Geopolymer from tin mining tailings waste using Salacca leaves ash as activator for dyes and peat water adsorption

This research investigated preparation of geopolymer as adsorbent for dye-containing and peat water treatment. The green synthesis of geopolymer utilized tin mine tailings waste as source and Salacca leaves ash as activator. For the detail of study, effect of Salacca leaves ash amount to the physicochemical characteristics of the geopolymer was studied in comparison with the use of NaOH as common activator. Instrumental characterizations by using XRD, gas sorption analysis, SEM, and TEM analyses were employed. From the study, it is found that the Salaca leaves ash exhibits the capability to be activator in geopolymerization as identified by increasing specific surface area along with the surface morphologies appeared from SEM and TEM analysis as well as the structural analysis by XRD measurement. The geopolymers showed the capability to adsorb methylene blue and methyl orange in high capacity, and obey pseudo-second order kinetics. The maximum adsorption capacities for methylene blue and methyl orange are 30.31 mg/g and 3.06 mg/g by geopolymer synthesized with TW: TEOS: SLA: H2O of 5: 2: 1: 5. The Freundlich isotherm model was the most appropriate for both dyes. In addition, the geopolymer also shows capability to enhance peat water quality as shown by the removal of chemical oxygen demand and with COD and NOM removal of 100 and 92% by 90 min of batch adsorption system. The continuous adsorption system by all geopolymer samples to the COD of the peat water is in good agreement with Thomas model (R2 =0.99).