Comparison of the Properties of Activated Carbons Produced in One-Stage and Two-Stage Processes

A comprehensive review of PETW recycling for supercapacitor applications

The rising measure of waste produced from polyethene terephthalate (PET) and the interest in eco-accommodating energy storage arrangements have prompted escalated examination into reusing waste PET into supercapacitors. This review aims to provide a comprehensive overview of the most recent advancements in the recycling of polyethylene terephthalate waste (PETW), as a supercapacitor electrode precursor. The review looks at different methodologies for recovering PET from waste, including mechanical, chemical, enzyme, etc. It further explores the combination strategies for electrode materials produced using PET. Besides, PET-derived materials' electrochemical performance in supercapacitor application is likewise broken down, with an emphasis on key electrochemical boundaries like capacitive behaviour, cyclic stability, and electrochemical impedance spectroscopy. The need for scalable and cost-effective recycling methods, the creation of eco-friendly electrolytes, and the improvement of the electrochemical performance of recycled PET-based supercapacitors are just a few of the issues and opportunities highlighted in this expanding eco-friendly industry. Overall, the goal of this review is to provide a comprehensive understanding of the cutting-edge developments in the use of recycled PETW as a precursor for supercapacitor electrodes, highlighting the eco-friendly energy storage solution's potential and contributing to a sustainable future.

Exploring Modified Rice Straw Biochar as a Sustainable Solution for Simultaneous Cr(VI) and Pb(II) Removal from Wastewater: Characterization, Mechanism Insights, and Application Feasibility

This study aimed to investigate the efficacy of a rice straw biosorbent in batch adsorption for the removal of chromium (Cr(VI)) and lead (Pb(II)) heavy-metal ions from wastewater. The biosorbent was chemically synthesized and activated by using concentrated sulfuric acid. The produced biosorbent was then characterized by using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses, which provided insights into surface morphology and functional groups. The study examined the effects of pH, rice straw dose, ion concentration, and contact time on metal ion adsorption. Optimal conditions for efficient removal (95.57% for Cr(VI) and 85.68% for Pb(II)) were achieved at a pH of 2.0, a biosorbent dose of 2 g/L, an initial concentration of 20 mg/L, and a contact time of 50 min in synthetic solutions. The isotherms and kinetics model fitting results found that both metal ion adsorption processes were multilayer on the hetero surface of rice straw biosorbent via rate diffusion kinetics. Thermodynamic investigations were conducted, and the results strongly indicate that the adsorption process is endothermic and spontaneous. Notably, the results indicated that the highest desorption rate was achieved by adding 0.3 N HCl to the system.

Removal of Methylene Blue from Water Using Magnetic GTL-Derived Biosolids: Study of Adsorption Isotherms and Kinetic Models

Global waste production is significantly rising with the increase in population. Efforts are being made to utilize waste in meaningful ways and increase its economic value. This research makes one such effort by utilizing gas-to-liquid (GTL)-derived biosolids, a significant waste produced from the wastewater treatment process. To understand the surface properties, the biosolid waste (BS) that is activated directly using potassium carbonate, labelled as KBS, has been characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and Brunauer-Emmett-Teller (BET). The characterization shows that the surface area of BS increased from 0.010 to 156 m²/g upon activation. The EDS and XPS results show an increase in the metal content after activation (especially iron); additionally, XRD revealed the presence of magnetite and potassium iron oxide upon activation. Furthermore, the magnetic field was recorded to be 0.1 mT using a tesla meter. The magnetic properties present in the activated carbon show potential for pollutant removal. Adsorption studies of methylene blue using KBS show a maximum adsorption capacity of 59.27 mg/g; the adsorption process is rapid and reaches equilibrium after 9 h. Modelling using seven different isotherm and kinetic models reveals the best fit for the Langmuir-Freundlich and Diffusion-chemisorptionmodels, respectively. Additional thermodynamic calculations conclude the adsorption system to be exothermic, spontaneous, and favoring physisorption.

Activation of Waste Materials with Carbon(IV) Oxide as an Effective Method of Obtaining Biochars of Attractive Sorption Properties towards Liquid and Gas Pollutants

Biochars that are the subjects of this report have been obtained from the residue of supercritical extraction of common nettle seeds with CO₂. The residue was subjected to direct activation with carbon(IV) oxide as an activator. The obtained biochars were found to have a specific surface area inthe range of 888-1024 m²/g and a basic surface. They were used for the adsorption of a liquid organic pollutant (methylene blue) and a gas inorganic pollutant (NO₂). As follows from the test results, the biochars were able to adsorb 150-239 mg of the dye. The Langmuir model was found to better describe the adsorption experimental data, while the kinetics of the process was better described by the pseudo-second-order model. From the thermodynamic analysis, it was inferred that the adsorption of methylene blue from a water solution was an endothermic and spontaneous reaction. It was established that elevated temperature of activation and the presence of air stream during adsorption had a positive impact on the adsorption of NO₂ by the biochars studied. The greatest sorption capacity of the biochars towards NO₂ was 59.1 mg/g.

Quantifying Environmental and Economic Impacts of Highly Porous Activated Carbon from Lignocellulosic Biomass for High-Performance Supercapacitors

Activated carbons (AC) from lignocellulosic biomass feedstocks are used in a broad range of applications, especially for electrochemical devices such as supercapacitor electrodes. Limited studies of environmental and economic impacts for AC supercapacitor production have been conducted. Thus, this paper evaluated the environmental and economic impacts of AC produced from lignocellulosic biomass for energy-storage purposes. The life cycle assessment (LCA) was employed to quantify the potential environmental impacts associated with AC production via the proposed processes including feedstock establishment, harvest, transport, storage, and in-plant production. A techno-economic model was constructed to analyze the economic feasibility of AC production, which included the processes in the proposed technology, as well as the required facility installation and management. A base case, together with two alternative scenarios of KOH-reuse and steam processes for carbon activation, were evaluated for both environmental and economic impacts, while the uncertainty of the net present value (NPV) of the AC production was examined with seven economic indicators. Our results indicated that overall “in-plant production” process presented the highest environmental impacts. Normalized results of the life-cycle impact assessment showed that the AC production had environmental impacts mainly on the carcinogenics, ecotoxicity, and non-carcinogenics categories. We then further focused on life cycle analysis from raw biomass delivery to plant gate, the results showed that “feedstock establishment” had the most significant environmental impact, ranging from 50.3% to 85.2%. For an activated carbon plant producing 3000 kg AC per day in the base case, the capital cost would be USD 6.66 million, and annual operation cost was found to be USD 15.46 million. The required selling price (RSP) of AC was USD 16.79 per kg, with the discounted payback period (DPB) of 9.98 years. Alternative cases of KOH-reuse and steam processes had GHG emissions of 15.4 kg CO2 eq and 10.2 kg CO2 eq for every 1 kg of activated carbon, respectively. Monte Carlo simulation showed 49.96% of the probability for an investment to be profitable in activated carbon production from lignocellulosic biomass for supercapacitor electrodes.

Microporous activated carbon developed from KOH activated biomass waste: surface mechanistic study of methylene blue dye adsorption

In this work, sugarcane bagasse waste (SBW) was used as a lignocellulosic precursor to develop a high-surface-area activated carbon (AC) by thermal treatment of the SBW impregnated with KOH. This SBW activated carbon (SBWAC) was characterized by crystallinity, porosity, surface morphology and functional groups availability. The SBWAC exhibited Type I isotherm which corresponds to microporosity with high specific surface area of 709.3 m²/g and 6.6 nm of mean pore diameter. Further application of SBWAC as an adsorbent for methylene blue (MB) dye removal demonstrated that the adsorption process closely followed the pseudo-second order kinetic and Freundlich isotherm models. Conversely, a thermodynamic study revealed the endothermic nature and spontaneity of MB dye adsorption on SBWAC with high acquired adsorption capacity (136.5 mg/g). The MB dye adsorption onto SBWAC possibly involved electrostatic interaction, H-bonding and π-π interaction. This work demonstrates SBW as a potential lignocellulosic precursor to produce high-surface-area AC that can potentially remove more cationic dyes from the aqueous environment.

Influence of Pyrolysis Parameters Using Microwave toward Structural Properties of ZnO/CNS Intermediate and Application of ZnCr2O4/CNS Final Product for Dark Degradation of Pesticide in Wet Paddy Soil

Pesticide is a pollution problem in agriculture. The usage of ZnCr2O4/CNS and H2O2 as additive in liquid fertilizer has potency for catalytic pesticide degradation. Colloid condition is needed for easy spraying. Rice husk and sawdust were used as carbon precursor and ZnCl2 as activator. The biomass–ZnCl2 mixtures were pyrolyzed using microwave (400–800 W, 50 min). The products were dispersed in water by blending then evaporated to obtain ZnO/CNS. The composites were reacted with KOH, CrCl3·6H2O, more ZnCl2, and little water by microwave (600 W, 5 min). The ZnCr2O4/CNS and H2O2 were used for degradation of buthylphenylmethyl carbamate (BPMC) in wet deactivated paddy soil. TOC was measured using TOC meter. The FTIR spectra of the ZnO/CNS composites indicated the completed carbonization except at 800 W without ZnCl2. The X-ray diffractograms of the composites confirmed ZnO/CNS structure. SEM images showed irregular particle shapes for using both biomass. ZnCr2O4/CNS structure was confirmed by XRD as the final product with crystallite size of 74.99 nm. The sawdust produced more stable colloids of CNS and ZnO/CNS composite than the rice husk. The pyrolysis without ZnCl2 formed more stable colloid than with ZnCl2. The ZnCr2O4/CNS from sawdust gave better dark catalytic degradation of BPMC than from rice husk, i.e., 2.5 and 1.6 times larger for 400 and 800 W pyrolysis, respectively.

Multiple heavy metal removal simultaneously by a biomass-based porous carbon

Activated carbon from sawdust was produced with an environmentally friendly process involving single-stage carbonization and activation with steam at 800°C. Production process is scalable because lignocellulosic biomass is ubiquitous worldwide as a waste or as a virgin material. Single-stage production without any cooling steps between carbonization and activation is easier in larger scale production. Monometal adsorption and multimetal adsorption of cobalt, nickel, and zinc were investigated by using the produced carbon, with a commercial one as control. Effect of pH, initial metal concentration, adsorbent dosage, and adsorption time was evaluated in batch experiments. Multimetal experiments showed the order of the maximum adsorption capacities: zinc > nickel > cobalt. Experimental adsorption capacities were 17.2, 6.6, and 4.5 mg/g for zinc, nickel, and cobalt, respectively, in multisolute adsorption. In case of monometal adsorption, adsorption capacity was notably lower. Experimental data fitted into the single-solute and multisolute Freundlich models. The best fit kinetic model varied among the metals. The Weber and Morris intraparticle diffusion model was used. Regeneration was performed with 0.1 M HNO₃ , 0.1 M HCl, or 0.1 M H₂ SO₄ . The adsorption capacity remained at the same within three adsorption-desorption cycles. PRACTITIONER POINTS: Activated carbon was produced from sawdust with environmentally friendly process Monometal adsorption and multimetal adsorption with heavy metals were studied Best-fitting models to the experimental data were single-solute and multisolute Freundlich models Regeneration could be performed with diluted acids Worldwide available raw material successfully used as adsorbent for heavy metals.

Evolution of physico-chemical properties of Dicranopteris linearis-derived activated carbon under various physical activation atmospheres

This work emphasizes the effect of the physical activation using CO2 and steam agents on the physicochemical properties of activated carbon produced from Dicranopteris linearis (D. linearis), a fern species widely distributed across tropic and subtropic ecoregions. The D. linearis-derived chars produced under pyrolysis at 400 °C for 1 h were activated in various CO2-steam proportions. As revealed by the IR and Raman spectra, the structure of the activated chars was heavily dependent on the relative proportion of CO2 and steam. The total specific surface area (SSA) of the activated chars proportionally increased with the increase in steam proportion and was comparable to the values of commercial activated char products. Specifically, the activation under CO2- and steam-saturated conditions has correspondingly resulted in SSA increasing from 89 to 653 m2g-1 and from 89 to 1015 m2g-1. Steam also enhanced the development of mesoporous structures of the D. linearis-derived char products, thereby extending their potential applications, particularly for industries that require high rigidity in the product such as pharmaceutical and cosmetic sectors.

Development of Rubber Seed Shell–Activated Carbon Using Impregnated Pyridinium-Based Ionic Liquid for Enhanced CO2 Adsorption

In this study, rubber seed shell was used for the production of activated carbon by chemical activation using an ionic liquid, [C4Py][Tf2N] as an activating agent. Sample RSS-IL 800 shows the highest specific surface area of 393.99 m2/g, a total pore volume of 0.206 cm3/g, and a micropore volume of 0.172 cm3/g. The performance of AC samples as an adsorbent for CO2 was also studied using a static volumetric technique evaluated at a temperature of 25 °C and 1 bar pressure. The CO2 adsorption capacity for sample RSS-IL 800 was 2.436 mmol/g, comparable with reported data from the previous study. Results also show that the CO2 adsorption capacity decreased at a higher temperature between 50 and 100 °C and increased at elevated pressure due to its exothermic behavior. The Langmuir model fits the adsorption data well, and the isosteric heat of adsorption proved that the physisorption process and exothermic behavior occur.

The Occurrence of Legacy P Soils and Potential Mitigation Practices Using Activated Biochar

The long-term application of manures in watersheds with dense animal production has increased soil phosphorus (P) concentration, exceeding plant and soil assimilative capacities. The P accumulated in soils that are heavily manured and contain excess extractable soil P concentrations is known as legacy P. Runoff and leaching can transport legacy P to ground water and surface water bodies, contributing to water quality impairment and environmental pollution, such as eutrophication. This review article analyzes and discusses current and innovative management practices for soil legacy P. Specifically, we address the use of biochar as an emerging novel technology that reduces P movement and bioavailability in legacy P soils. We illustrate that properties of biochar can be affected by pyrolysis temperature and by various activating chemical compounds and by-products. Our approach consists of engineering biochars, using an activation process on poultry litter feedstock before pyrolysis to enhance the binding or precipitation of legacy P. Finally, this review article describes previous examples of biochar activation and offers new approaches to the production of biochars with enhanced P sorption capabilities.

Carbon from Bagasse Activated with Water Vapor and Its Adsorption Performance for Methylene Blue

This research work reports on the potential of bagasse, a solid waste from sugar factories, to produce activated-carbon (AC) as an adsorbent. The activation was conducted under 500, 600, and 700 °C using steam as the activation agent to produce AC500, AC600, and AC700, respectively. The prepared-materials were characterized to understand their elemental content, surface morphology, thermal properties, functional groups identification, surface area, and pore size. AC700 provided the highest surface area of 592.36 m2/g and indicated the contribution of mesopores distributes along 1.5–8.0 nm of pore size. Therefore, an adsorption test was conducted with AC700 as adsorbent. The results show that methylene blue (MB) adsorption reached equilibrium after 30 min of adsorption time. The adsorption isotherm applied to a monolayer Langmuir isotherm was fitted by linearization, resulting in a constant R2 of 0.999. The MB adsorption to AC700 favorably occurred, as proven by the Freundlich parameter 1/n of 0.881, which is less than 1. The Dubinin-Radushkevich isotherm confirmed that the adsorption proceeded through physical interaction with adsorption energy of 3.536 kJ/mol.

The Impact of Coal Fly Ash Purification on Its Antibacterial Activity

Fly ash (FA) is produced from coal power plants’ combustion. FA is used in the concrete industry, as an ingredient in the brick and paving. Knowledge of the chemical composition and toxic metal content in FA is essential for evaluating its environmental risks. This study aimed to assess FA purification effect on its antibacterial activity against Escherichia coli and Bacillus cereus, by calculating percent bacterial reduction. Moreover, centrifugation time effect on the purification process was evaluated. Chemical composition and properties of purified FA were determined and compared with raw FA, using Fourier transform Infrared (FTIR); X-ray diffraction (XRD); X-ray photoelectron spectroscopy (XPS); energy-dispersive X-ray (EDXA); carbon, hydrogen, nitrogen, and sulfur (CHNS) elemental analysis; moisture content; and loss-of-ignition. Particle size was predicted by using dynamic laser scattering, BET and scanning electron microscopy (SEM). The CHNS results showed that purified FA contains the highest carbon content (88.9%), as compared to raw FA (82.1%). The particle size distribution (PSD) of FA microspheres ranges from 48.53 ± 17.9 to 52.98 ± 19.4 µm by using SEM. PSD, using dynamic laser scattering, showed polydispersed and non-uniform size in raw FA, ranging in size from 107.1 to 1027 nm, while purified FA manifests a monodispersed size from 103.3 to 127.3 nm. FA showed the least bacterial growth reduction %, while the purified fly ash (FA2) showed the highest bacterial growth reduction %, as compared to the control bacterial broth culture without fly ash.

Characterization of Chemically Activated Pyrolytic Carbon Black Derived from Waste Tires as a Candidate for Nanomaterial Precursor

Pyrolysis is a feasible solution for environmental problems related to the inadequate disposal of waste tires, as it leads to the recovery of pyrolytic products such as carbon black, liquid fuels and gases. The characteristics of pyrolytic carbon black can be enhanced through chemical activation in order to produce the required properties for its application. In the search to make the waste tire pyrolysis process profitable, new applications of the pyrolytic solid products have been explored, such as for the fabrication of energy-storage devices and precursor in the synthesis of nanomaterials. In this study, waste tires powder was chemically activated using acid (H2SO4) and/or alkali (KOH) to recover pyrolytic carbon black with different characteristics. H2SO4 removed surface impurities more thoroughly, improving the carbon black's surface area, while KOH increased its oxygen content, which improved the carbon black's stability in water suspension. Pyrolytic carbon black was fully characterized by elemental analysis, inductively coupled plasma-optical emission spectrometry (ICP-OES), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), N2 adsorption/desorption, scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), dynamic light scattering (DLS), and ζ potential measurement. In addition, the pyrolytic carbon black was used to explore its feasibility as a precursor for the synthesis of carbon dots; synthesized carbon dots were analyzed preliminarily by SEM and with a fluorescence microplate reader, revealing differences in their morphology and fluorescence intensity. The results presented in this study demonstrate the effect of the activating agent on pyrolytic carbon black from waste tires and provide evidence of the feasibility of using waste tires for the synthesis of nanomaterials such as carbon dots.

Preparation and Characterisation of Activated Carbon from Palm Mixed Waste Treated with Trona Ore

This study explores the use of a novel activating agent and demonstrates the production and characterisation of activated carbon (AC) from a combine palm waste (CPW) in 3:2:1 proportion by weight of empty fruit bunch, mesocarp fibre and palm kernel shell. The resulting biomass was processed by a microwave-assisted method using trona and compared with material produced by conventional routes. These results demonstrate the potential of trona ore as an activating agent and the effectiveness of using a combined palm waste for a single stream activation process. It also assesses the effectiveness of trona ore in the elimination of alcohol, acids and aldehydes; with a focus on increasing the hydrophilicity of the resultant AC. The optimum results for the conventional production technique at 800 °C yielded a material with S_BET 920 m²/g, V_total 0.840 cm³/g, a mean pore diameter of 2.2 nm and an AC yield 40%. The optimum outcome of the microwave assisted technique for CPW was achieved at 600 W, S_BET is 980 m²/g; V_total 0.865 cm³/g; a mean pore diameter 2.2 nm and an AC yield of 42%. Fourier transform infrared spectrometry analyses showed that palm waste can be combined to produce AC and that trona ore has the capacity to significantly enhance biomass activation.

Novel Activated Carbon Nanofibers Composited with Cost-Effective Graphene-Based Materials for Enhanced Adsorption Performance toward Methane

Various types of activated carbon nanofibers' (ACNFs) composites have been extensively studied and reported recently due to their extraordinary properties and applications. This study reports the fabrication and assessments of ACNFs incorporated with graphene-based materials, known as gACNFs, via simple electrospinning and subsequent physical activation process. TGA analysis proved graphene-derived rice husk ashes (GRHA)/ACNFs possess twice the carbon yield and thermally stable properties compared to other samples. Raman spectra, XRD, and FTIR analyses explained the chemical structures in all resultant gACNFs samples. The SEM and EDX results revealed the average fiber diameters of the gACNFs, ranging from 250 to 400 nm, and the successful incorporation of both GRHA and reduced graphene oxide (rGO) into the ACNFs' structures. The results revealed that ACNFs incorporated with GRHA possesses the highest specific surface area (SSA), of 384 m²/g, with high micropore volume, of 0.1580 cm³/g, which is up to 88% of the total pore volume. The GRHA/ACNF was found to be a better adsorbent for CH₄ compared to pristine ACNFs and reduced graphene oxide (rGO/ACNF) as it showed sorption up to 66.40 mmol/g at 25 °C and 12 bar. The sorption capacity of the GRHA/ACNF was impressively higher than earlier reported studies on ACNFs and ACNF composites. Interestingly, the CH₄ adsorption of all ACNF samples obeyed the pseudo-second-order kinetic model at low pressure (4 bar), indicating the chemisorption behaviors. However, it obeyed the pseudo-first order at higher pressures (8 and 12 bar), indicating the physisorption behaviors. These results correspond to the textural properties that describe that the high adsorption capacity of CH₄ at high pressure is mainly dependent upon the specific surface area (SSA), pore size distribution, and the suitable range of pore size.

Biochar and Energy Production: Valorizing Swine Manure through Coupling Co-Digestion and Pyrolysis

Anaerobic digestion is an established technological option for the treatment of agricultural residues and livestock wastes beneficially producing renewable energy and digestate as biofertilizer. This technology also has significant potential for becoming an essential component of biorefineries for valorizing lignocellulosic biomass due to its great versatility in assimilating a wide spectrum of carbonaceous materials. The integration of anaerobic digestion and pyrolysis of its digestates for enhanced waste treatment was studied. A theoretical analysis was performed for three scenarios based on the thermal needs of the process: The treatment of swine manure (scenario 1), co-digestion with crop wastes (scenario 2), and addition of residual glycerine (scenario 3). The selected plant design basis was to produce biochar and electricity via combined heat and power units. For electricity production, the best performing scenario was scenario 3 (producing three times more electricity than scenario 1), with scenario 2 resulting in the highest production of biochar (double the biochar production and 1.7 times more electricity than scenario 1), but being highly penalized by the great thermal demand associated with digestate dewatering. Sensitivity analysis was performed using a central composite design, predominantly to evaluate the bio-oil yield and its high heating value, as well as digestate dewatering. Results demonstrated the effect of these parameters on electricity production and on the global thermal demand of the plant. The main significant factor was the solid content attained in the dewatering process, which excessively penalized the global process for values lower than 25% TS.

Comparing the Physicochemical Properties of Upgraded Biomass Fuel by Torrefaction and the Ashless Technique

The purpose of this study was to investigate and compare the influence of torrefaction and an ashless process on the physical and chemical properties of pitch pine sawdust (PSD) and kenaf as types of woody and herbaceous biomass. The physicochemical properties of the materials pretreated by the ashless process with torrefaction including proximate and ultimate analysis, hydrophobicity, grindability, morphology, and structure were analyzed. The results showed that when ashless Kenaf was torrefied, the high heating rate and atomic ratios of O/C and H/C increased. The tendency of the torrefied, ashless Kenaf to absorb water decreased, and it became more hydrophobic (approximately 0% for the uptake rate of moisture). In addition, the grindability of the torrefied, ashless Kenaf was substantially improved compared to that of pretreated PSD. Brunauer–Emmett–Teller and scanning electron microscopy results showed that when Kenaf was pretreated, particles easily lost their fibrous structure and cracked as the number of macropores decreased. These results indicate that the herbaceous biomass of Kenaf, when pretreated with both torrefaction and the ashless process, exhibits improved physicochemical properties compared to the woody PSD.

Zinc Adsorption by Activated Carbon Prepared from Lignocellulosic Waste Biomass

Sawdust was used as a precursor for the production of biomass-based activated carbon. Carbonization and activation are single-stage processes, and steam was used as a physical activation agent at 800 °C. The adsorption capacity towards zinc was tested, and the produced activated carbon proved effective and selectively adsorbent. The effects of pH, initial concentration, adsorbent dosage, time, temperature, and regeneration cycles were tested. The adsorption capacity obtained in this study was compared favorably to that of the materials reported in the literature. Several isotherms were applied to describe the experimental results, with the Sips isotherm having the best fit. Kinetic studies showed that the adsorption follows the Elovich kinetic model.

Rice Husk-Derived High Surface Area Nanoporous Carbon Materials with Excellent Iodine and Methylene Blue Adsorption Properties

Iodine and methylene blue adsorption properties of the high surface area nanoporous carbon materials derived from agro-waste and rice husk is reported. Rice husk was pre-carbonized at 300 °C in air followed by leaching out the silica nanoparticles by extraction with sodium hydroxide solution. The silica-free rice husk char was mixed with chemical activating agents sodium hydroxide (NaOH), zinc chloride (ZnCl2), and potassium hydroxide (KOH) separately at a mixing ratio of 1:1 (wt%) and carbonized at 900 °C under a constant flow of nitrogen. The prepared carbon materials were characterized by scanning electron microscopy (SEM), Fourier transformed-infrared spectroscopy (FT-IR), powder X-ray diffraction (pXRD), and Raman scattering. Due to the presence of bimodal micro- and mesopore structures, KOH activated samples showed high specific surface area ca. 2342 m2/g and large pore volume ca. 2.94 cm3/g. Oxygenated surface functional groups (hydroxyl, carbonyl, and carboxyl) were commonly observed in all of the samples and were essentially non-crystalline porous particle size of different sizes (<200 μm). Adsorption study revealed that KOH activated samples could be excellent material for the iodine and methylene blue adsorption from aqueous phase. Iodine and methylene blue number were ca. 1726 mg/g and 608 mg/g, respectively. The observed excellent iodine and methylene blue adsorption properties can be attributed to the well-developed micro- and mesopore structure in the carbon material. This study demonstrates that the agricultural waste, rice husk, and derived nanoporous carbon materials would be excellent adsorbent materials in water purifications.