| The removal of dye and dissolved organic matter by flocculation is one of important research area in textile wastewater treatments. The color removal efficiency largely depends the flocculation efficiency of flocculants. Recently, flocculants develop rapidly along with the development of the flocculants' theory and chemical industry. Various flocculants categories have been developed including low molecular weight flocculants, high molecular weight flocculants, inorganic flocculants, organic flocculants and composite flocculants. This has been drawn attention of academe and enterprise.The results of research have been shown that organic high molecular weight flocculants can removal dye efficiently in widely range because of the structure characteristic of flocculants. And the excellences of organic high molecular weight flocculants for treating dye wastewater are independents to pH of wastewater, low dosage and low sludge. The surface charge of dye usually is negative, therefore, organic cationic polymer flocculants has been extensively studied and applied to dye wastewater treatment systems in the world. Ammonium flocculants is one of the most valuable flocculants because that the chemical structure of ammonium flocculants is inconstant, surface charge is independent to pH, and molecular is high. So, novel organic cationic polymer flocculant becomes extensively studied in recent years.Polyamine polymer is one of water-solubility organic cationic polymer flocculants. It has been shown to be applied for removing turbidity, algae, color and natural organic matter due to high positive charge, water solubility, handle molecular, high efficiency, innocuity and low cost. Moreover, it can be applied in petroleum exploitation, paper making, mining, textile etc. Because polyamine polymer has high positive charge and high molecular, it can remove contamination by charge neutralization and adsorption. Therefore, the flocculation efficiency of polyamine polymer is high. Compared with other cationic polymer flocculants, polyamine polymer do not react with chloride in wastewater or water, thus the efficiency of polyamine polymer will not decrease in wastewater or water containing chloride.Presently, there are a lot of papers about organic cationic polymer flocculants in the world, however, very limited work has been reported on organic cationic polymer flocculants in China, especially on polyamine polymer. Polyamine polymer just is applied to petroleum exploitation in China. Therefore, the object of this paper is to synthesize organic cationic polymer flocculant - polyamine polymer by Cross-Linking. And the influences of the kind and the amount of crosslinking modified additives on the characteristics of polyamine flocculants were investigated. At present, our country exact novel efficiency organic cationic polymer flocculant, so it is important to research novel polyamine polymer.The main contents and results are following:(1) A series of organic cationic polymer flocculants (dimethylamine-epichlorohydrin polymer) of dimethylamine and epichlorohydrin were synthesized by Cross-Linking. The influences of the factors such as the kind and the amount of crosslinking modified additives, polymerization temperature, and molar ratio of epichlorohydrin and dimethylamine, and polymerization time on the characteristics of polyamine flocculants were investigated. The results show that as for the cationicity and molecular weights of the polymers, the amount of crosslinking modified additives, polymerization temperature, molar ratio of epichlorohydrin and dimethylamine, and polymerization time all have an optimum value under certain polymerization conditions and that the kind of crosslinking modified additives has a great effect on the structure of the polymers. The results show that when molar ratio of epichlorohydrin and dimethylamine is set as 1.5: 1 and the amount of 1, 2-diaminoethane is 3 %, polyamine flocculants get the best viscosity and cationic degree and have excellent decoloration efficiency through the adsorption and subsequent formation of particle-polymer-particle bridges.(2) The structure of the polymer and its aggregate in aqueous solution were examined by means of various instrumental analysis techniques, including IR, NMR and Transmission Electron Microscope (TEM) respectively et al. The results show that the cationic polymers containing quaternary ammonium salts has formed。(3) At the end of the experiments, the flocculation efficiency of the polymers for dye liquor, printing and dyeing wastewater and oil refinery effluent were studied by jar test. The experimental results show that the cationicity, the molecular weight and the structure have a great effect on the flocculation efficiency of polyamine flocculants. In general, the larger the cationicity and molecular weight are, the better flocculation performance the polyamine flocculants have. However, the cationicity and molecular weight contradict with each other under certain conditions, that is to say the both characteristics can't be increased at the same time. Thus the cationicity and molecular weight should be geared to the difference of the printing and dyeing wastewater. Generally, for dispersed dye wastewater, polyamine flocculants perform mainly as adsorption bridging agents, while for water-soluble dye wastewater, polyamine flocculants show both charge neutralization and adsorption bridging functions. In conclusion, a certain kind of wastewater needs the flocculants with special structure.(4) The pilot scale experiment has been carried out for the production of polyamine flocculants and the results indicated that the preparation technology of the flocculants is reasonable and the production process is easy to control. The quality of the products produced by pilot scale experiment is about same as that of the products prepared in laboratory. The products produced by pilot scale experiment gave good coagulation/flocculation performance for the treatment of dyeing wastewaters and oil refinery effluents.(5) In order to extend the application of the polyamine flocculants in water and wastewater treatment, the polyamines were combined with polyaluminum chloride (PAC) to prepare the composite flocculants, and the coagulation/flocculation performance of the composite flocculants was investigated. The results show that the composite flocculants was characterized by the better coagulation/flocculation performance and cost effective than individual chemical.(6) The cationic polymer-epicholorohydrin-dimethylamine (PEPI-DMA) as intercalary reagent was used to prepare a series of cationic polymer/bentonite. The surface area, electric characteristic and structure characteristic of the PEPI-DMA/Bentonite were studied. The decoloring performance of the cationic polymer/bentonite on orcein dye was discussed. Exemplifying by one kind of bentonite with fairly good performance, the adsorption isotherm and the adsorptive dynamics of PEPI-DMA/Bentonites were studied. The results indicated that the surface area, electric potential, degree of aggregation and decoloring performance of the PEPI-DMA/Bentonite were greatly increased as compared with that of unmodified bentonite. The adsorption of PEPI-DMA/Bentonite to these three kinds dyeing water accorded with the isothermal adsorption equations of Langmuir and Freundlich. The adsorptive dynamics tallied with the Langmuir adsorption equation.The innovations of this paper are following:(1) Dimethylamine and epichlorohydrin crosslink and aggregate in water by various organic amines to produce a series of different structure and molecular polymers, these polymers are applicable in different wastewater and water. This technique is simple, mild, convenient and can easily be applied in factory. The molecular weight of the products by this technique is high and handle, and there is no waste during synthesizing.(2) The cationicity, the molecular weight and the structure of PEPI-DMA have a great effect on the flocculation efficiency of polyamine flocculants. In general, the larger the cationicity and molecular weight are, the better flocculation performance the polyamine flocculants have. The polyamine flocculants show both charge neutralization and adsorption bridging functions.(3) The efficiency of water treatment can improve and the cost of water treatment can decrease by combining the polyamines with polyaluminum chloride (PAC) or bentonite.The experimental results show that the dimethylamine-epichlorohydrin polymers are organic polymer flocculants with high performance and multi-function. It is necessary to develop and apply in wastewater treatment.
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