A recent study published in Engineering presents a novel approach to address oily water pollution and oily sludge (OS) issues using a multifunctional biomass-based carbon aerogel. This research, led by a team of scientists from multiple institutions, offers a potential step towards carbon reduction in the petroleum industry.

The oil industry generates significant amounts of oily wastewater and OS during extraction, transportation, and storage. Traditional methods of treating these pollutants, such as thermal dehydration, are energy-intensive and contribute to high carbon emissions. In this study, the researchers proposed solar-driven photothermal conversion technology with a biomass-based carbon aerogel (BCA-600) to efficiently dehydrate OS and purify oily water.

BCA-600, synthesized from carboxymethyl cellulose (CMC) and cotton, features a porous three-dimensional structure and excellent photothermal conversion characteristics. The material’s surface wettability can be adjusted, enabling it to adsorb high-viscosity crude oil on the water surface (with an adsorption capacity of 4.28 g/g) and achieve demulsification-separation in water-in-oil emulsions (up to 97.28% for hexane-water emulsion).

Experimental results show that BCA-600 can effectively promote the evaporation and dehydration of OS. When mixed with OS at a mass ratio of 10:2, the highest dehydration efficiency of 90.68% can be achieved. The presence of soil in OS was found to facilitate water evaporation, while the oil phase inhibited it. Additionally, BCA-600 can remain in the dehydrated OS and participate in the subsequent pyrolysis process. It was demonstrated to enhance OS pyrolysis by reducing the activation energy, which is beneficial for the removal of the oil phase.

An important aspect of this research is its potential for carbon reduction. The solar photothermal dehydration method significantly reduces carbon emissions compared to traditional thermal dehydration, with emissions being only about 1/100 of the latter. This makes it an environmentally friendly alternative for treating oily pollutants.

However, the study also identified some challenges. Evaporation of OS may release volatile organic compounds (VOCs) and heavy metals, which need to be addressed through appropriate filtering and containment strategies. Moreover, the solar photothermal dehydration efficiency is still limited by factors such as site conditions and natural lighting.

This research on BCA-600 provides a new and promising way to treat oily pollutants. Future work will focus on developing more efficient evaporation technology under solar irradiation and exploring the combination of solar photothermal and traditional thermal dehydration methods to overcome existing limitations and further improve the treatment process.

The paper “Solar-driven dehydration and purification of oily pollutants with a multifunctional biomass-based carbon aerogel: A potential step towards carbon reduction,” authored by Fawei Lin, Hongyun Yao, Chujun Luan, Chenxu Zhong, Huiyi Mao, Lei Che, Hongdi Yu, Guanyi Chen, Eslam Salama, Mona Ossman, Li’an Hou. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.01.008.