OPTIMIZING THE SYNTHESIS PROCESS FOR LITHIUM-ION SIEVE ADSORBENTS: EFFECT OF CALCINATION TEMPERATURE AND HEATING RATE ON REACTION EFFICIENCY AND PERFORMANCE

Abstract

Processing-structure-property relationships play a crucial role in tuning the performance of materials for a given application in order to attain a suitable set of optimal conditions, therefore, it is imperative to evaluate the parameters of either the synthesis, delithiation, adsorption, and desorption process. Through an orthogonal test design of the solid-state synthesis process, it was determined that a heating rate of 1 ℃/min had consistently higher reaction efficiencies of 68.1 %, 68.6 %, and 72.3 % at the calcination temperatures of 650 ℃, 700 ℃, and 750 ℃ respectively compared to heating rates of 4 ℃/min and 7 ℃/min. Moreover, a decrease in delithiation efficiency with increase in calcination temperature (99 % at 650 ℃, 96.1 % at 700 ℃, and 94.2 % at 750 ℃) at the 1 ℃/min heating rate was observed which was attributed to an increase in the average crystallite size. Adsorption performance of the synthesis-optimized zinc-doped lithium metatitanate showed consistently high adsorption efficiency (> 90 %) despite the low adsorption capacity (4.9 mg/g) which was attributed to the low initial lithium-ion concentration of the lithium chloride solution and high adsorbent dosage.Additionally, upon design of the synthesis-optimized zinc-doped lithium metatitanate adsorbent into various forms to mitigate adsorbent powder loss and improve the practicality of the adsorbents, granulation was established as the most suitable forming methodology owing to its retention of the high adsorption efficiency (> 90 %) when compared to the bare/powdered form of the adsorbent, despite the low adsorption capacity (4.8 mg/g).