Studi Pemanfaatan Tanin dari Gambir (Uncaria gambir Roxb) sebagai Produk Peluruh dan Pencegah Karat pada Logam

Abstract

Gambier (Uncaria gambier (Hunt.) Roxb) is a genus of flowering plant species in Rubiaceae family. Part of the gambier utilized is the sap which is extracted and then to be dried. Indonesia is the world largest exporter of gambier in the form of raw material. Gambier has major components namely catechin and tannin. Tanin can be used as rust deactivator. High tannin content in gambier may be used as anti-corrosion material thought corrosion is a problem in the industry. The aims of this study were to add value of raw gambier and to obtain the best product formulas that can remove the rust and protect metal from rust (antirust). Preliminary study was conducted by tannin extraction from raw gambier of Lima Puluh Kota regency, measuring the purity level of tannin which was extracted and proxymat analysis of raw gambier and tannin powder. The main study conducted by creating rust remover and anti-rust solution using two-factors completely randomized design consisting of composition factor of tannins and phosphoric acid. Tannin level used in the solution were 2,5%, 3,33% and 4,17%, while level of phosphoric acid were 2,9%, 5,8% and 8,7%. After obtaining the best composition of phosphoric acid and tannin, then the study continued by making ethanol concentration as variable which were 10%, 13% and 16%. Analysis test of solution effectiveness were rust lost of weight analysis and metal appearance analysis, while for anti-corrosion solution, the analysis of metal appearance analysis and Fourier Transform Infrared (FTIR) were done. The tannin level obtained from the material used was 66,76%. Rusty iron soaked with rust converter formula successfully lost its rust content after six hours soaked. From lost weight analysis, it was known that the addition of tannin or phosphoric acid has a significant effect (α = 5 %) to decrease the weight of rust, but the interaction between tannin and phosphoric acid showed no significant results. The best concentration of tannin, phosphoric acid, and ethanol in the formula were 3,33%, 5,8% and 16% respectively. On the test with anti-rust effectiveness yielded that the metal plate was immersed in 3% NaCl for one day, had experienced corrosion while the previous metal plate coated with anti-rust solution had no corrosion on the surface. After one week, the metal plate was given a protective layer had corrosion in certain points, whereas the metal plate that was not given protective layer had corrosion on all over the surface. Results of Fourier Transform Infrared (FTIR) analysis on a rusty metal plate coated with anti-rust solution for one week showed the presence of tannin shown by several functional groups namely OH, CO, C = C aromatic, and C = O and the reaction between tannin and metals at a wavelength of 1625 cm-1. The present of tanin indicated that gambier tannin could react well with metal so it can be used as anti corrosive product