Laboratory experiments were designed to identify the adsorption features of Pb~(2+) by sorghum vinasse (SV) under various conditions. The results showed that the adsorption capacity enhanced with the increasing pH and peaked (68.42 ± 1.42 mg g~(-1)) when pH = 6. With the SV dosage ranging from 0.0250 to 0.2000 g, the adsorption capacity declined from 55.59 to 44.84 mg g~(-1), and the Pb~(2+) removal rates increased from 13.52 to 91.14. The adsorption capacity reached 95.4 of the maximum adsorption capacity at the 10th min, then rose slowly with respect to contact time and equilibrated at the 360th min. When the initial Pb~(2+) content < 400 mg L~(-1), the adsorption capacity increased quickly, then it did not vary significantly with the increasing initial Pb~(2+) concentration. These suggest that the initial pH, adsorbent dosage, contact time, and the initial Pb~(2+) concentration can significantly affect the adsorption process. The pseudo-second-order kinetic and Langmuir model could well illustrate the adsorption process. The adsorption of Pb~(2+) on SV is a chemical and spontaneous process via monolayer adsorption involving physical absorption, ion exchange, surface complex with OFGs, and chemical reactions.
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