Degradation of Methyl Orange in Aqueous Solution by Microwave Irradiation in the Presence of Granular-Activated Carbon

The removal of methyl orange from aqueous solution by biochar and activated carbon under microwave irradiation and in the presence of hydrogen peroxide

“…The applied approach is based on the assumption that the adsorption capacity of carbon is similar whether or not the energy source and/or oxidant are present. Some experimental data suggest that this assumption has to be used with caution [12][13][14][15]. Under actual oxidation conditions, intermediate compounds are formed in the system that compete with the initial organic compound for the adsorption sites on carbon, affecting the adsorption capacity [12].…”

“…Some experimental data suggest that this assumption has to be used with caution [12][13][14][15]. Under actual oxidation conditions, intermediate compounds are formed in the system that compete with the initial organic compound for the adsorption sites on carbon, affecting the adsorption capacity [12]. The adsorption capacity of carbon can also be changed from exposure to the energy source and/or oxidant during the oxidation process, which may modify the porosity and surface chemistry [13,14].…”

“…More specifically, in this study a solvent extraction method was developed and applied to recover methyl orange from carbon (wood-based biochar and activated carbon) after a microwave treatment in the absence and presence of H 2 O 2 . This system was chosen based on the existence of two studies for comparison [12,16]. The developed method allowed us (1) to clarify whether microwave irradiation over a carbon catalyst can effectively degrade organic compounds in water, a technique which has been questioned in a recent study [15], and (2) to investigate the degradation of methyl orange over carbon catalysts by H 2 O 2 under microwave irradiation, a method that is promising [10] but in which the catalytic role of carbon is not well understood.…”

Study and application status of microwave in organic wastewater treatment – A review

“…These overheated spots are referred to as "hot spots" [70], and have been proven to have the capacity to promote the degradation of organic pollutants due to its high temperature [71].…”

“…The first one is that MW irradiation can always convert a non-catalyst (for example, an MW-absorbent such as AC and other kinds of carbonaceous materials) into an effective catalyst. The main mechanism is the generation of "hot spots" (near which organic pollutant degradation could take place easily [78][79][80] AC, as an excellent carbonaceous adsorbent for many kinds of pollutants [35,58,[78][79][80][81][82][83][84][85][86], has been studied widely. The rising temperature curves for granular-AC (GAC)…”