摘要
本文初步探讨了不同pH、离子强度及电解质种类对纳米氧化锌（ZnO NPs）稳定性（聚集沉降和溶解）的影响.沉降实验表明,pH越靠近零电荷点（-pH9.2）,ZnO NPs聚集体尺寸越大,沉降速度越快,稳定性越低;中性pH条件下,随着离子强度的增加,ZnO NPs ζ电位绝对值减小,聚集体尺寸相应变大,沉降速度加快,稳定性降低.中性pH时ZnO NPs ζ电位为正值,阴离子较阳离子更易使ZnO NPs聚集沉降,且SO2-4的影响远大于Cl-.溶解实验显示,pH2—11,Zn2＋都会释放到溶液中,pH〉7.5,ZnO NPs溶解量〈5%;pH〈6,超过60%的Zn2＋释放到溶液中.中性条件下,离子强度越高,ZnONPs越易溶解,且Ca2＋对纳米氧化锌溶解的促进作用强于Na＋.这表明离子对纳米氧化锌溶解的促进可能源于阳离子与颗粒表面的离子交换机制.
Because of the widespread production and utilization,zinc oxides nanoparticles（ ZnO NPs） are inevitably released into soil and may generate adverse biological effects on organisms. The stability of ZnO NPs significantly affects their mobility and ecotoxicity and thus has been widely concerned. This study assessed the stability（ aggregation,sedimentation and dissolution） of ZnO NPs influenced by different pH,ionic strength and electrolyte type. The results of sedimentation experiment showed that the absolute zeta potential decreased when the pH of nanoparticles suspension was closer to point of zero change（ - pH 9. 2）,which resulted in larger aggregate size,faster sedimentation and lower stability of ZnO NPs. Absolute zeta potential of ZnO NPs decreased with the increase of ionic strength,which led to larger particle size and faster sedimentation rate of ZnO NPs in neutral pH. Due to the positive charge on the surface,the influence of anions on ZnO NPs aggregation was more significant than that of cations,and the effect of SO2-4was greater than that of Cl-. The results of dissolution experiments showed that zinc ions could be released into the aqueous phase at pH from 2 to 11. When pH was higher than 7. 5,less than 5% of zinc was released,while when pH was lower than 6,over 60% of zinc was released. The dissolution of ZnONPs was investigated under the condition of different electrolyte types at neutral pH. The results indicated that the solubility of ZnO NPs increased with ionic strength,and the effect of Ca2 ＋on the dissolution of ZnO NPs was greater than that of Na＋. This result implied that ion exchange between cations and zinc ions on the surface of ZnO NPs might have facilitated the dissolution of the nanoparticles.
出处
《环境化学》
CAS
CSCD
北大核心
2014年第11期1821-1827,共7页
Environmental Chemistry
基金
国家自然科学基金重点项目(41230858)
国家自然科学基金面上项目(41171248)资助
关键词
纳米氧化锌
离子强度
PH
聚集
溶解
zinc oxides nanoparticles
ionic strength
pH
aggregation
dissolution
