Modification And Regeneration Of Activated Carbon By Non-thermal Plasma And Its Adsorption Properties For Organic Compounds

Now,activated carbon modification and regeneration becomes one of the most concerned research directions of activated carbon,but the current common modification and regeneration methods have high energy consumption,low efficiency and the secondary pollution caused by the utilization of chemical reagents,so it is high time to explore a new green modification and regeneration method.Non-thermal plasma has attracted extensive attention from scholars because of its low energy consumption,high energy density,and strong oxidizability,also most researches regarding on non-thermal plasma modification and regeneration of activated carbon have focused on air or oxygen systems.Compared with nitrogen,helium atoms have higher metastable energy,making it easier to achieve uniform discharge.Based on this,this thesis proposes a new activated carbon modification method in oxygen-helium plasma system,explores the effect of modification process on activated carbon,establishes a low temperature plasma activated carbon regeneration method in oxygen-helium-water vapor system,and specifies the characteristics of regeneration and recycling method in different systems.The specific content and main conclusions are shown as follows:Research on the surface modification of oxygen-helium low temperature plasma activated carbon.Via the constructed non-thermal plasma reaction experiment platform,the oxygen-helium non-thermal plasma is used to modify the wooden activated carbon,furthermore,the modified activated carbon was collected by adjusting the injection power,the modification time,the gas flow and other factors,The result shows that after plasma treatment,the physical and chemical properties of activated carbon have changed significantly.Plasma etching makes the surface of activated carbon rougher and improves the wettability,also the pore destruction and pore formation of plasma on activated carbon can coexist,so with the time going,the specific surface area and pore volume increase first and then decrease.Oxygen-helium low temperature plasma can quickly react with the surface of activated carbon,resulting in the loss of carbon element and the increase of oxygen element,also the surface of activated carbon is passivated and the oxidation resistance is enhanced.After 15 minutes treatment,the O/C ratio reaches its maximum and the number of carboxyl groups and carbonyl groups increased by nearly 58.55%and 82.2%respectively.Research on the adsorption characteristics and adsorption mechanism of modified activated carbon to organic matter.Prepared modified activated carbon under different atmospheres,preferably oxygen-helium as the best reaction gas.Also the effect of different modified conditions on the adsorption of aniline was studied and the adsorption capacity of modified activated carbon was evaluated from static and dynamic adsorption.The adsorption characteristics of modified activated carbon under different adsorption conditions were studied.The result shows that the aniline adsorption capacity of oxygen-helium non-thermal plasma-modified activated carbon increased by about 23.5%,and the breakthrough time of the dynamic adsorption column increased by 48.1%,neutral or alkaline solution is more conducive to activated carbon to adsorb aniline.The adsorption capacity of modified activated carbon for aniline is positively correlated with O/C,the surface oxygen-containing functional groups have a great influence on the adsorption of aniline.The hydrogen bonding of carboxyl and amino groups as well as the electron donor-acceptor structure formed by the carbonyl group and the aromatic ring of aniline are the main mechanism of modified activated carbon adsorption of aniline.The adsorption process is in accordance with Langmuir isotherm adsorption model and the adsorption kinetics conforms to the quasi-second-order dynamic model,the standard enthalpy valueΔH₀is less than zero,the adsorption is exothermic and spontaneous.Research on the regeneration characteristics of low temperature plasma activated carbon.Low-temperature plasma was used to regenerate activated carbon.The effects of regeneration location and regeneration atmosphere were investigated.The characteristics of different coupling modes of water regeneration under oxygen-helium system and the effect of regeneration on the physical and chemical properties of activated carbon surface were studied.The results showed that the regeneration rate of activated carbon treated in oxygen-helium atmosphere increased from 64.44%to85.11%compared with air.During water vapor coupled oxygen-helium low-temperature plasma treatment,the number of hydroxyl radicals increases,the oxidability is enhanced,and the regeneration rate is further increased to 95.11%.The ten-time regeneration rate is still above 80%,which is also better than the thermal regeneration method.After regeneration,the number of oxygen-containing functional groups of activated carbon increases,and the content of nitrogen is reduced,75.43%of nitrogen is bound to the edge of activated carbon,mainly pyrrole nitrogen.