Spectroscopic study of aluminium speciation in removing humic substances by Al coagulation

• Published in: Water research (Oxford) Vol. 33; no. 15; pp. 3271 - 3280
• Main Authors: Lu, Xiaoqiao, Chen, Zuliang, Yang, Xinhao
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1999; Elsevier Science
• Subjects: [formula omitted] NMR spectroscopy; adsorption; Al coagulation; aluminum; Applied sciences; brown coal; chemical speciation; coagulation; complexation; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; humic acids; humic substances; jar test; micro-infrared spectroscopy; organic matter; peat; Pollution; spectral analysis; swamp water; swamps; topsoil; water; Water treatment and pollution; X-ray diffraction; Australia; micro-infrared spectroscopy; adsorption; X-ray diffraction; humic substances; Al coagulation; 27 Al NMR spectroscopy; complexation; jar test; Infrared spectrometry; Drinking water treatment; Fourier transformation; Flocculation; Surface water; Marsh; Aluminium; NMR spectrometry; Experimental study; X ray diffraction; Humic acid; Speciation
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/S0043-1354(99)00047-0

Removal of humic substances (HS) isolated from swamp water, surface soil, peat and brown coal by aluminium (Al) coagulation under different conditions was studied using the jar test method and spectroscopic techniques. At lower pHs<4.5, humic substances formed soluble complexes with Al 3+ and the amounts of these HS–Al complexes increased with increasing concentration of the humic substances. Maximum removal of the humic substances was found to occur in the pH range from 5.0 to 7.0, due to the adsorption of humic substances on the surface of Al(OH) 3(s) crystal. Sequential extraction of the humic substances adsorbed on Al(OH) 3(s) using the Soxhlet technique with different solvents showed that the adsorption forces involved were great. The effects of humic substances on the Al speciation are discussed and a model is proposed to explain the mechanism for the removal of humic substances during the Al coagulation process.