Synthesis of Hydrophobic Cationic Polymeric Flocculants by the Introduction of a Hydrophobic Monomer, Cationic Monomer and the Application in Sludge Dewatering

Abstract

Dewatering pre-treatment, chemical conditions for sludge are practical approaches to advance the performance of sludge-dewatering, hence lessen the cost of sludge transportation and treatment. Cationic polymeric flocculants are used as chemical regulators because of their excellent performance and economic advantages. Current research focused on synthesizing flocculants Polyacrylamide, methacrylamido propyl trimethyl ammonium chloride, Lauryl acrylate, and Poly Acrylamide, methacrylamido propyl trimethyl ammonium chloride (PAT). The synthesis was achieved by ultraviolet initiated (UV-initiated)-induced polymerization technique. The chemical composition of the samples was investigated using Fourier transform infrared (FTIR) spectroscopy and hydrogen nuclear magnetic resonance (1H NMR). This study also evaluated the thermal stability of PATL and PAT by using thermogravimetric/differential scanning calorimetry (TGA). Moreover, the results of scanning electron microscopy (SEM) confirmed the strong floc structure has the ability to form porous and channel construction, making the filter cake a constructive drainage way. It is able to be used for water release and therefore helps to improve dehydration capacity. The hydrophobic flocculants properties in water were investigated by initiator concentration, initiation time and urea concentration. The experimental results confirmed that the optimal values for preparation of PATL were composed of initiator concentration of 0.4 wt.‰, urea level of 1.2 wt.‰; molar ratio of MPTAC to AM (5:95), irradiation time of 60 min and flocculants intrinsic viscosity of 1350 mL/g. Furthermore, it was found that PATL had stronger hydrophobic collaboration with satisfactory water solubility and also improved the dewatering performance. Sludge dewatering experiments confirmed that filter cake moisture content (FCMC) and specific resistance to filtration (SRF) for PATL flocculants reached to 65% and 6 × 1012 m/kg, respectively at the optimal dosage of dry solids about 30 mg · L–1 of sludge, exhibiting better performance than the conventional cationic flocculants (PAT).