Experimental study of adsorption characteristic of novel pyrazole-based metal-organic frameworks for volatile organic compounds

Abstract

Volatile organic compounds (VOCs) are the major indoor air pollutants that affect human health, comfort, and working performance. Sorbent material and adsorption technology are considered to be one of the most effective and economical ways to remove VOCs from indoor air. Among many sorbent materials, metal-organic frameworks (MOFs) have received more and more attention because of their superior performance in capturing a variety of compounds. In this work, the adsorption characteristic of a newly synthesized pyrazole-based metal-organic framework (Al-pda) for different VOCs was investigated. First, the single-pass VOC adsorption rates of Al-pda and activated carbon were tested under different low-concentration VOCs mixture, which is in line with the practical application in the indoor environment. The results showed that Al-pda had an especially high adsorption ability for formaldehyde. The single-pass efficiency of formaldehyde adsorption was up to 89% at the beginning of the test and gradually stabilized at 66%. Compared with activated carbon, Al-pda had significantly higher selectivity and adsorption efficiency for the capture of formaldehyde. Then the effect of relative humidity on formaldehyde adsorption was investigated. After increasing the relative humidity from 15% to 65%, Al-pda’s formaldehyde single-pass adsorption rate almost remained at a similar level. Preliminary research showed that Al-pda is a promising material for the selective adsorption of indoor formaldehyde under humid conditions. More work is needed to probe this new MOF’s adsorption mechanism and application method.