Li Kai, Zhang Dongqing, Niu Xiaojun, Guo Huafang, Yu Yuanyuan, Tang Zhihua, Lin Zhang, Fu Mingli
School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China.
Guangdong Provincial Key Laboratory of Petrochemical Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, PR China.
Sci Total Environ. 2022 Jun 20;826:154133. doi: 10.1016/j.scitotenv.2022.154133. Epub 2022 Feb 25.
The environment issues associated with global warming and climate change caused by continuous increase in greenhouse gas emissions have attracted worldwide concerns. As renewable resources with good adsorption property, biochar is an efficient and environmental friendly adsorbsent for CO capture. In this study, the CO adsorption behavior of biochars derived from feedstock mixtures of 70% pine sawdust and 30% sewage sludge by KOH modification was investigated. The textual properties and functional groups of the pristine biochars have been significantly enhanced after KOH activation. With highly developed microporosity, the specific surface area (SSA) of the KOH-modified biochars increased by 3.9-14.5 times. Furthermore, higher CO adsorption capacities of 136.7-182.0 mg/g were observed for the modified biochars, compared to pristine ones (35.5-42.9 mg/g). The development of micropores by KOH activation significantly increased the CO adsorption capacity. Meanwhile, the presence of hetero atoms (O and K) also positively influenced CO adsorption capacity of biochar. Noticeably, both physical and chemical adsorption played a crucial role in CO capture, which was verified by different characterization methods including high resolution scanning electron microscope, X-ray photoelectron spectroscopy and in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The Findings of this study demonstrate the -significance of chemical sorption by identifying the transformation of CO by biochar composites and in situ characterization of weakly adsorbed and newly formed mineral species during the CO sorption process. Moreover, BC700K showed 97% recyclability during 10 consecutive adsorption-desorption cycles at 25 °C, 1 bar. The results obtained in the present study may inspire new research interest and provide a comprehensive insight into the research subject to biochars derived from feedstock mixtures for CO capture.
温室气体排放持续增加所引发的与全球变暖和气候变化相关的环境问题已引起全球关注。作为具有良好吸附性能的可再生资源，生物炭是一种用于捕获二氧化碳的高效且环境友好的吸附剂。在本研究中，对通过氢氧化钾改性由70%松木锯末和30%污水污泥的原料混合物制备的生物炭的二氧化碳吸附行为进行了研究。经过氢氧化钾活化后，原始生物炭的结构性质和官能团得到了显著增强。由于具有高度发达的微孔结构，氢氧化钾改性生物炭的比表面积增加了3.9至14.5倍。此外，与原始生物炭（35.5至42.9毫克/克）相比，改性生物炭的二氧化碳吸附容量更高，为136.7至182.0毫克/克。通过氢氧化钾活化形成的微孔显著提高了二氧化碳吸附容量。同时，杂原子（氧和钾）的存在也对生物炭的二氧化碳吸附容量产生了积极影响。值得注意的是，物理吸附和化学吸附在二氧化碳捕获中都起着关键作用，这通过包括高分辨率扫描电子显微镜、X射线光电子能谱和原位漫反射红外傅里叶变换（DRIFT）光谱在内的不同表征方法得到了验证。本研究的结果通过确定生物炭复合材料对二氧化碳的转化以及在二氧化碳吸附过程中对弱吸附和新形成矿物物种的原位表征，证明了化学吸附的重要性。此外，在25℃、1巴的条件下，BC700K在连续10次吸附 - 解吸循环中显示出97%的可回收性。本研究获得的结果可能会激发新的研究兴趣，并为源自原料混合物用于捕获二氧化碳的生物炭的研究主题提供全面的见解。
