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The commercial activated carbon (AC) with enhanced adsorption performance capacity was studied via green functionalization. The adsorption of methylene blue (MB) from aqueous solution by deionized‑water functionalized activated carbon (DFAC) was investigated in a laboratory‑scale batch mode. The interaction effects of different operating parameters; adsorbent dosage (1‑5 g/L), pH (2-12) and agitation speed (100‑200 rpm) were studied. The ANOVA results suggested the quadratic model and the analyzed model were well fitted. The higher correlation coefficient, R2 value of 0.93 and low p-value (0.0002) indicating the fitness of the response surface quadratic model developed. The optimum conditions were found to be the adsorbent dosage of 4.7 g/L, pH of 12 and agitation speed of 150 rpm, in which 99.74% of MB removal was achieved. Additionally, the confirmatory experiment was conducted to evaluate the accuracy of the optimized conditions in which the range of deviation is was 4.07%.

Rapid urban and industrial sectors generate massive amounts of wastewater, creating severe ecological disruption and harming living organisms. The number of harmful pollutants such as dyes, heavy metals, antibiotics, phenolic compounds, and volatile and several organic chemicals discharged into aquatic systems varies depending on the effluent composition of various sectors. MXene-based composites with unique characteristics were spotlighted as newly developed nanomaterials specifically for environmental-related applications. Therefore, this review broadly discusses the properties, basic principles of MXene, and synthesis routes for developing different MXene-based nanomaterials. The most current strategies on the energy and environmental applications of MXene-based nanomaterials, particularly in photocatalysis, adsorption, and water splitting, were deeply explored for the remediation of different pollutants and hydrogen (H2) evolution from wastewater. The detailed mechanism for H2 evolution and the remediation of industrial pollutants via photocatalysis and adsorption processes was elaborated. The multi-roles of MXene-based nanomaterials with their regeneration possibilities were emphasized. Several essential aspects, including the economic, toxicity and ecological power of MXene-based nanomaterials, were also discussed regarding their opportunity for industrialization. Finally, the perspectives and challenges behind newly developed MXene and MXene-based nanomaterials for environmental pollution were reviewed.

The development of biomass-based CQD is highly attentive to enhancing photocatalytic performance, especially in secondary or ternary heterogeneous photocatalysts by allowing for smooth electron-hole separation and migration. In this study, kenaf-based carbon quantum dots (CQD) were prepared. The main objective of the current work was to investigate temperature, precursor mass and time in hydrothermal synthesis treatment to improve the CQD properties and methylene blue photocatalytic degradation. Optimization of kenaf-based CQD for inclusion in hydrothermal treatment was analyzed. The as-prepared CQDs have been characterized in detail by Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscope (HRTEM), photoluminescence (PL) and ultraviolet–visible (UV–Vis) spectroscopy. It was found that C200-0.5-24 exhibits a higher photocatalytic activity of the methylene blue dye and optimized hydrothermal conditions of 200 °C, 0.5 g and 24 h. Therefore, novel kenaf-based CQD was synthesized for the first time and was successfully optimized in the as-mentioned conditions. During the hydrothermal treatment, precursor mass controls the size and the distribution of CQD nanoparticles formed. The C200-0.5-24 showed a clearly defined and well-distributed CQD with an optimized nanoparticle size of 8.1 ± 2.2 nm. Indeed, the C200-0.5-24 shows the removal rate of 90% of MB being removed within 120 min.

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