Competence of corncob (Zea mays L.) powder with HCl activation as adsorbent to purify waste cooking oil: Reference in the batch adsorption process

Abstract

The quality of cooking oil needs to be maintained. To purify used cooking oil, an adsorption process involving adsorbents is required. In this study, a 100 mL sample of used cooking oil was taken. The oil was then left to settle for 20 min before measuring the initial turbidity level with a turbidimeter. In manufacturing adsorbents from corncob powder with sizes 50 mesh, 70 mesh, and 100 mesh, each weighed as much as 25 g, mixed with 150 ml of 0.1 M hydrochloric acid for 3 h, and dried in the oven. Each size of adsorbent was weighed as much as 2 g, 3 g, and 4 g. The adsorption process was done by mixing oil with corncob adsorbent in a beaker glass. Every 20 min, turbidity was measured using a turbidimeter for 5 h. Based on the turbidimeter results, an adsorbent size of 100 mesh with a mass of 4 g has an adsorption capacity of 12,728 mg/g with percentage reduction of turbidity of 94.5%. Based on the Scanning Electron Microscope-Energy Dispersive X-ray results, the surface of the HCl-activated adsorbent has pores with a distance of 10 µm, and the adsorbent contains carbon, oxygen, silica, and copper compounds. According to the Fourier Transform Infrared results, there is a change in functional groups, Brunauer-Emmett-Teller results show a change in surface area, and Gas Chromatography-Mass Spectrophotometry results show a decrease in free fatty acids in used cooking oil after purification.