Rimozione di rame mediante idrogeli di poliammidoammine : aspetti cinetici e influenza del pH

Polyamidoamine (PAA) hydrogels have been used to remove Cu(II) from aqueous solutions. Two PAA types were used: MBA/EDA (N-N’-Metilen-Bis-Acrilammide/Ethylenediamine) and MBA/CYS (N-N’-Metilen-Bis-Acrilammide/Cystein) in two particle size each (grains - 1mm<d<2mm and powder - d<1mm). The kinetics and adsorption capacity of MBA/EDA vs. particle size have been tested. Further tests were carried out to assess both the diffusive resistance of MBA/EDA and MBA/CYS hydrogels, by varying the mechanical stirring, and the pH effect. The removal capacity was evaluated by RSSCT (Rapid Small Scale Column Test) and batch multistep trials. As for the kinetics and adsporption the best fitting was obtained by a pseudo second order kinetics and Langmuir isotherm model. The mass transfer coefficient (k) was found to be equal to 0.304 [g/(mg•min)] for grains and 1.100 [g/(mg•min)] for powder. As far Langmuir parameters (K) was equal to 5.184 [L/g] and the maximal adsorption capacity, in conditions of saturation (qmax) was equal to 5.028 [mg/g]. As far diffusive resistance evaluation the removal extent depends on turbulence and particle size. Removal efficiency at different pH suggests that the structural links of hydrogels are pH-dependent and that the functionalization of MBA/CYS restricts the ability of complexation of Cu(II). For MBA / EDA removals are satisfactory above pH 6. The multistep batch tests have not obtained the desired result as it has not reached saturation of the adsorbent material, which has however been shown to vary its kinetic removal over time.