PREPARATION OF ACTIVATED CARBON FROM PALM OIL SHELL BY CHEMICAL ACTIVATION WITH Na₂CO₃ AND ZnCl₂ AS IMPRENATED AGENTS FOR H₂S ADSORPTION

Abstract

Hydrogen Sulfide (H₂S, rotten-egg) is one of the major environmental pollutants having its sources in natural and anthropogenic activities. It’s had smell gas produced by anaerobic digestion in acid condition from organic and inorganic compounds containing sulphur, presents dual problems of its toxicity and foul ordour. One of methods of its removal is adsorption. Activated carbon is a widely used adsorbent in the treatment of air pollution. Adsorption type and capacity are primarily based on the physical properties of pores, namely the surface area. Convetionnally, activated carbon is produced from biomass residues, wood coal and agricultural residuces. Today, one promising approach for the production of cheap and efficient activated carbon is used of waste from palm oil mill industries, which is palm oil shell. Palm oil shell is available in large quantities of approximately 0.53 million tonnes annually in Thailand. Palm oil shell is a by-products of the palm oil industry and was used as a raw material in this study due to its high carbon content, high density and low ash content. Normally, H₂S in biogas, which is found the range between as low as about 50-10,000 ppm depending on the feed material composition to prodction, can cause corrosion to engine and metal substance via of SO₂ from combustion. H₂S must be removed from biogas product prior to further utilization. Therefore, in these research the usage of palm oil shell is especially important due to its high value added for produced activated carbon adsorbent for H₂S adsorption in biogas product. In this study, fixed bed reactor (stainless steel with 54.1 mm internal diameter and 320 mm length) was studied to observe the effect of char product: Chemical agent ratio (Na₂CO₃ and ZnCl₂, 1:1 to 1:3), which there are activated at 700°C activation temperature for 2 h on the chemical and physical properties, BET surface area, the pore volume, micropore volume and hydrogen sulfide adsorption. The result showed that the BET surface area, BET surface area, the pore volume and micropore volume increased progressively with increasing the char product: Chemical agent ratio. The value of maen total pore volume of activated carbon increased with an increased char product: Chemical impregnation agent ratio (Na₂CO₃ and ZnCl₂) as is a 1:1 to 1:3, from 0.3743 to 0.4181 cc/g and 0.2877 to 0.3137 cc/g, respectively. The average micropore volume were 0.2224, 0.2411, 0.2270, 0.1721, 0.1686 and 0.1546 cc/g of AC_Na13, AC_Na12, AC_Na11, AC_Z13, AC_Z12 and AC_Z11, respectively. The results of yield, it was found that that the activated carbon for Na₂CO₃ agent is higher than activated carbon for ZnCl₂ agent. The highest of yield was 32.3% for AC_Na13. Moreover, the maximum BET surface area and H₂S adsorption was 743.71 m²/g and 247.33 ppm was obtained on AC_Na13. This gave H₂S adsorption more than commercial activated carbon (1%). Guideline for evaluation chemically activated carbon for potential application were suggestd. The conclusion showed that AC_Na13 has good chemical and physical properties scuh as chemical content and surface area, which showed that the highest H₂S adsorption (247.33 ppm). The carbon content and BET surface area of AC_Na13 were 78.76 (wt%) and 743.71 m²/g, respectively. Thus, chemical agent (Na₂CO₃) can be used effectively as an operating strategy to optimize surface area. The synthetices activated carbon with suggested BET surface area were is good agreement with those obtained with chemical activation by Na₂CO₃ impregnation. Moreover, activated carbon was used to the H₂S removal, it is also for environment benefit in which air pollution by H₂S emission and impact on human health could be potentially reduced.