Studying Deliquescent Relative Humidity Lowering in Mixtures of Five Fertilizer Ingredients Using Mixture Experiments and a Special Cubic Equation

Dian Yulianto1,5

Supa Wirasate2,5

Chakrit Sirisinha‬2,3

Manthana Jariyaboon2,5

Soranat Raibhu2,4,Email

1Materials Science and Engineering Program, Faculty of Science, Mahidol University, Nakhon Pathom, 73170, Thailand.

2Department of Chemistry, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.

3Rubber Technology Research Centre, Faculty of Science, Mahidol University, Nakhon Pathom, 73170, Thailand.

4Department of Industrial Engineering, Faculty of Engineering, Mahidol University, Nakhon Pathom, 73170, Thailand.

5Centre for Surface Science and Engineering, Faculty of Science, Mahidol University, Nakhon Pathom, 73170, Thailand.

Abstract

The lowering phenomenon of deliquescent relative humidity (DRH) in the binary to the quinary systems were studied. Gravimetric moisture sorption isotherm (MSI) experiments were employed to obtain data for estimating DRH. A special cubic model was constructed for the purpose of predicting DRH. The equation took into account all the significant effects including ingredients, all the binary interactions, and one ternary interaction. It gave relatively accurate predictions with an average relative deviation of 1.8% compared to values between 2.3% and 32.4% for equations reported elsewhere. DRH lowering occurred in all possible combinations of the ingredients, and the magnitudes of DRH lowering were exceptionally high when urea was present together with one or more deliquescent ingredients. Despite its insoluble nature, kaolin-based filler also caused DRH lowering, but its presences in the quaternary and quinary systems helped alleviated DRH lowering that were caused by other ingredients.

Studying Deliquescent Relative Humidity Lowering in Mixtures of Five Fertilizer Ingredients Using Mixture Experiments and a Special Cubic Equation