Thermochemical treatment of fly ash for synthesis of mesoporous activated carbon

A mesoporous activated carbon is produced from oil fly ash (OFA) using chemical and thermal treatments at different activation conditions. The ash samples were refluxed with a range of compositions of sulfuric, nitric, and phosphoric acids followed by thermal activation in a tubular reactor. The composition of the acids and the reaction temperature were optimized to yield mesoporous activated carbon with a high surface area and yield. Several characterization methods were used to study the surface characteristics, morphology, functional groups, phase transition, and adsorption. FTIR spectra show the existence of carboxylic and amine functional groups, which increase with increasing percentage of nitric acid. SEM spot analysis and EDX demonstrate that the carbon content increases from 77.4 to 95.7 % upon chemical treatment. Specimens treated with a mixture comprises of 3.6 mol L-1 H2SO4, 6.4 mol L-1 HNO3 and 5.9 mol L-1 H3PO4 and activated at 990 degrees C have a BET surface area of 375.7 m2 g-1 when compared to 4 m2 g-1 for the original OFA. The BJH adsorption pore distribution indicates an average pore size of 50 ? with a total mesopore volume of 0.2211 cm3 g-1 (73.6 % of the total pore volume). Thus, waste OFA is a suitable raw material for the production of activated carbon.King Abdul Aziz City for Science and Technology (KACST) through the science and technology unit at King Fahd University of Petroleum and Minerals (KFUPM) project No. 11- ENV1645-04Scopu

BET, FTIR, and RAMAN characterizations of activated carbon from waste oil fly ash

Activated carbon (AC), a porous material with high pore volume, attracts increasing attention owing to its potential applications in several fields. The development of a porous structure in AC marginally relies on both the treatment methods and the type of precursor. Thus far, both renewable and nonrenewable precursor sources have been used to synthesize AC with high surface area and pore volume. This study presents the synthesis of AC via physicochemical treatment of waste oil fly ash (OFA), a waste material produced from power plants. The aim was to produce AC by adding surface pores and surface functional groups to the basal plane of OFA. Toward this objective, OFA was first chemically leached/activated with various combinations of H2 SO4 and H3PO4 , and then physically activated with CO2 at 900 °C. The chemical activation step, synergistically combined with CO2 activation, resulted in an increase of 24 times the specific surface area of the OFA. The maximum increase in surface area was obtained for the sample physicochemically treated with 100% H2 SO4 . Moreover, the spectroscopic analysis confirmed the presence of acid functional groups after the chemical treatment step. To explore the surface heterogeneity, adsorptive potential distribution in terms of surface energy was also discussed as a function of the surface coverage. Following chemical activation, the OFA surface became heterogeneous. A major portion of the AC showed surface energy in the range of 40–50 erg/K, which was further increased as a result of physical activation at a higher temperature. Thus, the synergism created by physicochemical activation resulted in a material with high surface area and pore volume, and excellent adsorption characteristics. From the findings of this study, it was concluded that OFA is a cost-effective and environmentally benign precursor for the synthesis of AC.The authors would like to acknowledge the support of King Abdul Aziz City for Science and Technology (KACST) through the science and technology unit at King Fahd University of Petroleum & Minerals (KFUPM) for their funding this research, under project number 11-ENV1645-04.Scopu

Adsorption of CO2 on Cu/SiO2 nano-catalyst: Experimental and theoretical study

Copper-based silica is a promising catalyst for several reaction pathways for CO2 conversion to hydrocarbons. The activity of this catalyst in terms of conversion and product selectivity is affected by CO2 adsorption, surface reaction, and product desorption resistances on the surface of the catalyst. The effect of CO2 adsorption on the surface of Cu/SiO2 nano-catalyst was studied using the sol?gel method. The CO2 adsorption on the surface of SiO2 is investigated at different Cu loading, and the surface morphology is analyzed. The results showed a well-dispersed Cu in an amorphous silica structure with a surface area of 407.70 m2/g and pore volume of 0.000891 cm3/g. SEM analysis indicated non-uniform cluster shapes with large parallel slits and plate-like aggregates on the surface. Adsorption isotherms for different Cu loading provided a nonlinear CO2 uptake with increasing Cu content. The experimental results are supported by theoretical predictions obtained from molecular dynamic simulations and showed a 4% confidence limit when the Cu:SiO2 ratio was 2:1. Both results suggest physisorption of the CO2 molecules, CO2- with oxygen atoms on the surface. This work provides insights into the CO2 uptake at different pressure values, which is critical for the reaction kinetics and CO2 conversion to hydrocarbons.The authors would like to acknowledge the following: Deanship of Scientific research at the University of Jordan for supporting this research through project # 2163, the Gas Processing Center at Qatar University for conducting the characterization techniques for the samples, King Fahd University of Petroleum and Minerals for providing access to the dynamic molecular simulator, Eng. Raghad Abdul Samad and Eng. Arwa Sandouga for their help in this project.Scopu

Concurrent adsorption of cationic and anionic dyes from environmental water on amine functionalized carbon

Amine functionalized carbon (AFC) was synthesized from raw oil fly ash and later utilized it for simultaneous removal of methyl orange (MO) and rhodamine 6G (Rh6G) pollutant dyes from aqueous medium. AFC was analyzed through scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area and Fourier transform infrared spectroscopy (FTIR) to examine its morphology, porosity and structural characteristics, respectively. The effect of various process parameters like mixing time, pollutant concentration, adsorbent dose, initial solution pH, and temperature of the medium were investigated for dye removal process. The experimental findings showed that the percentage removal of Rh6G was higher than MO and both dyes showed synergism during the adsorption from binary dye solution. Pseudo-second-order model was most appropriate model for both dyes and thermodynamic parameters showed that the dyes removal process was endothermic in nature. Among various isotherm models, Hill and Toth isotherms best explain the adsorption of Rh6G and MO from binary dye solution.The support of King Abdul Aziz City for Science and Technology (KACST) through the science and technology unit at King Fahd University of Petroleum and Minerals (KFUPM) for funding this research through project No. 11-ENV1645-04 is gratefully acknowledged.Scopu