Wood, a natural renewable material, has drawn great attention in solar steam generation in recent years due to its intrinsic properties such as high hydrophilicity and low thermal conductivity. Until now, great achievements have been made in increasing the light absorption of wood-based solar evaporators, mainly through surface carbonization and coating. However, the complicated and cost-intensive preparation process of the light absorption layer prevents its large-scale application. In particular, the carbonized and coated surface could be importantly influenced by the scouring effect of waves and the corrosion of salt water. Herein, a facile, low-cost, and scalable in situ reduction method has been developed to prepared KMnO4 oxidized wood (K-wood) for solar steam generation, which not only shows high evaporation performance but also has high structural stability. In the preparation process, the reaction-product black MnO2 particles will be uniformly distributed on the surface of wood, making the K-wood exhibit a high solar absorbance of about 94%. Moreover, the K-wood could still maintain the inherent high hydrophilicity and excellent thermal insulation performance. Benefitting from all of these advantages, the K-wood achieved a high evaporation rate (1.22 kg m–2 h–1) and a high evaporation efficiency (81.4%) under 1 sun illumination (1 kW m–2). Importantly, the K-wood also exhibits excellent structural stability, such as having good acid–base resistance and also washing resistance, and could even withstand an ultrasound treatment for even 2 h. The reusability of the K-wood was also tested, and the evaporation rate remains nearly unchanged after 20 cycles in seawater evaporation. Moreover, the condensate water obtained by the homemade collection device shows low ion concentrations, demonstrating that the K-wood possesses an excellent ability in seawater desalination treatment. This study provides a simple method to manufacture a high-strength wood-based solar steam evaporation device, which has potential for future large-scale applications.

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Four diverse microstructured MgO-stabilized CaO sorbents with varying mixing characteristics of Ca and Mg were obtained from untreated, hydrated, precipitated, and milled dolomite. Different morphological characterizations (thermal decomposition, phase composition, morphology, and nitrogen adsorption) were performed, followed by an analysis of 30 carbonation/calcination cycles in a fixed-bed reactor. The mixed metal oxide (CaO−MgO) in the fresh calcined dolomite transformed into separate crystals of CaO and MgO in the cycled sorbent and resulted in a relative decrease in the cyclic CO 2 capture capacity. Favorable structures (decreased crystallinity, increased porosity, and surface area) were generated by water hydration treatment, which was expected to enhance the recyclability, as suggested by some authors. However, this sorbent produced separate Mg and Ca as the major components, leading to a decrease in the CO 2 capture compared to fresh calcined dolomite. Complete segregation between Ca and Mg was observed upon precipitation treatment, which gave rise to the lowest cyclic CO 2 uptake. This segregation was eliminated by the final ball-milling treatment, thereby regaining the original reactivity. These results demonstrate the dominant role of the mixing of Ca and Mg on the cyclic CO 2 capture capacity of dolomite-based sorbents.

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Highly efficient Li4SiO4 (lithium orthosilicate)/biomass‐based (Li4SiO4/bio‐based) sorbents for CO2 capture at high temperature, were developed using a water pretreated waste materials (biomass ashes). Three typical biomass ashes and a water pretreated biomass ash were as raw materials for preparing the Li4SiO4/bio‐based sorbents. These raw biomass ashes and their resulting Li4SiO4/bio‐based sorbents were characterized by energy dispersive X‐ray, X‐ray diffraction, scanning electron microscopy, nitrogen adsorption, and thermogravimetry. The stability of CO2 sorption was tested through 15 carbonation/calcination cycles in a fixed bed reactor. The characteristic results showed that the high amount of metals (especially alkali metals) of biomass ashes could produce low contents of silica and further led the amorphous silica nanoparticles to more severe quartz aggregation. Moreover, these different physical properties of biomass ashes had a significant effect on the phase composition, microstructure, specific surface area, and CO2 absorption properties of their synthesized Li4SiO4/bio‐based sorbents. With the higher contents of SiO2 and the smaller particle size, its resulting sorbent using the water pretreatment biomass ashes presented the higher amount of Li4SiO4, smaller particle size and larger specific surface area. This special structure appeared to be the main reasons for increasing in CO2 capture performance and kinetic behavior as illustrated by the thermogravimetric analyses. This pretreatment Li4SiO4/bio‐based sorbent also maintained its higher capacity during the multiple cycles. It was concluded that synthesis of Li4SiO4‐based sorbents obtained from the pretreated biomass ash is a promising approach for CO2 capture at high temperature. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 526–532, 2015

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