戴怡德臺灣大學:化學工程學研究所施雅齡Shih, Ya-LingYa-LingShih2010-06-302018-06-282010-06-302018-06-282008U0001-2707200821084600http://ntur.lib.ntu.edu.tw//handle/246246/187009以磁場抑制熱交換管及鍋爐內結垢的研究已有多年，關於磁場有預防結垢的功用，正反都有報導且意見頗為分歧，其原因可能甚複雜。而工業用水中通常含許有雜質，其對碳酸鈣成核及成長之影響相當顯著，所以雜質可能是原因之ㄧ。有鑑於此，本研究的目的在於探討雜質與磁場的競爭作用。實驗在改變溶液組成，例如亞鐵離子濃度，鍶離子濃度，活性比及過飽和度等探討磁場對文石成長的影響。研究方法是在攪拌槽中，利用帝斯卡磁能防垢器將溶液受磁二十個小時，確定其完全受磁，之後加入天然文石晶種並利用恆鈣離子定組成法來量測其成長速率。 在無磁場作用下，pH為9.0，離子強度為0.018M，離子活性比為5.54，溫度在25οC的條件下，過飽和度為0.73~1.42，文石成長速率接近零。但在同樣的操作條件下，有磁場時文石則會開始成長，其因推測為磁場使溶液中之分子聚集體(cluster)變為親文石狀態。 無磁場時，溶液中有亞鐵離子存在時，文石亦會開始成長，但在較高過飽和下，文石表面容易轉相為方解石晶型；溶液中有鍶離子則會使文石晶種表面轉相為方解石，且少量的鍶離子濃度就有顯著的影響。 磁場與亞鐵離子同時作用時，會使文石加速成長並在高過飽和度時會抑制表面轉相成方解石。有磁場時，亞鐵離子濃度達到0.5ppm時，即可以完全發揮作用，過量無益，且在此濃度下，雜質效應較磁場效應更大。高過飽和度1.42的操作下，磁場與亞鐵離子共同作用比僅有磁場無亞鐵離子時，成長速率可高至4.6倍，且晶種表面維持針狀之文石。 當溶液中有鍶離子時，在磁場作用下文石晶種之成長速率會比無磁場時緩慢許多。鍶離子存在時，磁場無法抑制晶種表面文石之轉相，而溶液中之分子聚集體為親文石狀態，所以成長緩慢。由SEM圖可知晶種在表面皆為轉相之過渡狀態，此期間所測得的成長速率在定量上亦較無意義。 在探討活性比對磁場作用之影響時，發現在R=1.00文石成長速率皆出現特殊情形，相比於R=5.54及R=0.40時成長速率較緩慢，由實驗結果猜測R=1.00為有利方解石之條件。Magnetic treatment device has been installed to suppress the scale formation in heat exchanger and boiler for many years; however, positive and negative effects have been reported. This treatment technique remains controversial, because the scientific mechanism is unclear and may be complicated. The process water generally contains impurities, which would influence the nucleation and growth of CaCO3. For this reason, the aim of this study was to explore the competing effects between the magnetic field and impurityhis report presents a study of how the solution conditions, including iron concentration, strontium concentration, activity ratio, relative supersaturation influence the effectiveness of magnetic field on the growth of aragonite. The solution was pumped through the Descal-A-Matic DC-1 and then back to the tank for 20h to make sure it was fully magnetized. The aragonite growth rates in the jacketed stirred tank were measured using a constant composition method. nder the conditions of pH=9.0, I=0.018M, R=5.54, T=25οC without magnetic field, the aragonite seeds growth rate approached to zero over a wide range of supersaturation (σara=0.73 to1.42). Under the same operating conditions, we found that aragonite started growing in the presence of magnetic field. It is conjectured that the structure of CaCO3 clusters in the supersaturation solution became similar to that of aragonite under the influence of magnetic field.ithout magnetic field and with the same operating conditions, we found that aragonite seeds started growing in the presence of ferrous ion (Fe(Ⅱ)) .But the surface of aragonite seed transformed into calcite morphology at high supersaturation and then stopped growing (i.e., σara> 1.33). In the presence of a small quantity strontium (Sr+2), the aragonite seed surface transformed to calcite and its growth rate is similar to that of calcite. nder the magnetic field, the Fe(Ⅱ) will cause a synergetic effect on the crystal growth of aragonite even at high supersaturation. At σ=1.42, the increasing of aragonite growth rate was about 4.6 fold of that obtained without Fe(Ⅱ). Under the influence of Sr+2, the growth rate of aragonite was significantly lower when the magnetic field was present. It is because the magnetic field were unable to suppress the conversion of aragonite to calcite, and the structure of clusters is similar to aragonite.n the presence of magnetic field, the aragonite growth rate still exhibited a minimum value at R=1.00 as the case without magnetic field. These experimental results suggest that R=1.00 is a condition that favors the formation of clusters with a structure that is similar to calcite in a supersaturated solution.目錄謝………………………………………………… …………..ii文摘要………………………………………………………………iii文摘要…………………………………………..….……..iv錄………………………………………………………….…….vi索引……………………………………………….……............x索引………...………………………………………..……...….xv一章 緒論…...………………………………………………...1二章 文獻回顧…………………………………………………..4-1微溶物系中過飽和度與成核、成長的現象………………….4-2微溶物系晶體的描述……………………………….……..….72-2-1 介穩相與穩定相…………………………………..72-2-2 晶體的型態與外觀………………………………..7 2-3-3 碳酸鈣的多晶型現象……………………………...92-3磁能防垢的理論…….………………..……………………....14-3-1表面效應…...……......……………..………………….14 2-3-2勞侖茲力效應……...………………………19-4磁場對碳酸鈣結晶的影響…..…………………………….…26 2-4-1磁場對碳酸鈣成長及成核的影響…………………....26-4-2磁場對碳酸鈣晶型的影響………………….………...31-5雜質對碳酸鈣結晶型的影響………………………..……….35 2-5-1雜質對碳酸鈣成長及成核的影響……………..……..35-5-2雜質對碳酸鈣晶型的影響…………………………...37三章 原理……………………………………..………………….38-1 各成長條件下實驗藥品用量之決定……..………….…..…38-2 恆鈣離子定組成方法……………….…..…..………………41-3 晶體成長速率的推導…………….…..……..…………42四章 實驗裝置與步驟………………………………..…………...44-1 實驗裝置………………………………………..…………...44-2 實驗藥品………………………………………..…………...49-3 分析儀器………………………………………..…………...50-4 操作原理………………………………………,,…………...51-5 實驗步驟………………………………………..…………...52-6 晶體成長速率之計算…………………………..…………...54-7 注意事項…………………………………...………...56五章 結果與討論………………………….................................57 5-1文石晶種表面結構……………………………..…………….57 5-2在無磁場作用下文石之成長…………………………..…….60 5-3在磁場作用下文石之成長速率…………………………..….61 5-3-1過飽和度效應………………………………….…..….61 5-3-2離子活性比效應……………………………………....64-4雜質存在下文石之成長………………………………………67 5-4-1亞鐵離子效應…………………………………….…...67 5-4-2鍶離子效應 ………………..……………………..….71 5-5磁場與雜質同時存在文石之成長………….…………….…76 5-5-1亞鐵離子濃度固定時過飽和度與活性比效應……...76 5-5-2亞鐵離子濃度效應……………………………….…..81 5-5-3鍶離子濃度效應………………………………….…..83 5-5-4鍶離子濃度固定時過飽和度效應…………….….…..88-6實驗的再現性………………………………………….…..90六章 結論…………………………………………………….….92考文獻……………………………………………………….….....94136 bytestext/htmlen-US雜質磁場亞鐵離子鍶離子活性比impuritymagnetic fieldFe+2Sr+2activity ratiothesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187009/1/index.html