ORIGINAL PAPERAcrylic acidallylpolyethoxy carboxylate copolymeras an environmentally friendly calcium carbonateand iron(III) scale inhibitorJingyi HuangGuangqing LiuYuming ZhouQingzhao YaoYong YangLei LingHuchuan WangKe CaoYahui LiuPeixin ZhangWendao WuWei SunReceived: 25 March 2012/Accepted: 12 September 2012/Published online: 30 October 2012? Springer-Verlag Berlin Heidelberg 2012AbstractA novel environmentally friendly type of cal-cium carbonate and iron(III) scale inhibitor AQn wassynthesized. The anti-scale property of the AQn copolymertoward CaCO3and iron(III) in the artificial cooling waterwas studied through static scale inhibition tests. Theobservation shows that both calcium carbonate and iro-n(III) inhibition increase with increasing the degree ofpolymerization of AQn from 5 to 15, and the dosage ofAQn plays an important role on calcium carbonate andiron(III) inhibition. The effect on formation of CaCO3wasinvestigated with combination of scanning electronicmicroscopy,transmissionelectronmicroscopy,X-raypowder diffraction analysis, and Fourier-transform infraredspectrometer, respectively. Inhibition mechanism is pro-posed that the interactions between calcium or iron ionsand polyethylene glycol are the fundamental impetus torestrain the formation of the scale in cooling water systems.KeywordsScale inhibitor ? Environmentally friendly ?Calcium carbonate ? DisperseIntroductionOpen recirculating cooling water systems are frequentlyused because they not only provide economical heatremoval but also recirculation of water conservation isaccomplished with substantial cost reductions. The coolingwater circulates to operating units where it picks up heatand the resulting warm water is cooled through vaporiza-tion by returning to the cooling tower. Dissolved and sus-pended matter contained in the water is concentrated incooling water recirculation. The precipitation of calciumcarbonate scale on heat transfer surfaces widely occurs,which involves the deposition of an insulating layer ontothe internal walls owing to its inverse temperature-solu-bility characteristics (Xyla et al. 1992; Saleah and Basta2008; Ben Amor et al. 2004). Deposits formation maycause severe corrosion and deterioration of heat exchange.The study of the mechanism of calcium carbonate crystalgrowth inhibition is an important theme for developing aneffective technique to prevent scale formation. The mostcommon and effective method of scale controlling is theuse of chemical additives as scale inhibitors that retard orprevent scale formation even in very small concentrations(Kjellin 2003). Several studies about calcium carbonatescale formation in the absence and presence of inhibitorshave been carried out (Kumar et al. 2010; Zhou et al. 2011;Liu et al. 2011; Suharso et al. 2011; Al Nasser et al. 2011;Zhang et al. 2010).Copolymerhas been used satisfactorily as a specific scaleinhibitor in the circulating cooling water systems developedin the late 1970s (Reddy and Nancollas 1973) because of itsstrong complexation of multifunctional groups and superiordispersion characteristic of macromolecule. This kind ofchemical inhibitors is applied widely in circulating coolingwater treatment contribute to their excellent performancesJ. Huang ? G. Liu ? Y. Zhou (&) ? Q. Yao ? Y. Yang ?L. Ling ? H. Wang ? K. Cao ? Y. Liu ? P. ZhangSchool of Chemistry and Chemical Engineering, SoutheastUniversity, Nanjing 211189, Peoples Republic of Chinae-mail: G. Liue-mail: Y. Zhou ? Q. YaoJiangsu Optoelectronic Functional Materials and EngineeringLaboratory, Nanjing 211189, Peoples Republic of ChinaW. Wu ? W. SunJianghai Environmental Protection Co., Ltd., Changzhou213116, Jiangsu, Peoples Republic of China123Clean Techn Environ Policy (2013) 15:677685DOI 10.1007/s10098-012-0540-zsuch as inhibiting formation of calcium carbonate and cal-cium sulfate scale. In addition, some of them can perform asa metal corrosion inhibitor. With the improvement ofenvironmental consciousness, the content of phosphorus inwater treatment agent has been of rigorous control. Con-cerning over accelerated aquatic eutrophication, the popu-larityofinhibitorscontaininghighphosphorusisdiminishing. As a result, the current trend for inhibitorusage is toward more environmentally friendly greenchemicals. On the other hand, the design or optimization ofthe recycling-water process on an industrial scale demandsa thorough understanding of all the fundamental parametersthat govern the various operations involved. Therefore, theinhibition varying with the solution temperature, pH, andCa2?and Fe2?concentration should be tested.Iron can originate from the feedwater or can developwithin the system through the corrosion of pipes and metalequipment. Ferrous ion, which is soluble in an aqueousmedium, is oxidized to ferric ion. At a low pH of up to about34, the ferric ion is also soluble in an aqueous medium, butat a pH of about 5 and above, it precipitates out in the formof iron hydroxide, that is, Fe(OH)3, or ir