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In order to reduce the environmental hazards of red mud (RM) and realize its resource utilization, in this study, RM-based iron-carbon micro-electrolysis material (RM-MEM) were prepared by a carbothermal reduction process using RM as raw material. The influence of the preparation conditions on the phase transformation and structural characteristics of the RM-MEM were investigated during the reduction process. The ability of RM-MEM to remove organic pollutants from wastewater was evaluated. The results showed that RM-MEM prepared at a reduction temperature of 1100 °C, a reduction time of 50 min and a coal dosage of 50% had the best removal effect for the degradation of methylene blue (MB). When the initial MB concentration was 20 mg L−1, the amount of RM-MEM material was 4 g L−1, the initial pH was 7, and the degradation efficiency reached 99.75% after 60 min. When RM-MEM is split into carbon free and iron free parts for use, the degradation effect becomes worse. Compared to other materials, RM-MEM has lower cost and better degradation. X-ray diffraction (XRD) analysis showed that hematite was transformed to zero-valent iron with the increase in the roasting temperature. Scanning electron microscopy (SEM) and energy spectroscopy (EDS) analysis showed that micron-sized ZVI particles were formed in the RM-MEM, and increasing the carbon thermal reduction temperature was beneficial to the growth of zero-valent iron particles. [Display omitted] • Waste-derived iron carbon micro-electrocatalyst by carbon thermal reduction method. • Iron carbon micro-electrocatalyst shows high efficiency in the degradation of MB. • Iron carbon micro-electrocatalyst shows the potential for practical application. [ABSTRACT FROM AUTHOR]

The graphite-phase carbon nitride (g-C 3 N 4) photocatalytic materials were prepared by one-step calcination method to degrade methylene blue (MB) and potassium butyl xanthate (PBX) under visible light irradiation. The prepared g-C 3 N 4 photocatalytic materials were investigated in detail by various characterizations, and the experiments showed that the graphitic phase carbon nitride photocatalytic materials were successfully prepared by the one-step calcination method. The material possesses excellent optical properties and strong visible light absorption, thus achieving photocatalytic degradation of MB and PBX. The catalyst dosage, pH, the initial concentration of pollutants have important effects on photocatalytic activity of MB and PBX. The photocatalytic degradation efficiency was 98.99% for MB and 96.83% for PBX under the optimal conditions (catalyst dosage, initial pollutant concentration and pH value were 500 mg L−1, 20 mg L−1 and 7, respevtively). The photocatalytic mechanisms on MB and PBX were elucidated. ·OH was the key specie for MB, while ·O 2 − was the key specie for PBX. This study advances the development of photocatalytic technology for mineral wastewater. [Display omitted] • g-C 3 N 4 photocatalyst was prepared by pyrolysis. • The separation of photogenerated electron-hole pairs lead to high efficiency. • Superoxide radicals and hydroxyl radicals are the main reactive groups. [ABSTRACT FROM AUTHOR]

With the vigorous development of industrial economy, energy and environmental problems have become the most serious issues affecting people's production and life. Therefore, the demand for clean energy production, effective separation and storage is growing. Metal-organic frameworks (MOFs), as a kind of porous crystalline materials with large surface area and porosity, which is self-assembled by metal ions or clusters and organic ligands through coordination bonds. Thanks to a number of unique characteristics such as adjustable pore environment, homogeneous void structure, abundant active sites, unprecedented chemical composition tunability and functional versatility, it has been widely studied, especially for the clean energy conversion in catalysis. In this review, we focus on the research progress of clean energy in catalysis based on MOFs. Emphasis is placed on MOFs with different structures of compositions and their applications in catalytic for clean energy conversion, such as CO oxidation, CO 2 reduction and H 2 evolution. In addition, the situation of MOFs assisting environmental remediation is also briefly described. Finally, the prospects and challenges of MOFs in clean energy and the remaining issues in this field are presented. [Display omitted] • MOFs based materials for CO2 Conversion and CO oxidation are summarised. • MOFs based materials for energy related hydrogen evolution are summarised. • MOFs based materials for environment catalytic degradation are discussed. • MOFs based membranes for various separation applications are summarised. • The advantage and disadvantage of MOF membranes are discussed. [ABSTRACT FROM AUTHOR]

The efficacy of novel polycarbonate ultrafiltration, aluminum oxide nanoparticle (Al 2 O 3 -NPs) volume fraction, temperature, and water/ethylene glycol (EG) ratio were evaluated to determine the thermophysical properties of the membrane. 5%–10% of Al 2 O 3 -NPs have been added to the PC. A machine learning approach was used to compare the volume fraction of Al 2 O 3 -NPs, the temperature, and the water-to-ethylene glycol (EG) ratio. To determine the impact of Al2O3-NPs loading on the Response Surface Method (RSM), DOE, ANOVA, ANN, MLP, and NSGA-II, the number of aluminum oxide nanoparticles (Al 2 O 3 -NPs), temperature, and water/ethylene glycol (EG) on membranes in PC ultrafiltration are evaluated. Based on the Relative Thermal Conductivity Model (RSM), the regression coefficient of Al 2 O 3 in water and EG was 0.9244 and 0.9170 with adjusted regression coefficients. A higher concentration of EG enhances the thermal conductivity of the membrane when the effective parameters are considered. The effect of temperature on the relative viscosity of the membrane led to the conclusion that Al 2 O 3 water/EG can cool at high temperatures while providing no viscosity change. When Al 2 O 3 is dissolved in water and EG, more EG is necessary to optimize the mode of reactivity. Using the MLP model, the calculated R-value is 0.9468, the MSE is 0.001752989 (mean square error), and the MAE is 0.01768558 (mean absolute error). RSM predicted the average thermal conductivity behavior of nanofluid better. The ANN model, however, has proven to be more effective than the RSM in simulating the relative viscosity of nanofluids. The NSGA-II optimized results showed that the minimum relative viscosity and maximum coefficient of thermal conductivity occurred at the lowest water ratio and maximum temperature. [Display omitted] • Membrane viscosity increases when water is a greater fraction of the base fluid. • MLP and RSM models were developed to predict Thermophysical properties Al2O3 in Water and EG. • The NSGA-II was coupled with RSM and MOPSO to conduct the optimization. • A wide range of applications for membrane technology in industry and in daily life. [ABSTRACT FROM AUTHOR]

Negative impacts of wastewater contamination include harm to the environment, people, plants, and animals. Metal-based heterogeneous catalysts, particularly transition metal oxide catalysts, are a therapeutic option. However, they have limited reusability and cause secondary contaminations through metal leaching. In this work, a new membrane catalyst made of perovskite-type fiber was created and tested to remove methylene blue from wastewater. These innovative 3D perovskite ceramic catalysts work well in the breakdown of pollutants and dramatically lessen possible secondary contaminations caused by metal leaching from catalysts. [Display omitted] • La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) hollow fibre perovskite catalyst was developed. • It was evaluated for the removal of methylene blue via advanced oxidation. • It significantly reduces secondary contamination of metal leaching from perovskite. [ABSTRACT FROM AUTHOR]

Tonnage oxygen production is still mostly based on the traditional technology of cryogenic distillation, a century-old, capital- and energy-intensive method. It is critical to create a novel low-cost, energy-efficient approach that can meet the growing demand for oxygen in industry from the clean environmental or energy standpoint. Ruddlesden-Popper (RP) perovskite like oxides -based ionic transport membranes for the oxygen transport have recently been developed as a possible replacement for the traditional cryogenic approach. In this work, we detailly reviewed the progress of RP perovskite oxides based membranes for oxygen transport from separation mechanism, material types, synthesis methods to the final separation performance. This work advances the development of RP perovskite membranes for oxygen transport. [Display omitted] • MIEC oxides are the prominent materials for oxygen transport. • Oxygen conduction mechanism of MIEC oxides was discussed. • Preparation methods of MIEC oxide permeable materials were summarized. [ABSTRACT FROM AUTHOR]

The mixed ionic–electronic conducting (MIEC) oxides have generated significant research efforts in the scientific community during the last 40 years. Since then, many MIEC compounds, most of which are based on perovskite oxides, have been synthesized and characterized. These compounds, when heated to high temperatures, form solid ceramic membranes with high oxygen ionic and electrical conductivity. The driving force for oxygen ion transport is the ionic transfer of oxygen from the air as a result of the differential partial pressure of oxygen across the membrane. Electronic and ionic transport in a range of MIEC materials has been studied using the defect theory, particularly when dopants are introduced to the compound of interest. As a result, many types of ionic oxygen transport limits exist, each with a distinct phase shift depending on the temperature and partial pressure of oxygen in use. In combination with theoretical principles, this work attempts to evaluate the research community's major and meaningful achievements in this subject throughout the preceding four decades. [Display omitted] • MIEC oxides are the prominent materials for oxygen transport. • Oxygen conduction mechanism of MIEC oxides was discussed. • Preparation methods of MIEC oxide permeable materials were summarized. [ABSTRACT FROM AUTHOR]

In recent years, the environmental pollution of microplastics has attracted much attention. To date, there have been a lot of researches on microplastics and a series of studies published. In this study, by bibliometric analysis method to evaluated the development and evolution on microplastics research trends and hot spots. A total of 2872 literature information was collected from the Web of Science (2004–2020), which was used for bibliometric visual analysis by CiteSpace. It was possible to see the contributing countries, institutions, authors, keywords, and future study directions in the microplastics sectors by looking at the visual representation of the results. (1) Since 2004, scientific advancements in this sector have advanced significantly, with a significant increase in speed since 2012. (2) China and the United States are the world's leading researchers in microplastics. (3) The study of microplastics was multidisciplinary, comprising researchers from the fields of ecology, chemistry, molecular biology, environmental science, and oceanography. (4) In recent years, researchers have concentrated their attention on the distribution and toxicity of microplastics in the environment, as well as their coupled pollution with heavy metal contaminants. In conclusion microplastics study in environmental science has become increasingly popular in recent years. Topics include dispersion, toxicity, and coupled pollution with heavy metal pollutants. Researchers in a wide range of fields are involved in microplastics research. Furthermore, policies and regulations about microplastics in global were summarized, and membrane technology has potential to remove microplastics from water. The above findings help to clearly grasp the content and development trend of microplastics research, point out the future research direction for scholars, and promote microplastics research and pollution prevention and control. [Display omitted] • 2872 articles on microplastics from 2004 to 2020 were analyzed. • Spatial and temporal distribution of research was described and the most cited articles and authors were pointed out. • Knowledge bases, developments, and hotspots of microplastics were identified. • Suggestions for the potential studies on microplastics were given. [ABSTRACT FROM AUTHOR]

The manganese is successfully induced as a "bridge joint" to fabricate a new adsorbent (CNC–Mn-PEI) connecting cellulose nanocrystal (CNC) and polyethyleneimine (PEI) respectively. It was used to remove As (III) from waste water. It has been proved that the incompact CNC and PEI were successfully connected by Mn ions, which induced the formation of O–Mn–O bonds and the removal efficiency is maintained in the broad pH range of 4–8, even with the influence of NO 3 − and CO 3 2−. The CNC–Mn-PEI was characterized by Brunauer–Emmett–Telley (BET) method and the results showed that the nanoparticle of the specific surface area was 106.5753 m2/g, it has a significant improvement, compared with CNC–Mn-DW (0.1918 m2/g). The isotherm and kinetic parameters of arsenic removal on CNC–Mn-PEI were well-fitted by the Langmuir and pseudo-second-order models. The maximum adsorption capacities toward As (III) was 78.02 mg/g. After seven regeneration cycles, the removal of As (III) by the adsorbent decreased from 80.78% to 68.2%. Additionally, the hypothetical adsorption mechanism of "bridge joint" effect was established by FTIR and XPS, which provided the three activated sites from CNC–Mn-PEI can improve the arsenic removal efficiency, and providing a new stratagem for the arsenic pollution treatment. [Display omitted] • The introduction of polyethyleneimine can effectively organize the forces between the molecular chains of manganese-based cellulose materials. • The removal efficiency of manganese-based cellulose materials was greatly enhanced with the introduction of polyethyleneimine for arsenite (III) removal. • The "bridging effect" of Mn was confirmed by inducing a large amount of the activated sites. [ABSTRACT FROM AUTHOR]

The present work investigates the proficiency of green silver oxide nanocatalyst synthesised from Monotheca buxifolia (Falc.) Dcne. leaves extract, and their application for biodiesel synthesis from novel Prunus bokhariensis seed oil (non-edible). The seed oil content of 55% and FFA content of 0.80 mg KOH/g were reported. Several analytical tools (EDX, FT-IR, SEM and XRD) were used to characterise the Ag 2 O nanocatalyst. Maximum (89%) FAME yield of the PBSOB (Prunus bokhariensis seed oil biodiesel) was achieved at ambient transesterification conditions i.e. 3.5 wt% nanocatalyst loading, 2.5 h reaction time, 130 °C of reaction temperature and 12:1 alcohol to oil ratio. The synthesised PBSOB was additionally characterised by analytical methods like, GC-MS and FT-IR. The different aspects of fuel were identified i.e. flash point (84 °C), kinematic viscosity (4.01 cSt @ 40 °C), sulphur content (0.0003 wt %), density (0.853 kg/L) and acid number (0.167 mg KOH/g). All the above properties were verified and agreed well with biodiesel international standards (European Union (14214), China GB/T (20828) and ASTM (6751, 951). In general, Prunus bokhariensis seed oil and Ag 2 O nanocatalyst seem to be remarkably active, cheap and stable candidates for the biodiesel industry in future. [Display omitted] • Seed oil content of 55% and FFA content of 0.80 mg KOH/g were measured for Prunus bokhariensis seed oil. • Prunus bokhariensis seed oil (PBSO) is efficient contender for biodiesel production. • GC-MS and FT-IR techniques were used to characterise synthesised PBSOB. • Green silver oxide nanocatalyst synthesised from leaves extract of Monotheca buxifolia (Falc.) Dcne. • 0.5 wt% green Ag 2 O nano catalyst and 2.5 h reaction time yielded 89% of PBSOB. [ABSTRACT FROM AUTHOR]

The present work investigates the proficiency of green silver oxide nanocatalyst synthesised from Monotheca buxifolia (Falc.) Dcne. leaves extract, and their application for biodiesel synthesis from novel Prunus bokhariensis seed oil (non-edible). The seed oil content of 55% and FFA content of 0.80 mg KOH/g were reported. Several analytical tools (EDX, FT-IR, SEM and XRD) were used to characterise the Ag 2 O nanocatalyst. Maximum (89%) FAME yield of the PBSOB (Prunus bokhariensis seed oil biodiesel) was achieved at ambient transesterification conditions i.e. 3.5 wt% nanocatalyst loading, 2.5 h reaction time, 130 °C of reaction temperature and 12:1 alcohol to oil ratio. The synthesised PBSOB was additionally characterised by analytical methods like, GC-MS and FT-IR. The different aspects of fuel were identified i.e. flash point (84 °C), kinematic viscosity (4.01 cSt @ 40 °C), sulphur content (0.0003 wt %), density (0.853 kg/L) and acid number (0.167 mg KOH/g). All the above properties were verified and agreed well with biodiesel international standards (European Union (14214), China GB/T (20828) and ASTM (6751, 951). In general, Prunus bokhariensis seed oil and Ag 2 O nanocatalyst seem to be remarkably active, cheap and stable candidates for the biodiesel industry in future. [Display omitted] • Seed oil content of 55% and FFA content of 0.80 mg KOH/g were measured for Prunus bokhariensis seed oil. • Prunus bokhariensis seed oil (PBSO) is efficient contender for biodiesel production. • GC-MS and FT-IR techniques were used to characterise synthesised PBSOB. • Green silver oxide nanocatalyst synthesised from leaves extract of Monotheca buxifolia (Falc.) Dcne. • 0.5 wt% green Ag 2 O nano catalyst and 2.5 h reaction time yielded 89% of PBSOB. [ABSTRACT FROM AUTHOR]