Papers by Keyword: Chemical Activation

Abstract: Porous carbon is one of the promising electrode materials for supercapacitors due to its unique and engineerable microstructural properties. The study of the synthesis of porous carbon from waste biomass is very important due to the abundance of natural resources, low cost production and contribute to solving environmental problems. In this study, porous carbons derived from candlnut shell with various type of activator was studied the chemical structural, morphological and electrochemical properties then evaluated as electrodes for supercapacitor. We have been successfully synthesized of porous carbon from candlenut shells using three steps of the process, i.e.: carboni-zation, activation and calcination. Carbonization was carried out at 700°C in a furnace using a closed crucible to minimize the oxygen. The chemical activation conducted using three types of activators, i.e. ZnCl₂, H₃PO₄ and KOH then calcination process by heated at 800°C for 1 h under Ar flow. The results of the Fourier-transform infrared (FTIR) analysis show that the carbonization process increases the content of aromatic C=C functional groups and reduce the OH, C-H, C-O and C=O functional groups. The carbonization process has also increased the electrical conductivity of the sample around 0.8525 S/m. The results of Scanning Electron Microscope (SEM) images can be observed that the activation process of carbon has formed which was indicated by the appearance of many pores on the surface area of carbon. N₂ adsorption/desorption isotherms (Brunauer–Emmett–Teller (BET)) characterization was indicated that the porous carbon is dominated by mesoporous with a pore size around 2-50 nm. BET characterization also can be determined the surface area of porous carbon around 477 m²/g for ZnCl₂, 636 m²/g for H₃PO₄, and 681 m²/g for KOH. This synthesized materials are further employed in a symmetric supercapacitor using simple glass cell. The best performance of supercapacitor achieved by KOH porous carbons with 16.30 F/g of specific capacitance, 2.26 Wh/kg of energy density and 1038 W/kg of power density.

Abstract: In this century, sustainability has become an essential element in any project to ensure a safe environment. The conversion of waste materials is an important step towards achieving sustainability. Moreover, converting these materials into adsorbents to treat wastewater shows great potential, especially due to its cost-effectiveness and the reduction of solid waste disposal. This research study aims to investigate the removal of Copper (Cu) from wastewater using waste tyre-recycled carbon black (WT-rCB) and modified waste tyre-recycled carbon black (WT-dAC) to determine their adsorption capability. The removal of Copper using WT-rCB and WT-dAC were investigated with various parameters: pH value, adsorbent dosage, and contact time. The chemical-physical activation process was employed to produce the WT-dAC. First, WT-rCB was impregnated with 1:5 wt% of 1 M KOH solution, then physically activated at 650 °C for 1 hr with flowing Nitrogen gas at 1 L/min. The adsorption study observed a removal efficiency of up to 65% using WT-dAC, while WT-rCB showed a removal efficiency of 22% under the optimum conditions. Eventually, the study demonstrates the employability of WT-dAC in the removal of Copper (Cu) from wastewater.

Abstract: This study investigates the potential for using mangosteen shell which is an agricultural waste to chemically activate using potassium hydroxide (KOH) or phosphoric acid (H₃PO₄) and then carbonized for 120 min at 673 K, to adsorb hexavalent chromium (Cr⁶⁺) from solution. The high iodine number and methylene blue number on the base-activation as a good adsorbent that a high surface area of this activated carbonaceous material is effective in removing Cr⁶⁺, with adsorption increasing with temperature, adsorption time, and initial feed concentration. With decreasing solution pH, the maximum of Cr⁶⁺ adsorption capacity and removal at a pH of 2.0 was achieved.

Abstract: Identification of the potential of cacao peel as the basic material of environmentally friendly supercapacitor electrodes had been identified. This identification was carried out through analysis of specific dimensions, densities, and capacitances. Activated carbon electrodes were made by a combination of chemical and physics activation methods. The technique of preparing carbon electrodes started from pre-carbonization, milling, chemical activation, pellet making, carbonization, and completed it with physics activation. In addition, the chemical activation applied 0.3 M KOH activator, whereas the physical activation used CO₂ gas at a temperature of 700°C. The physical properties were tested by density and X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dipersive X-Ray (EDX). While the electrochemical properties were tested using the Ciclic Voltammetric (CV) method. The results showed that the mass, diameter, thickness, and density of the electrode decreased after passing the carbonization-activation process. A value of 2θ in the range of 23,569^o for the reflection fields 002 and 44,781^o for the reflection field 100 was obtained in the XRD measurements . The X-ray diffraction curve pointed out that the surface area of C 0,3 M sample was sizeable with the Lc value and lattice distance d₀₀₂ around 20,01669 Å and 3,771705 Å. SEM analysis indicated the presence of pores between particles spread almost evenly on the surface of the sample, with an irregular and elongated shape. EDX testing showed carbon element of 87.05% while atomic percentage of 91.02%, and correspondently, electrochemical test showed the value of specific capacitance obtained at a concentration of 0.3 M was 90.2 F/gr with a density of 0.850gr/cm³. From the results of the tests obtained, it was shown that cacao peels was very potential to be used as electrodes for supercapacitors.

Abstract: In this research the questions of microsilica usage and ways of its activation for modification of structure of cement stone and cement on its basis. The actual questions corresponding any type of filler, particularly microsilica are: how and how much should be put, which mechanisms are involving to process of structuring, how much is received result of structure modification and others. Therefore the role of microdispersed fillers in modification process of cement rock and cement on its basis must be viewed in connection with other dimensional inclusions on different large-scale levels. Reducing of concrete consumption by its substitution by microsilica, has a positive influence to physico-chemical characteristics of concrete.

Abstract: Chromium absorption using modified zeolites in the form of mono-cation (H-Zeolite) was carried out. Modifications are intended to increase the ability of ion exchange. Modifications made were chemical activation by adding ammonium chloride solution and physically by calcination. Zeolite used came from Kasongan, while as an activity test liquid waste from the electro plating industry PT. Mega Andalan Electro Plating. The parameter used for this study is the comparison of zeolite mass with waste samples. Comparisons used are 1: 5, 1: 7, 1:10, 1:20 and 1:50. From the results of the study it can be seen that there is an increase in the ability of ion exchange in the modified zeolite and produces an optimum ratio of 1: 7 with an absorption efficiency of 13.44%..

Abstract: The influence of various methods of activation on the graphite particles average size and micro-relief of particles have been studied. It has been experimentally proved that the size of graphite particles decreases after the process of mechano-activation, however graphite particles don’t change significantly after being processed by chemical activation. It should be noted that in the course of chemical activation the state of particles surface varies on shearing cuts. Particles’ surface can be described as a poly stratified system, comprising separate complex-structured buildups of the “rosette” type, where the graphite petals are located around the reinforcing rod. Moreover, the graphite petals are placed at different angles to each other, and they are of different thickness. The empty space between these buildups is filled with graphite particles, their petals being orientated freely. The particles size decrease and the change in the particles surface state are followed by their porosity increase, which, in its turn, leads to the fact that graphite particles’ surface becomes “super-hydrophobic” and helps the capillary forces resist the filtration of the melt into the pores of graphite particles.

Abstract: The preparation of carbon materials from low-cost agricultural residues is presented in this work. Carbon products were prepared from carbonized cassava tuber (cassava tuber char, CTC) using a chemical activation assisted sonochemical process incorporating KOH as an activating agent. The physical properties such as proximate analysis, ultimate analysis and FTIR spectra of raw material were studied using cassava tuber collected from farmland in the Kanchanaburi Province. The structure of the precursor material played a significant role in influencing the quality and properties of the as-prepared carbon. It was found that the specific surface area of carbon products was improved through chemical activation assisted sonochemical process at 80 °C for 4 hours. The influence of KOH impregnation ratios on the specific surface area of the prepared carbon was also investigated in the activation step. Moreover, the properties of cassava tuber-carbon material were characterized by SEM, FTIR, XRD, and multipoint BET analysis. Finally, the application of cassava tuber carbon material as a carbon support for ZnO photocatalyst was investigated by a simple technique.

Abstract: The article provides an overview of manufacturing a binding agent via combined grinding a silicate lump and calcium chloride. The data on the mineralogical composition of a mechanically activated binding agent are presented. The paper also describes composition and properties of putty on the base of a modified binding agent, which is intended for interior finishing operations in buildings.

Abstract: Single and mixed coconut shell (CS) and palm kernel shell (PKS) were successfully converted to activated carbon by using potassium hydroxide (KOH) as activating agent. Mixed activated carbon was produced from coconut shell: palm kernel shell at different KOH concentrations of 30%, 40% and 50%. Activation process was performed in a conventional microwave oven at fixed power and time of 600W and 20 minutes respectively. The results showed that activated carbon produced from single and mixed biomass at 40% concentration of KOH exhibited higher adsorption capacity for iodine number and percentage removal of MB with comparison to 30% and 50% of KOH concentrations. The highest BET surface area of 441.19 m²/g was obtained by CSAc-40. Further both CSAc-40 and PKSAc-40 produced an average pore size diameter of less than 2.0 nm which is in the range of micropore region. On contrary, the mixed CSPKSAc-40 produced an average pore size diameter of 6.0 nm which is in the region of mesopore. All the CSAc-40, PKSAc-40 and mixed CSPKSAc-40 showed similar adsorption trend for iodine number and percentage removal of MB. Interestingly, this finding showed that in the mixed activated carbon some chemical reactions might have occurred during the activation process producing mesoporous instead of microporous as obtained by the single biomass activated carbon.