四溴双酚A的水溶性与辛醇/水分配系数及其影响因素初探

WATER SOLUBILITY AND OCTANOL/WATER PARTITION BEHAVIOUR OF TETRABROMOBISPHENOL A

用摇瓶法研究了pH值和金属离子对四溴双酚A(TBBPA)表观溶解度(S*w)的影响,并以摇瓶法考察了TBBPA在辛醇/水体系的分配行为,以及pH、pH与腐殖酸复合作用对分配行为的影响.结果表明,TBBPA表观溶解度受pH控制,在酸性条件下(pH<6.0)TBBPA水溶解度为0.15mg.l-1,随着pH值增加,TBBPA逐渐解离,表观溶解度变大,pH在6.5—7.5范围内其S*w-pH曲线呈指数增长趋势,pH7.5左右Sw*-pH曲线发生突变,pH8.5后增长趋势平缓,pH9.1时表观溶解度为26.5mg.l-1.金属离子在pH值介于6.5—7.5之间会增大TBBPA的表观溶解度,pH8.0后增溶作用减小.TBBPA的辛醇/水分配系数(lgKow)为5.20,随pH值增大,TBBPA倾向于进入水相,pH值介于7.0—8.0时表观辛醇/水分配系数(lgDow)随pH值增大以近线性趋势减小,且由此求得TBBPA的pKa1=7.2;腐殖酸能增大TBBPA的亲水性,且这种影响跟pH值和腐殖酸浓度有关,低浓度腐殖酸对TBBPA亲水性影响不大,随着腐殖酸浓度增大,TBBPA的亲水性显著增大了,但这种由腐殖酸浓度引起的TBBPA亲水性差异随pH值增大而缩小.

The effect of metal ions and pH on the apparent water solubility （S＊w） of tetrabromobisphenol A （TBBPA） was studied using batch equilibrium technique. Shake-flask method was used to study the partition of TBBPA between octanol and water system under different pH and different concentrations of humic acid （HA）.The results showed S＊ wof TBBPA was about 0.15mg·l^-1 at pH〈6.0. The S＊w-pH curve showed exponential growth as the pH increased from 6.5 to 7.5. At pH〉7.5,S＊w increased moderately with pH,and S＊w was found to be 26.5 mg·l^-1 at pH 9.1.Metal ions enhanced TBBPA＇s S＊ wbetween pH 6.5 and 7.5,while the effectiveness of metal ions in enhancing S＊ wof TBBPA decreased at pH 8.0.Octanol/water partition coefficient （lgKow） of neutral forms of TBBPA was 5.20. When pH range from 7.0 to 8.0,the apparent octanol/water partition coefficient of TBBPA （lgDow） decreased linearly with increaseing pH,indicating TBBPA tended to partition into the aqueous phase due to the dissociation of TBBPA. The enhancement of TBBPA hydrophilicity was affected by the concentration of humic acid and pH.TBBPA＇s hydrophilicity was increased at high concentrations of HA. However,the effect of humic acid concentration on enhancing TBBPA hydrophi-licity was weaken as pH increased.