The removal of Cu(II) ions from aqueous solutions at a pH of 5.0 was carried out using fixed-bed columns packed with alginate-chitosan (Alg-Ch) or alginate-chitosan sulfate (Alg-ChS) hydrogel beads. The effect of the initial Cu(II) concentration, flow rate, pH, and height of the column on the amount of Cu removed by the column at the breakpoint and at the exhaustion point is reported. The pH of the solution at the column’s exit was initially higher than that at the entrance, and then decreased slowly. This pH increase was attributed to proton transfer from the aqueous solution to the amino and COO⁻ groups of the hydrogel. The effect of operating conditions on the mass transfer zone (MTZ) and the length of the unused bed (H_LUB) is reported. At the lower flow rate and lower Cu(II) concentration used, the MTZ was completely developed and the column operated efficiently; by increasing column height, the MTZ has a better opportunity to develop fully. Experimental data were fitted to the fixed-bed Thomas model using a non-linear regression analysis and a good correspondence between experimental and Thomas model curves was observed.

A semicontinuous emulsion process varying comonomer feed composition in the course of the reaction is used here to produce copolymer chains of different composition as conversion proceeds. Polymeric material global composition and evidence of branching are determined by ¹H-NMR. The determined by GPC is beyond the range where the mechanical properties depend on molecular weight. Static and dynamic mechanical properties of variable composition copolymers exhibit highly improved copolymer type behavior for all tested compositions (styrene content between 30 and 85 wt%), showing high superiority of the mechanical performance in comparison with random copolymers and two-stage polymers of equivalent composition, synthesized also by emulsion polymerization.

Using a semicontinuous seeded emulsion polymerization process with a gradual variation in feed composition, butyl acrylate (BA)/styrene copolymers were obtained (variable composition copolymers, VCCs). BA seed particles of two different diameters were used to prepare copolymer materials with 50–85 wt.% styrene. In each reaction, cumulative copolymer composition was followed by ¹H-NMR; with such data, a histogram showing the relative content of copolymer chains corresponding to each composition interval was built. The VCCs presented higher moduli and ultimate mechanostatical properties than their equivalent core-shell type polymers. The mechanical performance of VCC materials was explained considering the respective histograms.