An innovative method for determining micro pore volume of synthetic resins

• An innovative method (CTVT) for determining the micro pore volume (Vc) of resins is proposed in this study.
• CTVT can determine micro and macro pore volumes of resins in one single test.
• Vc determined by CTVT for XAD-2000, XAD-1180, XAD-2 and SYA-2 are 0.213, 0.122, 0.048 and 0.335, respectively.
• Vc can be used to predict pore volume (Va) for various phenolic compounds (BA, PNP, PCP, PHL) onto resins.
• CTVT has advantages of easy to do experiments, chemicals saving and simple calculations.

Synthetic resins are widely used in purifying pharmaceutical products, such as extracting antioxidants and antibiotics. In a fixed bed operation, the tailing behavior in the desorption process is commonly observed and this behavior might be due to the slow mass transfer within micro pore of resins. Therefore, to obtain accurate micro pore volume of resin is important to understand and overcome the tailing behavior of the desorption process. Commonly used methods on determining pore volumes for porous materials are mercury intrusion and N2 adsorption methods. However, both methods are good for determination of pore volumes of activated carbons and silica gels, but they may not be appropriate for determination of resins’ pore volumes. Two micro pore volume determination methods (adsorption/desorption technique (ADT) and carbon tetrachloride vaporization technique (CTVT)) for resins are proposed and investigated in this study. Four styrene type resins (XAD-2000, XAD-1180, XAD-2 and SYA-2) were tested via both methods. Phenolic compounds (Phenol (PHL), p-chlorophenol (PCP), p-nitrophenol (PNP), and benzoic acid (BA)) and carbon tetrachloride (CCl4) were employed in ADT and CTVT methods, respectively. In general, there is a linear relationship between micro pore volumes of resins (Vm) and adsorbate's molecular volumes (Mv). Since CCl4 has the smallest molecular volume among these adsorbents, the micro pore volume (Vc) obtained by CCL4 is the highest. For example, micro pore volume of XAD-2000 determined by BA, PNP, PCP, PHL and CCL4 are 0.02, 0.05, 0.07, 0.11 and 0.21, respectively. In addition, micro pore volume (Va) of resins determined by phenolic compounds can be predicted by the CTVT method. Therefore, CTVT has advantages of easy operation and time/chemicals saving. It is a good candidate for determination of resins’ micro pore volumes. This finding might be useful for future preparation and application of resins for organics recovery.

Comparisons of experimental with predicted micro pore volumes via CTVT tests for various phenolic compounds onto resins.Figure optionsDownload as PowerPoint slide