Extractive spectrophotometric and inductively coupled plasma atomic emission spectrophotometric determination of titanium by using dibenzo-18-crown-6.
Dibenzo-18-crown-6 (DB18C6) is used for the liquid-liquid extraction, and recovery of titanium from paints, pigment, paper and pulp industries. The extraction mechanism of titanium(IV) from pH 4 medium with DB18C6 in dichloromethane was investigated. The DB18C6 concentration in organic phase, the concentration of titanium, the effect of pH and interference ions such as Mo(6+), V(5+), Nb(5+), Ta(5+), Zr(4+), Fe(3+), etc. in the aqueous phase and the temperature on the distribution coefficient for the Ti(IV) have been examined. The titanium was determined by spectrophotometric and inductively coupled plasma atomic emission spectroscopic (ICP-AES) method. Titanium forms a colourless complex with DB18C6 at pH 4.0 which is extracted with dichloromethane having molar absorptivity 1.53x10(4) lmol(-1)cm(-1) at 285 nm. It obeys Beer's law in the range of 0.16-3.84 ppm of titanium. The colour was developed with thiocyanate which has molar absorptivity 1.50x10(3) lmol(-1)cm(-1) at 425 nm. The extract is directly inserted in the plasma for ICP-AES measurement, which enhance the sensitivity several folds and the limits for estimation are 0.5-30 ngml(-1). The overall formation (logbeta(2)K'e) and extraction (K(ex)) constants calculated are 18.61+/-0.02 and 1.03+/-0.03x10(-10), respectively. The transportation of titanium has been discussed. The titanium is preconcentrated and determined in standard and environmental samples.
Agrawal
Y K
YK
Chemistry Department, School of Sciences, Gujarat University, Ahmedabad 380 009, India.
Sudhakar
S
S