Design of surfactant for water in diesel emulsion fuel for designing eco-friendly fuel

Abstract

Diesel engines are known as one of the biggest contributors to environmental problems caused by exhaust emissions and are the reasons for health hazardous. Nitrogen oxides (NOx) and particulate matters (PM) are the main pollutants from diesel engines. This problem attracts much interest regarding the development of eco- friendly fuels for the enhancement of the environment and human health. The use of water in diesel emulsion fuel with proper surfactants as a stable system can be proposed as an alternative to solve the problem. Selection of the appropriate surfactants is a very crucial task to obtain stable emulsion. Trial and error approach through experimental work is the conventional method to find the suitable surfactant as emulsifier for water in diesel emulsion. It is typically time consuming, costly and difficult to obtain the optimal target properties. The objective of this study is to design appropriate surfactants that can be used as emulsifiers for the formulation of water in diesel emulsions fuel using product design approach. There are four steps involved in this research. Step 1 is the problem definition. The surfactant problem is defined where the product attributes and needs are identified and translated to physico-chemical properties as the target properties and the target value of the target properties are set. There are four properties chosen as the target properties, which are surface tension, hydrophilic-lipophilic balance, critical micelle concentration and cloud point. Step 2 is the identification of pure component property. The property model for pure component is identified. Step 3 is designing the surfactants. In this step, the non-ionic surfactant database is screened and the chemical that does not fulfil the target properties will be eliminated. Step 4 is the selection of the surfactant. All the candidates fulfilled the target properties set in step 1. The price of the chemical will be used as criteria to choose the potential candidates. From 197 chemicals’ candidates from the chemical database library, two candidates are suggested as the potential surfactants for water in diesel emulsion fuel. These chemicals are propylene glycol stearate and polyoxyethylene (2) stearyl ether. These two chemicals had fulfilled all the target values of the target properties. The price of these chemicals are 16 times cheaper than the most common surfactant used for water in diesel emulsion fuel, which is SPAN 80.