| Resorcinol,as an important fine chemicals,is widely used in petroleum,chemical industry,papermaking,medicine and other industries.At present,resorcinol is produced by the method of sulfonated alkali fusion,which will discharge a large amount of resorcinol wastewater with a high concentration.Resorcinol is an endocrine disrupting agent(EDCs)Reproductive malformations,abnormal development and environmental pollution will be caused by discharge of this wastewater without treatment.Therefore,it is necessary to treat this wastewater without pollution.There are many ways to deal with resorcinol wastewater.Adsorption process with some advantages,such as mature technology,no new pollutants and low energy consumption,has become a common method of organic wastewater treatment.In traditional adsorption process,adsorption equipment includes contact filtration and adsorption equipment,fixed bed,fluidized bed,and so on.They all have many problems,such as bulky equipment,small adsorption rate and low bed utilization.Rotating packed bed(RPB),as a new type of mass transfer equipment enhancing chemical process,has the incomparable merits over other mass transfer and separation devices,such as reducing equipment energy consumption,reducing equipment volume and increasing yield.Until now the applications of RPB’s has been mainly focused on gas/liquid systems,such as absorption,stripping,distillation,and so on.There is not much data reported in literature concerning liquid/solid transfer in an RPB.Therefore,the adsorption and desorption process of resorcinol on activated carbon in RPB were studied in this paper,aiming at opening up a new process for the treatment of resorcinol wastewater.In this paper,RPB as adsorption equipment,activated carbon as adsorbent wastewater containing resorcinol was treated.The appropriate adsorption operation Conditions were obtained by investigating the flow rate,high gravity factor,p H and other factors on the impact of the resorcinol removal rate,adsorption isotherm equilibrium line and kinetic data weredetermined,and the adsorption mechanism of resorcinol adsorbed on activated carbon in RPB was presumed.The optimum operating conditions include: a temperature of 20 ℃,a high gravity factor of 41.30,a p H value of 5,a flow rate of 50 L/h and an adsorption time of 2 h.In this case,the removal efficiency of resorcinol reaches 96.86% with an initial concentration of resorcinol of 900 mg/L.The results indicate that the adsorption process fits Freundlich isotherm model,the adsorption heat is 14.65 k J/mol.The adsorption process is mainly consistent with the pseudo-second order kinetic model,Internal diffusion is not the only rate control step.The adsorption rate constant of the adsorption process is higher 1.626 and1.413 times than the conventional adsorption method of the fixed bed and magnetic stirrer,respectively.It is indicated that high gravity technology is beneficial to adsorption performance by strengthening the liquid to solid mass transfer.The selection of adsorbents was stuied in this paper.The effects of different adsorbents such as silica gel and 5A zeolite on the resorcinol adsorption in RPB were compared.The results show that the removal of resorcinol on activated carbon is more than molecular sieve which is over silica gel under the same operating conditions,which is related to specific surface area,pore size and surface physicochemical properties of adsorbent.In addition,the quasi-first-order and quasi-second-order kinetic models are used to analyze the experimental data.The results show that quasi-second-order kinetic equation is better to describe the adsorption process of resorcinol on different adsorbents.Finally,the desorption behavior of resorcinol from activated carbon in rotating packed bed was studied with ethanol as desorption agent,the effect of different desorption agents on the desorptionl rate of resorcinol was compared.The optimal operation conditions were determined with temperature of 20℃,high gravity factor of 32.63,p H value of 11,flow rate of 50 L/h,desorption agent ethanol of40 wt%and desorption time of 90 min.In these case,desorption rate of resorcinol reached93.90%.Compared with ultrapure water as desorption agent,the desorption rate of resorcinol with ethanol as desorption agent was increased Twenty-eight point one nine percent in RPB,fifteen point four percent in traditional fixed bed.pseudo-second-order kinetic model was adopted to study kinetics,the results show that the high gravity technology was beneficial todesorption performance by enhancing the mass transfer.The desorption rate constant increased with the increased of flow rate and high gravity factor.In addition,the desorption rate constant improved from 13.27×10-3 with ultrapure water as desorption agent to 25.48×10-3with ethanol as desorption agent.The results show that the suitable adsorption process condition include: a temperature of20 ℃,a high gravity factor of 41.30,a p H value of 5,a flow rate of 50 L·h-1 and an adsorption time of 2 h.The suitable desorption process condition include: temperature of20℃,high gravity factor of 32.63,p H value of 11,flow rate of 50 L/h,desorption agent ethanol of 40 wt%and desorption time of 90 min.In above cases,the removal efficiency and desorption rate of resorcinol reached 96.86% and 93.90%,respectively.1one ton of 900 mg/L resorcinol wastewater will be treated in RPB and traditional fixed bed under same process parameters,respectively.Calculations show the resorcinol qualities of adsorption and desorption were 870.77 g and 817.65 g in RPB,respectively;696.96 g and 248.94 g in traditional fixed bed.Compared with traditional fixed bed as adsorption and desorption equipment,8.14 kg of activated carbon are saved,916.82 liters of industrial ethanol are saved in RPB.The result of this paper shows that the high gravity with high can enhance liquid/solid mass transfer by increasing the contacting area,short the time to reach equilibrium.and has high adsorption and desorption efficiency.It has good potential and better application for industrial application. |
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