Comparison of NO2 removal using date pits activated carbon and modified commercialized activated carbon via different preparation methods: Effect of porosity and surface chemistry

• Activated carbons (AC) were prepared from date pits and commercial adsorbents.
• Textural, morphological and surface chemistry properties were analyzed.
• NO2 adsorption capacities were evaluated and correlated to AC characteristics.
• Microporosity, micropore size and surface groups affect NO2 adsorption capacity.
• Strong acidic groups inhibit the NO2 interaction with the AC surface.

This study aims to evaluate the NO2 adsorption capacities of activated carbons prepared by physical and chemical activation of date pits and to compare them with modified commercialized activated carbons. The texture, morphology and surface chemistry of the different carbons were evaluated by N2 and CO2 adsorption, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), temperature programmed desorption coupled with mass spectroscopy (TPD–MS), Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence (XRF) techniques. The obtained results show that activated carbon prepared from date pits are an efficient adsorbents for the removal of NO2 from the exhaust gases at ambient temperature. The obtained adsorption capacities are close to the ones obtained for the commercialized activated carbons. The analysis of the correlation between NO2 adsorption capacities and the textural and the surface chemistry properties shows that a higher microporosity volume, an homogenous microporosity and the presence of stable oxygen groups contribute strongly to the adsorption of NO2 on the activated carbon surface. In contrast, the presence of strong acidic groups such as carboxylic, anhydrides and lactones inhibits the reduction of NO2 into NO, which represents a crucial step for the NO2 adsorption.