Performance evaluation of phosphonium based deep eutectic solvents coated cerium oxide nanoparticles for CO2 capture.

The critical challenge being faced by our current modern society on a global scale is to reduce the surging effects of climate change and global warming, being caused by anthropogenic emissions of CO2 in the environment. Present study reports the surface driven adsorption potential of deep eutectic solvents (DESs) surface functionalized cerium oxide nanoparticles (CeNPs) for low pressure CO2 separation. The phosphonium based DESs were prepared using tetra butyl phosphoniumbromide as hydrogen bond acceptor (HBA) and 6 acids as hydrogen bond donors (HBDs). The as-developed DESs were characterized and employed for the surface functionalization of CeNPs with their subsequent utilization in adsorption-based CO2 adsorption. The synthesis of as-prepared DESs was confirmed through FTIR measurements and absence of precipitates, revealed through visual observations. It was found that DES6 surface functionalized CeNPs demonstrated 27% higher adsorption performance for CO2 capturing. On the contrary, DES3 coated CeNPs exhibited the least adsorption progress for CO2 separation. The higher adsorption performance associated with DES6 coated CeNPs was due to enhanced surface affinity with CO2 molecules that must have facilitated the mass transport characteristics and resulted an enhancement in CO2 adsorption performance. Carboxylic groups could have generated an electric field inside the pores to attract more polarizable adsorbates including CO2, are responsible for the relatively high values of CO2 adsorption. The quadruple movement of the CO2 molecules with the electron-deficient and pluralizable nature led to the enhancement of the interactive forces between the CO2 molecules and the CeNPs decorated with the carboxylic group hydrogen bond donor rich DES. The current findings may disclose the new research horizons and theoretical guidance for reduction in the environmental effects associated with uncontrolled CO2 emission via employing DES surface coated potential CeNPs.

Remediation techniques for elimination of heavy metal pollutants from soil: A review.

Contaminated soil containing toxic metals and metalloids is found everywhere globally. As a consequence of adsorption and precipitation reactions, metals are comparatively immobile in subsurface systems. Hence remediation techniques in such contaminated sites have targeted the solid phase sources of metals such as sludges, debris, contaminated soils, or wastes. Over the last three decades, the accumulation of these toxic substances inside the soil has increased dramatically, putting the ecosystem and human health at risk. Pollution of heavy metal have posed severe impacts on human, and it affects the environment in different ways, resulting in industrial anger in many countries. Various procedures, including chemical, biological, physical, and integrated approaches, have been adopted to get rid of this type of pollution. Expenditure, timekeeping, planning challenges, and state-of-the-art gadget involvement are some drawbacks that need to be properly handled. Recently in situ metal immobilization, plant restoration, and biological methods have changed the dynamics and are considered the best solution for removing metals from soil. This review paper critically evaluates and analyzes the numerous approaches for preparing heavy metal-free soil by adopting different soil remediation methods.

Competition adsorption of malachite green and rhodamine B on polyethylene and polyvinyl chloride microplastics in aqueous environment.

Microplastics (MPs) will cause compound pollution by combining with organic pollutants in the aqueous environment. It is important for environmental protection to study the adsorption mechanism of different MPs for pollutants. In this study, the adsorption behaviors of malachite green (MG) and rhodamine B (RhB) on polyethylene (PE) and polyvinyl chloride (PVC) were studied in single systems and binary systems, separately. The results show that in single system, the adsorptions of between MPs for pollutants (MG and RhB) are more consistent with the pseudo-second-order kinetics and Freundlich isotherm model, the adsorption capacity of both MPs for MG is greater than that of RhB. The adsorption capacities of MG and RhB were 7.68 mg/g and 2.83 mg/g for PVC, 4.52 mg/g and 1.27 mg/g for PE. In the binary system, there exist competitive adsorption between MG and RhB on MPs. And the adsorption capacities of PVC for the two dyes are stronger than those of PE. This is attributed to the strong halogen-hydrogen bond between the two dyes and PVC, and the larger specific surface area of PVC. This study revealed the interaction and competitive adsorption mechanism between binary dyes and MPs, which is of great significance for understanding the interactions between dyes and MPs in the multi-component systems.

Dicyandiamide-assisted synthesis of N-doped porous CoMn-Nx@N-C carbon nanotube composites via MOFs as efficient trifunctional electrocatalysts in the same electrolyte.

The development of low-cost, long-term stability, and good oxygen reversible catalytic reaction (ORR/OER) and hydrogen evolution (HER) activity under the same electrolyte concentration of electrocatalytic materials has an important role in the construction of large-scale applications and more valuable sustainable energy systems. Among them, the representative CoMn-Nx@N-C-900-0.2 showed good ORR/OER/HER catalytic activity in 0.1 M KOH alkaline electrolyte, specifically manifested by its half-wave potential E = 0.84 V in the ORR test, which was better than that of commercial Pt/C. The total oxygen electrode activity index of OER/ORR was E = 0.79 V, and it also showed good HER performance. When the current density was 10 mA cm-2, the operating potential was E = -0.266 V. The synergistic effects of the CoMn bimetallic alloy, tubular layered porous structure, which exposed more active area and various nitrogen species such as CoMn-Nx, were the main reasons for the improvement of the trifunctional catalytic performance of electrocatalytic materials. The synthesis strategy and analysis of the electrocatalyst performance provide a new reference for the development of multifunctional materials with high catalytic performance.

Precise regulation of defect concentration in MOF and its influence on photocatalytic overall water splitting.

In this work, the defective Cu-BDC with different defect concentration and Cu1+/Cu2+ coordinatively unsaturated sites (CUS) content were designed and synthesized by introducing defective linkers with different pKa values. The low-concentration defects in Metal-organic frameworks (MOFs) structure act as the active sites to enhance their photocatalytic activity. In contrast, the high concentration defects serve as the recombination centers of photogenerated electrons and holes to decrease the transfer efficiency of charge carriers. Cu-BDC-FBA shows an excellent bifunctional photocatalytic performance for overall water splitting due to the suitable defect concentration, which gives an oxygen production rate of 3114 µmol g-1 h-1 and hydrogen production rate of 16 829 µmol g-1 h-1, respectively. It is expected that this study can deepen the understanding of the relationship between defects and photocatalytic activity, and provide a new idea for the design and synthesis of defective MOFs photocatalysts with excellent performance.

Template-based textural modifications of polymeric graphitic carbon nitrides towards waste water treatment.

The composite materials based on graphitic carbon nitrides (g-C3N4) are remarkably better semiconductors, but the inherent photocatalytic performance in its generic synthesis form is not up to the mark. Eminence efforts have been made to improve its performance and photocatalytic efficiencies. Recently, extensive investigations have been performed to develop their texturally modified and highly porous structures to get around the big flaws of bulk g-C3N4. One significant disadvantage is the increase in the polycondensation while preparation at 550 °C results in g-C3N4 materials with restricted specific surface area (SSA) (<10 m2/g) and no textured pores. Textural modification has emerged as an efficient and progressive way to improve optical and electronic characteristics. The final texture and shape of CN are influenced by the precursor's interaction with the template. Researchers are interested in developing CN materials with high SSA and changeable textural properties (pore volume and pore size). Based on the literature review it is concluded that the soft templating approach is relatively simple, and straightforward to induce textural changes in the g-CN type materials. This review focused on improving the textural properties of bulk g-C3N4 via templating method, and the major advances in the modified g-C3N4 materials for the treatment of wastewater. The procedures and mechanisms of numerous approaches with varying morphologies are thoroughly explained.

Synergistic Catalysis of Co(OH)2/CuO for the Degradation of Organic Pollutant Under Visible Light Irradiation.

The exploration of advanced water treatment technologies e.g. heterogeneous photocatalysis is the most promising way to address organic pollution issues. Semiconductors based bimetallic photocatalysis with wide bandgap, have displayed splendid degradation performance in the UV light region, but their extension to the visible light/near infra-red region is still a matter of great concern. CuO, Co(OH)2, CoO and Co(OH)2/CuO nanocomposites were synthesized via simple co-precipitation method and further practiced for Rhodamine B (RhB) decomposition by introducing per-sulfate (PS) as a sacrificial agent. Results revealed that Co(OH)2/CuO catalyst had shown robust catalytic activity for RhB photodegradation (degradation time 8 min, k = 0.864 min-1) under light illumination, significantly less (12-60 times) than the other reported bimetallic catalysts. Catalyst also have verified excellent performance for a broader pH range (5-9) with excellent stability. Main reactive species responsible for the photocatalytic reaction were sulfate (SO4•-) and superoxide (O2•) radicals, duly verified by ESR and by using radical scavengers. With outstanding recycling abilities, this is probably the fewer successful attempt for RhB decolorization and can be highly favorable for effluent treatment by using the synergic effect of absorption and photodegradation.