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[Display omitted] • Fast synthesis of activated carbon occurred in less than 6 min. • Time and energy reduced in Activated Carbon synthesis via single-step microwave pyrolysis. • Largest surface area (1240 m2/g) was achieved in single-step microwave pyrolysis in only 3 min. • Mesoporosity in Activated Carbons influenced markedly the removal of Basic Blue 9. • Activated Carbons showed high CO 2 adsorption and excellent selectivity over N 2 and recyclability. Hierarchical porous activated carbons (ACs) were efficiently synthesized in less than 2 min using microwaves and phosphoric acid (H 3 PO 4), exhibiting excellent potential as adsorbent for carbon dioxide (CO 2) and Methylene Blue (MB). The method emphasizes the development of selective physicochemical and textural properties crucial for CO 2 post-combustion capture and textile dye removal from water, using agricultural waste as carbon precursor to address the environmental and economic challenges associated with the preparation of ACs. Dielectric properties confirmed H 3 PO 4 increased the microwave absorption properties of the biomass. Employing a single-step method, the resulting ACs exhibited large specific surface areas exceeding 1000 m2g−1, achieved in less than 2 min and relatively low energies (2.4 GJ ton-1). Sample 0.4H4 displayed a surface area of 1145 m2g−1 and a significant ultra-micropore (<0.7 nm) content, demonstrating a CO 2 uptake of 4.1 and 2.8 mmolg−1 at 0 and 25 °C, with high CO 2 /N 2 selectivity (>38). The sample exhibited rapid CO 2 uptake in 5 min and efficient regeneration after 20 adsorption–desorption cycles. Sample 0.3H3 developed large mesoporosity and a high surface area of 1217 m2g−1 with less than 3 min of treatment. The maximum dye removal was 281 mgg−1 and adsorption mechanisms involved diffusion into the mesoporous matrix, electrostatic interactions, H-bonding between AC and MB acid groups, and π–π interactions. The experimental data best fitted the Freundlich model. The results confirmed that microwaves have the potential to convert waste to micro-mesoporous ACs that can be used for a wide range of applications with significant processing time reductions and superior product qualities compared to conventional technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hybrid heating in preparation of activated carbons was investigated. • High CO 2 adsorption was achieved with low KOH impregnation ratio. • Synergic effects observed by using modest microwave intensity and temperature. • Linear correlation between CO 2 uptake and microporosity. • Langmuir model describes the adsorption mechanism in hybrid AC. Microwave has become an attractive technology in the valorisation of renewable biomass and in the mitigation of challenges of climate change. In this work, the synergic effects of coupling microwave and mild conventional heating conditions has been investigated in preparing engineered ultra-micropore carbons from lignocellulosic biomass. The processing conditions were systematically investigated and correlated to the physicochemical properties of activated carbons produced and their performance in post-combustion CO 2 capture. The highest CO 2 uptake (225 mg g−1) was achieved for the hybrid carbon produced at low temperature (600 °C) and modest microwave intensity. The synergic effect of hybrid heating was confirmed by the significant CO 2 uptake increase up to 80 and 60 % for the activated carbons prepared by microwave and conventional heating, respectively. The enhanced adsorption was confirmed by cyclic regeneration up to 99 % after 16 adsorption–desorption cycles, showing a linear correlation between the surface area, micropore volume and CO 2 uptake. The Pseudo-first order model accurately describes the adsorption phenomena, indicating that physisorption is the primary mechanism governing the process. The results acquired from this study highlight the process intensification in the synthesis of porous materials with comparable properties that are typically attained in conventional heating using energy intensive conditions. Additionally, this approach reveals the benefits of conventional treatment for increasing the material's microwave susceptibility and as consequence to reduce the processing time by microwave heating. The synergic effects confirms the potential of hybrid heating for applications where fast and selective heating is paramount. [ABSTRACT FROM AUTHOR]

[Display omitted] • The lower CO 2 adsorption was indeed observed through the higher Cu concentration. • Methanol formation rate was induced by amorphous and crystalline copper phases. • Cu-doping model was more suitable surface for the conversion of CO 2 into methanol. The role of copper crystallization in the enhanced methanol production via CO 2 hydrogenation over CuZrO 2 catalysts was explored along with a combination of experimental and computational studies. The catalysts were synthesized by a surfactant-assisted route followed by reflux in a one-pot method. Catalyst structure, bulk properties, surface reactivity, and reaction pathways were evaluated by XRD, BET, FRX, TPR, N 2 O-TPD, CO 2 -TPD, in situ DRIFTS, AP-XPS, and XRD. Calculations based on density functional theory (DFT) were performed to explore the formation of possible intermediates in a copper-driven conversion with surface models of the CuZrO 2 catalyst. The combination of experiments and DFT results revealed that the intermediate steps of the catalyzed reaction of CO 2 hydrogenation into methanol might depend on the incorporation of Cu in the zirconia sample. The catalyst containing only amorphous interfacial sites showed higher performance on CO 2 -to-methanol hydrogenation compared to the catalysts containing high crystallinity of copper. The superior activity of the 10CuZrO 2 catalyst is mainly ascribed to the cooperative effect between the highly dispersed copper nanoparticles and the basic sites. [ABSTRACT FROM AUTHOR]