The proper disposal and utilization of sludge is a critical issue around the world. This study aims to evaluate the potential of sludge extracts as inhibitors against chloride-induced corrosion of low-carbon steel. Acidic extract (ACE), alkaline extract (ALE) and water extract (WE) were obtained from pretreated sludge using nitric acid, sodium hydroxide and deionized water as extractants, respectively. Steel specimens were pre-passivated in simulated concrete pore solutions (SCPS) with and without sludge extracts. After the addition of chloride, electrochemical tests and surface analyses were performed. Results show that ACE has the highest phosphate and organic nitrogen contents, followed by ALE and WE. Electrochemical tests revealed enhanced corrosion resistance in SCPS with sludge extracts. ACE and ALE demonstrated higher corrosion inhibition efficiencies at 89.2% and 87.4%, attributed to synergistic effect of phosphate and organic ammonia nitrogen. WE exhibited reduced efficiency (69.8%) due to its low phosphate content. After long-term storage, the efficiency of WE declined significantly compared to ACE and ALE, probably due to the degradation of organic corrosion inhibition components. Mott-Schottky analysis indicated improved oxide passive film formation with all extracts, but phosphates may diminish this effect, necessitating further investigation.

中文翻译：

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污泥提取物作为碱性环境中钢筋缓蚀剂的潜在用途

污泥的妥善处置和利用是世界范围内的一个关键问题。本研究旨在评估污泥提取物作为低碳钢氯化物诱导腐蚀抑制剂的潜力。分别以硝酸、氢氧化钠和去离子水为萃取剂，从预处理污泥中获得酸性萃取物（ACE）、碱性萃取物（ALE）和水萃取物（WE）。钢样本在含有或不含污泥提取物的模拟混凝土孔隙溶液 (SCPS) 中进行预钝化。添加氯化物后，进行电化学测试和表面分析。结果表明，ACE的磷酸盐和有机氮含量最高，其次是ALE和WE。电化学测试表明，含有污泥提取物的 SCPS 具有增强的耐腐蚀性。由于磷酸盐和有机氨氮的协同作用，ACE和ALE表现出较高的缓蚀效率，分别为89.2%和87.4%。由于磷酸盐含量低，WE 的效率降低了 (69.8%)。经过长期储存，WE 的效率与 ACE 和 ALE 相比显着下降，可能是由于有机缓蚀成分的降解。莫特-肖特基分析表明，所有提取物都改善了氧化物钝化膜的形成，但磷酸盐可能会减弱这种效果，因此需要进一步研究。