Development of an adsorbent for the remediation of crude oil polluted water using stearic acid grafted coconut husk (Cocos nucifera) composite

Abstract

With increasing crude oil contamination scenes reported around the globe, highly promising materials are important to remove crude oil from water bodies for safeguarding the public health, aquatic life and sustaining agricultural activities. In this work, we have prepared agro-based material (Cocos nucifera husk) composite with high surface area and well-ordered framework of porosity for crude oil removal. Material characterization was carried out to expose the nature of the composite prepared and its affinity to oil sorption. Adsorption studies were evaluated in batch mode with the function of oil-water ratio, temperature, time and pH as well as reuse with suitable eluent. High adsorption efficiency was exhibited by the composite at low pH as the surfaces were predominantly positive at 0.05 mol/dm3 and 0.10 mol/dm3. Differential thermo gravimetric analysis (DTA) revealed that esterified coconut husk (CHs) was thermally stable at 432.7 °C. In addition, the composite demonstrated good potential as adsorbent with 96.4% crude oil removal after 50 mins at 0.2 g/100cm3. The adsorption isotherm data were well fitted to the Langmuir isotherm model as expected from the structural homogeneity of the conjugated material with maximum adsorption capacity of 69.86 mg/g. The experimental kinetic data were adequately matched by pseudo-second order kinetic model (R2 ≥ 0.99). Crude oil was eluted from the composite with ethanol and regenerated to the original pattern. The regenerated material exhibited the same functionality and was used successively in several adsorption -elution-reuse-cycle. Therefore, the newly developed composite material is an interesting, efficient and economic sustainable material.

Keywords

• Coconut husk
• Adsorption
• Crude oil
• Esterification
• Regeneration