The mechanically strong robust superhydrophobic composite coatings was developed using environmentally friendly biocompatible carnauba wax and phenyltriethoxysilane to fabricate super hydrophobic cotton fabrics through suspension technique in order to utilize them for wide range of applications. The carnauba wax and phenyltriethoxysilane (PTES) were used to modify the surface of cotton to obtain the biomass-based porous materials with super-hydrophobicity, which will provide significantly lower surface free energy and micro/nano-scaled structures. The incorporation of PTES contributes to enhanced surface morphology and mechanical stability due to its inherent tri-functional cross-linking behavior. The mechanical stability and hydrophobic behavior of the carnauba composite coatings are influenced by the concentrations of the constituent materials. The maximum value of water contact angle was obtained about 175° by changing the concentrations of the constituent materials. The developed porous materials can be used to separate oil-water emulsion efficiently and possess strong heavy oil absorption capabilities with repeated cycles. Development of bio-materials coated cotton hydrophobic filter will be considered as cutting-edge concept in the field of oil-water separation to recover oil-spill and to protect environment.