Umudike Journal of Engineering and Technology

Sulphuric acid H₂SO₄ and water H₂O were mixed within concentration range of 0 to 100 wt% H₂SO₄ and the corresponding quantities of heat (enthalpy change) of mixing were quantified at various constant compositions and temperatures at one atmosphere (pressure). The heats of mixing were evaluated at intervals of 10 wt% from 0 to 60 wt%; 5 wt% from 65 to 75 wt%; 1 wt% from 75 to 85 wt% and 2 wt% from 90 to 100 wt% H₂SO₄. The equation for the enthalpy change of mixing for binary liquid mixtures was used to evaluate the heats of mixing at different compositions. A plot of heat of mixing against composition at different temperature indicated that maximum heats of mixing occurred within the concentration range of 70 to 77 wt% H₂SO₄. Within this range, maximum and minimum heats of mixing of -12207.8kJ/kmole and -1155.7kJ/kmole occurred with 76 wt% H₂SO₄ at temperatures of 0^oC and 96^oC respectively. Therefore, maximum heat for dealumination of kaolin clay can be obtained from sulphuric Acid-Water system within the range of 70 to 77 wt% of sulphuric acid.