Ehtisham Muhammad, Badawi Ahmad K, Khan Asad Muhammad, Khan Rafaqat Ali, Ismail Bushra
Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus 22060 Pakistan
Civil Engineering Department, El-Madina Higher Institute for Engineering and Technology Giza 12588 Egypt
RSC Adv. 2024 Feb 19;14(9):6165-6177. doi: 10.1039/d3ra08152d. eCollection 2024 Feb 14.
Sorption-based atmospheric water harvesting (SBAWH) is a highly promising approach for extracting water from the atmosphere thanks to its sustainability, exceptional energy efficiency, and affordability. In this work, ZnFeO and ZnCoFeO were evaluated for moisture adsorption. The desired materials were synthesized by a surfactant-assisted sol-gel method. Synthesized samples were characterized using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometry (VSM), and point of zero charge (PZC). Crystallinity and phase composition were evaluated by XRD analysis. Several parameters were determined using XRD analysis: lattice parameter, unit cell volume, crystallite size, and bulk density. The morphology of synthesized materials was assessed SEM, and unveiled the acquisition of consistent, homogeneous, and uniform crystals. Elemental composition was determined through EDX spectroscopy. Water adsorption on the surface was evaluated by FTIR spectroscopy. The magnetic properties of synthesized ZnFeO and cobalt-doped ZnFeO ferrites were investigated using VSM. The negative charge on the ZnCoFeO surface was explored using PZC. Adsorption studies on synthesized materials were conducted with the help of an atmospheric water harvesting (AWH) plant created by our team. Moisture adsorption isotherms of synthesized materials were determined using a gravimetric method under varying temperature and relative humidity (45-95%) conditions. The moisture content () of ZnCoFeO and ZnFeO was 597 mg g and 104 mg g, respectively. Key thermodynamic properties, including isosteric heat of adsorption (), change in Gibbs free energy (Δ), and change in sorption entropy (Δ), were evaluated. was negative, which confirmed the sorption of water vapors on the material surface. Δ and Δ indicated that water-vapor adsorption was spontaneous and exothermic. A second-order kinetics study was carried out on synthesized materials, demonstrating their chemisorption behavior. The latter was due to the oxygen defects created by replacement of Co and Fe at tetrahedral and octahedral sites. Water vapors in the atmosphere became attached to the surface and deprotonation occurred, and the hydroxyl ions were formed. Water vapor attached to these hydroxyl ions. A second-order kinetics study was carried out to confirm the chemisorption behavior of synthesized materials.
基于吸附的大气取水（SBAWH）是一种极具前景的从大气中提取水分的方法，因其具有可持续性、卓越的能源效率和可承受性。在这项工作中，对ZnFeO和ZnCoFeO的水分吸附性能进行了评估。所需材料通过表面活性剂辅助溶胶 - 凝胶法合成。使用X射线衍射（XRD）分析、扫描电子显微镜（SEM）、能量色散X射线（EDX）光谱、傅里叶变换红外（FTIR）光谱、振动样品磁强计（VSM）和零电荷点（PZC）对合成样品进行了表征。通过XRD分析评估结晶度和相组成。使用XRD分析确定了几个参数：晶格参数、晶胞体积、微晶尺寸和堆积密度。通过SEM评估合成材料的形貌，揭示了获得一致、均匀的晶体。通过EDX光谱确定元素组成。通过FTIR光谱评估表面的水吸附。使用VSM研究了合成的ZnFeO和钴掺杂的ZnFeO铁氧体的磁性。使用PZC探索了ZnCoFeO表面的负电荷。在我们团队创建的大气取水（AWH）装置的帮助下，对合成材料进行了吸附研究。在不同温度和相对湿度（45 - 95%）条件下，使用重量法测定合成材料的水分吸附等温线。ZnCoFeO和ZnFeO的水分含量分别为597 mg/g和104 mg/g。评估了关键的热力学性质，包括等量吸附热（）、吉布斯自由能变化（Δ）和吸附熵变化（Δ）。为负，这证实了水蒸气在材料表面的吸附。Δ和Δ表明水蒸气吸附是自发的且放热的。对合成材料进行了二级动力学研究，证明了它们的化学吸附行为。后者是由于在四面体和八面体位点上Co和Fe的取代产生的氧缺陷。大气中的水蒸气附着在表面并发生去质子化，形成了氢氧根离子。水蒸气附着在这些氢氧根离子上。进行了二级动力学研究以确认合成材料的化学吸附行为。
