| The contamination of water resources poses a grave peril to the ecological balance and the survival of humankind.,and it is urgent to change the current situation of water resources pollution.During the preparation of materials,the previous research team discovered a magnetic activated carbon that can be made by a simple one-step process,which solves the problem of difficult separation and recovery of activated carbon during the adsorption process.If the magnetic activated carbon can have significant effects in sewage treatment,it can promote the development of activated carbon in the field of sewage treatment.In reality,the pollutants in water are complex.If we can explore the most suitable type of polluted water for this magnetic material,we can maximize its removal performance.Under these conditions,studying the adsorption mechanism is more conducive to practical application.Further operations are required to completely remove contaminants.The use of activated carbon in advanced oxidation processes(AOPs)has a strong ability to activate oxidants,and the activated oxygen species generated after activation have a good degradation effect on pollutants.Among them,free radical pathways dominated by hydroxyl radicals(·OH)and sulfate radicals(SO42·-)and non free radicals dominated by singlet oxygen(1O2)are the most common.Most of the 1O2 in solution is produced by ·OH and SO42·-.This article will explore the removal process of organic pollutants in water from the perspective of adsorption using activated carbon as a material.In the third chapter,magnetic activated carbon(Mag-AC)prepared by iron doped activated carbon is used as an adsorbent,and bisphenol A(BPA)is used as the target pollutant as an example to study the specific adsorption process.Adsorption isotherms are an effective method for us to study the adsorption process,but the traditional Langmuir and Freundlish Adsorption Isotherms have certain limitations.Such as the surface site of the adsorbent proposed by Langemuel Adsorption Isotherm only one adsorbate molecule.And the adsorbate molecules are monolayer adsorption on the surface of the adsorbent,etc.This are the premise that using of Langemuir Adsorption Isotherms.These assumptions limit the understanding of more complex adsorption processes to some extent,and do not explain the adsorption mechanism between adsorbents.Therefore,this chapter uses advanced statistical physics models to fit the process of Mag-AC adsorption of BPA,and explores adsorption site density,maximum saturated adsorption capacity,and thermodynamic parameters(Enthalpy,Entropy,Gibbs free energy).According to the coefficient of determination(R2)of statistical indicators,it is believed that the dual-energy bilayer model can more accurately fit the process of Mag-AC adsorption of BPA.According to the evaluation of each stereoscopic parameter and energy parameter,it is concluded that the temperature controls the aggregation at the adsorption site.With the increase of temperature,the adsorbate molecule(n)from parallel single-molecule adsorption to non-parallel multimolecular adsorption.At the same time,the number of average adsorption sites(D)occupied by unit adsorbate molecules decreases.Because the saturated adsorption capacity(Q0)is controlled by D,Q0 also decreases with increasing temperature.The thermodynamic parameters show that the system increases entropy before reaching the saturated adsorption capacity.When reaches the maximum saturated adsorption capacity,it began to decline.The whole adsorption process is exothermic.In Chapter 4,Mag-AC is also used as an adsorbent.However,in similar studies,most have chosen the similar research proces.Pyrolysis at the right temperature,testing the adsorbent performance in different environments,and finally fitting using the adsorption isotherm model.The control variable method is often used to test the performance of sorbents,which tends to ignore the effects of interactions between different conditions.Moreover,an adsorbent typically adsorbs only one or two contaminant molecules.If it can be found that the adsorbent adsorbs a certain type of pollutant,it is more important to use the adsorbent to centrally adsorb this type of sewage.Corresponding Surface(RSM)and Random Forest(RF)were used to optimize and predict the adsorption process.RSM is used to explore the interaction between factors,using less data to generate mathematical models to estimate the relationship between factors and responses(removal rates).RF is an integrated machine learning technology based on Python.It can describes the nonlinear relationship between variables and responses,and predicts the importance of various functional groups and the changes in the process.According to various data,temperature,Fe doping amount and Fe doping amount squared had the greatest influence on BPA removal rate.MagAC has the best adsorption effect on the functional groups containing benzene rings,C-C and S=O in pollutant molecules.In Chapter 5,contaminants in water are eliminated by means of degradation.Whether the adsorption of pollutants on the surface of activated carbon is beneficial for activating oxidants to generate free radicals and participate in degradation is discussed.A type of catalyst with a high specific surface area,such as activated carbon,often adsorbs pollutants(such as Acid Orange(AO7))onto the surface during degradation.Activated carbon activates oxidants(such as PMS)to generate active oxygen species,which attack pollutant molecules to achieve degradation effects.However,it is difficult for active oxygen species to move on the surface of the catalyst,coupled with the obstruction of pollutant molecules,and the free radical pathway changes to a non free radical pathway.Through experimental analysis of free radical quenching and electron paramagnetic resonance(EPR).In this study,AC-Fe PEI-NaHCO3 was used as a catalyst to clarify that the non free radical pathway dominated by 1O2 played a major role in the degradation of AO7.The results showed that the adsorption of AO7 on the surface of AC-Fe PEI-NaHCO3 was not conducive to the activation of PMS by AC-Fe PEI-NaHCO3,resulting in a free radical pathway dominated by ·OH and SO4·-to achieve degradation.In summary,this article uses activated carbon as the main material,focusing on the adsorption process,to explore the removal of organic pollutants. |
PDF Full Text Request