羧甲基壳聚糖掺杂聚苯胺的制备及其在盐酸溶液中对碳钢的缓蚀性能研究

SYNTHESIS AND INHIBITION STUDIES OF CARBOXYMETHL CHITOSAN DOPED POLIANILINE FOR MILD STEEL IN HYDROCHLORIC ACID

选用结构中同时带有羟基、羧基和氨基的羧甲基壳聚糖为掺杂酸,通过改变掺杂酸与苯胺单体的比例实现了产物从纳米纤维(直径为100nm)到空心微米小球(直径为200nm)的转变.傅立叶红外(FTIR)和紫外可见光谱(UV)表征结果表明,纳米纤维和空心微米小球均为掺杂态聚苯胺.另外,采用电化学交流阻抗技术和动电位极化方法研究了所得聚苯胺在0.5mol/L盐酸溶液中对碳钢的缓蚀作用.结果表明,聚苯胺的加入量为40mg/L时,其对碳钢的缓蚀效率高达91.6%～92.3%.

Carboxymenthyl chitosan （ CM-CTS） with hydroxyl,carboxyl and amino groups was chosen as doping acid to synthesis polyaniline（ PANI）. It was succeed to convert the produced nanofibres into hollow microspheres via changing the ratios of carboxymenthyl chitosan and aniline monomer from 0. 01 to 0. 5. The results of FTIR and UV-Vis absorption spectra were identical to those of the emeraldine salt state of PANI. Because―OH in CM-CTS and N―H in PANI are easy to form hydrogen bonds,N ― H peak in FTIR was depressed with the addition of doping acid. Besides,the corrosion inhibition property of PANI was demonstrated for mild steel in acidic environment using electrochemical impedance spectroscopy （ EIS）,potentiodynamic polarization and scanning electronic microscopy（ SEM）. The results revealed PANI had performed excellently as corrosion inhibitor for mild steel in 0. 5 mol /L hydrochloric acid and its inhibition efficiency was up to 91. 6% ～ 92. 3% even with a low concentration of 40 mg /L. The single capacitive loop in Nyquist plots revealed the charge transfer controlled the corrosion process. The value of double layer capacitance increased with the increase of PANI concentrations because PANI molecule replaced water molecule and absorbed on the surface of mild steel and inhibited the corrosion effectively. The parallel polarization curves obtained in the absence and presence of different inhibitor concentrations indicated that the addition of PANI had not changed the mechanism of either steel dissolution or hydrogen evolution reaction,contrary,it acted by simple blocking the mild steel surface. The corrosion potential in polarization shifted unobviously and it behaved as a mixed-type inhibitor.