Preparation and flocculation performance of modified starch flocculant DTCS-AM

Key words:  dithiocarbamate  modified starch  flocculant  graft co-polymerization

Abstract:

The dithiocarbamate modified starch (DTCS) was obtained by the cross linking reaction and etherification reaction with the starch as raw material. Then the modified flocculant DTCS-AM was prepared using the DTCS as backbone through the graft copolymerization reaction with acrylamide. The influences of some parameters on the graft copolymerization reaction, such as amount of monomer, reaction temperature, time, as well as the concentration of the initiator, were investigated. Afterward the product was characterized by using infrared spectroscopy and scanning electron microscopy (SEM). The DTCS-AM 's flocculation ability of treating Shengli Oilfield drilling wastewater was evaluated. The results indicate that the optimal synthetic conditions are obtained as follows:T=40℃, t=3h, initiator concentration 4mmol/L, mass ratio of starch to acrylamide monomer 1∶2.2. The images of the SEM show that there exists a good flocculation structure of the DTCS-AM. Under 80mg/ L of the flocculant dosage, the COD removal rate of Shengli Oilfield drilling wastewater can be more than 95％ when the DTCS-AM is used to treat the wastewater.