School of Engineering, Brown University, Providence, RI, 02912, United States.
Woodard & Curran, 50 Millstone Road, Building 400, East Windsor, NJ, 08520, United States.
Chemosphere. 2024 Oct;365:143331. doi: 10.1016/j.chemosphere.2024.143331. Epub 2024 Sep 14.
Granular activated carbon (GAC) and ion exchange resin (IXR) are widely used as adsorbents to remove PFAS from drinking water sources and effluent waste streams. However, the high cost associated with GAC and IXR generation has motivated the development of less expensive adsorbents for treatment of PFAS-impacted water. Thus, the objective of this research was to create an economically viable and sustainable PFAS adsorbent from sewage sludge. Stepwise pyrolysis at temperatures from 300 °C to 1000 °C yielded biochars whose specific surface area (SSA) and porosity increased from 41 to 148 m/g, and from 0.062 to 0.193 cm/g, respectively. On a per organic char basis, the SSA of the biochar was as high as 1183 m/g, which is comparable to commercially-available activated carbons. The adsorption of perfluorooctane sulfonic acid (PFOS) on sludge biochar increased with increasing pyrolysis temperature, which was positively correlated with increasing porosity and SSA. When 1000 °C processed biochar was tested with a mixture of eight PFAS, preferential adsorption of longer carbon chain-length species was observed, indicating the importance of PFAS hydrophobic interactions with the biochar and the availability of a wide range of mesopores. The adsorption of each PFAS was dependent upon both chain length and head group, with longer chain-length species exhibiting greater adsorption than shorter chain-length species, along with greater adsorption of species with sulfonic acid head groups compared to their chain length counterparts with carboxylic acid head groups. These findings demonstrate that biochar derived from municipal solid waste can serve as a cost-effective and sustainable adsorbent for the removal of PFOS and PFAS mixtures from source waters. The circular economy benefits and waste reduction potential associated with the use of sewage sludge-derived biochar supports the development of a viable sludge-derived biochar for the removal of PFAS from water.
颗粒状活性炭 (GAC) 和离子交换树脂 (IXR) 被广泛用作吸附剂，以去除饮用水源和废水废水中的 PFAS。然而，GAC 和 IXR 生成的高成本促使人们开发更廉价的吸附剂来处理受 PFAS 影响的水。因此，本研究的目的是从污水污泥中开发出一种经济可行且可持续的 PFAS 吸附剂。在 300°C 至 1000°C 的温度范围内逐步热解，得到的生物炭比表面积 (SSA) 和孔隙率分别从 41 增加到 148 m/g，从 0.062 增加到 0.193 cm/g。就有机炭生物炭而言，其 SSA 高达 1183 m/g，与市售的活性炭相当。全氟辛烷磺酸 (PFOS) 在污泥生物炭上的吸附随着热解温度的升高而增加，这与孔隙率和 SSA 的增加呈正相关。当用 8 种 PFAS 的混合物测试 1000°C 处理的生物炭时，观察到对长链碳长物种的优先吸附，这表明 PFAS 与生物炭的疏水相互作用以及中孔的广泛存在很重要。每种 PFAS 的吸附都取决于链长和头基，长链长物种的吸附大于短链长物种，并且磺酸基团的物种的吸附大于其羧酸基团的具有相同链长的物种。这些发现表明，源自城市固体废物的生物炭可以作为一种具有成本效益和可持续性的吸附剂，用于从源水中去除 PFOS 和 PFAS 混合物。使用污水污泥衍生的生物炭的循环经济效益和废物减少潜力支持开发可行的污泥衍生生物炭，用于从水中去除 PFAS。
