Effect Of Synthetic Technics On Species Distribution Of Aluminum And Application Of Polyaluminum

In this paper, an array polyaluminum was synthesized with capillary injection in different technics, including basicities, initial Al concentration, temperature, mixing intensity and base injection rate. Based on the analysis of the kinetics process of Al-Ferron complex colorimetric, a optimized Al-Ferron complex colorimetric method was used to eliminate the deviation of Ala(monomeric Al) and Alb(polymeric Al). Al-Ferron complex colorimetric kinetics parameters have been investigated and the species distribution of aluminum have been calculated more truely. The effect of different technics on the process of Al-Ferron complex colorimetric , the rate constant kb (the rate coefficient of apparent pseudo-first-order Alb-Ferron reaction) and the species distribution of aluminum and the hydrolysis-polymerization-precipitation process of aluminum were studied. In order to instruct the implication of PAC in wastewater treatment truly and obtain the optimal coagulation effection, polyaluminum of different basicities were also used to treat the coke-water. The optimal basicity, dosage and pH were investigated and the effects of basicity and pH on the quantity of residual aluminum were also studied.The results showed that polyaluminum synthesized with capillary injection in different technics obey to pseudo-first-order Alb-Ferron reaction. Basicity affect the species distribution of aluminum evidently but have no evident effect on the rate constant(kb). With increasing of basicity, the quantity of Alb and Alc increased while the quantity of Ala decreased. Initial Al concentration affect the kb apparently. When Initial Al concentration is 0.0002mol.1-1 or 0.002mol.l-1, kbis 0.610 or 0.480, which is higher than the kb of PAC with the Initial Al concentration 0.1mol.1-1. Temperature and mixing intensity affect kb not evidently but affect the species distribution of aluminum a little. When mixing intensity is 150 r.min-1, the quantity of Ala is less while the quantity of Alc is more. When mixing intensity increased to 1000 r-min-1, Ala and Alb were the main species of aluminum. When temperature is 20 C and 90 C, the species distribution of aluminum of PAC synthesized were verysimilar .The main species of both is Alb and the quantity of Alc is 16% and 19%. While when temperature is 160 C, the quantity of Ala and Alb decreased but Alc increased to 41%. Base injection rate also have no evident effect on kb but have a little effect on the species distribution of aluminum of PAC. When the base injection rate is 0.15 ml.min-1 and 0.5 ml.min-1, the species distribution of aluminum of PAC synthesized were very similar. When the base injection rate is 2ml.min-1, the quantity of Ala is 10% less than others while the quality of Alb is 15% more than others.Study on the coagulation performance of PAC on Coke-water Treatment showed that the optimal dosage of PAC(calculated in Al) is from 1.5 mmol/L to 2.5 mmol/L and the optimal pH is from 6 to 8. When pH is lower than 6, the removal effection of COD increased with pH increased. When pH is higher than 8, the removal effection of COD decreased with pH increased. pH is important to the residual aluminum. When pH is lower than 6, the residual aluminum decreased with pH increased. The residual aluminum is lowest when pH is near to 7. When pH increased further, the residual aluminum increased again. It can also be found that the lowest residual aluminum was obtained when the basicity is 1.5 because basicity affect the species distribution of aluminum evidently. By comparsion the removal efficience of COD and residual aluminum, we can found that the residual aluminum decreases in consistence with the decrease of COD.