Please answer all the above questions correctly providing necessary, formulae, equations, expressions, diagrams, charts, graphs, tables and plots.

1. a) What is bimodal solubility curve in liquid- liquid extraction process? Explain the types of liquid- liquid equilibrium and explain the significance of plait point with a neat diagram? 5+3+2=10 b) A feed of 100kg/min of 1.2wt% mixture of acetic acid in water is to be extracted with 1-butanol at 1atm and 26.7C. The desired outlet concentration in the exiting stream is 0.1wt% of acetic acid The solvent of pure 1-butanol is fed contercurrently to the feed with the flow rate of 75kg/min Determine the composition of the exiting 1-butanol phase (i.e. the extract phase). Also find the number of equilibrium contacts (stages) needed. The equilibrium relation at 26.7C is y=1.613x 15 2. a) Briefly discuss the characteristic features of solvent for its application in liquidliquid extraction process and mention the significance of 'critical solution temperature'. 6+4=10 b) Describe with neat diagram the design equation of fixed bed adsorption column using the concept of mass transfer zone, break through point and length of unused bed. 5+4+6=15 [ Turn over 3. a) Explain the effect of temperature on different types of liquid- liquid equilibrium. 5 (b) Mention the design calculations for a single stage mixer settler device using equilibrium plot on equilateral triangular coordinates 5 c) Breakthrough data of acetone in air flowing through a bed of adsorbent are given in Table 1. Calculate (i) Breakthrough time if breakthrough concentration is 2.5% of feed concentration. (ii) The velocity of stoichiometric front and fraction of bed utilised. (iii) The length of unused bed