The study about the adsorption of phosphate on four variable charge soils and some minerals revealed that two stage adsorption appeared in the adsorption isotherms of phosphate on 4 soils and there was a maximum adsor...The study about the adsorption of phosphate on four variable charge soils and some minerals revealed that two stage adsorption appeared in the adsorption isotherms of phosphate on 4 soils and there was a maximum adsorption on Al-oxide-typed surfaces between pH 3.5 to pH 5.5 as suspension pH changed from 2 to 9, but the adsorption amount of phosphate decreased continually as pH rose on Fe-oxide typed surfaces. The adsorption amount of phosphate and the maximum phosphate adsorption pH decreased in the order of yellow-red soil > lateritic red soil > red soil > paddy soil, which was coincided with the content order of amorphous Al oxide. The removement of organic matter and Fe oxide made the maximum phosphate adsorption pH rise from 4.0 to 5.0 and 4.5, respectively. The desorption curves with pH of four soils showed that phosphate desorbed least at pH 5. Generally the desorption was contrary to the adsorption with pH changing. There was a good accordance between adsorption or desorption and the concentration of Al in the suspension. The possible mechanisms of phosphate adsorption are discussed.展开更多
文摘The study about the adsorption of phosphate on four variable charge soils and some minerals revealed that two stage adsorption appeared in the adsorption isotherms of phosphate on 4 soils and there was a maximum adsorption on Al-oxide-typed surfaces between pH 3.5 to pH 5.5 as suspension pH changed from 2 to 9, but the adsorption amount of phosphate decreased continually as pH rose on Fe-oxide typed surfaces. The adsorption amount of phosphate and the maximum phosphate adsorption pH decreased in the order of yellow-red soil > lateritic red soil > red soil > paddy soil, which was coincided with the content order of amorphous Al oxide. The removement of organic matter and Fe oxide made the maximum phosphate adsorption pH rise from 4.0 to 5.0 and 4.5, respectively. The desorption curves with pH of four soils showed that phosphate desorbed least at pH 5. Generally the desorption was contrary to the adsorption with pH changing. There was a good accordance between adsorption or desorption and the concentration of Al in the suspension. The possible mechanisms of phosphate adsorption are discussed.
文摘目的研究3种沉淀抑制剂(PPI)羟丙基甲基纤维素K4M(Hydroxypropyl methyl cellulose K4M,HPMC K4M)、醋酸羟丙甲纤维素琥珀酸酯MG(Hypromellose Acetate Succinate MG,HPMC AS MG)、聚乙烯己内酰胺-聚醋酸乙烯酯-聚乙二醇接枝共聚物(Polyvinylpyrrolidone,Soluplus)对临床口服剂量下pH值诱导延胡索乙素(dl-THP)过饱和相行为的影响。方法绘制dl-THP的pH值-溶解度相图和p H值转换过程中的去过饱和曲线,用溶解度相图佐证dl-THP相行为,以质量浓度-时间曲线下面积和过饱和度为指标分析沉淀抑制剂对dl-THP相行为的影响;采用偏振光显微镜、差示扫描量热法分析沉淀性质。结果临床给药剂量下,dl-THP在pH值转换过程中最大过饱和度为3.93,随时间推移失去过饱和;HPMC K4M、HPMC AS MG、Soluplus在pH值转换180 min内均能维持过饱和度。HPMC K4M、HPMC AS MG、Soluplus在浓度5%时维持过饱和度分别为1.19、1.89、1.36,浓度20%时为1.30、2.35、1.86、浓度50%时为1.30、2.60、2.07。偏振光显微镜和差示扫描量热法结果表明产生结晶沉淀。结论沉淀抑制剂均能改善pH值诱导延胡索乙素过饱和相行为,且这种改善行为随沉淀抑制剂种类和浓度的不同而不同,HPMC AS MG作用效果最佳。
