A prolonged evaluation of air contamination level with CO2 in a college student’s laboratory using nanosized MgO

Abstract

Three nanocrystalline eco-friendly MgO samples, as pure and modified with 1% (wt/wt) F− or K2O at 600 °C, with high surface area and mesoporous nature were prepared by a simple sonochemical process. The three samples were characterized by XRD, surface area, porosity and TEM techniques. These samples were kept in contact with the atmosphere in the middle of a student’s organic chemistry laboratory and were examined toward capturing the ambient CO2 molecules through continuous exposure for a period of 8 weeks. The capturing capacity of these samples was shown to be in the following order: MgO > MgO-1%F > MgO-1%K2O. After 8 weeks, the amount captured by MgO was 346.2 $$ {\text{mg}}_{{{\text{CO}}_{2} }} \,{\text{g}}^{ - 1} $$, while MgO-1%F captured 311.4 $$ {\text{mg}}_{{{\text{CO}}_{2} }} \,{\text{g}}^{ - 1} $$, and finally MgO-1%K2O had the lowest capturing capacity of 252.9 $$ {\text{mg}}_{{{\text{CO}}_{2} }} \,{\text{g}}^{ - 1} $$. The obtained results showed that our samples are characterized by prolonged activity and reactivity toward the capturing of ambient CO2 molecules. Another series of experiments were carried out by passing pure CO2 gas (instead of the atmospheric CO2) over such samples, inside a glass cubic chamber, for 1 week. The results showed a similar trend in the TG desorption and TPD curves of pure CO2 as those recorded in ambient atmosphere. Values of the molar enthalpy change (ΔH) for CO2 desorption, corresponding to the two steps recorded for each sample in all durations, were calculated and were in agreement with those published formerly. Deconvolution of the IR-broad band, between 1800 and 1200 cm−1, revealed the presence of different types of basic sites on the surface of these samples under investigation.