UTILIZATION OF AVOCADO SEED WASTE AS ADSORBENT FOR NH3 AND H2S GASES REMOVAL

• Main Author: Dewi Hamani, Aprilia
• Format: Theses
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/46810
• Institution: Institut Teknologi Bandung

Avocado seed waste can be used as raw material for making activated carbon for adsorption purposes. This study aims to analyze the efficiency of avocado seed utilization as raw material for activated carbon adsorbent to remove ammonia (NH3) and hydrogen sulfide (H2S) gasses compounds. Avocado seed waste that has been dried by heating for 24 hours at 110oC then carbonized in the N2 atmosphere at 700oC with a heating rate of 10oC per minute for 3 hours. The process is continued with the activation of avocado seed carbon on heating to a temperature of 850oC with a mixture of N2 and CO2 gas flow for 15 minutes, 2 hours and 3 hours. Preliminary tests of avocado seed activated carbon were carried out to see the surface area (BET analysis), morphology (SEM analysis), water content, ash content, and the iodine number. The adsorption test was carried out using a glass-based adsorption column with a diameter of 1.2 cm and a height of 36 cm. NH3 and H2S gas used as adsorbate are synthesis gas. NH3 gas adsorption experiments were carried out with variations in the mass of 1 gram, 3 grams and 5 grams of avocado seed activated carbon with variations in gas concentration of 10 ppm, 20 ppm and 40 ppm. H2S gas adsorption experiments were carried out with variations in the mass of the adsorbent of 0.1 grams, 0.2 grams and 0.3 grams of activated carbon of avocado seeds with an gas inlet concentration of 20 ppm. NH3 and H2S gas respectively from the air bag in the adsorption column using a vacuum pump with a flow rate of 1,121.6 ml/min for NH3 adsorption test and 1,056.4 ml/min for H2S gas adsorption test. Inlet and outlet gas concentrations are measured using a gas sensor Type SKY2000-M2. The surface area of avocado seed activated carbon (SBET) is 102.88 m2/gram (15 minutes activation), 523.041 m2/gram (2 hours activation), and 381.969(3 hours activation). Avocado seed activated carbon used for the adsorption process is activated carbon with the highest surface area (523,041 m2/gram). Moisture content and ash content of activated carbon of avocado seeds by the activation method for 2 hours respectively were 4.90% and 13.46%. The iodine number of avocado seed activated carbon is 1,089.07 mg/g. The adsorption capacity of avocado seeds is 0.139 mg NH3/g and 811.45 mg H2S/g. Based on the breakthrough curve from the results of the NH3 and H2S adsorption processes, at the same adsorbate concentration, the more the mass of activated carbon of avocado seeds used as adsorbents, the longer the adsorption process reaches the breakpoint time and saturation conditions. The higher the inlet concentration of NH3 gas used, the faster the adsorption process reaches the breakpoint time and saturation conditions. Based on kinetics studies, both pseudo-first-order and pseudo-second order can describe adsorption well, although pseudo-second-order tends to be more suitable to describe the process that occurs. Both results show that NH3 adsorption on avocado seed activated carbon is relatively a combination of chemical and physical adsorption with a tendency for chemical processes to be greater than physical processes. The NH3 and H2S adsorption processes in this study occurred in the monolayer following the tendency of the results of isotherm studies which showed Langmuir isotherm is the best fitted to the adsorption process. The composition of N elements in avocado seed activated carbon before and after the NH3 adsorption process from the EDS test results showed no significant change (from 15.86% to 15.98%). The composition of S element in avocado seed activated carbon before and after the H2S adsorption process from the EDS test results showed a significant change (from 0.08% to 16.78%). Avocado seed activated carbon is more suitable to adsorb H2S compared to NH3 gas adsorption.