An Adsorption Kinetic Model for Sulfur Dioxide Adsorption by ZL50 Activated Carbon

Intensification of NO x Conversion over Activated Coke by Ozone Oxidation for Sintering Flue Gas at Low Temperatures

Denitration (De-NO x ) over activated cokes (ACs) for sintering flue gas needs intensification. Gaseous reactions in a gas mixture containing NO, NO2, and NH3, with the effect of O2 concentration and moisture, were taken into consideration in the study of NO x conversion over ACs. Experimental studies on NO x conversion with and without NH3 over ACs were conducted using a fixed-bed reactor at 100 °C. The results demonstrated that moisture significantly affected NO x removal over ACs, especially the NO2 conversion. Under dry conditions, a disproportionation reaction of NO2 over ACs dominated NO x conversion with no NH3, whereas apparent fast selective catalytic reduction (SCR) over the ACs was observed in the presence of NH3. Regardless of the presence of absence of NH3 in wet mixtures, NO2 adsorption on ACs via the disproportionation route dominated the NO x conversion. Increasing the NO2/NO ratio in the simulated flue gas enhanced the NO x conversion rate over ACs. -C(ONO2) deposition on ACs generated by the disproportionation route inhibited NO x conversion with time. O3 oxidation was found to be efficient in increasing the NO2/NO ratio and intensifying the NO x conversion compared with commercially direct NH3-SCR over ACs. Increasing the temperature and decreasing the gas hourly space velocity can promote NO x conversion over ACs after O3 oxidation. NO oxidized with O3 coupled with NH3 spray and continuous regeneration of ACs is a potential method for removing NO x from sintering flue gas.

Production of activated carbon from biodiesel solid residues: An alternative for hazardous metal sorption from aqueous solution

In this study, the potential for the sorption of Pb(2+) and Cd(2+) from aqueous solutions using HNO3-treated activated carbon (TAC) obtained from radish press cake (Raphanus sativus L.), a solid residue from biodiesel production, was investigated. Activated carbon (AC) was obtained by physical activation with CO2(g). Chemical modification with HNO3 was employed to increase the sorption capability of the AC. The sorption of Pb(2+) and Cd(2+) was studied in monometallic systems in equilibrium with different metal-ion concentrations (10-400 mg L(-1)). The experimental sorption equilibrium data were fit to the Langmuir and Freundlich isotherm models. The maximum sorption capacity (qmax) obtained for AC from the Langmuir isotherm was 45.5 mg g(-1) for Cd(2+) and 250 mg g(-1) for Pb(2+). Moreover, TAC presented qmax of 166.7 mg g(-1) (1.48 mmol g(-1)) for Cd(2+) and 500.0 mg g(-1) (2.41 mmol g(-1)) for Pb(2+)showing the effect of chemical modification. Sorption-desorption studies showed that the interaction between metals and TAC is reversible and this sorbent can be reused for several consecutive cycles. Furthermore, the sorption of Cd(2+) and Pb(2+) by TAC was not affected by the presence of competing ions. The experimental data obtained in this study indicated that this solid residue is viable for the production of sorbents that remove metals, such as cadmium and lead, from wastewaters and thereby contribute to the sustainable development of the production of biodiesel.