Ozonized 2-hydroxypropyl-ß-cyclodextrins as novel materials with oxidative and bactericidal properties.

Ozonized (2-Hydroxypropyl)-ß-cyclodextrins (Oz-HPbCDs) were produced by direct gas/solid reaction between gaseous ozone (O3) and solid HPbCD. The solid materials obtained were first characterized using physical and chemical methods and compared to the initial HPbCD. The main process parameters of the synthesis were studied independently to assess their effect on the oxidizing power of Oz-HPbCDs. The ability of the Oz-HPbCDs to retain their oxidative properties over time was evaluated, at different storage temperatures, for a period of at least two months. Lastly, aqueous solutions of HPbCD and Oz-HPbCD at different concentrations were contacted with bacterial strains of Escherichia coli and Streptococcus uberis to see whether these materials might have bactericidal properties. Since normal bacterial growth was noted with HPbCD, the antimicrobial efficiency of Oz-HPbCDs was clearly demonstrated on these two types of bacteria.

Performance of green antiscalants and their mixtures in controlled calcium carbonate precipitation conditions reproducing industrial cooling circuits.

Cooling circuits in many industrial sectors are faced with daily issues of scaling. One preventive treatment consists in injecting a polymer additive in the circuit to inhibit precipitation of calcium carbonate. Among the used additives, very few are "green" and the efficiency of new candidates are difficult to test directly in industrial conditions. The present study compared performance between two "green" polymer additives, polyaspartic acid (PASP) and polyepoxysuccinic acid (PESA), versus a traditional gold-standard, homopolymer of acrylic acid (HA) in a laboratory scale set-up designed to be representative of an industrial circuit. Results showed that HA and PASP are both inhibitors of calcium carbonate crystal growth. This inhibition resulted from adsorption of polymer additive molecules on the crystal surface, as confirmed by adsorption measurement. Under the same conditions, PESA additive, showed a high rate of calcium ion complexation and a very low inhibition rate. But, PESA was shown to be a nucleation delayer. Mixing PESA and PASP can gave nucleation retardation of about 19 h, which approximates the 24 h water residence time in industrial cooling circuits, as well as almost 90% calcium carbonate crystal growth inhibition. This synergy offers promising prospects for preventive scaling treatment.