title: Adsorption of methyl violet from aqueous solutions by the biochars derived from crop residues.
abstract: The adsorption of methyl violet by the biochars from crop residues was investigated with batch and leaching experiments--adsorption capacity varied with their feedstock in the following order: canola straw char>peanut straw char>soybean straw char>rice hull char. This order was generally consistent with the amount of negative charge of the biochars. Zeta potentials and Fourier transform infrared photoacoustic spectroscopy, combined with adsorption isotherms and effect of ionic strength, indicated that adsorption of methyl violet on biochars involved electrostatic attraction, specific interaction between the dye and carboxylate and phenolic hydroxyl groups on the biochars, and surface precipitation. Leaching experiments showed that 156 g of rice hull char almost completely removed methyl violet from 18.2 L of water containing 1.0 mmol/L of methyl violet. The biochars had high removal efficiency for methyl violet and could be effective adsorbents for removal of methyl violet from wastewater.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P. O. Box 821, Nanjing, China. rkxu@issas.ac.cn
authors.forename: Ren-kou
authors.initials: RK
authors.lastname: Xu
authors.forename: Shuang-cheng
authors.initials: SC
authors.lastname: Xiao
authors.forename: Jin-hua
authors.initials: JH
authors.lastname: Yuan
authors.forename: An-zhen
authors.initials: AZ
authors.lastname: Zhao
mesh_terms: D000327:Adsorption; D002412:Cations; D002606:Charcoal / Q000737:chemistry*; D018556:Crops, Agricultural / Q000737:chemistry*; D005840:Gentian Violet / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D007700:Kinetics; D009994:Osmolar Concentration; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014866:Waste Products / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D002412:Cations; D012996:Solutions; D014866:Waste Products; D014874:Water Pollutants, Chemical; C540010:biochar; D002606:Charcoal; D005840:Gentian Violet