Preparation And Adsorption Properties Of Resin Matrix Composites

Antibiotics as emerging pharmaceutical contaminants in aquatic enviromment.,Traditional wastewater treatment processes cannot remove these chemicals efficiently,some novel technologies including nanofiltration,reverse osmosis,advanced oxidation and adsorption have been developed in recent years.Adsorption has been proven to be an effective process for removal of various antibiotic pollutants from aqueous solutions because of its simple design,flexibility,easy operation and low capital cost.Thus,more highly-selective and easily-regenerative adsorbents need to be prepared for effectively removing antibiotics from water.The activated carbon/melamine formaldehyde resin(AC/MF),melamine formaldehyde resin/melamine urea formaldehyde resin(MF/MUF),polyaniline/phenolic resin(PANI/PF)composite were synthesized via water bath method,chemical oxidation polymerization method,respectively.The composites was characterized by scanning electron microscopy(SEIM)and Fourier transform infrared(FT-IR)spectroscopy.Norfloxacin(NOR),amoxicillin(AMX)and sulfonamide(SAs)were used as typical pollutants in antibiotics.The adsorption performance was investigated by single factor experiments,which were used to preliminarily discuss adsorption mechanism.(1)The AC/MF composite was synthesized by water bath method to study their adsorption properties for NOR.The results showed that the removal efficiency of AC/MF composite for NOR solution was 98.87%when the pH value of solution was 7.01,the AC/MF dosage was 0.02 g and the treatment time was 180 min at a temperature of 303 K.Thermodynamic studies showed that the adsorption behavior of NOR fit well the Freundlich adsorption isotherm model and the maximum adsorption capacity was found to be 48.75 mg·g-1.Standard values of Gibbs-free energy(?G),enthalpy(?H)and entropy(?S)revealed that the adsorption process is a spontaneous and endothermic process.The kinetic data were well described by pseudo second-order kinetic model.The whole adsorption process was jointly controlled by both liquid film diffusion and intraparticle diffusion,and liquid film diffusion was the rate-dominating step.The dominant adsorption mechanisms of NOR on AC/MF composite are hydrophobic effect,?-? interactions and electrostatic attraction.After six adsorption-desorption recycles,AC/MF still has strong adsorption performance for NOR and could be recycled and reused.(2)The MF/MUF composite was synthesized by water bath method to study their adsorption properties for AMX.The results showed that the removal efficiency of MF/MUF composite for AMX solution was 98.45%when the pH value of solution was 7.01,the adsorbent dosage was 0.1 g and the treatment time was 180 min at a temperature of 303 K.Thermodynamic studies showed that adsorption isotherm studies have suggested that the adsorption of AMX by MF/MUF is fitted with both the Langmuir adsorption model and the Freundlich adsorption model,and it meets the adsorption of monolayer coverage at high temperature,and conforms to multi-molecular coverage adsorption at low temperature,RL is 0.06-0.136,belonging to the preferential adsorption.The thermodynamic behavior analysis indicates that the adsorption of AMX is a spontaneous and endothermic process.Kinetic studies show that the adsorption process of MA/MUF on AMX conforms to the Elovich and Avrami model and controlled by film diffusion procedure.MF/MUF still remains certain ability of adsorption of AMX after regenerated six times by NaOH solution.(3)The PANI/PF composite was synthesized by chemical oxidation polymerization method to study their adsorption properties for SAs.The results showed that the solution was added with 0.15 g of adsorbent under acidic or neutral conditions and adsorbed fo 180 min at 303 K.The removal efficiency of SAs was 97.69%.Thermodynamic studies show that the adsorption process of SAS by PANI/PF conforms to the Freundlich model.Thermodynamic studies(?H=4.28<40 kJ·mol-1 and ?G<0)showed that the adsorption process is a spontaneous physical adsorption process.The adsorption process of PANI/PF for SAs presents an ideal fit to the pseudo second-order kinetic and Avrami model and controlled by film diffusion procedure.After six times of regeneration with HCl solution,the removal efficiency of sulfonamide by PANI/PF was still as high as 68.28%,indicating that PANI/PF after regeneration still remains certain adsorption performance for SAs.