AbstractThe aim of this work was to characterise the affinity of protein preparations from Moringa oleifera seeds, specifically extract (seeds homogenised with 0.15 M NaCl), fraction (extract precipitated with 390 mg mL−1 of ammonium sulphate) and cMoL (coagulant M. oleifera lectin) to bind humic acids using a haemagglutinating activity assay with rabbit erythrocytes and a radial diffusion assay in agarose gel. Specific haemagglutinating activity (SHA) decreased by 94 % for the extract and cMoL

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... and by 50 % for the fraction in the presence of humic acid. Precipitation bands were observed in the diffusion gel. Both results suggested humic acid-cMoL binding. Carbohydrates, potassium, and calcium ions and pH affected the SHA of cMoL. As an example of application, cMoL was immobilised on a column packed with sepharose receiving 20 mg mL−1 of carbon humic acid solution, 30 mg of humic acid per gram of support was removed. This result suggested that protein preparations might be used in water treatment to remove humic acids.