Synthetic carbons activated with phosphoric acid III. Carbons prepared in air
Synthetic carbons activated with phosphoric acid III. Carbons prepared in air
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DOI：
10.1016/s0008-6223(03)00031-9
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发表时间：
2003
期刊：
影响因子：
10.9
通讯作者：
Alexander M Puziy;O. Poddubnaya;A. Martínez-Alonso;F. Suárez-García;J. Tascón
中科院分区：
文献类型：
--
作者：
Alexander M Puziy;O. Poddubnaya;A. Martínez-Alonso;F. Suárez-García;J. Tascón
合成活性炭通过在空气气氛中在400-900°C区间的各种温度下磷酸活化苯乙烯-二乙烯基苯共聚物来制备。通过元素分析、阳离子交换容量测量、红外光谱、电位滴定、溶液中的铜吸附以及-196 °C时N2和0°C时CO2的物理吸附对碳进行了表征。结果表明，类似于在氩气中获得的合成磷酸活性炭，在空气中用磷酸活化的合成炭具有酸性特征，并显示出相当大的阳离子交换性能。对于在空气中获得的碳，含氧表面基团沿着含磷基团对CEC的贡献更高。在高达600°C的温度下制备的碳上确定了三种类型的表面基团，在更高温度下制备的碳上确定了四种类型。这些基团被指定为“超强酸”（pK<0）、含磷（pK=1.1-1.2）、羧酸（pK=4.7-6.0）和酚（pK=8.1-9.4）基团。在800°C下制备的碳的阳离子交换容量最大。在低于800°C的温度下在空气中获得的合成磷酸活性炭的铜吸附高于在氩气中获得的类似碳。增加是由于额外形成的含氧表面基团。计算的铜结合常数揭示了含磷基团和羧基对铜从水溶液中吸附的重要性。所有的碳显示出多峰孔径分布，同时包括微孔和中孔，但多孔结构不是决定这些碳的阳离子交换能力的主要因素。合成磷酸活性炭显示出更大的发展孔隙率时，在空气中获得相比，碳在氩气中。
Synthetic activated carbons were prepared by phosphoric acid activation of a styrene–divinylbenzene copolymer in an air atmosphere at various temperatures in the 400–900°C interval. The carbons were characterized by elemental analysis, cation-exchange capacity measurement, infrared spectroscopy, potentiometric titration, copper adsorption from solution and physical adsorption of N2at −196°C and CO2at 0°C. It was shown that, similarly to synthetic phosphoric acid activated carbons obtained in argon, the synthetic carbons activated with phosphoric acid in air possess an acidic character and show considerable cation-exchange properties. The contribution of oxygen-containing surface groups along with phosphorus-containing groups to CEC is higher for carbons obtained in air. Three types of surface groups were identified on carbons prepared at temperatures up to 600°C, and four types on carbons prepared at higher temperatures. These groups were assigned to ‘super-acidic’ (pK<0), phosphorus-containing (pK=1.1–1.2), carboxylic (pK=4.7–6.0) and phenolic (pK=8.1–9.4) groups. The cation-exchange capacity was at a maximum for the carbon prepared at 800°C. Copper adsorption by synthetic phosphoric acid activated carbons obtained in air at temperatures lower than 800°C is higher than for similar carbons obtained in argon. The increase is due to additional formation of oxygen-containing surface groups. Calculated copper binding constants revealed the importance of phosphorus-containing and carboxylic groups for adsorption of copper from aqueous solution. All carbons show a multimodal pore size distribution including simultaneously micropores and mesopores, but the porous texture is not a prime factor in determining the cation-exchange capacities of these carbons. Synthetic phosphoric acid activated carbons show a greater development of porosity when obtained in air as compared to carbons carbonized in argon.