A comprehensive comparative study on methylene blue removal from aqueous solution using biochars produced from rapeseed, whitewood, and seaweed via different thermal conversion technologies
A comprehensive comparative study on methylene blue removal from aqueous solution using biochars produced from rapeseed, whitewood, and seaweed via different thermal conversion technologies
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DOI：
10.1016/j.fuel.2022.125428
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发表时间：
2022-08-10
期刊：
影响因子：
7.4
通讯作者：
Lester, Edward
中科院分区：
文献类型：
--
作者：
Guelec, Fatih;Williams, Orla;Lester, Edward
本文首次对使用来自三种截然不同的英国生物质原料（通过三种不同的热处理技术生产）的生物炭吸附亚甲基蓝染料的潜力进行了全面的比较分析。生物炭由油菜籽、白木和海藻（Laminaria Digitata）制成，通过水热转化、热解和烘焙生产。为每种生物炭在不同温度、pH 值和初始染料浓度下开发了吸附动力学模型。海藻基生物炭实现了相对较高水平的亚甲基蓝吸附能力（接近 150 毫克/克），油菜籽基生物炭的亚甲基蓝吸附能力处于合理水平（接近 60 毫克/克），而白木基生物炭的吸附水平相对较低（< 30 毫克/克）。伪二级动力学模型与实验结果最吻合。 Langmuir 吸附等温线更适合海藻生物炭，而 Freundlich 吸附等温线更适合油菜籽生物炭。 Langmuir 吸附等温线显示出海藻基生物炭相对较高的最大吸附容量（Qo）；类似于海藻烘焙的 175 毫克/克，类似于海藻热解的 117 毫克/克。对于海藻-烘焙 < 海藻-热解 < 0，观察到负吉布斯自由能（δ G 度）值，这表明由于吸附的自发性质，亚甲基蓝的去除可能是热力学上有利的过程。我们的调查表明，从废水中去除亚甲基蓝可能是海藻基生物炭的潜在应用，作为整个生命周期增值途径的一部分。然而，它并不适合所有类型的生物质，这强调需要为不同类型的生物质定制独特的增值途径。
This paper presents, for the first time, a comprehensive comparative analysis of the potential of using biochars from three distinctly different UK-sourced biomass feedstocks, produced via three different thermal processing techniques, to adsorb methylene blue dye. Biochars were made from rapeseed, whitewood, and seaweed (Laminaria Digitata), produced via hydrothermal conversion, pyrolysis, and torrefaction. Adsorption kinetic models were developed for each biochar at different temperatures, pH and initial dye concentrations. Relatively high levels of methylene blue adsorption capacity were achieved by seaweed-based biochars (similar to 150 mg/g), with reasonable levels for rapeseed-based biochars (similar to 60 mg/g), whilst adsorption levels were found to be relatively low for whitewood-based biochars (< 30 mg/g). A Pseudo-second-order kinetic model provided the best fit with experimental results. The Langmuir adsorption isotherm showed a better fit for seaweed biochars, while the Freundlich adsorption isotherm was a better fit for the rapeseed-based biochars. The Langmuir adsorption isotherms showed relatively high maximum adsorption capacity (Qo) for seaweed-based biochars; similar to 175 mg/g for seaweed-Torrefaction and similar to 117 mg/g for seaweed-Pyrolysis. Negative Gibbs free energy (delta G degrees) values were observed for the seaweed-Torrefaction < seaweed-Pyrolysis < 0, which indicates that the methylene blue removal could be a thermodynamically favourable process due to the spontaneous nature of the adsorption. Our investigation has shown that the removal of methylene blue from wastewater could be a potential application for seaweed-based biochars as part of a holistic whole life cycle valorisation pathway. However, it is not suitable for all types of biomasses which emphasises the need for tailoring unique valorisation pathways for different types of biomasses.