title: [Physical and fractal properties of polyaluminum chloride-humic acid (PACl-HA) flocs].
abstract: The powder of polyaluminum chloride-humic acid (PACl-HA) flocs was prepared by cryo-freezing-vacuum-drying method. These flocs were characterized by X-ray diffractometry, FTIR spectroscopy, elementary analysis and surface area determination. The results show that these flocs are amorphous, mainly composed by elements of C, O, Al, and reserve some characteristic functional groups from PACl, HA or Kaolin. The N2 absorption-desorption data determined the microstructure of PACl-HA flocs: 130 - 161 m2 x g(-1) of BET specific surface area, 0.38 - 0.52 cm3 x g(-1) of BJH cumulative absorbed volume and 7.7 - 9.6nm of BJH desorption average pore diameter. The peak values of pore size distribution (PSD) curves were found at 8.4 - 11.2nm of pore diameter. The self-similar and rough surface was observed in SEM images of PACl-HA flocs. The surface fractal dimensions D(s) of the flocs determined from both SEM images method and N2 absorption-desorption one were 2.03 - 2.26 and 2.24 - 2.37, respectively. The correspondent fractal scale for the former method was 23 - 390nm, mainly belonging to exterior surface scales, and the lowest limit of the fractal scale for the latter method was 0.2nm and fell in pore surface scales. This demonstrated that the flocs surface had multi-scale fractal properties. Furthermore, some difference was given between the pore surface fractal dimensions D(s) calculated from N2 absorption data and desorption data. The calculated pore surface D(s) values of much more than three through thermodynamic model had discrepancy from Sahouli et al's results.
authors.affiliation: College of Nature Resource and Environment, The Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China. wangyilinet@sina.com
authors.forename: Yi-Li
authors.initials: YL
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Bai-Yu
authors.initials: BY
authors.lastname: Du
mesh_terms: D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D005427:Flocculation; D017709:Fractals; D006812:Humic Substances; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011108:Polymers / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013499:Surface Properties; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D017607:Aluminum Compounds; D002712:Chlorides; D006812:Humic Substances; D011108:Polymers; D000077410:Aluminum Chloride