title: [Adsorption of methylene blue from water by the biochars generated from crop residues].
abstract: Biochars were prepared from straws of rice, peanut and soybean and rice hull using a low temperature pyrolysis method and adsorption of methylene blue by these biochars were investigated with batch and leaching experiments. Results indicated that biochars have high adsorption capacity for methylene blue and followed the order: rice straw char > soybean straw char > peanut straw char > rice hull char. This order is generally consistent with the amount of negative charge and specific surface area of these biochars. While methylene blue was mainly adsorbed specifically by the biochars, because the adsorption of methylene blue increased with the increase of ionic strength and the adsorption led to the shift of zeta potential of biochar particles to positive value direction. Langmuir equation fitted the adsorption isotherms well and can be used to describe the adsorption behaviors of methylene blue by the biochars. The maximum adsorption capacity of methylene blue predicted by langmuir equation was 196.1, 169.5, 129.9 and 89.3 mmol x kg(-1) for rice straw char, soybean straw char, peanut straw char and rice hull char, respectively. Leaching experiments show that rice hull char of 156 g can remove methylene blue from 30 L water containing 0.3 mmol x L(-1) of methylene blue completely and the cumulative amount of methylene blue absorbed by the biochar reaches 57.7 mmol x kg(-1). The biochars can be used as efficient adsorbents to remove methylene blue from waste water of dye.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. rkxu@issas.ac.cn
authors.forename: Ren-Kou
authors.initials: RK
authors.lastname: Xu
authors.forename: An-Zhen
authors.initials: AZ
authors.lastname: Zhao
authors.forename: Shuang-Cheng
authors.initials: SC
authors.lastname: Xiao
authors.forename: Jin-Hua
authors.initials: JH
authors.lastname: Yuan
mesh_terms: D000327:Adsorption; D010367:Arachis / Q000737:chemistry; D002606:Charcoal / Q000737:chemistry*; D018556:Crops, Agricultural / Q000737:chemistry*; D008751:Methylene Blue / Q000302:isolation & purification*; D012275:Oryza / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry*; D013025:Glycine max / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D014874:Water Pollutants, Chemical; C540010:biochar; D002606:Charcoal; D008751:Methylene Blue