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Research on Performance Evaluation and Anti-scaling Mechanism of Green Scale Inhibitors by Static and Dynamic Methods

Abstract : Increasing environmental concerns and discharge limitations have imposed additional challenges in treating process waters. Thus, the concept of "Green Chemistry" was proposed and green scale inhibitors became a focus of water treatment technology. Finding some economical and environmentally friendly inhibitors is one of the major research focuses nowadays. In this dissertation, the inhibition performance of different phosphonates as CaCO3 scale inhibitors in simulated cooling water was evaluated. Homo-, co-, and ter-polymers were also investigated for their performance as Ca-phosphonate inhibitors. Addition of polymers as inhibitors with phosphonates could reduce Ca-phosphonate precipitation and enhance the inhibition efficiency for CaCO3 scale. The synergistic effect of polyaspartic acid (PASP) and Polyepoxysuccinic acid (PESA) on inhibition of scaling has been studied using both static and dynamic methods. Results showed that the anti-scaling performance of PASP combined with PESA was superior to that of PASP or PESA alone for CaCO3, CaSO4 and BaSO4 scale. The influence of dosage, temperature and Ca2+ concentration was also investigated in simulated cooling water circuit. Moreover, SEM analysis demonstrated the modification of crystalline morphology in the presence of PASP and PESA. In this work, we also investigated the respective inhibition effectiveness of copper and zinc ions for scaling in drinking water by the method of Rapid Controlled Precipitation (RCP). The results indicated that the zinc ion and copper ion were high efficient inhibitors of low concentration, and the analysis of SEM and IR showed that copper and zinc ions could affect the calcium carbonate germination and change the crystal morphology. Moreover, the influence of temperature and dissolved CO2 on the scaling potential of a mineral water (Salvetat) in the presence of copper and zinc ions was studied by laboratory experiments. An ideal scale inhibitor should be a solid form compound having a very low solubility, but the value of this solubility is big enough to ensure a total scaling inhibition. A new type of scale inhibitor we synthesized possesses these properties. In fact, the synthesized inhibitor has a very poor solubility (about 1.5 mg/L) at 20°C for Paris's tap water. Its anti-scaling properties have been evaluated by RCP method. A complete scaling inhibition was obtained with a concentration of 30 µg/L (ppb) for Salvetat water at 30°C. Moreover, the introduction of the synthesized solid inhibitor to a water system can be easily realized by using a cartridge.
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Submitted on : Sunday, October 30, 2011 - 8:57:16 AM
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  • HAL Id : pastel-00637079, version 1

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Dan Liu. Research on Performance Evaluation and Anti-scaling Mechanism of Green Scale Inhibitors by Static and Dynamic Methods. Environmental Engineering. Ecole nationale supérieure d'arts et métiers - ENSAM, 2011. English. ⟨NNT : 2011ENAM0025⟩. ⟨pastel-00637079⟩

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