%0 Journal Article
%T Particle Size Variation and Prediction of Molecular Weight of Bi(III) Hydrolyzed Polymer Using Light Scattering Technique
%A N. Priyadarshini
%A M. Sampath
%A Shekhar Kumar
%A U. Kamachi Mudali
%J ISRN Inorganic Chemistry
%D 2013
%R 10.1155/2013/194120
%X The present paper gives an overview of the hydrolysis reactions up to colloid formation of Bi(III) in aqueous nitric acid medium using light-scattering measurements. The hydrolysis products of Bi were polynuclear complexes such as dimers, pentamers, and the most important is the hexameric species. In the present investigation Bi3+ polymers were prepared by diluting different concentrations of Bi(NO3)3¡€5H2O solutions to pH 1£¿¡À£¿0.1 by adding 0.1£¿M NaOH solution as it starts to precipitates at pH 1.4. The degree of polymerization was found to be 5-6£¿units. Particle size measurements were performed, and it has been found that particle size increases at high concentration of Bi due to aggregation. Refractive index measurements were also performed. The molecular weight of hydrolyzed polymeric species of Bi was determined by using Debye plot, and it was estimated as 1236 Da. The second virial coefficient was found to be 6.24£¿¡Á£¿10£¿3£¿mLg£¿1 Da. The present investigation confirms that the predominant complex in the solution has 5-6 Bi atoms. 1. Introduction Among numerous reactions that govern the chemical behavior of metal ions in aqueous medium, the knowledge of hydrolysis, colloid formation, and precipitation is of highest priority. In general, metal ions in aqueous solutions form a variety of hydrolysis complexes, such as mono- and polynuclear hydroxospecies [1]. The polynuclear complexes are formed followed by hydrolysis, and in general it can be represented as The pH is the most governing factor where soluble hydrolysis species are present. It is limited due to the formation of colloids or precipitation of hydroxides and oxides. Aqueous chemistry of Bi is primarily dominated by trivalent complexes [2]. readily hydrolyzes in aqueous solutions ( ) and has high affinity to oxygen. In addition to that Bismuth is a strong Lewis acid and begins to undergo hydrolysis at low pH values ( ) [3, 4]. The aqua ion has been characterized using many techniques which includes extended X-ray absorption fine structure (EXAFS) and low angle X-ray scattering (LAXS) spectroscopy and concluded that 8 water molecules are coordinated to . But dynamic simulations show that the number of coordinated water molecules is 9 (i.e., ) and is found analogous to structures found among lanthanides [5]. Numerous studies on hydrolysis of Bi show that the predominant species at higher concentration is . It has been widely agreed that the hydrolyzed species of Bi are polymeric existing as dimers , pentamers , and the most important among them is the hexameric species at moderate Bi concentrations
%U http://www.hindawi.com/journals/isrn.inorganic.chemistry/2013/194120/