以廢玻璃和天然孔洞材料製備濕控材料

Preparation of humidity control materials from waste glass and natural porous materials

吳天輝(Dinh-Hieu Vu)

指導教授 ： 王鯤生

國立中央大學/工學院/環境工程研究所/博士(2012年)

摘要

陶瓷建材提供適當的孔隙大小與構造，而被發展成室內濕控材料。此種材料以吸、脫附室內水分來調控環境濕度變化，而其反應機制以凱文(Kelvin)公式探討孔隙大小和相對濕度之相互關係。
過去十幾年來，濕控材料以石灰砂漿、無定形白炭黑、煤粉與無機鹽石灰石、粘土砂石膏、生物複合材料、熱塑性輻射渣和沸石-水泥等製作而成。然而其產製成本高、具可燃性和耐久性差等缺點。另一種方法是以無機材料，如氯化鈣和矽膠製成，但這些材料對水的吸、脫附表現較差，或可能對人體健康有害。因此，發展低成本、能量效率高、耐久性強且安全的天然孔材做濕控材料，為值得研究之方向。
本研究探討以火山灰或風化火山灰和廢玻璃燒結以製備濕控材料的可行性。並評估該濕控材料之孔隙率、孔洞分布和濕氣脫附，做為建材之工程特性。結果顯示：混合30wt%的火山灰和70wt%廢玻哩，燒結8000C 、5 分鐘，可得到最佳之水分吸、脫附和工程性質。所製備之濕控材料可得到52.08%的孔隙率和163.73 m2/g的BET表面積，而其主要孔洞直徑分布於約9 nm，依據日常生活環境之實際濕度水準，該中孔範圍有利於濕氣縮合。該濕控材料總水分脫附量為0.047cm3/g。另外，結果顯示濕控材料之體密度1.34 g/cm3、緊縮度2.61%、燒結後點火損失4.64%、彎曲強度6.58 MPa，整體工程特性表現符合陶瓷建材商業需求。本研究建議以天然孔洞材料如火山灰(例如含量多之allophane)和廢玻璃，以適當之燒結條件製備濕控材料，能兼具經濟及環境利益。
最後，本研究依據凱文(Kelvin)公式，評估在水平衡狀態下之體積吸、脫附效益，結果顯示所評估之體績效益遠小於在平衡狀態下之體積脫附，建議為孔洞型態效益(頸縮結構)。

關鍵字

濕控材料 ； 燒結 ； 火山灰 ； 廢玻璃

並列摘要

Ceramic constructional material, which provides proper pore size and structure, has been developed for the purpose of indoor air humidity control. Such materials control humidity by adsorption and desorption of indoor moisture with the variation of ambient humidity, a mechanism governed by the Kelvin equation relationship between pore size and relative humidity.
In the past decade the humidity control material (HCM) has been produced from raw material such as lime mortars, amorphous fumed silica, pulverized limestone with inorganic salts, clay–sand plaster, bio-composites, thermoplastics reinforced with pinups radiate sawdust, and zeolite-cement. The resultant HCMs, however, are costly due to production process, or flammable or, weak, and nondurable for construction use. In other cases, inorganic compounds such as calcium chloride and silica-gel have been used, but these materials exhibit poor water adsorption-desorption, or might be harmful to human health. Therefore, it is desirable to develop a low-cost, energy-efficient, durable, and safe HCM that incorporates natural porous materials.
This work investigated the feasibility of HCM by sintering a mixture of volcanic ash or weathered volcanic ash and waste glass. The porosity, pore size distribution, and moisture adsorption of the resultant HCMs were characterized, and their engineering properties for use as building material were evaluated as well. The results indicate that a mix design of 30wt% volcanic ash soil to 70wt% waste glass, sintered at 8000C for 5 minutes would yield a HCM of optimum performance both in moisture adsorption/desorption and engineering properties. The target HCM was found to have the porosity of 52.08%, with a BET surface area of 163.73 m2/g, and a major pore diameter distribution falling within a range around 9 nm, the mesopore range that facilitates the condensation of moisture in pores corresponding to the practical range of humidity levels in our living environment. This HCM showed a total amount of water adsorption of 0.047cm3/g. In addition, the resultant HCM showed the bulk density of 1.34 g/cm3, the shrinkage of 2.61%, the ignition of loss of 4.64% after sintering, and the bending strength of 6.58 MPa, representing all the engineering properties meeting the commercial requirements for building ceramics. The results of this study suggest that HCM can be prepared by sintering natural porous materials such as volcanic ash soil (i.e. rich in allophane) and waste glass with appropriate sintering conditions; and their application for humidity control material is both economical and environmentally beneficial.
Finally, based on the Kelvin equation, this study investigated the estimated effective adsorption volume and the volume adsorption water at equilibrium: the results indicate the estimated effective volume is much smaller than the adsorption volume at equilibrium; suggesting the effects of pore morphology (the bottle neck structure).

並列關鍵字

Humidity control material ； Sintering ； Volcanic ash ； Waste glass

參考文獻

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