Can Chen,Zheng Zhang,Pengyu Chen,Jiguang Huang,Heng Zhang,Dan Gao,Tao Li,Haiping Chen
Solar-interfacial evaporation has shown great potential for desalination using green energy. However, salt accumulation and long-term stability of the evaporators are urgent problems. Here, we designed a ceramic interfacial evaporator using black glaze and coal fly ash (CFA) with durability and technological maturity characteristics. A porous CFA ceramic substrate was prepared by the dry pressing method, and the black glaze was coated on the surface as a photothermal material. The thermal conductivity and porosity of the CFA ceramic are 0.564 W·m −1 K −1 and 40 %, respectively. The average evaporation rate was 1.443 kg·m −2 h −1 under one sun. Outdoor solar desalination experiments were conducted. The highest evaporation rate was 2.949 kg·m −2 h −1 under natural sunlight. The ceramic evaporator showed good salt resistance during two days of continuous desalination experiments. This work highlights the feasibility of using CFA-based ceramic evaporators for efficient solar-driven seawater desalination.
The coal fly ash (CFA) produced from coal-fired power generation is classified as a common solid waste; thus, improving the recovery and utilization rate of CFA is highly desirable. In this study, a novel strategy using CFA and Al 2 O 3 as raw materials, to prepare hierarchically porous ceramic composites that serve as potential candidates for future building materials is developed. In this process, the well-developed self-assembly method in which an anionic modifier is used to prepare hydrophobic powders that form an attractive oil/water network via electrostatic interactions , thereby yielding honeycomb-like structures. In order to explore the mechanism of preparation, five samples with different mixture ratios of alumina and CFA were prepared according to 1: 0, 2: 1, 1: 1, 1: 2, and 0: 1 (Alumina: CFA). Compared with the sample prepared with pure CFA, the as-prepared CFA/Al 2 O 3 composite exhibited both superior porosity and high mechanical property. When the porosity is as high as 73 ± 0.17%, the compressive strength is as high as 80.9 ± 3.4mpa (alumina: CFA = 1:1). As the porosity decreases to 49.3 ± 0.7%, the compressive strength reaches 159.33 ± 36.89mpa (alumina: CFA = 1:2). Moreover, this work obtains the highest compressive strength-porosity related B-value in comparison to previously reported CFA-based composites and provides a new insight into the effective recycling of CFA and offers a novel approach to prepare CFA/Al 2 O 3 composite with excellent overall mechanical properties .
Municipal solid waste incineration fly ash (MSWIFA) is considered a hazardous solid waste, traditionally disposed by solidified landfill methods. However, solidified landfills present challenges with leaching heavy metals, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). To address this issue, this study examined two pretreatment methods for MSWIFA: sintering at 850℃ for 30 min and washing with three water baths (20 min each) at a 3:1 liquid–solid ratio. Then, the pretreated MSWIFA was employed in geopolymer synthesis, along with gold tailings (GT) and coal fly ash (CFA). The optimal raw material ratio was GT:CFA:MSWIFA = 5:4:1 after pretreatment, which resulted in maximum compressive strengths of 20.95 and 25.87 MPa for the sintered and washed samples, respectively. Washing removed 87.3 % of soluble chlorides from MSWIFA, enhancing the compressive strength of the geopolymer. High-temperature treatment effectively reduced the leaching concentrations of heavy metals and the toxic equivalent quantity (TEQ) of PCDD/Fs. The leaching concentrations of heavy metals (Cu, Zn, Cd, Pb) and the TEQ of PCDD/Fs were all below the limits established by Chinese standards GB 5085.3–2007 and HJ 1134–2020. X-ray Diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, and energy dispersive spectroscopy analyses revealed that the primary hydration products of the geopolymer are C–(A)–S–H gels. Washing treatment facilitated the formation of ettringite and Ca(OH) 2 , which enhanced the pore structure and optimized the performance of the geopolymer. Thermogravimetric analysis revealed the good thermal stability of the geopolymer, indicating that the high-temperature and washing pretreatments minimally impacted its thermal stability.
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