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When fluoride levels in water exceed permitted limits (>1.5 mg L−1), water pollution becomes a major concern to humans.

Capacitive deionization (CDI) is a newly developed desalination technology with low energy consumption and environmental friendliness. The surface area restricts the desalination capacities of traditional carbon-based CDI electrodes while battery materials emerge as CDI electrodes with high performances due to the larger electrochemical capacities, but suffer limited production of materials. LiMn

Metal-organic framework (MOFs) composites are new kind of porous materials, with great specific surface area and extremely high porosity. MOFs have been in the catalytic application due to excellent catalytic properties such as, their unique structure and dispersed active centers. Hence, the chemical, environment and energy-related fields disciplines have made substantial applications of MOFs and its composites. Moreover, several researchers have made conducted extensive studies regarding the application of MOFs materials for air pollution control such as, including functionalization, loading, carbonization, oxidation of MOFs materials, and application of MOFs as sensors for air pollution monitoring. This review article is aimed at providing precise information about the efforts made by some researchers in the field of MOFs and MOFs derived materials and their application in other disciplines. The following areas have been succinctly reviewed: (1) general introduction of MOFs materials, (2) synthesis of various MOFs materials, composites and their derivatives, (3) catalysis of MOFs materials, composites and their derivatives on different air pollution, (4) summary and future prospects. We hope this review will help researchers understand more about the research progress of MOFs materials in the catalysis of air pollution.

2D carbon ribbon/Al2O3 was synthesized with two-dimensional metal organic frameworks 2D-MOFs as precursors using the solvothermal and calcination methods. Batch experiments of adsorption parameters such as pH, liquid/solid ratio, adsorption kinetics, adsorption thermodynamics, and anions competitions were investigated to understand the adsorptive behavior of fluoride on carbon ribbon/Al2O3 and nitrogen-doped carbon ribbon/Al2O3. The adsorption of fluoride on carbon ribbon/Al2O3 could be described as the chemical and multilayer adsorption, while the adsorption of fluoride on nitrogen-doped carbon ribbon/Al2O3 followed the chemical and monolayer adsorption phenomenon. The fluoride on nitrogen-doped carbon ribbon/Al2O3 had a much faster adsorption rate of 3.1×10−7 m/s than carbon ribbon/Al2O3, which was 1.2×10−7 m/s. The nitrogen-doping on carbon ribbon enhances structural defects and improves the adsorption performance of fluoride. Also, the diacetylene linkages (—C≡C—) and pyridinic-N were studied to understand their influences on removing fluoride. The result indicates that carbon ribbon and nitrogen-doped ribbon could serve as good adsorbents for removing fluoride.

Capacitive deionization (CDI) is an emerging eco-friendly desalination technology with mild operation conditions. However, the energy consumption of CDI has not yet been comprehensively summarized, which is closely related to the economic cost. Hence, this study aims to review the energy consumption performances and mechanisms in the literature of CDI, and to reveal a future direction for optimizing the consumed energy. The energy consumption of CDI could be influenced by a variety of internal and external factors. Ion-exchange membrane incorporation, flow-by configuration, constant current charging mode, lower electric field intensity and flowrate, electrode material with a semi-selective surface or high wettability, and redox electrolyte are the preferred elements for low energy consumption. In addition, the consumed energy in CDI could be reduced to be even lower by energy regeneration. By combining the favorable factors, the optimization of energy consumption (down to 0.0089 Wh·gNaCl−1) could be achieved. As redox flow desalination has the benefits of a high energy efficiency and long lifespan (~20,000 cycles), together with the incorporation of energy recovery (over 80%), a robust future tendency of energy-efficient CDI desalination is expected.

The outbreak of the COVID-19 pandemic has severely impacted human lives, human activities, and the world economy. In response to curb its spread, pandemic risk reduction measures such as mass lockdowns, extensive travel bans, and mass quarantine were imposed globally.

The MIL-53(Al)-NH2 was designed to remove fluoride with hierarchical hollow morphology. It was used as an adsorbent for fluoride removal at a wide pH range (1-12) due to the positive zeta potential of MIL-53(Al)-NH2. The pH did not significantly influence the fluoride adsorption into MIL-53(Al)-NH2. However, the adsorbent indicated good adsorption capacity with maximum adsorption of 1070.6 mg g-1. Different adsorption kinetic and thermodynamic models were investigated for MIL-53(Al)-NH2. The adsorption of fluoride into MIL-53(Al)-NH2 followed the pseudo-second-order model and a well-fitted Langmuir model indicating chemical and monolayer adsorption process. When mass transfer model was used at initial concentrations of 100 ppm and 1000 ppm, the rates of conversion were 8.4 × 10-8 and 4.7 × 10-8 m s-1. Moreover, anions such as [Formula: see text], [Formula: see text], [Formula: see text], Cl-, and Br- also had less effect on the adsorption of fluoride. Also, experimental and theoretical calculations on adsorption mechanism of MIL-53(Al)-NH2 revealed that the material had good stability and regenerative capacity using alum as regenerant. In a nutshell, the dominant crystal face (1 0 1) and adsorption sites Al, O, and N combined well with F-, HF, and HF2- through density functional theory. It opens a good way of designing hollow MOFs for adsorbing contaminants in wastewater.

Fluoride concentration in drinking water has become a global challenge due to its effects on the human body. While small level (1–1.5 mg·L−1) strengthens enamel and bone formation, higher concentra...

Metal-organic frameworks (MOFs) based membranes with superior mechanical properties are of particular interest in purification, separation, and catalysis. Nevertheless, their fabrication still remains a grand challenge. Here, fungus hyphae (Mucor) were used as a robust scaffold to load the MOFs and induced the formation of porous and flexible membranes. ZIF-8 was used as a representative of MOFs. The ZIF-8@Mucor membrane was formed by the in-situ growth of ZIF-8 on hyphae and then a vacuum filtration of the ZIF-8/hyphae composite. ZIF-8 was effectively dispersed on the ZIF-8@Mucor membrane, and the shear modulus of ZIF-8@Mucor-3 was 864 MPa by calculation. The ZIF-8@Mucor membrane exhibited promising properties for adsorption application to remove the highly toxic Pb2+. The adsorption capacity of this membrane was as high as 1443.29 mg/g. Results from dynamic adsorption indicated that the penetration concentration of Pb2+ ions was less than 5% of the original level before 80 min whereas after 160 min, penetration concentration of Pb2+ ions was more than 90%. This study would open a new way of how to synthesize composite MOFs/bacterial membranes for energy and environment purposes.

Bauxite is a widely available Al-O-rich mineral with great potential for abating fluoride. However, low adsorption capacity, a narrow workable pH range, and a lack of clarity on the best removal mechanism hinder its application. In this work, a highly efficient bauxite nanocomposite (Bx-Ce-La@500) was synthesized via doping and pyrolysis, and its fluoride adsorption in industrial wastewater was examined. Doping Ce/La synergistically improved the fluoride adsorption affinity of the composite (from pH

Capacitive deionization (CDI) is a newly developed desalination technology with low energy consumption and environmental friendliness. The surface area restricts the desalination capacities of traditional carbon-based CDI electrodes while battery materials emerge as CDI electrodes with high performances due to the larger electrochemical capacities, but suffer limited production of materials. LiMn2O4 is a massively-produced lithium-ion battery material with a stable spinel structure and a high theoretical specific capacity of 148 mAh·g−1, revealing a promising candidate for CDI electrode. Herein, we employed spinel LiMn2O4 as the cathode and activated carbon as the anode in the CDI cell with an anion exchange membrane to limit the movement of cations, thus, the lithium ions released from LiMn2O4 would attract the chloride ions and trigger the desalination process of the other side of the membrane. An ultrahigh deionization capacity of 159.49 mg·g−1 was obtained at 1.0 V with an initial salinity of 20 mM. The desalination capacity of the CDI cell at 1.0 V with 10 mM initial NaCl concentration was 91.04 mg·g−1, higher than that of the system with only carbon electrodes with and without the ion exchange membrane (39.88 mg·g−1 and 7.84 mg·g−1, respectively). In addition, the desalination results and mechanisms were further verified with the simulation of COMSOL Multiphysics.

Farming is the major economic activity of the people in the Asutifi-North District of Ghana however, farmers in this District are mainly characterized by small-farm holdings of less than 3 acres per farmer as a result of shrinking agricultural land due to increasing small and large-scale mining in the District. Currently, mining has become the major competitor to farming in terms of land-use conversion within the District. Though mining activities have led to several land-use conversions, little or no studies have been done in that regard. Studies over the years have focused on the environmental impacts of mining with less emphasis on the impacts of mining on farmers' welfare. This paper examines the factors influencing farmers' participation in land-use conversion for mining, its impacts on farmers' welfare, and the criteria of compensation given to affected farmers by the large-scale mine. Multi-staged sampling comprising both purposive and random sampling techniques was employed to gather data from 300 farmers in 5 mining communities in the district. The data obtained were analyzed using descriptive statistics and the Heckman two-stage model involving the Probit and OLS equations. Results indicate that variables such as farmer's age, sex, distance from household to farm, farmer's experience, total land size, and distance to the nearest access road were factors that influenced farmers' decision to participate in land-use conversion. Also, participants of land-use conversion had an annual income of (GH₵ 189)-$31.68 more than the non-participants however, their incomes are not sustainable hence compelling them into illegal mining. This paper has a guiding significance for policy decision making for gold mining in Ghana.

Water pollution has caused the ecosystem to be in a state of imbalance for a long time. It has become a major global ecological and environmental problem today. Solving the potential hidden dangers of pollutants and avoiding unauthorized access to resources has become the necessary condition and important task to ensure the sustainable development of human society. To solve such problems, this review summarizes the research progress of nanomaterials in the field of water aimed at the treatment of water pollution and the development and utilization of new energy. The paper also tries to seek scientific solutions to environmental degradation and to create better living environmental conditions from previously published cutting edge research. The main content in this review article includes four parts: advanced oxidation, catalytic adsorption, hydrogen, and oxygen production. Among a host of other things, this paper also summarizes the various ways by which composite nanomaterials have been combined for enhancing catalytic efficiency, reducing energy consumption, recycling, and ability to expand their scope of application. Hence, this paper provides a clear roadmap on the status, success, problems, and the way forward for future studies.

The MIL-53(Al)-NH

N dopping can enhance the electrochemical efficiency of carbon materials, but the effect of N on the electrochemical-mediated removal of Cr(VI) has been mostly ignored. Here, we report highly porous N-doped carbon spheres for electrochemical-mediated removal of Cr(VI), and the role of N on Cr(VI) removal has been systematically investigated using both experimental evaluations and theoretical validation. Experimental findings revealed that the removal capacity of Cr(VI) reached 186.5 mg·g−1 with a removal rate of 100%. In addition, the underlying processes for the role of N species have been investigated using density functional theory (DFT) calculations. The result agrees with the findings from the experimental evaluations thus suggesting that the removal process of Cr(VI) was mainly distributed by pyridinic-N and oxidized-N. This study has demonstrated that the removal of Cr(VI) by N species forms a crucial part in the removal of Cr(VI) using N-doped carbon materials and offers a possible alternative approach for enhancing the removal efficiency of carbon materials.

Metal-organic frameworks (MOFs) based membranes with superior mechanical properties are of particular interest in purification, separation, and catalysis. Nevertheless, their fabrication still remains a grand challenge. Here, fungus hyphae (Mucor) were used as a robust scaffold to load the MOFs and induced the formation of porous and flexible membranes. ZIF-8 was used as a representative of MOFs. The ZIF-8@Mucor membrane was formed by the in-situ growth of ZIF-8 on hyphae and then a vacuum filtration of the ZIF-8/hyphae composite. ZIF-8 was effectively dispersed on the ZIF-8@Mucor membrane, and the shear modulus of ZIF-8@Mucor-3 was 864 MPa by calculation. The ZIF-8@Mucor membrane exhibited promising properties for adsorption application to remove the highly toxic Pb

Fluoride has been reported as one of the major water pollutants with myriads of health implications when present in water beyond permissible limits (>1.5 mg L−1). While the adsorption technology of treating fluoridated water remains one of the best options, the choice of suitable adsorbent remains a problem. However, shortcomings of some adsorbents such as low adsorption capacity, slow adsorption rate, narrow pH range, and high-cost make them unsustainable. Modification of adsorbents has become the most attractive method for effectively improving the treatment of fluoridated water. The objective of this work was to bring to light the surface modifications and sorption mechanisms of bauxite as a sorbent for fluoride removal. Bauxite is robust with sufficient mechanical strength and naturally abundant making it a suitable candidate over other conventional adsorbents for fluoride removal. Four main types of surface modification of adsorbents were identified; thermal activation, impregnation, functionalization, and chemical grafting. Materials such as surfactants, oxidizing agents, acids, bases, and metals could be used for surface modification. Modified bauxite demonstrated higher adsorption capacity over their unmodified ones due to the significant improvement in their surface area, pore size, pore-volume, and some structural transformations such as ordered and stable interlinked mesopores which facilitated effective chemisorption. This guarantees a stable chemical structure with more active sites and requires a minimum dose to reach equilibrium at a wider pH range (3–11). Finally, the mechanisms of fluoride sorption onto bauxite is a complex process involving intra-particle diffusion, physisorption, and chemisorption processes.

The world is suffering from chronic water shortage due to the increasing population, water pollution and industrialization. Desalinating saline water offers a rational choice to produce fresh water thus resolving the crisis. Among various kinds of desalination technologies, capacitive deionization (CDI) is of significant potential owing to the facile process, low energy consumption, mild working conditions, easy regeneration, low cost and the absence of secondary pollution. The electrode material is an essential component for desalination performance. The most used electrode material is carbon-based material, which suffers from low desalination capacity (under 15 mg·g−1). However, the desalination of saline water with the CDI method is usually the charging process of a battery or supercapacitor. The electrochemical capacity of battery electrode material is relatively high because of the larger scale of charge transfer due to the redox reaction, thus leading to a larger desalination capacity in the CDI system. A variety of battery materials have been developed due to the urgent demand for energy storage, which increases the choices of CDI electrode materials largely. Sodium-ion battery materials, lithium-ion battery materials, chloride-ion battery materials, conducting polymers, radical polymers, and flow battery electrode materials have appeared in the literature of CDI research, many of which enhanced the deionization performances of CDI, revealing a bright future of integrating battery materials with CDI technology.