| In recent years, the haze and fog issue in China has been widely concerned. It is found that secondary organic aerosol formation of haze is an important factor, which was mainly caused by volatile organic compounds (VOCs). Thus, VOCs must be controlled imperatively. Adsorption is the most widely used technology for controlling VOCs. However, commonly applied adsorbents, such as activated carbon, had problems including regeneration difficult, high adsorption cost, and secondary pollution.The sorbent of PCH-calcination performs a good adsorption of VOCs. However, calcinations process consumes high level of energy and time in preparing PCH-calcination, and easily leads to the layer and pores of organobentonite collapse and affects the adsorption properties. Therefore, on the basis of traditional PCH-calcination preparation methods, the study focused on a new type of plasma preparation of PCH-plasma. Firstly, we studied the effects of different surfactants, cationic surfactants after proportion and PCH-calcination pillared agent ratio on VOCs adsorption performance of PCH-calcination, optimization of organobentonite prepared to lay the foundation for the study of plasma modification; after that the research focused on the influence of the plasma discharge parameters and discharge conditions on PCH-plasma effect, and from the point of view of the physical and chemical structure modification mechanism in-depth analysis.Results showed that PCH-calcination’s adsorption properties of VOCs related with carbon chain length of cationic surfactant. The specific surface area of PCH-calcination synthesized by cetyl trimethyl ammonium bromide (CTMAB) reached 608.3 m2/g, with adsorption of cyclohexanone to 129 mg/g. The adsorption property of PCH-calcination positively correlated with additive amount of cationic surfactant. When the ratio of PCH-calcination and cationic surfactants exceed 1:2, the increase of the adsorption capacity of cyclohexanone is not obvious. The adsorption properties of PCH-calcination related to the addition amount of pillared agent. In addition, the results showed that the higher the adsorption temperature was, the smaller the amount of adsorption of cyclohexanone was. The initial adsorption rate increases with the increase of cyclohexanone flow; adsorption of cyclohexanone PCH-calcination along with the increase of the concentration of cyclohexanone. In summary, this study exploited the most appropriate method of preparation of organobentonite and dynamic adsorption process of cyclohexanone as follow:CTMAB ratio of 1:1, pillared agent ratio of 1:120, the temperature of dynamic adsorption process is 30℃, cyclohexanone flow of 500 mL/min, cyclohexanone concentration of 20 mg/m3. The basic conditions for this method are as preparation of PCH-plasma and adsorption properties of cyclohexanone research.In the process of preparation of PCH-plasma, discharge time, discharge gap, the initial discharged voltage and positive or negative corona and so on, these discharge parameters will affect the adsorption properties of PCH-plasma. Results showed that the adsorption properties of PCH-plasma first increased and then decreased with discharge time increasing from 1 h to 8 h, cyclohexanone ring adsorption increased from 40 mg/g to 132 mg/g. The adsorption capacity at 10 h decreased to 123 mg/g. This phenomenon is due to PCH-plasma surface area and mesoporous pore volume increase with the discharge time of the first increase and then decrease, the specific surface area from 153.5 m2/g increased to 468.8 m2/g, pore volume from 0.28 cm3/g increased to 0.75 cm3/g. XPS showed the carbon content of oganobentonite rose from 24.32%(no discharge) to 64.97%(8 h after discharge), the oxygen content falling from 55.13% to 19.19%. Results of XPS show that the composition of PCH-plasma, like carbon, oxygen, and C=OR and other functional groups, play a key role in its adsorption ability with increasing discharge time. Study have shown that C=OR relative content in gradually increasing, which promotes PCH-plasma to adsorb cyclohexanone. The bigger the discharge gap is, the better adsorption properties of PCH-plasma is. When discharge gap increases from 5 mm to 15 mm, the adsorption amount of cyclohexanone ring increases from 40 mg/g up to 80 mg/g, the specific surface area was increased from 237.8 m2/g to 358.3 m2/g, pore volume increased from 0.40 cm3/g to 0.51 cm3/g. Adsorption properties of PCH-plasma was positively correlated with the initial discharge voltage, the initial discharge voltage from 10.0 kV up to 11.5 kV, adsorption capacity from 51 mg/g increased to 94 mg/g, the specific surface area from 204.6 m2/g increased to 394.9 m2/g, pore volume from 0.40 cm3/g increased to 0.49 cm3/g. Negative corona is more conducive to the modify oganobentonite, when the adsorption amount of positive corona modification is 48 mg/g, the specific surface area and pore volume are 307.0 cm3/g and 0.49 m2/g; while the adsorption capacity of negative corona modification is 53 mg/g, the specific surface area and pore volume are 254.4 cm3/g and 0.42 m2/g. In addition, the paper also studied the effect of oxygen concentration and flow rate in plasma modification on the adsorption properties of PCH-plasma. The results showed a higher concentration of oxygen in favor of modified oganobentonite and better adsorption properties. When the oxygen concentration is 20%, the adsorption of modified oganobentonite amount of cyclohexanone is 12 mg/g, the specific surface area and pore volume are 142.8 m2/g and 0.35 cm3/g; when the oxygen concentration was increased to 100%, the adsorption capacity increased to 69 mg/g, specific surface area and pore volume were increased to 342.8 m2/g and 0.50 cm3/g. Adsorption properties with the increase of oxygen flow and increased oxygen flow rate from 100 ml/min to 1000 ml/min, the adsorption amount from 39 mg/g up to 57 mg/g, a specific surface area from 233.1 m2/g was increased to 287.0 m2/g, pore volume of from 0.42 cm3/g is increased to 0.63 cm3/g. The smaller the treated amount of the PCH-plasma, the better beneficial effect of PCH-plasma is. But too small processing amount may lead to the occurrence of not burning during the preparation of PCH-plasma so that poor modified process effects. When the treated amount was 1.0 g adsorption capacity is 51 mg/g, while the processing amount was 0.1 g, the adsorption capacity is 107 mg/g. The specific surface area was increased from 275.6 m2/g to 383.2 m2/g, the pore volume from 0.45 cm3/g by great to 0.67 cm3/g. From the above results in our study, the PCH-plasma which was discharged for 8 h with plasma, adsorption amount of cyclohexanone was 132 mg/g, meets or exceeds the amount of adsorption of the PCH-calcination. |
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