A new insight into resource recovery of excess sewage sludge: Feasibility of extracting mixed amino acids as an environment-friendly corrosion inhibitor for industrial pickling

• Published in: Journal of hazardous materials 2014-08, Vol.279, p.38-45
• Main Authors: Su, Wen, Tang, Bing, Fu, Fenglian, Huang, Shaosong, Zhao, Shiyuan, Bin, Liying, Ding, Jiewei, Chen, Cuiqun
• Format: Article
• Language: English
• Subjects: Adsorption; Amino acids; Amino Acids - chemistry; Amino Acids - isolation & purification; Applied sciences; Chemical engineering; Corrosion inhibition characteristic; Corrosion inhibitors; Electrochemistry; Entropy; Environmental Pollution - prevention & control; Exact sciences and technology; Excess sludge; Feasibility Studies; Food-Processing Industry; Green corrosion inhibitor; Hydrolysates; Hydrolysis; Inhibition; Microscopy, Electron, Scanning; Other industrial wastes. Sewage sludge; Polarization; Pollution; Sewage - analysis; Spectroscopy, Fourier Transform Infrared; Surface chemistry; Thermodynamics; Ultrasonic-assisted hydrochloric acid-hydrothermal process; Volume reduction; Wastes
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2014.06.053

•A value-added product was extracted from the municipal excess sludge.•The effective components contained in the product were mixed amino acids.•The product could provide a reliable protection to the steel from the acid medium.•A new insight into the resource recovery of excess sewage sludge was provided. The work mainly presented a laboratory-scale investigation on an effective process to extract a value-added product from municipal excess sludge. The functional groups in the hydrolysate were characterized with Fourier transform infrared spectrum, and the contained amino acids were measured by means of an automatic amino acid analyzer. The corrosion-inhibition characteristics of the hydrolysate were determined with weight-loss measurement, electrochemical polarization and scanning electron microscopy. Results indicated that the hydrolysate contained 15 kinds of amino acid, and their adsorption on the surface could effectively inhibit the corrosion reaction of the steel from the acid medium. Polarization curves indicated that the obtained hydrolysate was a mixed-type inhibitor, but mainly restricted metal dissolution on the anode. The adsorption accorded well with the Langmuir adsorption isotherm, involved an increase in entropy, and was a spontaneous, exothermic process.