A Short Review on CO2 Capture Using Bamboo Char Derived Through Pyrolysis Method and Studies on Kinetic, Isotherm, and Thermodynamic

This review highlights the effectiveness of bamboo biochar and empty fruit bunch (EFB) fibres as low-cost adsorbents for ammonia nitrogen removal from wastewater. Both materials are highlighted for their abundant availability and substantial adsorption capabilities. Bamboo biochar, derived from pyrolysed bamboo, benefits from its high surface area and porosity, enhanced further through chemical activation that increases its functional groups and pore structure. This modification significantly improves its efficiency in adsorbing ammonia nitrogen. Similarly, EFB, a by-product of palm oil production, is treated through carbonisation and activation, which enhances its adsorption properties. The review also discusses the potential for combining bamboo biochar and EFB, as their complementary properties could offer a more effective solution for wastewater treatment. The paper emphasises the advantages of these materials in addressing environmental challenges and highlights the need for further research into their combined use, as well as their potential for reuse and regeneration to promote sustainability. This review provides insights into optimising adsorbent modifications and exploring practical applications in wastewater treatment. Keywords: Bamboo biochar; Modified empty fruit bunch; Combined adsorbent; Ammonia nitrogen Adsorption; Wastewater

This review highlights the effectiveness of bamboo biochar and empty fruit bunch (EFB) fibres as low-cost adsorbents for ammonia nitrogen removal from wastewater. Both materials are highlighted for their abundant availability and substantial adsorption capabilities. Bamboo biochar, derived from pyrolysed bamboo, benefits from its high surface area and porosity, enhanced further through chemical activation that increases its functional groups and pore structure. This modification significantly improves its efficiency in adsorbing ammonia nitrogen. Similarly, EFB, a by-product of palm oil production, is treated through carbonisation and activation, which enhances its adsorption properties. The review also discusses the potential for combining bamboo biochar and EFB, as their complementary properties could offer a more effective solution for wastewater treatment. The paper emphasises the advantages of these materials in addressing environmental challenges and highlights the need for further research into their combined use, as well as their potential for reuse and regeneration to promote sustainability. This review provides insights into optimising adsorbent modifications and exploring practical applications in wastewater treatment. Keywords: Bamboo biochar; Modified empty fruit bunch; Combined adsorbent; Ammonia nitrogen Adsorption; Wastewater

Cadmium (Cd) is a byproduct of zinc production. It has a high solubility, mobility and biological accumulation leading to a risk of bone and kidney damage after long-term exposure. Sorption is an effective method to treat Cd-contaminated water. As a great potential contaminant sorbent, biochar can be produced from rice husk, coconut shell and bamboo under their respective optimum conditions for the sorption of toxic metal ions were used as representatives. Sorption models of kinetics and isotherms were used to fit the experimental results. Pseudo-first-order models fitted the data better than pseudo-second-order for all types of biochar. The Cd2+ sorption capacity of coconut shell char and bamboo char was higher than rice husk char (7.3723 mg/g ≈ 7.3835 mg/g > 5.0345 mg/g). Freundlich model fitted the results of coconut shell biochar and bamboo biochar better than Langmuir model, which indicate a strong bond for Cd2+ sorption. In contrast, for rice husk biochar Langmuir model fitted the results better than Freundlich model indicating monolayer sorption mechanism dominated the sorption.

Copyright © Korean Carbon Society http://carbonlett.org Over the years, the furnace has been used as a common heating method to manufacture activated carbon. In a furnace, heat is transferred through conduction and convection. The outer surface of the sample is in contact with the generated heat, which slowly diffuses inwards as a result of the thermal gradient between the surface and the core of the material’s particles. Another method of heating employs microwave irradiation. Even though it is less energyand time-consuming, the microwave method has several critical issues with respect to temperature control and thermal runaway, especially in the scaling-up of the microwave heating process [1]. Generally, the activation of a carbonaceous precursor can be performed through physical (steam, air or CO2) or chemical activation (activators such as ZnCl2, KOH, etc.) or a combination of both. The chemical activation is normally preferable over physical activation since it is a faster process with a lower activation temperature. Moreover, the activated carbon produced via chemical activation usually possesses high specific surface area (as determined by the Brunauer-Emmett-Teller, BET method), good pore development and high carbon yield [2,3]. In recent years, potassium salts such as KOH and K2CO3 have been widely used in the manufacture of low cost activated carbon. It has been found that activated carbon prepared by KOH activation is highly microporous when compared to that produced through ZnCl2 or H3PO4 activation [4-6]. Besides, KOH also enhances the specific surface area and the formation of—OH functional groups on the carbon surface [7]. Over the past 5 years, many advantages of KOH activation have been revealed in the literature [8]. However, the adverse drawbacks of employing KOH have been overlooked in many of the published studies. In this paper, the preparation of activated carbon by KOH activation using conventional heating is reviewed and discussed. The limitations and implications of using KOH in the activation process are highlighted. The selection of appropriate potassium salts for activated carbon preparation is also recommended. The physical preparation of activated carbon is comprised of two major processes, namely, carbonization and activation of the carbonized sample [4]. Chemical activation is a single step process, as both carbonization and activation occur simultaneously at temperatures ranging between 400oC and 700oC, which is lower than that of physical activation [9]. However, in some cases, additional carbonization or a pre-carbonization step is performed to produce char prior to chemical impregnation and activation [5,4,10-13]. Thus, potassium hydroxide activation can be achieved through either direct chemical activation or char-impregnated chemical activation. In direct chemical activation, a selected carbonaceous precursor is first dried overnight to remove moisture and then chemically treated at a desired impregnation ratio (weight of KOH over weight of precursor). The impregnated solid is then heated in a furnace at a specified temperature and time. Carbonization of the precursor is often omitted when the impregnated solid is already suitable for activation. Table 1 exhibits recently developed activated carbon preparation methods using various precursors and KOH activation with conventional heating. From Table 1, it can be seen that DOI: http://dx.doi.org/ DOI:10.5714/CL.2015.16.4.275

The increase in burning, deforestation, and the exorbitant use of fossil fuels have contributed to the increase in carbon dioxide emissions; this gas is responsible for the intensification of the greenhouse effect and radical climate changes. In this way, it becomes necessary to find alternatives to reduce its emission. Porous carbon materials synthesized from lignocellulosic waste can be employed in technologies for capture and utilization of CO2 due to the advantages such as selectivity, low-cost synthesis, high surface area and pore volume, and thermal and chemical stability. Considering the availability of Brazil nut biomass residues in the Amazon region, this article proposes to synthesize activated carbon from the lignocellulosic residue using physical and chemical activation methods for CO2 capture. The analysis of N2 adsorption-desorption isotherms proves the predominance of a microporous structure when using the two synthesis methods described here. In physical activation, the surface area was 912 m2/g, while, in chemical activation, it was 1421 to 2730 m2/g. The sample treated via the chemical method (BS6-K1) showed better performance in CO2 adsorption, with adsorption results of 3.8 and 6mmol/g of CO2 at 25 ℃ and 0°C, respectively, at 101kPa. CO2 adsorption capacity is due to the high volume of ultramicropores. It is believed that the microporous carbon material synthesized from Brazil nut residues is an alternative precursor for carbon materials used as CO2 capture.

Residual biomass of chia seeds (Salvia hispanica) oil extraction as low cost and eco-friendly biosorbent for effective reactive yellow B2R textile dye removal: Characterization, kinetic, thermodynamic and isotherm studies

Bamboo biochar is effective at adsorbing a wide range of heavy metals and is relatively stable under environmental conditions. Cadmium contamination in aquatic systems poses a significant risk to environmental and human health, creating a need for efficient, low-cost adsorbents for water treatment. In this study, pristine and chemically activated biochars derived from M. baccifera bamboo were evaluated for Cd(II) removal from aqueous solution. The objective was to investigate the effect of chemical activation on adsorption performance and to elucidate the adsorption mechanisms using equilibrium and kinetic analyses. Biochar was activated using various concentrations of potassium hydroxide (KOH) and phosphoric acid (H 3 PO 4 ). Among the tested methods, activation with 60% KOH demonstrated the highest adsorption efficiency, leading to its selection for further characterization and adsorption studies. Batch experiments revealed that the adsorption process is significantly influenced by pH, with optimal removal observed at pH 5. The equilibrium data were best represented by the Langmuir isotherm, indicating maximum adsorption capacities of 15.15 mg/g for pristine biochar and 24.39 mg/g for activated biochar. Kinetic analysis indicated that the adsorption kinetics conform to the Pseudo-second-order model, with Intraparticle diffusion and liquid-film diffusion identified as contributing factors in the rate-controlling steps. Fourier-transform infrared (FTIR) spectroscopy analysis showed shifts in the O-H, C=O, and C-O functional groups. These changes suggest that surface complexation and ion exchange are the primary mechanisms involved in the binding of cadmium ions. The results of this study demonstrate that KOH activation significantly improves the physicochemical properties and adsorption performance of bamboo biochar. This research highlights the potential of activated biochar derived from Melocanna baccifera as a sustainable and locally available adsorbent for the removal of cadmium from contaminated water. This also supports its potential application in cost-effective water purification systems.

Solving two environmental problems simultaneously: Scalable production of carbon microsheets from structured packing peanuts with tailored microporosity for efficient CO2 capture

The development of environmentally friendly slow-release fertilizers with effective water retention is an urgent need in modern agriculture. Although biochar can improve soil fertility as a nutrient carrier, it suffers from poor slow-release performance and water retention. Conversely, soy protein hydrogels, characterized by their hydrophilic nature with threedimensional cross-linked networks, can retain large amounts of water and facilitate the slow release of fertilizers and water due to their high specific surface area. Hence, a novel slow-release composite material with high water retention was prepared by introducing bamboo biochar into a soy protein-based hydrogel (SPB) network through graft copolymerization. The findings indicated that the bamboo biochar promoted the SPB cross-linked network density, which improved the swelling rate of SPB materials and soil water-holding capacity. Moreover, SPB-2-4% and SPB-3-4% exhibited superior slow-release capabilities for nitrogen fertilizer. Cucumber seedlings treated with SPB materials containing bamboo biochar demonstrated enhanced growth and chlorophyll content than those treated with biochar-free SPB materials. Compared with the control, the cucumber plants treated with SPB-2-4% displayed a significant increase in fresh weight, root length, and leaf area by 139.32%, 99.20%, and 149.45%, respectively, which can be attributed to the positive synergistic effect of soy protein and bamboo biochar. Furthermore, the nutrients and porous structures of bamboo biochar favor the proliferation of microorganisms, enriching the soil microbial community. Therefore, the bamboo biochar-soybean protein hydrogel composites have great application prospects for sustainable agriculture and provide a new direction for the development of slow-release and water-retention fertilizers.

Adsorption characteristics of individual and binary mixture of ciprofloxacin antibiotic and lead(II) on synthesized bamboo-biochar.

Structural elucidation of physical and chemical activation mechanisms based on the microdomain structure model

One of the most important things that every human being on the planet must be aware of is sustainability. The term ‘sustainability’ refers to all aspects of the environment, including numerous characteristics such as the long-term viability of water bodies. Water pollution has been rapidly increasing over the last two decades for a variety of reasons. The significant development of industries is beneficial to the country's economy. Even though the wastes generated by these various industries and disposed of without proper treatment and practises have caused and continue to pollute the water bodies. Nitrates are one of the pollutants that can be found in most polluted river bodies. Nitrates can be found in river bodies from agricultural waste water due to pollutants released primarily from fertilizers used in excess amounts for agricultural practises. Adsorption proved to be the best solution for controlling the nitrate content in water. In this study, nitrates and nitrites are removed from adsorbent fish scales. The removal of fish scales as an adsorbent has been thoroughly researched. These studies involve different isotherm studies, kinetic studies as well as thermodynamic studies. Following the completion of the analysis, the results revealed that nitrates and nitrates can be effectively removed with fish scales, with the maximum percent biosorption found to be 97.96 and 99.72% at contact times of 140 min and 100 min, respectively, the pH is kept at 6, the temperature is kept at 303 degrees Celsius, and the adsorbent dosage is kept at 0.4 g for maximum adsorption. Thermodynamic studies has been also conducted where the results showed that the reaction is endothermic and spontaneous in nature based on the values of ΔS, ΔH and ΔG. In addition to the above analysis, isothermal and kinetic studies were performed, with the Langmuir isotherm studies fitting perfectly and the affinity between the pollutants and adsorbent indicating that second-order kinetic studies are best suited.KeywordsAdsorbentKinetic studiesIsotherm studiesThermodynamic studiesFish scalesAdsorption

Nanostructured bio-adsorbents were prepared by physical or chemical activation of the residue of supercritical extraction of raspberry seed. Their physicochemical properties were determined by elemental analysis, low-temperature nitrogen adsorption/desorption, Boehm titration and scanning electron microscopy. The biocarbon obtained as a result of physical activation of the precursor showed basic character of the surface and its SBET was 700 m2/g. The chemical activation of the residue of supercritical extraction of raspberry seed with potassium carbonate favored generation of acidic functional groups and SBET of this biocarbon was 1177 m2/g. The nanostructured biocarbons were used for removal of Rhodamine B from its aqueous solutions. The process was best described by the Langmuir isotherm and the maximum capacity of the monolayer was 181.82 mg/g and 277.83 mg/g for the physically and chemically activated samples, respectively. The adsorption energy obtained from the Dubinin–Radushkevich isotherm indicated that the process observed was physisorption, while the kinetics of the process was best described by the pseudo-second-order model. The negative values of Gibbs free energy indicated the spontaneous character of the process. For the chemically activated sample, the highest sorption capacities toward Rhodamine B were obtained in an acidic environment, while for the physically activated sample—in a basic environment. The yield of desorption decreased for the media: distilled water > hydrochloric acid > acetic acid, which means that Rhodamine B molecules were weakly bound to the biocarbon surface.

Activated carbon is produced from the coconut shell through physical and chemical activation. The pyrolysis method was employed in this research for physical activation at an optimum temperature of 600oC and 1,000oC, for chemical activation immersed using 10% Na2CO3 activating agent. This research has produced two samples, namely the physical activation of 1,000oC and the physics-chemical activation of Na2CO3. The X-Ray Diffraction (X-RD) spectrum of activated carbon in the samples 1,000oC and Na2CO3 contained silicate minerals, iron ore and quartz, respectively, and it showed the formation of carbon and graphite structures in the hkl (002) and (100) planes. Through Scherrer’s method, the average size of the Na2CO3 crystals sample is 15.03 nm and the sample crystal sample of 1,000oC is 54.53 nm; the size of the Nano-scale crystals was formed when the temperature increases ≥ 600° C. The X-RD resulted the percentage of elemental content carbon phase volume fraction (Fv) and impurity (I) in the 1,000oC sample of 75.61%, 24.39% and the Na2CO3 sample of 77.87%, 22.13% . These results indicate that the carbon content in chemical activation is much better than the physics activation. SEM results with magnification of 5,000x, it is very clear the porosity formed of the 10 μm picture size are 0.8 μm in Na2CO3 sample and 1.00 μm in 1,000oC sample.

Low-cost activated carbons were prepared from waste polyurethane foam by physical activation with CO2 for the first time and chemical activation with Ca(OH)2, NaOH, or KOH. The activation conditions were optimized to produce microporous carbons with high CO2 adsorption capacity and CO2/N2 selectivity. The sample prepared by physical activation showed CO2/N2 selectivity of up to 24, much higher than that of chemical activation. This is mainly due to the narrower microporosity and the rich N content produced during the physical activation process. However, physical activation samples showed inferior textural properties compared to chemical activation samples and led to a lower CO2 uptake of 3.37 mmol·g−1 at 273 K. Porous carbons obtained by chemical activation showed a high CO2 uptake of 5.85 mmol·g−1 at 273 K, comparable to the optimum activated carbon materials prepared from other wastes. This is mainly attributed to large volumes of ultra-micropores (<1 nm) up to 0.212 cm3·g−1 and a high surface area of 1360 m2·g−1. Furthermore, in consideration of the presence of fewer contaminants, lower weight losses of physical activation samples, and the excellent recyclability of both physical- and chemical-activated samples, the waste polyurethane foam-based carbon materials exhibited potential application prospects in CO2 capture.