title: Effects of low-molecular-weight organic acids on Cu(II) adsorption onto hydroxyapatite nanoparticles.
abstract: Adsorption kinetics and adsorption isotherms of Cu(II) onto a nanosized hydroxyapatite (HAP) in the absence and presence of different low-molecular-weight organic acids are studied in batch experiments. The results show that the adsorption kinetics of Cu(II) onto the HAP are best described by pseudo-second-order model, and the adsorption isotherms of Cu(II) onto the HAP fit Dubinin-Radushkevich model very well with high correlation coefficient (R(2)=0.97-0.99). The amount adsorbed of Cu(II) onto the HAP at pH 5.5 was much higher than that at pH 4.5. The presence of organic acids significantly decreased the adsorption quantity of Cu(II), clarifying the lower sorption affinities of Cu(II)-organic acid complexes onto the HAP rather than Cu(II) ion. The decreased maximal adsorption quantity of Cu(II) onto the HAP increased with the increasing logarithm of cumulative formation constants of Cu(II) and organic acids. The stronger coordination of organic acid with Cu(II), the more decreased Cu(II) adsorption quantity onto the HAP.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Yu-Jun
authors.initials: YJ
authors.lastname: Wang
authors.forename: Jie-Hua
authors.initials: JH
authors.lastname: Chen
authors.forename: Yu-Xia
authors.initials: YX
authors.lastname: Cui
authors.forename: Shen-Qiang
authors.initials: SQ
authors.lastname: Wang
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Zhou
mesh_terms: D000143:Acids / Q000737:chemistry*; D000327:Adsorption; D003300:Copper / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D053768:Metal Nanoparticles; D008970:Molecular Weight; D009930:Organic Chemicals / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D000143:Acids; D009930:Organic Chemicals; D003300:Copper; D017886:Durapatite