THE SYNTHESIS OF N,O-CARBOXYMETHYL CHITOSAN-g- OLIGO(ASPARTIC ACID) AS CORROSION INHIBITOR ON CARBON STEEL AND SCALE INHIBITOR

• Main Author: JALIL BAARI (NIM:20516052), MUHAMAD
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29083
• Institution: Institut Teknologi Bandung

Corrosion on the inner surface of crude oil and natural gas pipelines due to fluid mixtures that <br /> <br /> produces CO2 co-insisted by the scale formation was the serious problem in oil and gas <br /> <br /> industry. Corrosion can cause thinning and leakage of pipeline, while scalling will reduce <br /> <br /> diameter of flowing pipe as well as blockage of some pipeline parts along the oil and gas <br /> <br /> transportation routes from oil wells to the treatment place, then it would be potentially <br /> <br /> causing financial loss and also environmental damage. Therefore, it is necessary to apply a <br /> <br /> method that can control corrosion rate as well as capable to prevent scale formation on that <br /> <br /> system, effectively and efficiently. Polymer compounds containing double bonds and <br /> <br /> heteroatoms are known to be effective as corrosion inhibitor because it can be complexing <br /> <br /> agent or chelating agent when those adhere on metal surfaces, it has good thermal stability <br /> <br /> and can cover larger metal surface areas. Chitosan is one of the biopolymers that can be used <br /> <br /> as a corrosion inhibitor, but it has low solubility in water. Increasing the solubility of chitosan <br /> <br /> in water can be done by carboxymethylation reaction. Meanwhile, oligosuccinimide (OSI) is <br /> <br /> an intermediate of oligoaspartic acid that was known to be effective as a scale inhibitor. In <br /> <br /> this study, N,O-carboxymethyl chitosan (N,O-KMK) and oligosuccinimide were synthesized. <br /> <br /> Then, it followed by grafting onto copolymerized reactions between N,O-KMK and OSI to <br /> <br /> produce N,O-carboxymethyl chitosan-g-oligo(aspartic acid) or N,O-KMK-g-OASP which <br /> <br /> has double functions both as corrosion inhibitor and scale inhibitor. The structure analysis of <br /> <br /> precursors and copolymer was performed by Fourier Transform Infrared (FTIR), Nuclear <br /> <br /> Magnetic Resonance (NMR) spectroscopy, and Liquid Chromatography-Mass Spectroscopy <br /> <br /> (LC-MS). The thermal stability of polymers was analyzed by thermogravimetric (TGA). <br /> <br /> Subsequently, the efficiency of corrosion inhibition was measured by Electrochemical <br /> <br /> Impedance Spectroscopy (EIS), potentiodinamic polarization (Tafel) and weight loss test <br /> <br /> methods in 1% (w/v) NaCl solution saturated by CO2 gas, while scale inhibition was <br /> <br /> analyzed by static scale inhibition test. FTIR spectrum of N,O-KMK-g-OASP showed an <br /> <br /> increasing peak intensity in the wave number 1650 cm-1 from streching vibration in the <br /> <br /> bonding of amide carbonyl groups because more amide groups was formed after the <br /> <br /> copolymerization reaction. N,O-KMK and OSI were classified as mixed inhibitors. Each of <br /> <br /> them was effective enough to reduce corrosion rates at 35 oC and 25 oC respectively. N,OKMK <br /> <br /> still inhibited corrosion rate at 55 oC, but more rapidly coagulated, while OSI has <br /> <br /> higher inhibition efficiency at room temperature but it becomes ineffective at 55 oC. N,OKMK- <br /> <br /> g-OASP is classified as an anodic inhibitor, the efficiency of corrosion inhibition <br /> <br /> increased by increasing concentrations and temperature. N,O-KMK-g-OASP evaluation <br /> <br /> results as a CaCO3 scale inhibitor showed the inhibition efficiency up to 95.77% when the <br /> <br /> concentration amount 30 ppm. These results show that OSI, N,O-KMK and N,O-KMK-g- <br /> <br /> OASP are effective to reduce the corrosion rate on carbon steels in 1% (w/v) NaCl solution <br /> <br /> saturated by CO2 gas. In addition, N,O-KMK-g-OASP also showed effective performance as <br /> <br /> a CaCO3 scale inhibitor. <br />