Badr Layla, Sultan Rabih
Department of Chemistry, American University of Beirut, P.O. Box 11-0236, 1107 2020 Riad El Solh, Beirut, Lebanon.
J Phys Chem A. 2009 Jun 18;113(24):6581-6. doi: 10.1021/jp8094984.
We study the factors that affect the morphology of Co(OH)(2) Liesegang rings, in a way to obtain concentric rings with large spacing, upon an appropriate variation in the experimental conditions. Such well-resolved patterns are obtained under optimum conditions: decrease in the concentration of the outer electrolyte, increase in the concentration of both the inner electrolyte and the gelatin in the hosting gel medium, and increase in the strength of a constant radial electric field applied across the pattern domain. The effect of pH on the bands in a 1D Co(OH)(2) Liesegang pattern is also investigated. The initial pH of the diffusing solution plays a central role in altering the band morphology, because the outer electrolyte (NH(4)OH) is a base, strongly affected by the H(+) equilibrium. The number of bands decreases and the interband spacing increases with decreasing pH of the NH(4)OH solution. The pattern morphology in that case is controlled by the NH(4)Cl/NH(4)OH ratio.
我们研究了影响氢氧化钴（Co(OH)(2)）李塞尔环形态的因素，通过在实验条件上进行适当变化，以获得具有大间距的同心环。在最佳条件下可得到如此清晰分辨的图案：降低外部电解质的浓度，增加内部电解质和主体凝胶介质中明胶的浓度，以及增加施加在图案区域上的恒定径向电场强度。还研究了pH值对一维氢氧化钴（Co(OH)(2)）李塞尔图案中条带的影响。扩散溶液的初始pH值在改变条带形态方面起着核心作用，因为外部电解质（NH(4)OH）是一种碱，受H(+)平衡的强烈影响。随着NH(4)OH溶液pH值的降低，条带数量减少且带间距增加。在这种情况下，图案形态由NH(4)Cl/NH(4)OH比例控制。
