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The objective of this study was to investigate isotherm adsorption of carbon microparticles from pineapple peel waste. Carbon microparticles were prepared by carbonizing pineapple peel waste at 215-250°C and grinding using a saw-milling process. To investigate adsorption properties of carbon microparticles, experiments were done by evaluating adsorption of curcumin (as a model of adsorbate) in the ambient temperature and pressure under constant pH condition. To confirm the adsorption characteristics, carbon particles with different sizes (i.e., 100, 125, and 200 ?m) were tested, and the adsorption results were compared with several standard isotherm adsorption models: Langmuir, Freundlich, Temkin, and Dubinin- Radushkevich. To support the adsorption analysis, several characterizations (i.e., optical microscope, sieve test, and Fourier transform infrared analysis) were conducted. The adsorption test showed that the adsorption profile is fit to the Freundlich model for all variations, indicating the multilayer adsorption process on heterogeneous surfaces and interactions between adsorbate molecules. The results from other isotherm models also confirmed that the adsorption process occurs physically via Van der Waals force in binding adsorbate on the surface of adsorbent.

This study aims to demonstrate the preparation of carbon microparticles obtained from red dragon fruit peel waste and their adsorption isotherm characteristics. The carbon microparticles were prepared by combining carbonization (at 250°C) and saw-milling process, and to get carbon microparticles with a specific size, sieve analysis was used. The adsorption isotherm was done by testing the adsorption ability of carbon microparticles with a specific size into curcumin solution in the batch-type reactor. The adsorption results were then compared to several standard isotherm models (i.e., Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models) for understanding what phenomena happen during the adsorption process. The adsorption analysis was also confirmed by testing several sizes of the carbon microparticles to predict the proposal mechanism in the adsorption process. The analysis results showed that the multilayer adsorption process occurs for all sizes in the micrometer range, and the process involves physical interactions between adsorbate and surface of adsorbent. The existence of multilayers is due to the possibility in the existence of porous structure in the carbon microparticles. This study is important for giving an alternative solution for reusable organic waste as well as supporting the fundamental researches in the further applications of carbon particles as catalyst and adsorbent.