N掺杂碳量子点对Q235碳钢在0.5 M H₂SO₄中的缓蚀作用

Corrosion Inhibition of N-Doped Carbon Quantum Dots on Q235 Carbon Steel in 0.5 M H₂SO₄

摘要: 为解决传统缓蚀剂毒性高、生物降解性差等问题，本文以辣椒秸秆为碳源、尿素为氮源，采用水热法制备氮掺杂碳量子点，研究其在0.5 M H₂SO₄溶液中对Q235碳钢的缓蚀性能与作用机理。通过傅里叶红外光谱、电化学测试、扫描电子显微镜及吸附等温模型分析，结果表明：氮掺杂碳量子点表面富含羟基、羧基、C-N等活性官能团，可在碳钢表面自发形成单分子层吸附膜，属于物理–化学混合吸附，符合Langmuir吸附等温模型。该缓蚀剂为混合型缓蚀剂，缓蚀效率随浓度的升高而提升，200 mg/L为最优浓度，298 K时缓蚀效率达97.2%。温度升高会削弱吸附稳定性，使缓蚀效率略有下降，但高浓度N-CDs在308 K下仍保持良好的防护效果。SEM形貌显示，添加缓蚀剂的碳钢表面平整无明显腐蚀，空白组则出现严重腐蚀与剥落。本研究制备的氮掺杂碳量子点绿色高效、成本低廉，为农业废弃物高值化利用与碳钢酸性环境防腐提供了新思路。

Abstract: To address the problems of high toxicity and poor biodegradability of traditional corrosion inhibitors, nitrogen-doped carbon quantum dots (N-CDs) were prepared by hydrothermal method using chili straw as carbon source and urea as nitrogen source in this paper. The corrosion inhibition performance and mechanism of N-CDs on Q235 carbon steel in 0.5 M H₂SO₄ solution were investigated. Characterizations, including Fourier transform infrared spectroscopy, electrochemical measurements, scanning electron microscopy and adsorption isotherm analysis, were adopted. The results show that N-CDs are rich in active functional groups such as hydroxyl, carboxyl and C-N, which can spontaneously form a monolayer adsorption film on the surface of carbon steel. The adsorption belongs to physical-chemical mixed adsorption and conforms to the Langmuir adsorption isotherm model. The inhibitor is a mixed-type inhibitor, and its inhibition efficiency increases with the increase in concentration. The optimal concentration is 200 mg/L, with the inhibition efficiency reaching 97.2% at 298 K. The increase in temperature weakens the adsorption stability and slightly reduces the inhibition efficiency, but high-concentration N-CDs still maintain good protection at 308 K. SEM images reveal that the carbon steel surface with inhibitor is smooth without obvious corrosion, while the blank sample suffers from severe corrosion and peeling. The N-CDs prepared in this study are green, efficient and low-cost, providing a new strategy for high-value utilization of agricultural waste and corrosion protection of carbon steel in acidic environments.