采用电化学石英晶体微天平研究碳酸钙垢生长规律及阻垢剂的影响

Studies on the Scaling Pattern of Calcium Carbonate and the Influence of Scale Inhibitor by Using Electrochemical Quartz Crystal Microbalance Technique

为深入分析碳酸钙垢生长规律和阻垢剂对垢生长动力学的影响,使用电化学石英晶体微天平(EQCM)快速测垢的方法研究了施加的恒电压、温度、Ca^(2+)浓度对碳酸钙(CaCO_3)结垢的影响,评价了羟基乙叉二膦酸(HEDP)、膦酰基羧酸(POCA)和氨基三甲叉膦酸(ATMP)3种阻垢剂的阻垢性能,并对结垢过程进行了分段线性拟合。结果表明,随电压、温度和Ca^(2+)浓度的增大,CaCO_3结垢速率增大,其中电压的影响最大;在50℃时,结垢量随阻垢剂浓度的增加而降低;HEDP的最佳加量为5数10 mg/L,POCA和ATMP的较优加量为20 mg/L;在阻垢剂加量为10 mg/L的条件下,CaCO_3结垢过程中的结垢量—时间曲线出现3个阶段:结垢阶段、阻垢剂的扩散和不稳定作用阶段、阻垢剂稳定作用阶段;通过数据拟合得到反映两个稳定沉积过程的线性动力学方程,以斜率k值表征其结垢动力学参数,按加入阻垢剂前后的k值之差与未加入阻垢剂k值的比值计算POCA、HEDP和ATMP的阻垢效率分别为98.50%、93.86%和97.23%,扩散时间分别为1021、622和537 s,ATMP的阻垢效果最好。

In order to analyse the growth behavior and the influence of scale inhibitor on it,electrochemical quartz crystal microbalance（EQCM） was used to measure the scaling process rapidly. The effect of applied potential,temperature and the concentration of Ca2 ＋on the scaling of Ca CO3 was studied. Additional evaluating of scaling inhibition properties of three scale inhibitors,such as 1-hydroxyethylidene-1,1-diphosphonic acid（HEDP）,copolymer of phosphono and carboxylic acid（POCA）and amino trimethylene phosphonic acid（ATMP）was conducted. Partial fitting of scaling curve was also carried out. The results showed that the scaling rate increased with the increase of potential,temperature and the concentration of Ca2 ＋. Particularly,polarization potential had remarkable impact on the scaling process. The total scaling amount decreased with the increase of scale inhibitor concentration at 50℃. The optimum dosage for HEDP was 5—10 mg/L,while 20 mg/L for POCA and ATMP respectively.There were three stages of the scaling curve with 10 mg/L dosage of scale inhibitor,such as scaling,the diffusion of scale inhibitor and stable stage. Two stable depositing process equations were obtained by fitting the experimental data,and the slope value k standed for the kinetic parameter of scaling. The inhibition efficiency of POCA,HEDP and ATMP was calculated as 98.50%,93.86% and 97.23%,with the diffusion time of 1021,622 and 537 s,respectively,by regarding the deviation of k before and after adding the scale inhibitor. ATMP had the best inhibition performance among three scale inhibitors.