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【求助】凝胶形成了，如何保持反应体系pH恒定？
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最近看了些英文文献： 凝胶在几分钟内形成 ，形成的凝胶还要不断搅拌几个小时，这期间用HCl控制pH，保持在4.75。 总觉得这个工艺有问题 （1）既然形成凝胶了，转子可能就转不动了，不能搅拌了，如果还能搅拌的话，得需要较大的转速，转速过大，剪切力过大，就会使凝胶解体。 （2）凝胶不像液体那样容易混匀，而是胶体，加入的盐酸怎样才能均匀分布到各个部位呢。 (3)既然是凝胶，不是溶液，pH计都不能插到凝胶中去，充分接触凝胶，又怎样测得pH是否是 4.75呢？ 不知大家有何高见，怎样理解这个操作过程。 [ Last edited by cyh2010 on 2009-4-28 at 21:22 ] |
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原文如下： 100 mg of HA were dissolved in 20 ml of double distilled water, then PAHy (64 mg) was added to this solution. The reaction mixture was maintained in a thermostatic bath at 37 C and the pH was adjusted to 4.75 by adding HCl 0.1 N solution. Then activating agent EDC was added to the mixture. After EDC addition, gelation occurred in few sec. The obtained gels were stirred at 37 C for 4 h and during this time the value of pH wascontinuously controlled and maintained at 4.75 by using HCl 0.1 N solution. After 4 h, each gel was purified by several washes with double distilled water, centrifuging, from time to time, at 12000 rpm at 4 C for 15 min, then recovered after lyophilization. [ Last edited by cyh2010 on 2009-4-30 at 08:32 ] |
9楼2009-04-30 08:27:35
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