ABSTRACT
Coagulation kinetics and floc properties are of great fundamental and practical importance in the field of water treatment. To investigate the performance of Fe(VI) and Fe(III) salt on particle coagulation, Malvern Mastersizer 2000 was employed to continuously and simultaneously monitor the kaolin floc size and structure change, and population balance modeling was used to investigate the coagulation mechanism. The results show dosage increase had positive effect on collision efficiency and floc strength and negative effect on restructure rate. Low shear rate resulted in higher collision efficiency and stronger floc. Low water temperature had a pronounced detrimental effect on coagulation kinetics. Temperature increase showed the most significant positive effect on collision efficiency, floc strength and restructure rate. The optimum pH zone for the coagulation was found to be between 6 and 8. Further pH increase lowered the collision efficiency and floc strength and increased the restructure rate. FeCl3 resulted in a larger ratio of the mass to volume of kaolin flocs (compactness) than those induced by ferrate.
Subject(s)
Ferric Compounds , Water Purification , Flocculation , Kaolin , WaterABSTRACT
In the title compound, {[Co(2)(C(16)H(6)O(8))(C(12)H(8)N(2))(H(2)O)(2)]·H(2)O}(n), one Co(II) ion has a {CoN(2)O(4)} distorted octa-hedral environment defined by two N atoms of one 1,10-phenanthroline (phen) ligand, three O atoms of the carboxyl-ate groups of three biphenyl-3,3',4,4'-tetra-carboxyl-ate (BPTC) ligands, one of which is bidentate, and one O atom from one coordinated water mol-ecule. The other Co(II) atom is surrounded by six O atoms from four different BPTC ligands and one coordinated water mol-ecule. Each BPTC ligand forms eight coordination bonds with seven Co(II) atoms, leading to a layer structure along the ac plane. Uncoordinated water mol-ecules occupy the space between the layers, and inter-act via inter-layer O-Hâ¯O hydrogen bonds along the b axis, generating a three-dimensional supra-molecular network.
ABSTRACT
Nanocomposites based on silver sulfide (Ag2S) and Ca-montmorillonite (Ca(2+)-MMT) were synthesized by a simple hydrothermal method. The nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectra (FTIR). The as-prepared Ag2S-MMT nanocomposites were firstly demonstrated to possess intrinsic peroxidase-like activity and could rapidly catalytically oxidize the substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue product which can be seen by the naked eye in only one minute. The experimental results revealed that the Ag2S-MMT nanocomposites exhibit higher thermal durance. Based on the TMB-H2O2 catalyzed color reaction, the Ag2S-MMT nanocomposites were exploited as a new type of biosensor for detection and estimation of H2O2 through a simple, cheap and selective colorimetric method.