Extraction of Phenols From Aqueous Solutions by Magnetic Sorbents Modified with Humic Acids

Sorption of phenol, 4-nitrophenol, pentachlorophenol, and nonylphenol is studied using a magnetic sorbent based on Fe3O4 nanoparticles modified with humic acids (HAs) isolated from various natural sources (brown coal, peat, chernozem, and sapropel). The properties of the resulting sorbents, namely, specific surface area, saturation magnetization, and content of hydroxyl and carboxyl groups, as well as nitrogen, are studied. The best conditions for the extraction of all phenols are achieved at pH 3–6, except for pentachlorophenol, for which the highest degree of extraction is achieved at pH 3–4. The maximum recoveries of phenol, 4-nitrophenol, pentachlorophenol, and nonylphenol are 61, 68, 89, and 94%, respectively.