Abstract
本研究主要以稻殼灰(黑灰.白灰)為主原料,添加高嶺土及澱粉作為無機燒 結助劑及黏結劑.孔洞形成劑,利用濕混.成型.製成生胚後再將之高溫燒結 以得到具有孔隙度及強度之多孔陶瓷骨材外;並將所得之骨材應用於處理 染整廢水,以瞭解其吸附特性,作為爾後實際應用之參考. 由實驗發現(1) 經由煮沸.酸洗.600度熱處理後可獲得不具晶型及表面積值為236m2/g之白 灰粉末(2)黑灰骨材經過缺氧氣氛加熱處理後之成品,其表面水流沖刷流失 量較小,表面燒結效果較佳.表面積值則亦大於在有氧氣氛下處理之樣品. 而在配方方面使用較大量的澱粉(較小量的高嶺土)有助於表面積之提升, 但會使強度變弱.在所有配方中以高嶺土:澱粉:黑灰粉末=0.9:0.3:2(B6) 之樣品最適合用於製作多孔骨材(表面積值106m2/g.強度124psia.孔隙 度69%)(3)對於白灰骨材,白灰添加量越大(高嶺土添加量越小)則表面積值 越大,但骨材強度會減低,水流沖刷流失量則增大;白灰骨材之配方中以高 嶺土:澱粉:白灰=1:0.15:5(W2-1)之配方最適合用於製作多孔骨材(表面積 值85m2/g.強度119psia.孔隙度73%)(4)在吸附實驗方面雖然吸附劑中以白 灰粉末之表面積及吸附容量最高,但在工程應用上應以骨材較為合適;而經 過骨材之再生實驗可發現,二種骨材中雖然白灰骨材在初期表面積值略小 於黑灰骨材,但在再生後,由於黑灰骨材表面積(約損失8.7%>2.4%)及吸附 容量(12%>3%)損失率皆大於白灰骨材,故就長期使用而言,應以白灰骨材較 適於作為填充骨材(5)在吸附劑表面改質方面.我們可以視被吸附的種類藉 由水合或酯化反應調整吸附劑之表面特性,以增加其對被吸附物之處理能 力.即欲處理親水性物質(如剛果紅)時可藉由水合反應增加其表面OH基濃 度,而欲處理親油性物質(如C24H38O4)時則可藉由酯化反應使其表面特性 較具親油性,以增加吸附劑對親水性或親油性物質之處理能力. In this study, the main raw material was rice hull ash (RHA) which was wet-mixed with kaoline (as sintered aids) and starch (as both binder and pore former).The mixture, was then by dried, molded and fired to obtain porous aggregates having desired strength and porosity for adsorption applications. The adsorptive capacities of these aggregates were then measured toward treating wastewater form textile industries to evaluate its efficiency for such an application. The following results were observed: (1) By washing with boiling acid and calcining at 600^C, an amorphous white ash with 236m2/g surface area was formed. (2) For black-aggregates heated under deficient oxygen condition, it showed better sintering, smaller weight loss in flowing water, and larger surface areathan samples heated in air. Samples with more starch (less kaoline) exhibitedlarger surface area, get lower mechanical strength. We found the optimal composition to be kaoline:starch:ash=0.9:0.3:2 (sample B6) which showed porosity of 69%, surface area of 106m2/g and strength of 124psia. (3) For white-aggregates containing more ash (less kaoline), it showed lower strength, higher weight loss in flowing water and larger surface area. The optimal composition was found to be kaoline:starch:ash=1:0.1:5 (sample W2-1) which had porosity of 73%, surface area of 85m2/g and strenngth of 119 psia. (4) From the adsorption experiments, we found that : (a) white ash offered the largest surface area and adsorption capacity, but its aggregates were more suitable in engineering application; (b) the white-aggregates which showed lower rates of loss in both surface area (2.4<8.7%) and capacity (3<12%) through the recycle test than black-aggregates, even thought they have less initial surface area and capacity, the white-aggregates were optimalones for the long term engineering applications. (5) Esterification and rehydration can be applied to modify the surface properties of these samples. As the extent of esterification was increased, it became less hydrophilic and more organophilic, and therefore exhibited a larger capacity toward oil(C24H38O4). On the contrast, as the extent of hydration was increased, the samsample becamemore hydrophilic and showed higher capacity toward molecules found in wastewater from textile industries.