Indoor Air Purification of Volatile Organic Compounds (VOCs) Using Activated Carbon, Zeolite, and Organosilica Sorbents

Abstract

Indoor air pollution is a complicated problem involving a mix of many diverse contaminants that can negatively affect human health at elevated concentrations. Volatile organic compounds (VOCs) are some of the more toxic chemicals detected in indoor air. We evaluated the performance of materials commonly found in commercial air purifiers (activated carbon and zeolite clay) and a novel organosilica for their ability to remove VOCs from indoor air. Data from batch sorption experiments with toluene and benzene were modeled using Freundlich, Langmuir, and Temkin isotherm fitting techniques to quantify important sorption parameters. A new experimental technique was developed for conducting in situ gas chromatography measurements of batch sorption experiments in 20 mL glass vials that allowed for direct gas measurement after sorption without any further sample processing. Samples were analyzed for the VOC concentration remaining in the vial using gas chromatography with a flame ionization detector (GC-FID). The maximum adsorption capacity of activated carbon for toluene and benzene was 46.9 and 55.5 mg/kg, respectively, according to Langmuir adsorption isotherm fits. The adsorption capacities of organosilica for toluene and benzene were 3.49 and 2.05 mg/kg, respectively. Zeolite yielded minimal adsorption capacity compared with the two other sorbents. Projections from the experimental sorbent capacities indicate that under normal operating conditions (10 m3 with four air changes per hour and 200 cubic feet per minute), an air purifier filter could remove 30 ppb of VOCs for up to 690 days.

Agro-Waste Valorization into Carbonaceous Eco-Hydrogel: A Circular Economy and Zero Waste Tactic for Doxorubicin Removal in Water/Wastewater

“…Further evidence that the Langmuir isotherm offered a superior match for the data was provided by the fact that the 1/ n values obtained for Doxo.HCL were less than 1. The Temkin isotherm exhibits that due to interactions between the adsorbent and adsorbate, the heat of adsorption for all molecules in the layer should fall linearly as the surface coverage increases rather than logarithmically …”

“…The Temkin isotherm exhibits that due to interactions between the adsorbent and adsorbate, the heat of adsorption for all molecules in the layer should fall linearly as the surface coverage increases rather than logarithmically. 72 The data acquired from the experimental study were used for calculating the Langmuir, Freundlich, and Temkin isotherms. The Langmuir and Temkin model adsorption describes the maximum adsorption capacity and the isotherm on a homogeneous surface, whereas Freundlich and Temkin discuss multilayer adsorption 3 represented using eqs 3, 4, and 5, respectively,…”

Prediction for the Adsorption of Low-Concentration Toluene by Activated Carbon

“…In the study conducted by Seo et al [26], the value of R 2 of the Langmuir model was 0.9956, which could fit the adsorption of toluene by activated carbon at 0.4-1.6 ppm. Mobasser et al [27] conducted adsorption tests on activated carbon, zeolite, and organosilica with a toluene concentration of 0.02-1 ppm and found that the Freundlich model fitted well. The D-R model was less frequently used than the Langmuir and Freundlich models because of its complex form and the greater number of parameters involved.…”

“…Figure 4. Application of the adsorption isotherms for toluene adsorption in the previous studies[15,17,[25][26][27][28][29][30][31][32].…”

Experimental and Modeled Results Describing the Low-Concentration Acetone Adsorption onto Coconut Shell Activated Carbon

“…The Temkin model assumes that the adsorption heat of all molecules in the adsorption layer decreases linearly with the coverage rate due to the adsorbent-adsorbent interaction, and is characterized by the uniform distribution of bond energy up to a maximum binding energy, which is suitable for describing chemisorption. The formula is as follows [37]:…”