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hpf5132001Òø³æ (СÓÐÃûÆø)
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the oxygen mono-coordinated titanium, pK1 for >Ti-OH2+ ¡ú >Ti-OH + H+ is 2.60, pK2 for >Ti-OH ¡ú > Ti-O- + H+ is 9.00 while for oxygen di-coordinated titanium, the pK2 value for. >Ti2=OH¡ú >Ti2=O- + H+ is 5.50. It can be seen when the acidity of the medium is less than pH 4, the bridging group >Ti2OH was fully in the molecular form. The surface charge of the column mainly stemmed from the species of >TiOH2+. In this case, an EOF might be reversal. At pH over the range from 4 to 7, the terminal group on the coated material is >TiOH. The surface charge might originate from the dissociation of the bridging group >Ti2OH but at pH 4¨C5.5, only a little current was found. Much less surface charge is probably the reason, since its pK value is 5.50. At pH above 6, anodic EOF was switched into cathodic EOF due to the presence of highly dissociated >Ti2OH. A buffer region was observed at pH around 9. This corresponds to the pK2 value of the terminal >TiOH group. Ï£Íû¸÷λ³æÓѰïÎÒ¿´¿´£¬°Ñ´óÖµÄÒâ˼дÏÂÀ´¾Í¿ÉÒÔÁË£¬²»Ê¤¸Ð¼¤£¡ |
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ganguihua1983
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hpf5132001(½ð±Ò+2,VIP+0):bdxcb
hpf5132001(½ð±Ò+3,VIP+0):wertgwetw
hpf5132001(½ð±Ò+2,VIP+0):bdxcb
hpf5132001(½ð±Ò+3,VIP+0):wertgwetw
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Ñõµ¥Ðµ÷îÑ£¬Îªpk1 >Ti-OH2+ ¡ú >Ti-OH + HÊÇ2.60 £¬ pk2>Ti-OH ¡ú > Ti-O- + H+ÊÇ9.00 £¬¶ø¶ÔÓÚÑõµ¥Ðµ÷îÑ£¬ p k2ºÜÓмÛÖµ¡£>Ti2=OH¡ú >Ti2=O- + H+ ÊÇ5.50 ¡£ ¿ÉÒÔ¿´³ö£¬µ±ÌåϵµÄPH<4£¬ÄÇôÇÅÁ¬»ùÍÅ>Ti2OHÖ÷ÒªÊÇÒÔ·Ö×ÓµÄÐÎʽ´æÔÚ.ͨµÀ±íÃæµÄµçºÉ·¢ÉúÄæ×ªÓÉÓÚTiOH2+¡£ÔÚÕâÖÖÇé¿öÏ£¬µçÉøÁ÷·¢Éú·´Ïò¡£µ±pH³¬¹ý4-7Õâ¸ö·¶Î§Ê±£¬Í¿²ã±íÃæµÄ»ùÍžÍÊÇ >TiOHÁË¡£Í¨µÀ±íÃæµÄµçºÉ¿ÉÄÜÖ÷ÒªÀ´×Ô>Ti2OHµÄµçÀ룬µ«ÔÚ pH 4¨C5.5ʱֻÓÐ΢ÈõµÄµçÁ÷¡£±íÃæµçºÉÈç´ËÉÙµÄÔÒò¿ÉÄÜÊÇÒòΪ pK ÖµÊÇ 5.50. ÔÚ pH ³¬¹ý 6, ÓÉÓڸ߶ȵçÀëµÄTi2OHµÄ´æÔÚÑô¼«µÄµçÉøÁ÷ת±äΪÒõ¼«µÄµçÉøÁ÷¡£. ¿¼²ìÁË pH ÔÚ9×óÓҵĻº³åÒº. ÕâÏàÓ¦ÓÚ pK2 ʱµÄTiOH¡£ ²»ÊǺܶ® |
8Â¥2007-10-12 19:45:50
hobbyzhang
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hpf5132001(½ð±Ò+2,VIP+0):¹ÄÀø
hpf5132001(½ð±Ò+2,VIP+0):¹ÄÀø
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It can be seen when the acidity of the medium is less than pH 4, the bridging group >Ti2OH was fully in the molecular form. ¿ÉÒÔ¿´³ö£¬µ±ÌåϵµÄËá¶ÈÖµµÍÓÚPH=4£¬ÄÇôÇÅÁ¬»ùÍÅ¡·Ti2OHÖ÷ÒªÊÇÒÔ·Ö×ÓµÄÐÎʽ´æÔÚ¡£ ºÃÄÑ Ã»ÓÐÉÏÏÂÎÄ ²»ºÃ·Òë |

2Â¥2007-10-12 18:00:26
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hpf5132001(½ð±Ò+1,VIP+0):¹ÄÀø
hpf5132001(½ð±Ò+1,VIP+0):¹ÄÀø
Ñõµ¥Ðµ÷îÑ£¬Îªpk1 >îÑoh2 + ¡ú >îÑŶ+ÇâÀë×ÓÊÇ2.60 £¬ pk2¹©>îÑŶ¡ú >îÑ-ÁÚ+ÇâÀë×ÓÊÇ9.00 £¬¶ø¶ÔÓÚÑõÆøæ·-е÷îÑ£¬ p k2¼ÛÖµ¡£ > ti2 =Ŷ¡ú > ti2 =ÁÚ+ÇâÀë×ÓÊÇ5.50 ¡£¿ÉÒÔ¿´³ö£¬µ±Ëá¶ÈÖеȵÍÓÚphֵΪ4 £¬ÇŽÓ×é> ti2ohÍêÈ«ÔÚ·Ö×ÓÐÎʽ¡£±íÃæµçºÉµÄרÀ¸£¬Ö÷ÒªÀ´×ÔÖÖ> tioh2 + ¡£ÔÚÕâÖÖÇé¿öÏ£¬Ò»¸öeofµÄ¿ÉÄÜÄæ×ª¡£ÔÚphÖµ³¬¹ý·¶Î§£¬´Ó4ÈÕÖÁ7ÈÕ£¬ÂëÍ·×é¶ÔÍ¿²ã²ÄÁÏ> tioh ¡£±íÃæµçºÉ¿ÉÄÜÔ´ÓÚÀëÇŽÓ×é> ti2ohµ«ÔÚphÖµ4-5.5 £¬Ö»ÊÇÒ»¸öСµçÁ÷±»·¢ÏÖ¡£Éٵöà±íÃæµçºÉ¿ÉÄÜÊÇÔÒò£¬ÒòΪËüµÄpkֵΪ5.50 ¡£ÔÚphÖµ¸ßÓÚ6 £¬Ñô¼«eofµÄÊÇÇл»µ½Òõ¼«eofµÄÒòΪ´æÔڸ߶ȷÖÀëÐÔ> ti2oh ¡£Ò»¸ö»º³åÇøÓò£¬¹Û²ìÔÚphֵԼΪ9 ¡£ÕâÏ൱ÓÚ¸Ãpk2¼ÛÖµµÄÖÕ¶Ë> tioh×é¡£ |
4Â¥2007-10-12 19:02:07
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5Â¥2007-10-12 19:12:24













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