SYNTHESIS AND PERFORMANCE TESTING OF GEOPOLYMER FROM BIOMASS ASH AS ADSORBENT

• Main Author: Rosmayanti, Irna
• Format: Theses
• Language: Indonesia
• Subjects: Teknik kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/70740
• Institution: Institut Teknologi Bandung

Indonesia, as the third-largest-producer of rice in the world, has abundant biomass reserves in the form of rice husks. In 2020, the amount of rice husk in Indonesia reaches 16 million tons and its utilization is not optimal yet. Burning of rice husk at 500-700 oC produces 25-30% rice husk ash which contain amorphous silica content of up to 90%. Rice husk ash is potential to be used as geopolymer precursor which can be applied as adsorbent for synthetic dyes, constituent of textile and batik industrial waste such as Rhodamine B and Indigo Carmine. The objective of this study is to synthesize a geopolymer from biomass ash in the form of rice husk ash and evaluate its performance as an adsorbent for synthetic dye. The geopolymer synthesis is carried out using a 23 full factorial experimental design with center point replications to study effects of the Si/Al ratio of geopolymer precursor (1.5; 2.5; 3,5), ratio of Na2SiO3/NaOH (2.0; 2.5; 3.0) and concentration of H2O2 as geopolymer foaming agent (0.3; 0.6; 0.9) %-weight to adsorption removal efficiency. Characteristic of product was evaluated by identification of mineral phase, functional group and pore morphology. Performance testing of geopolymer as an adsorbent is carried out through the adsorption of synthetic dye at a contact time 24 hours to determine adsorption kinetics and adsorption isotherm. Synthesis of geopolymer from biomass ash resulting porous geopolymer beads about 3-5 mm in diameter with Si-O-Si and Si-O-Al as main functional group. Amorphous phase and open pores in geopolymer indicated potency of geopolymer to be applied as adsorbent. In this research, geopolymer more efficient in removing Indigo Carmine dye than Rhodamine B dye, with removal efficiency of Indigo Carmine up to 94.8%. Ratio of Si/Al and ratio of Na2SiO3/NaOH is has significant effect to dye adsorption by geopolymer. The adsorption kinetics and adsorption isotherms were fitted well by a pseudo-second-order model and a Langmuir isotherm model, respectively with k2=100.83 g.mg-1.min-1 and maximum adsorption capacity is 12.43 mg/g.