Preparation And The Flocculation Characteristics Of The Environmental Friendly Flocculants

The chemical flocculation has been an important technique employed to treat wastewater. The development of exploration environmental friendly flocculants plays a major role in the application of this technique. Here, peanut shell and starch were used to prepare two kinds of flocculants, i.e. the modified cellulose-, and starch-based flocculants. Then, the flocculation characteristics of these two flocculants were evaluated.Firstly, methacrylatoethyl trimethyl ammonium chloride(DMC) as a monomer was adopted to modify the cellulose in peanut shell by a grafting process; a kind of quaternary ammonium cationic-type cellulose flocculant was obtained. The parameters of reaction time, p H, and the weight ratio of DMC and peanut shell were studied to reveal their effects on the flocculation characteristic of this flocculant. In the acidic solutions, the results show that the modified cellulose flocculant exhibits an effective flocculation treatment, when the weight ratio of DMC and peanut and reaction time were kept at 2 and 5 h, respectively. In addition, the dosage of flocculant, p H and temperature also affect the disposal of wastewater. The modified cellulose flocculant can be competent for the disposal of the kaoline solution with a concentration of 20 g/L, as the dosage of the focculant, p H and teSecondly, DMC was also applied to modify the starch, and the modified starch flocculant with a nature of the ammonium cationic-type flocculant. The effects of weight ratios of DMC and starch, reaction temperature, reaction time, the dosage of the initiator on the grafting were studied. The optimized parameters for the preparation of this flocculant are as follows: the weight ratios of DMC and starch=1:1.5, reaction temperature = 70℃, reaction time = 3 h, the dosage of initiator =7 wt%, and p H=4. Also, the disposal of this flocculant for the kaoline solutions was also studied. When p H was 4 and flocculant dosage was 1.5g/ L,the transmission rate of the treated solution is 88.9%. The values of transmission rates vary to 83.2% and 70.3%, as the p H values were adjusted to 7 and 10, respectively. Thus, the modified starch can be employed in a wide p H range.