(371e) Grafted Nanopyroxene for the Removal of Polar Organic Compounds from Produced Wastewater

A large amount of water is needed for bitumen extraction processes and, subsequently, a significant amount of Oil Sand Process-affected Water (OSPW) is produced and discharged into tailing ponds. The OSPW contains organic compounds such as Naphthenic Acid (NA), which is considered the main organic pollutant occurring naturally in tailing ponds. The removal of NA from OSPW has been of paramount importance in order to meet government environmental regulations and has been challenging due to its high solubility in water, which in turn makes it resistant to the conventional oil water separation processes. The current technologies used for the removal of NA present several shortcomings, such as high capital requirements and operating costs, and they are largely ineffective in meeting government regulations. Despite the fact that the adsorption process is promising for the removal of dissolved contaminants in the OSPW, classical adsorbents lack several properties that can be best established using nanoparticles.

Nanoparticles poses unique properties that make them desirable, such as large surface area, high efficiency, high reactivity, dispersibility, low cost and selectivity. Nanoparticle technology is becoming the new frontier in wastewater treatment due to its high efficiency, low cost and easy to implement processes.

In this study, silica-based nanoparticles were prepared in the lab for their proven advantages over classical adsorbents. These nanoparticles needed to be modified in order to attract polar organic compounds. After several studies, grafting was chosen, this entails the modifying and functionalizing of the surface of the nanoparticle with a naturally occurring and environmentally friendly polymer in order to achieve high affinity towards the polar organic compounds present in the OSPW. The preparation of the Grafted Nano Silica (GNIS) was accomplished and optimized using different polymer molecular weights as well as different preparation procedures.

A synthetic wastewater solution was prepared by dissolving NA in water. Microscopic batch adsorption took place to carefully study several factors influencing the adsorption process; including: contact time, initial concentration, GNIS amounts and the pH of the solution. The Sips, Langmuir and Freundlich adsorption isotherm models were employed using the experimental data to describe and understand the adsorption behavior.

This study confirmed that GNIS could be employed as efficient adsorbents for naphthenic acid removal from wastewater where classical adsorbents could be ineffective or costly.