Design Of A New Liquid Phase Adsorption Vessel For In Situ Detection Of Adsorption Processes

Adsorption is a surface phenomenon defined as an increase or a change in the concentration of a particular component at the surface or interface between two phases.Compared with gas adsorption,liquid phase adsorption system is more complex.At present,liquid phase adsorption is still quantitatively analyzed by manual sampling and offline detection.The existing processes were complicated,the amount of data is a little,and the detection of the rapid adsorption stage at the beginning is difficult.Based on our previous work,in this work a new liquid phase adsorption vessel(Y-shaped adsorption vessel)was designed and optimized,and combined with fiber-optic sensing spectrometer to realize in-situ automatic on-line detection and analysis of liquid phase adsorption.The new system consists mainly of a fiber optic spectrometer,a light source,and Y-shaped adsorption vessel.Y-shaped adsorption vessel consists of a flask with a side port and an inner tube,thermostatic devices with stirring and an immersed fiber-optic dipping probe.In the adsorption system,the sorbent is separated from the fiber-optic dipping probe with nylon net attached to inner tube,which is different form our previous work,where nylon adsorption bag was used as adsorption bag.The inner tube not only eliminates the interference of the adsorbent particles on the fiber dipping probe,but also makes the in-situ adsorption detection closer to the contact mode of the adsorbent and the adsorbate in the conventional adsorption,thereby,realizing that the in-situ measurement in this paper,the macroporous resin HPD100 and HKUST-1 were used to adsorb rutin and DBT analytes at different detection wavelengths respectively.The in-situ liquid-phase adsorption method was established in the wavelength range of 190-660 nm.In-situ liquid phase adsorption kinetics,adsorption thermodynamics and in-situ detection of organic volatile systems were realized by this system.1.By investigating the effects of 4 cm,5 cm,6 cm long inner tube on adsorption mass transfer,5 cm long inner tube was selected as optimal inner tube and used in subsequent experiments.Y-shaped adsorption vessel,adsorption bag and the traditional adsorption modes were investigated under the conditions of 5 cm inner tube and 200-mesh nylon separation net.Nylon nets with seven different meshes were investigated with 5 cm inner tube.Finally,100-mesh nylon net was selected as the best isolation net.Y-shaped adsorption vessel and adsorption bag were compared under the conditions of 5 cm inner tube and 100-mesh nylon separation net.It is concluded that the adsorption rate of the device using Y-shaped adsorption vessel is significantly higher than that of the adsorption device using the adsorption bag,and when the adsorption reaches equilibrium,the equilibrium adsorption amounts of two modes are basically equal.It shows that the new adsorption vessel effectively increases the adsorption rate under the conditions of in situ detection,and is suitable for in-situ detection of liquid phase adsorption process.2.When the new adsorption vessel is combined with fiber-optic sensing in-situ liquid phase detection device,the spectrometer is not affected by temperature,and the output signal is relatively stable,indicating that the optimized system can be used for in-situ detection of adsorption kinetics and thermodynamics.The adsorption kinetic experiment was carried out by using the new system.The adsorption kinetics model was fitted.It was found that the linear correlation coefficient of the pseudo-second order kinetics model is larger than that of pseudo-first order kinetic model.The adsorption rate increases with increasing of temperature.The adsorption thermodynamics experiment was carried out with the new system.From the calculated thermodynamic parameters,it can be concluded that when the temperature range is from 303 K to 323 K,?H,?G and?S have negative values,the adsorption of rutin by HPD100 was a favorable,spontaneous,exothermic adsorption process.3.Dibenzothiophene was used as model sulfide compounds,and cyclohexane in which dibenzothiophene was dissolved was used as model oil.The adsorption test of DBT in simulated oil by HKUST-1 was carried out by the method of hollow fiber membrane protection.The standard curve of DBT in cyclohexane measured by fiber optic spectrometer is y=0.0104x-0.0231,R~2=0.9988(326 nm)and the optimal pretreatment temperature of HKUST-1 is 150°C,and the optimal pretreatment time is 2 h.The isothermal adsorption parameters of DBT to HKUST-1 were obtained by batch binding.It can be concluded that the Langmuir model is fits better to the simulated adsorption data.The whole adsorption process of DBT in small volume of simulated oil by HKUST-1 was detected by the fiber optic sensing in-situ liquid phase adsorption detection system,and in-situ detection of volatile organic solvent system was achieved.