| 摘要: | 本研究主要是利用稻殼(rice husks, RHs)製備出新型活性碳(activated carbon, AC)以作為固相萃取法(solid-phase extraction, SPE)的吸附材質，將此材質填充於固相萃取管柱中，以進行水樣中壬基酚(4-nonylphenols, 4-NPs)之萃取測試。研究中將稻穀摻混二氯化鋅，並加熱到800˚C，使二氯化鋅與碳化合，藉由對二氧化矽不同的處理方式，製備出三種型態的活性碳吸附劑，分別為 (1) 未經處理:AC–Si(含二氧化矽)、(2) 鹼性(base)處理: AC–B–Si(移除部分二氧化矽)及(3) 完全鹼性(base)處理: AC–B(無二氧化矽)。利用BET量測其表面積分別為1352 m2/g、1666 m2/g及1721 m2/g。因AC–B具有最大的表面積，證實在二氧化矽移除的步驟中會使活性碳形成開放性孔洞並增加表面積。利用稻殼所製備出的活性碳型吸附劑，孔洞中因具有特殊官能基，能增加與待測物之間的吸引力，進而提升萃取效率，含有矽烷醇官能基的吸附劑會顯著影響對4-NPs的萃取效率。將製備出之活性碳應用於河川水4-NPs之萃取，其萃取回收率分別為AC–Si: 32.1%，AC–B–Si: 82.6%及AC–B: 51.8%。在三種活性碳中以AC–B–Si具有較佳之萃取效果，主要是因此種活性碳中含有矽醇官能基及較大表面積，與待測物壬基酚能產生氫鍵作用(hydrogen bonding)，提升4-NPs之回收率。此研究結果顯示，利用廢棄之稻殼能製備出新型活性碳，且可有效應用之河川水中壬基酚之萃取。相較於商業化SPE管柱，此新型活性碳價格低廉，效率等同商業化管柱，期望未來能廣泛且有效應用於不同新興汙染物之萃取上。Enrichment efficiency of activated carbon (ACs) from rice husks (RHs) as a new sorbent for solid-phase extraction (SPE) to extract 4-nonylphenol isomers (4-NPs) in water samples was evaluated. The ACs prepared from RHs usually exhibits low specific surface area due to its high ash content, but in case of its application for SPE, there are other factors need to be considered, such as the existence of functional groups inside the sorbent, that can enhance interaction of non-polar sorbent with analyte in the water matrices. In this case, silanol groups from ash content may affect the extraction efficiency for 4-NPs. The ACs made from RHs were chemically impregnated with ZnCl2 and carbonized at 800oC. To investigate the role of silica, three types of ACs were prepared, i.e., untreated ACs (AC–Si, contain silica), base treated ACs (AC–B–Si, remain some silica inside), and ACs made by base treated RHs (AC–B, no silica), and the surface area obtained from these treatments were 1352 m2/g, 1666 m2/g, and 1712m2/g respectively. ACs made by base treatment has a highest surface area (related to BET), which indicated that silica removal process promotes the formation of open pore system on ACs and enhances the surface area of ACs. However, extraction efficiency measured by GC-MS in SPE process showed the reversal trends (i.e., AC–Si= 32.08%, AC–B–Si= 82.63%, AC–B=51.78%), among them the AC–B–Si sorbent reveal the best performance in SPE process. It is indicated that although silica usually exhibits low specific surface area, but control presence of silica as a polar functional group has a positive influence in the interaction between non-polar sorbent and 4-NPs. |
