Thesis Archive
SYNTHESIS AND ADSORPTION ANALYSIS OF FLY ASH-BASED GEOPOLYMER/ALGINATE BEADS (GAB) FOR NICKEL REMOVAL IN CONTAMINATED WATER
AUGUIS, Maureen Jayne A.
AUGUIS, Monique Joice A.
ONA, Maria Danica T.
Abstract:
Combination of materials often generate superior properties fit to address the prerequisites of certain processes and applications. The development of geopolymer/alginate beads (GAB) combines the microporous framework of fly ash-based geopolymers and the natural abundance, low cost, and chelating ability of alginate for improved adsorption performance. In this study, fly ash was used as precursor material for the geopolymer. Various geopolymer/alginate ratios, ranging from (1:0.12 to 1:2), were synthesized. Only those that formed and maintained their spherical shape after settling, immersion and sonication were characterized and utilized for the batch adsorption tests. Through SEM-EDS analysis, it was visually observed that the cross-linking of the alginate phase with the geopolymer matrix occurred throughout the entire sample rather than just on the surface of the sphere. The absence of Na+ ions also proves that the Ca2+ ions have already replaced them and facilitated the said cross-linking. Such findings are also consistent with the FTIR results where an increase in the functional bands were observed with the addition of the alginate phase. Consequently, shifts in peaks were observed which is also indicative of the occurrence of crosslinking between geopolymer and alginate. The synthesized GAB were used as adsorbents for 1000 mg L-1 Ni (II). Factors such as the effect of contact time, adsorbent dosage, and GAB formulation were investigated by means of batch adsorption tests. GAB demonstrated increasing Ni (II) uptake with time. Optimal removal was obtained after 72 hours for dosages 0.075 g/mL Ni and 0.125 g/mL Ni and 168 hours for 0.025 g/mL. Consistent for all three formulations, 0.025 g/mL had the highest metal uptake with a value of 33.57 ± 0.40 mg g-1. The equilibrium data fitted best with the Jovanovic isotherm, which indicates the presence of mechanical contact between the adsorbed and bulk phases. For the kinetics study, the adsorption data of GAB-F3 with a dosage 0.025 g/mL fitted the pseudo second order model, suggesting a chemical adsorption mechanism and revealed a theoretical Qe value of 35.0877 mg g-1.
Adviser:
PROMENTILLA, Michael Angelo B.
ORBECIDO, Aileen H.