O. J. Ijabo and S. V. Irtwange
Four physical properties of RHA, eleven chemical components and maximum moisture up-take were determined at eight relative humidity levels of 30 to 100%. Particle size, bulk density, particle density, specific gravity, loss on ignition and moisture up-take were determined by gravimetric methods in triplicate. The chemical components, except carbon content, were determined using ICPOES. Single factor ANOVA was used for all determinations that were replicated except for maximum moisture uptake where a 5 x 8 two factor experiment was used. All the properties replicated showed significant difference at α = 0.05. That is ash type had effect on all single factor properties while both ash type and relative humidity level affected maximum moisture up-take. All the 23 properties determined were correlated and the results show that maximum moisture up-take in RHA is strongly positively correlated with magnesium oxide and manganese dioxide, fairly correlated with titanium dioxide, but strongly negatively correlated with particle size, alumina, lime and ferric oxide and averagely negatively correlated with phosphorous pentoxide. Fresh dry open heaps of RHA available in rice mills is economical to use as desiccant. Therefore, the cost of sieving RHA from open heaps to reduce the mean particle size should be weighed against direct use in order to obtain maximum benefit when used as a desiccant.
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