Effective Removal Of Phenolic Compounds By A Newly-synthesized Adsorption Resin: Design,Preparation And Adsorption Properties

The various chemical industry processes are often accompanied by the production of phenolic compounds-containing wastewater.As kinds of protoplasm poison,phenolic compounds possess the carcinogenic,teratogenic and mutagenic harm.On the other hand,as kinds of organic chemical materials,phenolic compounds are widely existed in all kinds of natural product.As an efficient separation technology,resin adsorption has wide applied in the treatment of phenolic aqueous phase.At present,the commercial adsorption resins are characterized by the low adsorption efficiency and weak selectivity.Therefore,it is urgent to develop a new type of phenolic adsorptive resin charactered with high adsorption capacity and easy regeneration.The pore structure,modification group,polarity and steric hindrance of hyper-crosslinked resins would determinated its adsorption capacity.Therefore,the chloromethylated styrene divinylbenzene polymer(CMPS)was reacted with crosslinking reaction firstly.Through the different crosslinking reaction conditions,a series of hyper-crosslinked resins were obtained.By elemental analysis,infrared spectroscopy,N2 adsorption desorption analysis and scanning electron microscope analysis,the polymer structure of the series of hyper-crosslinked resins were characterized.And the functional groups,composition,pore structure,surface structure and other basic physicochemical characteristics of the resins were quantitative description accordingly.After that,through the comparison of five kinds of phenols(phenol,hydroquinone,phloroglucin,salicylic acid,gallic acid)adsorped by different adsorbents,it was found that the crosslinking reaction of resin determines its adsorption properties directly.With the more thoroughly of the crosslinking reaction,resins possess the higher specific surface area and the more uniformed pore distribution,and the adsorption ability of the resin towards phenolic compounds is higher accordingly.Through the intensive study of adsorption properties of optimized HF-06 in different pH and temperature conditions,the adsorption capacity of HF-06 is in the following order salicylic acid>phenol>gallic acid>hydroquinone>phloroglucin,the different adsorption capacities of HF-06 towards adsorbates are related to the molecular volume and hydrophilic hydrophobic property of the adsorbate.The adsorption capacity of HF-06 is 15% higher than NDA150.The process of adsorption is mainly physical and partial chemical action.It is the Van der Waals' force and hydrogen bonding between resin and adsorbate molecules.Through the modified experiment on the partial hypercrosslinked resin,a series of amino,hydroxyl,cross-linked bridge and complex functional group modified resin were obtained.By the comparison with commercial NDA150,the adsorption performance of the series resins towards phenol,hydroquinone,phloroglucin and gallic acid was compared.It was found that isatin modified group possesses a higher adsorption contribution than others.After that,salicylic acid and gallic acid were selected as the adsorbent owing to their different properties of matter.By the adsorption capacity compare of HF-X9,H103,CHA-111,HPD500,XAD-7 and XAD-4,it was found that the adsorption capacity of HF-X9 is higher than the series of commercial resins,and the adsorption capacity of the resins was determined by the volume and hydrophilicity of the adsorbate molecules.The adsorption capacity of hyper-crosslinked resin was higher than macroporous adsorption resin,and the adsorption superiority of salicylic acid on the hyper-crosslinked resin was higher than gallic acid.The static adsorption test of HF-X9 was texted,including the equilibrium adsorption experiments,adsorption kinetics and adsorption thermodynamics study.It is found that the two adsorbents adsorped by HF-X9 was an exothermic physical adsorption process.The adsorption capacity of salicylic acid and gallic acid fitted by Freundlich equation were 350.7 mg/g and 160.8 mg/g,the differences adsorption capacity was caused by the different molecular size and hydrophobicity of two adsorbate molecules.Moreover,the adsorption properties of HF-X9 towards salicylic acid and gallic acid in the fixed bed adsorbent column were studied.The adsorption curve was fitted by Tomas model,Clark model and Yoon model,and it was found that the rate control steps of dynamic adsorption process of adsorption column is the binding process between the adsorbate molecules and the adsorption sites.By respectively using of 1% NaOH solution,ethanol,363 K water and 298 K pure water as the dynamic desorption liquid,it is found that alkali and ethanol perform the higher desorption efficiency and concentration,and the desorption efficiency of hot water is relative poor with no impurity-introduced.Based on the series resins adsorb phenolic compounds,this paper clarifies the structure-activity relationship between resins and phenolic compounds,and it would provide a theoretical basis and technical support for the preparation of adsorbents with high capacity,the harmless treatment and resource recovery of phenolic compounds.