Biomass derived hierarchical porous carbon for high-performance O2/N2 adsorption; a new green self-activation approach

Recent advancements and prospects in carbon-based nanomaterials derived from biomass for environmental remediation applications

The conversion of waste biomass into a value-added carbonaceous nanomaterial highlights the appealing power of biomass valorization. The advantages of using sustainable and cheap biomass precursors exhibit the tremendous opportunity for boosting energy production and their application in environmental remediation processes. This review emphasis the development and production of carbon-based nanomaterials derived from biomass, which possess favourable characteristics such as biocompatibility and photoluminescence. The advantages and limitations of various nanomaterials synthesised from different precursors were also discussed with insights into their physicochemical properties. The surface morphology of the porous nanomaterials is also explored along with their characteristic properties like regenerative nature, non-toxicity, ecofriendly nature, unique surface area, etc. The incorporation of various functional groups confers superiority of these materials, resulting in unique and advanced functional properties. Further, the use of these biomass derived nanomaterials was also explored in different applications like adsorption, photocatalysis and sensing of hazardous pollutants, etc. The challenges and outcomes obtained from different carbon-based nanomaterials are briefly outlined and discussed in this review.

Facile synthesis of Persian gum-graphene oxide composite as a novel adsorbent for CO2 capture: characterization and optimization

Burning fossil fuels releases toxic gases into the environment and has negative effects on it. In this study, Persian gum@Graphene oxide (Pg@GO) was synthesized and used as a novel adsorbent for CO2 capture. The characterization of materials was determined through XRD, FTIR, FE-SEM, and TGA analysis. The operating parameters including temperature, Pressure, and adsorbent weight were studied and optimized by response surface methodology via Box-Behnken design (RSM-BBD). The highest amount of CO2 adsorption capacity was 4.80 mmol/g, achieved at 300 K and 7.8 bar and 0.4 g of adsorbent weight. To identify the behavior and performance of the Pg@GO, various isotherm and kinetic models were used to fit with the highest correlation coefficient (R2) amounts of 0.955 and 0.986, respectively. The results proved that the adsorption of CO2 molecules on the adsorbent surface is heterogeneous. Based on thermodynamic results, as the value of ΔG° is - 8.169 at 300 K, the CO2 adsorption process is exothermic, and spontaneous.

Efficient CO2 adsorption using chitosan, graphene oxide, and zinc oxide composite

This study was deeply focused on developing a novel CTS/GO/ZnO composite as an efficient adsorbent for CO2 adsorption process. To do so, design of experiment (DOE) was done based on RSM-BBD technique and according to the DOE runs, various CTS/GO/ZnO samples were synthesized with different GO loading (in the range of 0 wt% to 20 wt%) and different ZnO nanoparticle's loading (in the range of 0 wt% to 20 wt%). A volumetric adsorption setup was used to investigate the effect of temperature (in the range of 25-65 °C) and pressure (in the range of 1-9 bar) on the obtained samples CO2 uptake capability. A quadratic model was developed based on the RSM-BBD method to predict the CO2 adsorption capacity of the composite sample within design space. In addition, CO2 adsorption process optimization was conducted and the optimum values of the GO, ZnO, temperature, and pressure were obtained around 23.8 wt%, 18.2 wt%, 30.1 °C, and 8.6 bar, respectively, with the highest CO2 uptake capacity of 470.43 mg/g. Moreover, isotherm and kinetic modeling of the CO2 uptake process were conducted and the Freundlich model (R2 = 0.99) and fractional order model (R2 = 0.99) were obtained as the most appropriate isotherm and kinetic models, respectively. Also, thermodynamic analysis of the adsorption was done and the ∆H°, ∆S°, and ∆G° values were obtained around - 19.121 kJ/mol, - 0.032 kJ/mol K, and - 9.608 kJ/mol, respectively, indicating exothermic, spontaneously, and physically adsorption of the CO2 molecules on the CTS/GO/ZnO composite's surface. Finally, a renewability study was conducted and a minor loss in the CO2 adsorption efficiency of about 4.35% was obtained after ten cycles, demonstrating the resulting adsorbent has good performance and robustness for industrial CO2 capture purposes.

Natural Products Derived Porous Carbons for CO2 Capture

As it is now established that global warming and climate change are a reality, international investments are pouring in and rightfully so for climate change mitigation. Carbon capture and separation (CCS) is therefore gaining paramount importance as it is considered one of the powerful solutions for global warming. Sorption on porous materials is a promising alternative to traditional carbon dioxide (CO2 ) capture technologies. Owing to their sustainable availability, economic viability, and important recyclability, natural products-derived porous carbons have emerged as favorable and competitive materials for CO2 sorption. Furthermore, the fabrication of high-quality value-added functional porous carbon-based materials using renewable precursors and waste materials is an environmentally friendly approach. This review provides crucial insights and analyses to enhance the understanding of the application of porous carbons in CO2 capture. Various methods for the synthesis of porous carbon, their structural characterization, and parameters that influence their sorption properties are discussed. The review also delves into the utilization of molecular dynamics (MD), Monte Carlo (MC), density functional theory (DFT), and machine learning techniques for simulating adsorption and validating experimental results. Lastly, the review provides future outlook and research directions for progressing the use of natural products-derived porous carbons for CO2 capture.

Amine functionalized benzene based hypercrosslinked polymer as an adsorbent for CO2/N2 adsorption

In this work, benzene based hypercrosslinked polymer (HCP) as an adsorbent was modified using amine group to enhance CO₂ uptake capability and selectivity. Based on BET analysis result, the HCP and the modified HCP provide surface area of 806 (m² g^-1) and micropore volume of 453 (m² g^-1) and 0.19 (cm³ g^-1) and 0.14 (cm³ g^-1), respectively. The CO₂ and N₂ gases adsorption were performed in a laboratory scale reactor at a temperature between 298 and 328 K and pressure up to 9 bar. The experimental data were evaluated using isotherm, kinetic and thermodynamic models to identify the absorbent behavior. The maximum CO₂ adsorption capacity at 298 K and 9 bar was obtained 301.67 (mg g^-1) for HCP and 414.41 (mg g^-1) for amine modified HCP. The CO₂ adsorption thermodynamic parameters assessment including enthalpy changes, entropy changes, and Gibbs free energy changes at 298 K were resulted - 14.852 (kJ mol^-1), - 0.024 (kJ mol^-1 K^-1), - 7.597 (kJ mol^-1) for HCP and - 17.498 (kJ mol^-1), - 0.029(kJ mol^-1 K^-1), - 8.9 (kJ mol^-1) for amine functionalized HCP, respectively. Finally, the selectivity of the samples were calculated at a CO₂/N₂ composition of 15:85 (v/v) and 43% enhancement in adsorption selectivity at 298 K was obtained for amine modified HCP.

Inorganic Skeleton Reinforcement-A Generic Approach to Improve the Mechanical Properties of Biochar

Biochar is considered as a promising candidate for emerging sustainable energy systems and environmental technology applications. However, the improvement of mechanical properties remains challenges. Herein, we propose a generic strategy to enhance the mechanical properties of bio-based carbon materials through inorganic skeleton reinforcement. As a proof-of-concept, silane, geopolymer, and inorganic gel are selected as precursors. The composites' structures are characterized and an inorganic skeleton reinforcement mechanism is elucidated. Specifically, two types of reinforcement of the silicon-oxygen skeleton network formed in situ with biomass pyrolysis and the silica-oxy-al-oxy network are constructed to improve the mechanical properties. A significant improvement in mechanical strength was achieved for bio-based carbon materials. The compressive strength of well-balanced porous carbon materials modified by silane can reach up to 88.9 kPa, geopolymer-modified carbon material exhibits an enhanced compressive strength of 36.8 kPa, and that of inorganic-gel-polymer-modified carbon material is 124.6 kPa. Moreover, the prepared carbon materials with enhanced mechanical properties show excellent adsorption performance and high reusability for organic pollutant model compound methylene blue dye. This work demonstrates a promising and universal strategy for enhancing the mechanical properties of biomass-derived porous carbon materials.

Durable superhydrophobic/superoleophilic melamine foam based on biomass-derived porous carbon and multi-walled carbon nanotube for oil/water separation

In the present study, fabrications of two eco-friendly superhydrophobic/superoleophilic recyclable foamy-based adsorbents for oil/water mixture separation were developed. Hierarchically biomass (celery)-derived porous carbon (PC) and multi-walled carbon nanotube (MWCNT) were firstly synthesized and loaded on pristine melamine foam (MF) by the simple dip-coating approach by combining silicone adhesive to create superhydrophobic/superoleophilic, recyclable, and reusable three-dimensional porous structure. The prepared samples have a large specific surface area of 240 m²/g (MWCNT), 1126 m²/g (PC), and good micro-mesoporous frameworks. The water contact angle (WCA) values of the as-prepared foams, PC/MF and MWCNT/MF, not only were 159.34° ± 1.9° and 156.42° ± 1.6°, respectively but also had oil contact angle (OCA) of equal to 0° for a wide range of oils and organic solvents. Therefore, PC/MF and MWCNT/MF exhibited superhydrophobicity and superoleophilicity properties, which can be considered effective adsorbents in oil/water mixture separations. In this context, superhydrophobic/superoleophilic prepared foams for kind of different oils and organic solvents were shown to have superior separation performance ranges of 54-143 g/g and 46-137 g/g for PC/MF and MWCNT/MF, respectively, suggesting a new effective porous material for separating oil spills. Also, outstanding recyclability and reusability of these structures in the ten adsorption-squeezing cycles indicated that the WCA and sorption capacity has not appreciably changed after soaking into acidic (pH = 2) and alkaline (pH = 12) as well as saline (3.5% NaCl) solutions. More importantly, the reusability and chemical durability of the superhydrophobic samples made them good opportunities for use in different harsh conditions for oil-spill cleanup.

Radical and non-radical cooperative degradation in metal-free electro-Fenton based on nitrogen self-doped biochar

To achieve sustainable metal-free electron-Fenton, N self-doped biochar air-cathode (BCAC) was prepared by pyrolyzing coffee residues. During the pyrolysis process, the endogenous N transformed from edge-doping to graphite-doping. Particularly, N vacancies started to evolve when the peak temperature exceeded 700 °C. A high Tetracycline removal rate of 70.42% was obtained on the BCAC at the current density of 4 mA cm^-2. Quenching tests incorporated with ESR spectroscopy were adopted to identify the specific oxidants produced on the cathode. The results showed that •OH (37.36%), •O₂^- (29.67%) and ¹O₂ (24.17%) played comparable role in the tetracycline removal, suggesting the coexist of radical and non-radical oxidants in our electro-Fenton system. According to the structure characterization and the DFT calculation, graphitic N was suggested as the critical site for H₂O₂ generation, and both graphitic N and pyridinic N were electroactive sites for H₂O₂ activation to •OH. Graphitic N and N vacancies with stronger capabilities in O₂ adsorption and electron-trapping were proposed as the electroactive sites for ¹O₂ and •O₂^- formation. This work predicts a novel electro-Fenton process with cooperative radical and non-radical degradation on N self-doped carbonaceous catalysts at a mild condition, which is extremely meaningful for boosting sustainable electro-Fenton technology.

Adsorption Equilibrium, Thermodynamic, and Kinetic Study of O2/N2/CO2 on Functionalized Granular Activated Carbon

A volumetric system was used to assess carbon-based adsorbents for evaluation of the gas separation, equilibrium, and kinetics of oxygen (O₂), nitrogen (N₂), and carbon dioxide (CO₂) adsorption on granular activated carbon (GAC) and functionalized GAC at 298, 308, and 318 K under pressures up to 10 bar. The effects of ZnCl₂, pH, arrangement of the pores, and heat-treatment temperature on the adsorptive capabilities of O₂, N₂, and CO₂ were evaluated. High-performance O₂ adsorption resulted with a fine sample (GAC-10-500) generated with a 0.1 wt % loading of ZnCl₂. The optimal sample structure and morphology were characterized by field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, and powder X-ray diffraction. On the basis of the adsorption-desorption results, the fine GAC provides a surface area of 719 m²/g. Moreover, it possessed an average pore diameter of 1.69 nm and a micropore volume of 0.27 m³/g. At 298 K, the adsorption capacity of the GAC-10-500 adsorbent improved by 19.75% for O₂ but was not significantly increased for N₂ and CO₂. Isotherm and kinetic adsorption models were applied to select the model best matching the studied O₂, N₂, and CO₂ gas uptake on GAC-10-500 adsorbent. At 298 K and 10 bar, the sip isotherm model with the highest potential adsorption difference sequence and gas adsorption difference compared with pure GAC adsorbent as O₂ > N₂ > CO₂ follows well for GAC-10-500. Eventually, the optimal sample is more effective for O₂ adsorption than other gases.

The role of surface chemistry on CO2 adsorption in biomass-derived porous carbons by experimental results and molecular dynamics simulations

Biomass-derived porous carbons have been considered one of the most effective adsorbents for CO₂ capture, due to their porous structure and high specific surface area. In this study, we successfully synthesized porous carbon from celery biomass and examined the effect of external adsorption parameters including time, temperature, and pressure on CO₂ uptake in experimental and molecular dynamics (MD) simulations. Furthermore, the influence of carbon’s surface chemistry (carboxyl and hydroxyl functionalities) and nitrogen type on CO₂ capture were investigated utilizing MD simulations. The results showed that pyridinic nitrogen has a greater tendency to adsorb CO₂ than graphitic. It was found that the simultaneous presence of these two types of nitrogen has a greater effect on the CO₂ sorption than the individual presence of each in the structure. It was also revealed that the addition of carboxyl groups (O=C–OH) to the carbon matrix enhances CO₂ capture by about 10%. Additionally, by increasing the simulation time and the size of the simulation box, the average absolute relative error for simulation results of optimal structure declined to 16%, which is an acceptable value and makes the simulation process reliable to predict adsorption capacity under various conditions.

Oxygen and nitrogen enriched pectin-derived micro-meso porous carbon for CO2 uptake

Oxygen and nitrogen enriched micro–meso porous carbon powders have been prepared from pectin and melamine as oxygen and nitrogen containing organic precursors, respectively.