The Adsorption Properties Of Modified Zeolites And Modified Bentonite On Heavy Metal Ions

This research mainly discusses two aspects:the CPB and CTAMB modified zeolites were used to adsorb the Cr2O72-,Pb2+,and different adsorption effect on the different metal ions had been studied; the Zeta potential, infrared spectra (FTIR) and X-ray diffraction (XRD) of the modified and unmodified zeolites had been analyzed;the effect of the pH had been studied. The chitosan,zeolite,bentonite and ionic liquid were used as material to prepare the microspHeres that chitosan crosslinked zeolite and bentonite (CTS/IL/Z, CTS/IL/B). And the adsorption capacity of Cu2+. Cr2O72- �'� Pb2+ on CTS/IL/Z、CTS/IL/B were studied; Its adsorption capacity of the heavy metal ions was affected by the pH and dosage also were explored; the Zeta potential, infrared spectra (FTIR) and scanning electron microscope(SEM) of the modified and unmodified zeolites had been analyzed;the adsorption mechanism also had been analyzed;On this basis, regeneration process of adsorbent in the acid solution was studied.The research results are as follows:(1) The modification of zeolite by surfactantsFrom the adsorption experiment of Cr2O72-,Pb2+,we can find that the adsorption of the modified zeolites for Cr2O72- improved 4-6 times than that of unmodified zeolites,and it is exact contrary for Pb2+.When pH=4-6,the adsorbent have better adsorption for Cr2O72- and Pb2+.Through the fitting data,we can find that the sorption processes followed Langmuir model and pseudo-second-order kinetics equation. The Zeta potential of unmodified zeolites was -35.90 and the Zeta potential of CTMAB-Z,CPB-Z were 5.65,21.60.(2) The microspheres of CTS/IL/Z,CTS/IL/BThe Cu2+,Cr2O72-and Pb2+ were adsorbed by the microspheres of CTS/IL/Z and CTS/IL/B,we can find the adsorption capacity of CTS/IL/Z and CTS/IL/B on Cu2+ were 118.8 mg/g,125.5 mg/g; and for Pb2+ were 324.48 mg/g,250.0 mg/g. The adsorption capacity of CTS/IL/Z and CTS/IL/B on Cr2O72- improved 5 times than unmodified zeolite and bentonite. This showed that the adsorption capacity of CTS/IL/Z and CTS/IL/B on Cu2+,Cr2O72- and Pb2+ improved than unmodified zeolite and bentonite. The influencing factor of adsorption process, adsorption isotherm equation and kinetics models were studied, we can find that:when pH=4,the removal rate of CTS/IL/Z,CTS/IL/B for Pb2+ were 98% and 99%,the removal rate of CTS/IL/Z,CTS/IL/B for Cu2+ was 99% at pH=6; the higher adsorption capacities of CTS/IL/Z, CTS/IL/B in the acidic condition for Cr2O72-.The adsorption data of CTS/IL/Z, CTS/IL/B for Cu2+,Cr2O72- and Pb2+ fitted the Langmuir isotherm model and seudo-second-order model.The selective adsorption of CTS/IL/Z, CTS/IL/B on different heavy metal ions in the coexistent system. The order of the adsorption capacities was:Cu2+> Pb2+> Cr2O72-. From the egeneration experimen we can find that the regenerative effect is good used 0.1mol/LH2SO4. The FTIR, Zeta potentials and SEM were used to analyzed the adsorbent, we can find the electrostatic interaction and chelation mechanism were the main adsorption function.From the study,we can find the different adsorption of surfactant modified zeolite and unmodified zeolite for Pb2+,Cr2O72-.The Zeta potential,FTIR and XRD of modified zeolite and unmodified zeolite had been determined,we can find the surfactants with bilayer form combining to the zeolite surface,the charges on the modified zeolite is positive while on the unmodified zeolite is negative.And we proposed that the electrostatic adsorption was the main reason of the different adsorption of modified zeolite and unmodified zeolite on heavy metals. The adsorption capacity of CTS/IL/Z,CTS/IL/B on Cu2+,Pb2+ and Cr2O72- increased than unmodified zeolite and bentonite. The FTIR,SEM and Zeta potential of the CTS/IL/Z,CTS/IL/B have been determined,we can find the electrostatic adsorption and chelation were the mian adsorption mechanism.