高比表面積畜糞活性碳之製備及特性分析與液相吸附應用

本研究利用酪農畜牧場所衍生的乳牛與黃牛糞料(共三種、二個來源)，首先進行其熱化學性質分析，然後以熱裂解程序將其轉化為多孔生質炭材料之可行性。在研究中係利用固定床碳化爐進行碳化(400~900℃)實驗，同時藉熱重量分析(Thermogravimetric analysis, TGA)、真密度量測與比表面積-孔洞體積分析，進行牛糞衍製生質炭之孔洞特性分析。分析數據顯示，乳牛與黃牛糞料之熱化學性質差異性不大，含碳量41~45 wt%、熱值約18 MJ/kg。以固定床裂解爐所製備的生質炭之特性，碳化溫度越高越有利於其孔洞之生成和真密度的增加，雖然在最高溫(900℃)之條件下可得到生質炭之BET比表面積值超過360 m2/g與真密度約2.3 g/cm3，但較佳之溫度條件應為600~800℃，因為此時之特性變化較為明顯。另外，畜糞在使用鉀鹽(KOH)含浸後進行化學活化後，放進通入N2的裂解爐以升溫速率10℃/min、裂解溫度800℃、停留時間30 min的操作條件下，可製得BET比表面積高達1952 m2/g的畜糞活性碳。而應用所製牛糞活性碳進行甲烯藍吸附試驗得知，吸附能力qe值高達151 mg g-1以上，所以表示其吸附能力效果不錯，可以應用在去除廢水中有機汙染物，能創造畜糞生物資源之高附加價值性碳材料與減緩溫室氣體排放之環境效益，也可使農業更具有機化與競爭力，進而達成農業之生態-生產-生活目標，以及農業資材之環境永續利用。

關鍵字

牛糞；生質炭；活性碳；孔洞性質；液相吸附

並列摘要

This work studied the utilization of cattle manures derived from the dairy and yellow cattle in the livestock farms, which included the determinations of their thermochemical properties and the feasibility of converting them into porous carbon materials using pyrolytic activation. A series of carbonization/activation experiments were conducted in a fixed-bed reactor at temperature range of 400-900℃. The resulting carbon products (biochar and activated carbon) were subject to the analyses of elemental analysis, true density, surface area/pore volume, and surface morphology by scanning electron microscope (SEM). Based on the carbon contents of 41.4-44.5 wt% and the calorific values of 17.5-18.4 MJ/kg, the differences of manure characteristics between dairy and yellow cattle are not significant. The pore properties (maximal BET value ˃360 m2/g) and true densities (maximal value ≈ 2.3 g/cm3) of resulting dairy-manure biochars indicated an increasing trend as temperature increased, especially in the ranges of 600-800℃. More importantly, the maximal BET surface area reached 1,952 m2/g for the KOH-activated carbon prepared at the temperature of 800℃ for holding 30 min, as compared to those of K2CO3-activated carbons. Furthermore, the equilibrium adsorption capacity for removal of methylene blue at 25℃ by using the resulting activated carbon was up to 151 mg/g or more, showing that the manure-based carbon adsorbent has a high potential for removal of organic pollutants from aqueous solution.