A novel macromolecule flocculant dithiocarboxyl amino-methylated polyacrylamide (DTAPAM), which can be used to remove heavy metal ions, was synthesized with polyacrylamide, formaldehyde, dimethylamine, carbon disulfide and sodium hydroxide. The removal of Cd(Ⅱ) in aqueous solution was investigated to determine the optimal preparation conditions for DTAPAM. The main influencing factors and central values of levels in the preparation process were confirmed by Plackett-Burman design and steepest ascent experiment. And then through central composite design (CCD) of response surface methodology (RSM), the preparation conditions of DTAPAM were optimized. The results showed that the regression of the quadratic polynomial model established with CCD was significant while the lack of fit was not significant. The multiple correlation coefficient (R2) was 0.9371, which demonstrated the model had good fitness. The optimum conditions for the preparation of DTAPAM were as follows:the concentration of PAM was 2.7%; the molar ratio of PAM, CS2 and NaOH was 1:2:1.4; pre-reaction temperature was 23℃; pre-reaction time was 15min; main-reaction temperature was 40℃; and main-reaction time was 90min. Under the optimum conditions, the removal rate of Cd(Ⅱ) could reach 95.83%, which was close to the predicted value 94.08% of the model. The result proved that the model established by RSM was reasonable and feasible.
Navarro R R, Wada S, Tatsumi K. Heavy metal flocculationby Phosphonomethylated-polyethyleneimine and Calcium Ions[J]. Separation Science and Technology, 2003,38(10):2327-2345.
Magallanes J F, Olivieri A C. The effect of factor interactionsin Plackett-Burman experimental designs:Comparison of Bayesian-Gibbs analysis and genetic algorithms[J]. Chemometrics and Intelligent Laboratory Systems, 2010,102(1):8-14.
[18]
Rao P, Divakar S. Lipase catalyzed esterification of α-terpineol with various organic acids:Application of the Plackett-Burman design[J]. Process Biochemistry, 2001,36(11):1125-1128.
Kiran B, Kaushik A, Kaushik C P. Response surface methodological approach for optimizing removal of Cr (Ⅵ) from aqueous solution using immobilized cyanobacterium[J]. Chemical Engineering Journal, 2007,126(2/3):147-153.
Chang Q, Hao X K, Duan L L. Synthesis of crosslinked starch-graft-polyacrylamide-co-sodium xanthate and its performances in wastewater treatment[J]. Journal of Hazardous Materials, 2008,159(2/3):548-553.