kaolinite and potassium-persulfate

Flocculation process is one of the most widely used techniques for water and wastewater treatment, and also for sludge dewatering. Synthesis of natural biopolymers or modification of natural biopolymers as environmentally friendly flocculants is highly desired in the field of environmental protection. In this work, a water soluble copolymer flocculant, STC-g-PDMC (starch-graft-poly (2-methacryloyloxyethyl) trimethyl ammonium chloride) was synthesized through grafting a monomer, (2-methacryloyloxyethyl) trimethyl ammonium chloride (DMC), onto starch initiated by potassium persulphate. Acetone and ethanol were used for copolymer precipitation and purification in the synthesis, which diminished the toxicity during the synthesis process. The graft copolymer was characterized using Fourier-transform infrared spectroscopy, (1)H nuclear magnetic resonance, X-ray powder diffraction, thermogravimetric analysis and elemental analysis. The prepared STC-g-PDMC exhibited a highly effective flocculation capability for kaolin suspensions compared with starch and polyacrylamide as control. The charge neutralization effect played an important role in the flocculation process at low flocculant dosages. When it was used as dewatering agent for anaerobic sludge, the conditioned sludge could be easily filtered after the dosage reached 0.696% of the dry weight of sludge. Such a graft copolymer is a promising green agent for wastewater treatment and sludge dewatering applications.

Topics: Acetone; Cations; Ethanol; Flocculation; Kaolin; Methacrylates; Molecular Weight; Polymerization; Potassium Compounds; Sewage; Starch; Sulfates; Waste Disposal, Fluid; Water Purification

In this work, pulp mill wastewater was treated using a novel copolymer flocculant with a high water-solubility, which was synthesized through grafting (2-methacryloyloxyethyl) trimethyl ammonium chloride (DMC) onto chitosan initiated by potassium persulphate. The experimental results demonstrate that the two main problems associated with the utilization of chitosan as a flocculant, i.e., low molecular weight and low water-solubility, were concurrently sorted out. The physicochemical properties of this flocculant were characterized with Fourier-transform infrared spectroscopy, (1)H nuclear magnetic resonance spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy. Reaction parameters influencing the grafting percentage, such as temperature, reaction time, initiator concentration and monomer concentration, were optimized using an orthogonal array design matrix. With an increase in grafting percentage, the water-solubility of the flocculant was improved, and it became thoroughly soluble in water when the grafting percentage reached 236.4% or higher. Its application for the treatment of pulp mill wastewater indicates that it had an excellent flocculation capacity and that its flocculation efficiency was much better than that of polyacrylamide. The optimal conditions for the flocculation treatment of pulp mill wastewater were also obtained.

Topics: Chitosan; Choline; Flocculation; Industrial Waste; Kaolin; Kinetics; Magnetic Resonance Spectroscopy; Methacrylates; Paper; Potassium Compounds; Solubility; Sulfates; Waste Disposal, Fluid; Water; Water Pollutants, Chemical