A novel copolymer PADA which has two functions of flocculation and surface activity was synthesized in aqueous solution. The copolymer was applied to filtration aiding on wet-process phosphoric acid (WPA). The results show that PADA can increase the filtration rate of the phosphoric acid slurry and decrease the moisture of the filter cake. The mechanism of filtration aiding was studied. PADA neutralizes the surface potential of the phosphogypsum and makes the microcrystal particles flocculate to conglobation, which indicate that electrostatic neutralization and flocculation might be the action modes in the process of filtration aiding. The shortest flocculation time and largest average diameter of floccules can be obtained with the addition of 10 ppm PADA. The average pore size and porosity of the filter cake are enlarged by 0.22 μm and 15.38% respectively with the addition of PADA. The surface contact angle of the phosphogypsum is increased by 3.4° with PADA presence.

A non-ionic copolymer PAMA which has two functions of flocculation and surface activity was synthesized in aqueous solution. The copolymer was also characterized by means of infrared spectroscopic and unclear magnetic. The application performance of PAMA were studied, and the results show that the filtration rate of the phosphoric acid can be increased by about 3.8 times,the water content of the filter cake can be reduced by about 9.8%. Meanwhile, PAMA may increase the cake porosity by 25.82%,increase the mean void area about 7 times ,increase the surface contact angle of phophogypsum by 9.8°and decrease the surface tension by 7.4 mN·m-1 according to the SEM photos and hydrophobic experiment. All this confirms that PAMA is useful for vacuum filter system of wet process phosphoric acid.

A cationic amphiphilic copolymer was synthesized with acrylamide (AM), dimethyl diallyl ammonium chloride (DMDAAC), monomer B by solution copolymerization. Through the orthogonal test, the optimum synthesis condition was obtained as follow: the solid content of the polymerization system is 10%, the pH value is 4.0, the polymerization temperature is 60°C, the concentration of the initiator is 0.06%, and the monomer ratio of m (AM): m (DMDAAC): m (monomer B) is 70:10:20. The copolymer was used for the filtration aiding in the wet process phosphoric acid. The filtration rate of the gypsum slurry is increased by 4.8 times, and the filter cake moisture is reduced by 11.79%, with the addition of PADB. The mechanism of filtration aiding was also researched, which shows that PADB can change the mean diameter of crystals and agglomerate the tiny crystals; PADB can decrease the surface tension of the filter liquor and enhance the hydrophobicity of the gypsum.

Advancing front model, carrier-facilitated transfer model and reversible reaction model were applied to simulate extracting chromium (Ш) from wastewater by emulsion liquid membrane using di-(2-ethylhexyl) phosphoric acid as carrier and Span-80 as surfactant. Parameters of the mathematic models were gained from the designed experiments, and the reversible reaction model can be used with a reasonably accuracy as estimates of chromium (Ш) permeation. The experimental results demonstrate that the role of reversibility of the chemical reaction between internal phase and membrane phase should be considered, and the diffusion resistance is the primary resistance of the mass transfer process.