Use of polyaminoamide dendrimers starting from different core-initial molecules for inhibition of silica scale: Experiment and theory

Abstract

Silica has been regarded as one of the toughest contaminants in industrial water systems due to scaling. Several reports have shown that different generations of PAMAM are studied for silica scale inhibition efficiency and only the polyamidoamine PAMAM dendrimers with the core of ethylenediamine are discussed. However, hardly any data is available for PAMAMs with different reactive cores. In the light of this, the current work gets involved in the synthesis of amine-terminated dendrimers (PAMAM) of generation 0 G with reactive cores of different carbon chain lengths by divergent method employed to inhibit the growth of silica. The dendrimers of generation 0 G (PAMAM-0 G) with different carbon chain lengths (1,2-Ethylenediamine; 1,3-Diaminopropane; 1,4-Butanediamine and 1,6-Diaminohexane) as the core were synthesized by economical and green approach. The results showed that PAMAM-0 G-Prop was the most effective inhibitor, producing 415 mg/L molybdate reactive silica (83 % of the original quantity) at 40 mg/L after 24 h, an additional 295 mg/L as compared to the control. Also, PAMAMs profoundly affected the morphology of silica particles, resulting in a large quantity of small particles in solutions containing PAMAM-0 G-Prop or PAMAM-0 G-Eth, yet a small number of large ones in solutions containing PAMAM-0 G-But and PAMAM-0 G-Hex. By Molecular dynamics (MD) simulation, the results showed that the adsorption energy of PAMAM-0 G-Prop was greater than that of other PAMAM molecules. The order of adsorption energy of four dendrimers was PAMAM-0 G-Prop > PAMAM-0 G-But > PAMAM-0 G-Eth > PAMAM-0 G-Hex, and was certified by the analysis of correlation function. Finally, the simulation results provided theoretical basis for evaluating the properties of scale inhibitors and synthesizing novel efficient water treatment chemicals.