Experimental investigation of the modification of starch by grafting acrylamide using electron beam irradiation in order to synthesize water-soluble copolymers having flocculation abilities is performed. The influence of the variation of the parameters acrylamide/starch (AMD/St) weight ratio, electron beam irradiation dose and dose rate, as well as the presence or absence of metallic silver nanoparticles is investigated. The characterization of graft copolymers was carried out by monomer conversion coefficient, residual monomer concentration, intrinsic viscosity and Huggins’ constant. Models, describing the dependencies of the quality characteristics (their means and variances) from the process parameters, are estimated by implementation of the robust engineering approach in the case of qualitative and quantitative factors. Multi-criteria optimization involving requirements for economic efficiency, assurance of low toxicity, high copolymer efficiency in flocculation process and good solubility in water is also presented.