Gao Baoyu

Impact factors and thermodynamic characteristics of aquatic humic acid loaded onto kaolin

The adsorption of humic acid (HA) on kaolin particles was studied at various conditions of initial solution pH, ionic strength and solid-to-liquid ratio. The resulting affinity of interactions between humic acid and kaolin was attributed to the surface coordination of HA in ambient suspensions of mineral particles and the strong electrostatic force at low pH. Addition of inorganic salt can also influence the adsorption behavior by affecting the HA molecular structure, the clay particle zeta potential and so on. Equilibrium data were well fitted by the Freundlich model and implied the occurrence of multilayer adsorption in the process. In addition, the enthalpy dependent of system temperature was 79.17 kJ/mol, which proved that the mechanism of HA adsorption onto kaolin was comprehensive, including electrostatic attraction, ligand complexation and hydrogen bonding.

Role of Fe(III) in Microbial Activity and Extracellular Polymeric Substances

Over the past few decades, most of research has been conducted on the extraction method, composition and cell surface characteristics connected with EPS. It was recently proposed that activated sludge flocs are comprised of different types of EPS with distinct metal ion binding characteristics. Fe(¢ó) was a common wastewater composition, in practice, which may promote the biofilm activity and amount distinctly. But few detailed research was conducted on the correlation Fe (¢ó)with the composition and microbiology activity with EPS. Experimental results indicated that the variation of Fe (¢ó)concentration in influent produced biofilm with different abundances of EPS and different composing and microbial activity characteristics. The biofilm that was fed on large amount of Fe (¢ó) had more EPS than the biofilm that was fed on little amount of Fe (¢ó). The contents of polysaccharide and protein improved considerably as Fe (¢ó) participated in. The results demonstrate that the Fe (¢ó) had a positive effect on EPS and activity of biofilm. The performance of biological degradation was much more closely correlated with the amount of protein than with the amount of polysaccharide.

Influence of Oxidative Poly-Si-Fe Coagulant on Adsorption of Humid Acid

A new polymer, oxidative Poly-Si-Fe (PSF) coagulant was prepared by an oxidization and copolymerization method. The influence of the oxidization of PSF on the adsorption of humid acid (HA) was explored, in comparison with that of polyferric aluminum (PFA). The results show that PSF changes the molecular structure of HA, leading to the improvement of adsorption of HA.