Metal organic framework (MOF) nanoparticles are recognized for their effective removal of metal ions from aqueous systems. However, the application of nanoparticles in a powder form as synthesized is ...not practical and recovery is not easy. We prepared a recyclable magnetic MOF nanoparticle phase and used a widely available waste biomass to generate biochar to support magnetic nanoparticles applied in the treatment of aqueous antimony pollution. A mushroom waste biochar was used to support a magnetic UIO-66-2COOH (denoted as BSMU). Adsorption of trivalent antimony (Sb (III)) onto the BSMU was evaluated. The results showed that optimum conditions for preparation of the BSMU were the mass ratio of MMOF to biochar 4:1, the temperature 70 °C, the time 4 h, and the initiator 4 mM. Under such conditions, sorption capacity reached 56.49 mg/g for treatment of Sb (III) solution at 100 mg/L and pH 9.1. Alkaline conditions (such as pH 9.1) are more favorable for adsorption than acidic conditions, and coexisting ions including NO3−, Cl−, SO42−, and PO43− had no significant negative effect in adsorption, and with the use of low dose, higher adsorption density achieved. The adsorption followed a pseudo second order kinetics model and Freundlich isotherm model. It resulted in a higher enthalpy changes (ΔHθ) and activation energy (Ea) of 97.56 and 8.772 kJ/mol, respectively, and enhanced the rate pf random contact between antimony and the BSMU, as indicated by a higher entropy change (ΔSθ) up to 360 J/mol·K. As a result, it readily absorbs antimony. These adsorption properties identified in this study would provide a valuable insights into the application of nanoparticles loaded biochar from abundant biomass in environmental remediation.
•A biochar supported magnetic MOF adsorbent for removal of Sb (III) is proposed.•The adsorbent is highly effective in the removal of Sb (III).•The removal performance relies on the mass ratio of MMOF to biochar.•The main adsorption of Sb (III) onto the adsorbent is chemical sorption.
Many global mining activities release large amounts of acidic mine drainage with high levels of manganese (Mn) having potentially detrimental effects on the environment. This review provides a ...comprehensive assessment of the main implications and challenges of Mn(II) removal from mine drainage. We first present the sources of contamination from mineral processing, as well as the adverse effects of Mn on mining ecosystems. Then the comparison of several techniques to remove Mn(II) from wastewater, as well as an assessment of the challenges associated with precipitation, adsorption, and oxidation/filtration are provided. We also critically analyze remediation options with special emphasis on Mn-oxidizing bacteria (MnOB) and microalgae. Recent literature demonstrates that MnOB can efficiently oxidize dissolved Mn(II) to Mn(III, IV) through enzymatic catalysis. Microalgae can also accelerate Mn(II) oxidation through indirect oxidation by increasing solution pH and dissolved oxygen production during its growth. Microbial oxidation and the removal of Mn(II) have been effective in treating artificial wastewater and groundwater under neutral conditions with adequate oxygen. Compared to physicochemical techniques, the bioremediation of manganese mine drainage without the addition of chemical reagents is relatively inexpensive. However, wastewater from manganese mines is acidic and has low-levels of dissolved oxygen, which inhibit the oxidizing ability of MnOB. We propose an alternative treatment for manganese mine drainage that focuses on the synergistic interactions of Mn in wastewater with co-immobilized MnOB/microalgae.
Dissolved organic matter (DOM) is not only a vector for the migration of aquatic environmental pollutants, but is also key to the control of water pollution. Economic and effective DOM removal ...through coagulation is essential in water treatment processes. This work investigated the role of carboxylated magnetic metal organic frameworks (MMOFs) nanoparticles in polymeric iron-based coagulation for the removal of aquatic DOM using a MMOFs-doped polyferric iron-based coagulant (MMOF-PIC). Analytical methodologies and tools used in this research included scanning electron microscopy (SEM), zeta potential, molecular weight cut off (MWCO), vibrating sample magnetometer (VSM) measurement, excitation emission matrix spectroscopy (EEMs), and X-ray photoelectron spectroscopy (XPS). The results showed that MMOF-PIC had the potential to change the structure of the polyferric iron-based coagulant (PIC) and charge, as determined by a porous surface morphology, a higher medium polymeric species distribution, and a more positive zeta potential. The MMOFs consequently enhanced PIC action on the removal of UV254 exposed DOM species with molecular weight <30 kDa, including aromatic CC based compounds, org-N as primary amines and amide/peptide bound species, water containing microbial metabolites and protein-like materials. The coagulation of DOM was enhanced by improving charge neutralization, adsorption-bridging and sweep-flocculation in the presence of MMOFs nanoparticles. This was due to hydrogen bonds, π-π bonds and covalent bonds resulting from actions of nanoparticles and pollutants. These results indicate that magnetic MOF nanoparticles can improve PIC coagulation for DOM, enhancing future removal of target pollutants.
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•Carboxyl magnetic MOFs (MMOFs) doped polymeric-iron was prepared.•MMOFs and PIC coexisting in the same system can enhance coagulation for DOM.•MMOFs changed PIC’s structure, charge and adsorption properties.•Chemical bond binding force contributed to enhanced adsorption.
In this study, we identified the sources of trace metals, investigated their spatial distribution in topsoil and assessed their potential ecological risk in the area surrounding a typical manganese ...mining area in Xiangtan, Hunan Province, China. The concentrations of Mn, Cu, Pb, Zn, Cd, Ni, Cr and Hg in the topsoil of the study area were measured. Except for Cr and Hg, all trace metals exceeded the corresponding soil background values for Hunan Province. The spatial variation in trace metals was visualized by GIS, and the results show that trace metals in topsoil are enriched mainly around mines and smelters. Two groups of trace metals were identified using the spatial distribution, trend analysis, Pearson's correlation and principal component analysis: Mn, Cu, Pb, Zn, Cd and Ni can be attributed to industrial and mining activities, whereas Cr and Hg are of natural origin. The results also revealed the extent of the influence of secondary processes such as the prevailing wind direction, erosion of mine tailings and rainwater runoff play significant roles in the wider dispersal and transfer of trace metals. In addition, the environmental risk of metal pollution was evaluated by applying the geoaccumulation index and potential ecological risk index (PERI) to the study area. The accumulated PERI for metals of concern is at highest risk level in the main manganese mine area. This decreases to a moderate risk around the manganese mine area, highlighting locations for further risk management concern. Furthermore, nearly 80% of the potential ecological risk was from Cd across the study area.
After the successful preparation of empirical double network hydrogel beads from graphene oxide/sodium alginate(GO/SA), its cationic metal adsorption performance in aqueous solutions were ...investigated. Taking Mn(II) as an example, the contribution of several factors including pH, bead dosage, temperature, contact time and initial concentration ions to adsorption efficiency were examined. The Transmission Electron Microscopy (TEM) results indicate that the GO/SA double (GAD) network hydrogel bead strongly interpenetrate and the adsorption of Mn(II) is mainly influenced by solution pH, bead dose and temperature. The GAD beads exhibit an excellent adsorption capacity of 56.49 mg g
. The adsorption process fit both Pseudo-second order kinetic model (R
> 0.97) and the Freundlich adsorption isotherm (R
> 0.99) and is spontaneous. After seven rounds of adsorption-desorption cycle, the adsorption capacity of GAD hydrogel remained unchanged at 18.11 mg/g.
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•MEBR coupling intermittent DC and MBR was established to treat coal chemical industry wastewater.•MEBR exhibited significant efficiency improvement and membrane fouling ...reduction.•Changes in properties of mixed liquor caused by electrokinetics accounted for fouling migration.•MEBR with intermittent DC and iron anode promoted microbial community evolution.
A membrane electro-bioreactor (MEBR) embracing biological treatment, electrokinetic phenomena and membrane filtration was established by applying intermittent direct current (DC) to MBR. MEBR exhibited significant improvement of treatment performance and reduction of membrane fouling. COD and total phenols removal efficiencies increased to 83.53% and 93.28% at an exposure mode of 24′-OFF/6′-ON, compared to 71.24% and 82.43% in MBR. Trans-membrane pressure increment rate declined dramatically in MEBR, which was mainly attributed to the increase of sludge floc size and decrease of zeta potential, soluble microbial products and specific resistance to filtration, resulted from electrokinetic effects such as electrocoagulation, electrophoresis, electroosmosis and electromigration of ions. It was notable that DC exposure exerted distinct evolution on microbial community, with the improvement of microbial community richness and diversity. The relative abundances of functional genera were promoted noticeably in MEBR. An interactive relevance existed among microbial community structure, mixed liquor properties and operational parameters.
The pollution level of potentially toxic elements (PTEs) in surface soils is detrimental to the ecosystem and human health. In this research, various indices such as an index of geo-accumulation ...(Igeo), contamination factor (CF), degree of contamination (DC), and principal component analysis (PCA) were implemented to identify and evaluate the soil PTEs pollution; and then human health risk assessment model used to establish the link between heavy metals pollution and human health in the urban region of south India. Results exhibited that the mean concentration of Cr, Cu, Ni and Zn were found to be 1.45–6.03 times greater than the geochemical background values. Cr and Cu were the most profuse PTEs measured in the soils. The pollution indices suggest that soil of the study region is mainly moderate to highly polluted. The non-carcinogenic health risk assessment proposed by the United States Environmental Protection Agency (USEPA) suggested the mean hazard indices (HIs) were below one which denotes no significant of non-carcinogenic risks to both children and adults. Furthermore, carcinogenic risk assessment results advised ~80% of cancer risk was caused by Cr contents, while other heavy metals indicate that neither children nor adults in the study region were of carcinogenic risks.
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•Potentially toxic elements (PTEs) contamination levels were estimated by using profound methods such as contamination factor, degree of contamination and index of geo-accumulation.•Assessment of non-carcinogenic and carcinogenic risks for children and adults were investigated in the study region.•Principal component analysis of PTEs were studied and also generated their spatial distribution maps in the investigated region.
Removing dissolved organic matter (DOM) with polyaluminium chloride is one of the primary goals of drinking water treatment. In this study, a new HMW framework was proposed, which divided the factors ...affecting coagulation into three parts consisting of hydraulic condition (H), metal salt (M), and background water matrix (W). In this framework, H, M and W were assumed to be interacted with each other and combined to determine coagulation efficiency. We investigated the feasibility of the framework to determine the treatment efficiency through mathematical models. Results showed that non-linear artificial neural network (ANN) model was a better fit to the experimental data than the linear partial least squares (PLS) model: the ANN model could explain 76% of the total variations while the PLS could only explain 71%. The PLS did not follow the variations of observed values adequately. These experiments showed that the interaction between the HMW framework components were not simple linear relationships. The ANN model was able to optimize the composition of the HMW framework improving the efficiency of DOM removal through the components of HMW such as velocity gradient (G value), coagulant dosage, solution pH, and background water matrix. Overall, HMW framework is a new classification of factors affecting coagulation, leading to a better understanding of the coagulation process and sensitivity to influencing variables.
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●A new HMW framework to determine coagulation behaviors was proposed.●HMW framework included hydraulic condition, metal salt and background water matrix.●ANN model with HMW framework was applicable to optimization of coagulation of DOM rather than linear model.●The ANN model could explain 76% of the total variations.
Purpose of Review
Many factors influence the health impact of exposure to metalliferous mine dusts and whilst the underpinning toxicology is pivotal, it is not the only driver of health outcomes ...following exposure. The purpose of this review is twofold: (i) to highlight recent advances in our understanding of the hazard posed by metalliferous mine dust and (ii) to broaden an often narrowly framed health risk perspective to consider the wider aetiology of the potential determinants of disease.
Recent Findings
The hazard posed by metalliferous dusts depends not only on their abundance and particle size but other properties such as chemical composition, solubility, shape, and surface area, which all play a role in the associated health effects. A better understanding of the mechanisms that lead to toxicity, such as recent advances in our understanding of the role played by reactive oxygen species (ROS), can help in the development of improved in vitro models to support risk assessments, whilst biomonitoring studies have the potential to guide risk management decisions for mining communities.
Summary
Environmental exposures are complex; complex geochemically and complex geographically. Research linking the environment to human health is starting to mature, highlighting the subtlety of multiple exposures, mixtures of substances, and the cumulative legacy effects of life in disrupted and stressed environments. We are evolving more refined biomarkers to identify these responses, which enhances our appreciation of the burden of effects on society and also directs us to more sophisticated risk assessment approaches to adequately address evolving regulatory and societal needs.
•Relations between pH, depth, and PTEs concentration in weakly alkaline red loam.•Comparison of migration ability of Pb, Cr, As, Cd, and Sb in the soil.•Relationships between leaching concentration, ...depth, and total concentration of soil PTEs.•Comparison of risks to humans and the ecological environment of PTEs in the soil.
Mining activities usually caused soil polluted by potential toxic elements (PTEs). This paper used the analysis of correlation, variance, and power analysis to clarify the relationship and migration characteristic of 90 samples in 30 sampling points at the depths of 30, 100, and 200 cm. The results showed in the weakly alkaline red loam, pH had no significant effect on the total concentration of PTEs in the soil. The greater the depth was, the greater the total concentration of PTEs in the soil. And depth had no significant effect on the soil pH. The cadmium (Cd) migration process in the soil was more severe than other elements. The arsenic (As) migration ability was lower than other elements. Except for chromium (Cr), lead (Pb) and antimony (Sb) had the strongest migration ability. Soil depth and total PTEs concentration had no significant effect on the leaching concentration of As and Sb, whether it was by water leaching or acid leaching. From the perspective of the potential ecological risk index, Pb and Cr had low or no risk, while As, Sb, and Cd needed to be dealt with. From the perspective of Hazard Quotient, Pb, Cr, and Cd have low or no non-carcinogenic risk, while As and Sb did the opposite. This research inspired understanding the process of soil PTEs migration, and helping local government to control the distribution of PTEs.
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