esterase enzymes from E. coli were retrieved by first identifying a common domain (Alpha Beta hydrolase domain) using the InterPro database. Molecular docking of esterase enzymes and pollutants was used, resulting in the best binding enzymes to their respective organic wastewater pollutants, including bezafibrate which showed the best binding with all enzymes ranging from -6.33 kcal/mol to -9.87 kcal/mol . Subsequently, the majority of the ligands (organic wastewater pollutants) reacted with enzymes such as the ORFC-like enzymes, which were computationally annotated in this study for the first time, yuaR (strain K12), menH (strain ETI89/UPEC), and menH (strain O157). :H7) has significant binding affinities and consists of a common Alpha Beta hydrolasefold-1 domain. This suggests that esterase enzymes containing the Alpha Beta hydrolasefold-1 domain may be involved in the efficient degradation of organic wastewater pollutants.

Biogenic Green Synthesis of Zinc Oxide Nanoparticles from Defatted Coconut Presscake for Wastewater Treatment

Defatted coconut meat presscake is a by-product of coconut milk production, often discarded or used as low-value products, but has the potential to treat wastewater. This study aimed to characterize zinc oxide nanoparticles (ZnO NPs) synthesized from defatted coconut meat presscake and determine their effect on the degradation of contaminants in wastewater and antibacterial properties. The nanoparticles were synthesized via a co-precipitation method using zinc nitrate as a precursor and defatted coconut meat presscake extract as a reducing agent. The nanoparticles were characterized using FTIR (Fourier Transform Infrared Spectroscopy), FE-SEM (Field-Emission Scanning Electron Microscopy), XRD (X-ray diffraction), and TGA (Thermogravimetric Analysis). The ZnO NPs exhibited a hexagonal wurtzite structure with an average size of 54 nm. The photocatalytic degradation of methylene blue under UV light irradiation showed a degradation efficiency of 79.5% within 180 minutes. Treated wastewater with ZnO NPs at concentrations of 0.5, 1, and 5 mg/L showed a significantly reduced microbial load, with averages of 10.2×106, 8.3×106, and 3.8×106 CFU/mL, respectively, compared to untreated wastewater (16.5×106 CFU/mL), indicating the antimicrobial properties of ZnO NPs. Therefore, ZnO NPs synthesized from defatted coconut meat presscake extract offer an eco-friendly solution for efficiently treating wastewater from the food industry.

Promisingly prioritized elimination performance of europium and uranium from industrial wastewater by recyclable polydopamine functionalized hydroxyapatite/ZIF-67 hybrids

In recent decades, the nuclear industry has undergone robust growth leading to an increasingly severe issues of radionuclide contaminants in wastewater. Consequently, the development of a novel, efficient, regenerative and environmentally friendly adsorbent has become a significant challenge. In this study, recyclable polydopamine functionalized hydroxyapatite/ZIF-67 (HAP/ZIF-67/PDA) hybrids with a mass of functional groups, were successfully synthesized using the ultrasonic-assisted method. The especially characterized techniques illustrated that the HAP/ZIF-67/PDA hybrids were outstanding stable, excellent physicochemical properties and abundant functional groups. The elimination performances of Eu(III) and U(VI) from wastewater were also explored and deliberated through macroscopic experiment under diverse wastewater chemistry environment. The optimal adsorption capacity of HAP/ZIF-67/PDA was approximately 1.33 × 10-3 mol/g for Eu(III) and 8.85 × 10-4 mol/g for U(VI), surpassing those reported materials in previous literatures. The particular adsorption isotherms of Eu(III) and U(VI) were favorably fitted by Langmuir model, illustrating that the adsorption Eu(III) and U(VI) were totally endothermic reaction. The remarkable adsorption performance of HAP/ZIF-67/PDA hybrids (within 80 min for Eu(III) and 100 min for U(VI)) was verified through dynamic model, and then the kinetics results were well simulated through pseudo-second-order kinetic model, which further illustrated outstanding performance for rapidly treating Eu(III) and U(VI) under extreme emergency conditions. The primary adsorption mechanisms HAP/ZIF-67/PDA hybrids towards Eu(III) and U(VI) were surface complexation, competitive interaction, cation change, π-π* bonds and electrostatic interaction. Based on the excellent adsorption performance and recyclability of HAP/ZIF-67/PDA, it holds significantly potential and promising prospects for the efficient elimination of lanthanide and actinium contaminants from the practical treatments and disposals fields of industrial wastewater.

Construction of CS-SDAEM long-chain polysaccharide derivative on TA@CNTs coated PVDF membrane with effective oil-water emulsion purification and low contamination rate

Currently, the most effective way to improve the anti-fouling performance of water treatment separation membrane is to enhance the hydrophilicity of the membrane surface, but it can still cause contamination, leading to the occurrence of flux reduction. The construction of a strong hydration layer to resist wastewater contamination is still a challenging task. In this study, a defect-free hydration layer barrier was achieved by grafting chitosan polysaccharide derivatives (CS-SDAEM) on the membrane, which achieved in effective fouling prevention and low flux decline rate. A layer of tannic acid-coated carbon nanotubes (TA@CNTs) has been uniformly deposited on the commercial PVDF membrane so that the surface was rich in -COOH groups, providing sufficient reaction sites. These reactive groups facilitate the grafting of amphiphilic polymers onto the membrane. This modification strategy achieved in enhancing the antifouling performance. The modified membrane achieved low contamination rate with DR of 16.9 % for wastewater filtration, and the flux recovery rate was above 95 % with PWF of 1100 (L·m−2·h−1). The membrane had excellent anti-fouling performance, which provided a new route for the future development of water treatment membrane.

Comprehensive review of surface contamination in nuclear waste waters: identification, quantification, and mitigation strategies

Abstract The safety and reliability of nuclear facilities hinge critically on addressing metallic surface contamination in nuclear waste waters. This contamination poses significant hazards to the environment, human health, and the structural integrity of equipment. Key contaminants include heavy metals such as lead, cadmium, and mercury from industrial processes, and radioactive isotopes like uranium, plutonium, and cesium, which present severe radiological risks due to their formation during nuclear reactions and fuel cycles. Corrosive chemicals further exacerbate the problem by promoting the accumulation of rust and other metallic compounds. Additionally, organic contaminants from equipment leaks and microbiological elements, including fungi and bacteria, can form biofilms that accelerate the corrosion process. The objective of this review is to evaluate the various techniques used to identify and quantify these contaminants on metal surfaces, such as surface sampling and microbiological analysis. By implementing appropriate mitigation measures based on these findings, it is possible to reduce risks and ensure the safety and operational integrity of nuclear plants. This comprehensive assessment aims to provide a framework for enhancing contamination management practices in nuclear facilities.

Evaluating a green liquid phase plasma discharge process and working mechanism for remediating cobalt contamination in water

Cobalt is a toxic heavy metal contaminant in water and wastewater causing health concerns and on the other hand, a valuable element to recycle. In this study, performance of a novel and green continuous liquid phase plasma discharge (CLPD) process was investigated for removal and recovery of cobalt from aqueous solution without use of any catalysts or chemicals. The CLPD reactor design features two conductive channels and stable electric discharge at the orifice of two dielectric plates sandwiched among the electrodes. The effects of operating factors of the CLPD process were evaluated with liquid flow rate (25–100 mg/L) and applied power (200–300 W), and the highest removal efficiency of cobalt (93 %) was obtained within 25 min at a 50 ml/min liquid flow rate and 300 W applied power. The CLPD energy efficiency for cobalt removal under this condition was 27.44 g kW-1h−1. Reaction kinetics with scavenger tests revealed that oxidative reactive species, i.e., hydroxyl radical and superoxide radicals, produced at the discharge zone were responsible for cobalt removal from water by producing cobalt oxide particles and the reaction pathways were proposed. The CLPD process not only allowed for the efficient removal of cobalt (II) from water but also synthesized cobalt oxides particles with averaged size of 2.75 µm, which can be applied as catalyst. The overall results indicated that the novel CLPD is a robust and highly effective process to remove and recover cobalt from water.