Purple sweet potato has the potential as a natural antioxidant based on the high levels of anthocyanin contained therein. Anthocyanin is polar compounds that are more easily extracted in acidic conditions. Antosianin has benefits as an antioxidant and antidote to free radicals, so it plays a role in preventing the occurrence of aging, cancer, and degenerative diseases and others. The purpose of this study was to determine the appropriate solvent and pH to extract the purple sweet potato anthocyanin by the method of differential pH spectrophotometry. Samples were added 96% ethanol and the aquades were acidified with 1% HCl so the pH of the solvent was 1, 1.5, 2, and 2.5. The extracts obtained were diluted with pH 1 and pH 4.5 solvents and then determined their anthocyanin levels based on the spectrophotometric differential pH method. The results showed that solvent and pH had an effect on total anthocyanin content. The ethanol and pH 1,5 solvents gave the highest total anthocyanin content and the highest purple sweet potato absorbance of 5.9558 mg / L.

Cadmium was one of the metals classified in the type of nonessential heavy metal that classified as carcinogenic and is one of the pollutants in the environment, especially water. The content of cadmium in water tends to have very low levels, so certain techniques are needed to determine the level of pre concentration. In the pre concentration technique adsorbents were needed which could absorb cadmium, one of which is calcium-alginate microcapsule modified with EDTA. Calcium-alginate was  modified with EDTA to increase the ability of the microcapsule to absorb cadmium metal. The purpose of this study was to determine the optimum conditions for making Calcium-alginate-EDTA microcapsule in adsorbing cadmium. The stages of this research were optimization of Calcium-alginate-EDTA resin with variable in the form of Calcium chloride concentration (0.05 M; 0.1 M; 0.5 M; 1 M; and 2 M), EDTA mass (0.50 g ; 0.75 g; 1 g; 2 g and 2.5 g) and the concentration of sodium-alginate (0.5%; 1%, 1.5%; 2%, and 3%); Characterization of microcapsule functional groups by infrared spectrophotometry and determination of the retention capacity of Calcium-Alginate-EDTA microcapsule for cadmium absorption by atomic absorption spectrophotometry. The results of infrared characterization showed a change in transmittance in the functional groups C-O dan C-N that occurred in the microcapsule after binding to cadmium metal at wave number 1436.97 cm-1. The optimum conditions for making Calcium-alginate-EDTA resins were in conditions of 0.1 M Calcium chloride concentration, 1% sodium-alginate concentration and EDTA mass 0.75 g EDTA with retention capacity of  Cd was 0.0301 mg/g.

Oxidation and hydrolysis damage to cooking oil can occur due to repeated use of cooking oil. Adsorption by utilizing eggshells, which contain high calcium carbonate and have a natural pore structure that can improve the quality of used cooking oil. This study aims to determine the physical properties and characteristics of the thermally activated chicken eggshell adsorbent and to determine the ability of the adsorbent to absorb acid and metal cadmium. The steps carried out in this study were the manufacture of adsorbents, quality tests of the adsorbents produced, and testing of adsorbents on used cooking oil samples based on acid numbers and decreasing levels of metal cadmium in the samples. The adsorption process of used cooking oil was carried out with variations in the mass of the adsorbent, namely 5, 7, 9, and 11 grams, and stirring time for 10, 20, 40, and 60 minutes. Based on the results of the study, it was found that the optimum conditions for decreasing the acid number with the use of an adsorbent mass of 11 grams and a stirring time of 60 minutes resulted in an acid number was 0.9974 mg NaOH/g with a decrease in the acid number of 76.54%, while for cadmium metal it decreased by 100% with adsorption capacity of 2.57124 mg/g.

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