Preparation And Applied Research Of Poly Aluminum Silicate Sulfate From Rice Husk Silica

In this paper, the flocculant of poly aluminum silicate sulfate (PASS) was synthesized by sodium silicate from rice husk ash which is the agricultural wastes, and it was used for the treatment of wastewater. The effects of the mass fraction of silica, activated pH of silicate, molar ratio of aluminum and silicon and other factors on its flocculant performance was examined, and the better conditions of preparing PASS was got, based on this, the flocculant performance of PASS and commodity poly aluminum chloride (PAC) was compared, and the composite flocculant of PASS and organic polymer flocculant-poly acrylamide (PAM) and poly dimethyl diallyl ammonium chloride (PDMDAAC) was carried out after discussions, at the same time, the Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analysis its structure and morphology.The flocculant of poly aluminum silicate sulfate (PASS) was prepared under different process conditions, and its flocculation to Kaolin simulated wastewater was also examined. The results show that:the mass fraction of silica is 7%, activated pH of silicate is 3.5, the molar ratio of aluminum and silicon is 3:1, and the activation time of silicic acid and sample aging times are one hour, under this condition,when the simulated wastewater was treated by PASS, the removal rate of turbidity was 94.26% when dosage (by Al2O3 meter) was 15mg/L. The flocculant of poly aluminum silicate sulfate (PASS) was prepared under different process conditions, and its flocculation to Ink wastewater was also examined. The results of single factor experiment and orthogonal experiment show that:the mass fraction of silica is 7%, activated pH of silicate is 2.0, the molar ratio of aluminum and silicon is 1:2, and the activation time of silicic acid and sample aging times are one hour, at this time, when the ink wastewater was treated by PASS, the removal rate of turbidity was 97.29%, the decolourization rate was 94.26% when dosage (by Al2O3 meter) was 60mg/L.In order to investigate the flocculation performance of poly aluminum silicate sulfate (PASS)from rice husk silica, the comparative experiments of flocculation performance about PASS and product poly aluminum chloride (PAC)was done, the results show, the removal rate of turbidity of PASS(the dosage was 5mg/L)and PAC(the dosage was 30mg/L) was same basically when the high turbidity (280-290NTU) simulated wastewater was treated, the removal rate of turbidity of PASS was higher than PAC about 26% when the low turbidity (18-20NTU) simulated wastewater was treated at dosage (by Al2O3 meter) of 7mg/L, and the residual turbidity of wastewater which was treated by PASS has reached the requirement of national standard for domestic and drinking water when the dosage was 15 mg/L; the flocculation of PASS was better than PAC when the high turbidity (450-500NTU) oil wastewater was treated at the same dosage,and the value of SS about wastewater which was treated by PASS has reached the requirement of sewage discharge in the national standard when the dosage was 70mg/L;the removal rate of turbidity of PASS was higher than PAC about 15% when the low turbidity (5-10NTU) oil wastewater was treated at dosage (by Al2O3 meter) of 150mg/L; the removal rate of turbidity and decolourization rate were 97.29% and 94.26% respectively when the ink wastewater was treated at dosage (by Al2O3 meter) of 60mg/L, the ratio was higher around 11% than PAC’s, the value of SS and chromatic about wastewater which was treated by PASS has reached the requirement of sewage discharge in the national standard when the dosage was 60 mg/L.The flocculent property of composite flocculant was investigated after the organic polymer flocculant-poly acrylamide (PAM) and poly dimethyl diallyl ammonium chloride (PDMDAAC) composited with poly aluminum silicate sulfate (PASS). The results show that the homogeneous and stable composite flocculant formed after PASS and PDMDAAC was composited, and the best quality mixing ratio of PASS and PDMDAAC was 40:1, the dosage of PASS was reduced significantly when it was used for wastewater treatment; a small amount of precipitation can be seen after PASS and PAM mixed, they cannot form homogeneous stable complexes, so the PASS (the dosage was 3mg/L) was added first,and then the PAM (the dosage was 0.5mg/L) was added when the wastewater was handed, flocculation effect was enhanced significantly then they used alone, and the floc was also tightness.The Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to analysis the structure and morphology of poly aluminum silicate sulfate (PASS). The results show that the Si-O-Al bond was formed after aluminum and silicon compound, and PASS does not contain the crystalline material under the optimum conditions, meanwhile the morphology analysis shows that PASS formed the structure of compact chain network. So the above shows, PASS is the formation of amorphous polymer instead of a simple mixing of raw materials.