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In this study, rice husk was the precursor for a KOH-activated carbon with high surface area and high micro-porosity. CO2 adsorption capacity of this material was measured by thermogravimetric analysis. The CO2 adsorption kinetic showed that equilibrium was reached 30 min after the solid-gas phases came into contact and is well-described by the pseudo-first order model (R2 > 0.99 and 95 % confidence level). Intraparticle diffusion model revealed multilinearity over the CO2 adsorption range. Isotherm data at 25, 35, and 45 °C were well-fitted by the Freundlich model, revealing the adsorbent's surface heterogeneity and the exothermic behavior of the process. The material reached a maximum CO2 adsorption capacity of 2.54 mmol/g. A comparison with literature data showed a good agreement. [ABSTRACT FROM AUTHOR]

The study to reduce heavy metals pollution from water using the KOH-activated carbon was studied the factors affecting the adsorption capacities of Cu(II) and Pb(II), in particular, initial metals concentration, pH of the solution, and contact time in static conditions. Using X-ray photoelectron spectroscopy and FTIR analysis to determine the elemental composition and surface functional groups of the activated carbon surface, the presence of oxygen-related functional groups was observed. The maximum adsorption capacities were 135.8 mg g-1 and 31.0 mg g-1 for removal of lead and copper solutions with the initial concentration of 300 mg L-1 of metal at 318 K, respectively. The removal percentage was found to be higher for Pb (II) when compared with Cu (II).

This review covers research on the use of potassium hydroxide (KOH) to produce and modify activated carbon. The methods employed for activation by considering the activation process, carbonization, temperature, activation time, and KOH ratio to material are described and how the surface area, surface morphology, and functional groups are affected by the KOH ratio. Characterization techniques and preparation conditions are summarized. The activated carbon pore structure mainly depends on the burn‐off size and the time for activation is linked to the overall activation reaction rate. The increase in surface area and pore size depends on the ratio of KOH, showing that KOH affects the surface chemistry of the activated carbon. The sorbent‐sorbate interactions are strongly influenced by different parameters, which were also calculated in this review and used to evaluate such interactions. [ABSTRACT FROM AUTHOR]

The study to reduce heavy metals pollution from water using the KOH-activated carbon was studied the factors affecting the adsorption capacities of Cu (II) and Pb (II), in particular, initial metals concentration, pH of the solution, and contact time in static conditions. Using X-ray photoelectron spectroscopy and FTIR analysis to determine the elemental composition and surface functional groups of the activated carbon surface, the presence of oxygen-related functional groups was observed. The maximum adsorption capacities were 135.8 mg/g and 31.0 mg/g for removal of lead and copper solutions with the initial concentration of 300 mg/L of metal at 318 K, respectively. The removal percentage was found to be higher for Pb (II) when compared with Cu (II). [ABSTRACT FROM AUTHOR]

Knowledge of adsorption mechanism and behavior of organic compounds by KOH-activated carbons (KOH-ACs) from wastewater is crucial to its environmental application in wastewater treatment as adsorbent. A superior adsorbent, KOH-activated carbon (KOH-AC), with large surface area (3143 m 2 /g), total pore volume of 2.03 cm 3 /g, relatively low micropore fraction of 53.2%, and having adsorption capacities of organic compounds up to > 1000 mg/g, was prepared. It is an adsorbent significantly different with common ACs because the molecular sieving effect, widely observed for common ACs, is insignificant for KOH-AC. This difference could be attributed to the lower micropore fraction of KOH-AC than common ACs. A negative relationship of adsorption capacity of 25 aromatic compounds (including phenols, anilines, nitrobenzenes and polycyclic aromatic hydrocarbons) with chemical melting point was observed, suggesting that adsorption is dependent on the packing efficiency and stacking density of molecules on KOH-AC. A linear solvation energy relationships of adsorption affinity of 25 aromatic compounds with solute solvatochromic parameters was also observed, that can be used to quantify the contributions of π-π interaction, hydrogen-bonding interaction and hydrophobic effect to adsorption on KOH-AC. Combined with the reported results of adsorption of organic compounds on carbon nanotubes and biochars, it was also observed that external surface area of adsorbents is controlling the packing efficiency and stacking density of molecules on adsorbents and thus affecting adsorption capacity of organic compounds. Moreover, micropore surface area and the fraction of micropores are the adsorbent properties mainly affecting adsorption affinity of organic compounds. The observations and the developed correlations in this study would be helpful in the application of KOH-AC as superior adsorbent by enhancing the understanding of adsorption mechanisms of organic compounds on KOH-AC and by giving a method to predict the adsorption behaviors. [ABSTRACT FROM AUTHOR]

The interconnected open-channel carbon nanosheets were prepared from the agro-waste pineapple leaf fiber using a simple hydrothermal technique and KOH chemical activation under heat treatment in Ar atmosphere. The obtained activated carbon showed amorphous structure with porous graphitized carbon nanosheets and a high specific surface area of 1681 m 2 g −1 . When used as an active material for supercapacitor, such natural fiber-derived carbon nanosheets revealed a high electrochemical performance (the specific capacitance was as high as 202 F g −1 at 5 mV s −1 in 1 M H 2 SO 4 ) and a superb cycling stability even after 10,000 cycles of operation. The carbon nanosheets reported herein, therefore, represent a green energy material that combine the benefit of sustainability of an active component and the promise of high-performance energy storage device. [ABSTRACT FROM AUTHOR]