| Summary: | The extraction of biogenic silica from Salacca leaf ash and its utilization as an adsorbent for salicylic acid has been successfully conducted. The caustic extraction by refluxing the ash in NaOH followed by slow titration using acid produced the silica gel. The sintering of the dried gel was varied at 300, 400, and 500°C to evaluate its physicochemical character for adsorption purposes. Instrumental analysis of X-ray diffraction, scanning electron microscopy, gas sorption analysis, and Fourier transform infrared spectroscopy (FTIR) were employed. The kinetics of salicylic acid adsorption was investigated in a batch adsorption system and showed the fitness of the adsorption with a pseudo-second-order kinetics. The isotherm studies revealed that salicylic acid adsorption obeyed the Langmuir model. At varied sintering temperatures, the highest adsorption capacity and affinity were achieved at a temperature of 500°C, due to the increasing specific surface area. The maximum adsorption capacity of 36.7 mg/g is comparable with other work, but at less cost and synthesis process. The varied pH for adsorption is a suggestion that the neutral pH is the most feasible compared to the acidic and basic conditions. © 2021 The Authors.
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