Study On The Preparation And Adsorption Properties Of Selective Materials Towords Ag(?) In Industrial Wastewater

Precious metals are often used in many industries such as electronics,pulp and jewelry,and the wastewater produced by these industries usually contains large amounts of Ag?I?.The wastewater contained Ag?I?will has a serious effect on ecosystem and human health.Meanwhile,silver is also valuable resource that is worth recycling.Therefore,how to effectively treat heavy metal-laden wastewater and simultaneously realize recycling is a common fundamental issue for scientists and entrepreneurs.A new high selectively functional monomer was designed and synthesized in this study,and successful preparation of three new selective adsorbents based on this.Adsorption performance of the three adsorbents towords Ag?I?was studied.The main contents of this study are as follows:1.Homocysteine thiolactone hydrochloric acid was used to react with acryloyl chloride to synthesize a new high selectively functional monomer–thiolatone acrylamide?Tla Am?.Then,silver ion-imprinted polymer was successfully prepared via precipitation polymerization by using Ag?I?as template ion,TlaAm as functional monimer and EGDMA as crosslinker.SEM shows that the Ag-IIP is a granular polymer microsphere which posses rough surface.BET found that specific surface area of Ag-IIP(148.25 m² g^-1)is significantly higher than that of Ag-NIP(14.75 m²g^-1),which was proved that there are a large number of imprinted cavities in Ag-IIP.The experimental data of adsorption for Ag?I?on Ag-IIP fits well with the Langmuir adsorption isotherm,indicated that the adsorption sites are distributed uniform.The theoretical maximum adsorption capacity of Ag-IIP is 25.07 mg g^-1.The adsorption kinetics follows the pseudo-second-order model,and analysis of the experimental data fitted D-R model shows that adsorption mechanism of capturing Ag?I?onto Ag-IIP is a chemisorption.Ag-IIP has high selectivity for Ag?I?in mixture solution contained a variety of competitive ion,and the selectivity coefficient higher than 15.The adsorption capacity decreased by 9.8%after 6 cycles,and actual wastewater experiment shows that the Ag-IIP still has good adsorption capacity in complicated water environment.Furthermore,XPS proves that the Ag?I?in aqueous solution was bound with sulfur of Ag-IIP.2.Ag-IIP does not possess excellent adsorption capacity due to a large number of crosslinking agents was added in the synthesis process which reduces density of binding sites in material.Therefore,the thiolactone functionalized acrylamide?PAM-TL?was successfully synthesized through facile free radical polymerization of Tla Am without crosslinking agents.SEM shows that the Ag-IIP is spherical particles which posses smooth surface.EDS mapping and elemental analysis show that the percentage of S in PAM-TL is much higher than that of Ag-IIP,which proves PAM-TL has higher density binding site.Isothermal adsorption for Ag?I?onto PAM-TL is well fitted Sips model,which effectively fits to the Freundlich isotherm model at low sorbate concentration and fits to of Langmuir model at high adsorbate concentration.The theoretical maximum adsorption capacity after 12 h of Ag-IIP is 145.7 mg g^-1which much higher than that of Ag-IIP.The adsorption kinetics fits well with pseudo-second-order model which reveal that it is chemisorption.Meanwhile,experimental data are tremely good fitted with Weber and Morris model which indicates that the adsorption process is involved a diffusion mechanism.Through four selective adsorption experiments,PAM-TL has excellent adsorption selectivity for Ag?I?because of there are abundant available binding sites in PAM-TL and strong interaction between binding sites with Ag?I?.The adsorption capacity of PAM-TL was increased in the first four adsorptions-desorptions experiments due to the swelling of the material.Actual wastewater experiment shows that PAM-TL can be applied to complicated enviornment.3.PAM-TL is found easily agglomerated in the aqueous solution due to the with the poor hydrophilicity thiolatone group of functional monomer Tla Am,which cause a serious effect on adsorption rate.Therefore,PAM-TL@SF was successfully prepared though a small amount of sodium allylsulfonate with anionic hydrophilic group was added in the synthesis process.SEM shows that PAM-TL@SF is a spherical polymer with uniform size and the particle size is about 1um.The average pore diameter and pore volume of PAM-TL@SF are slightly larger than that of PAM-TL.Contact angle analysis confirmed that PAM-TL@SF had higher hydrophilicity.The isothermal adsorption of PAM-TL@SF for Ag?I?is well fitted with the Langmuir model,and the theoretical maximum adsorption capacity after 12 h is 222.22 mg g^-1.The kinetic experiments showed that PAM-TL@SF adsorbed quickly in the first 30 min,and the adsorption capacity of PAM-TL@SF was higher than that of PAM-TL at the same time.The distribution coefficient of PAM-TL@SF for Ag?I?is 2731.07 mL g^-1and the selectivity coefficients of other metal ions were above 200,which showing excellent adsorption selectivity.The pH experiment and Zeta potential proved that PAM-TL@SF was more suitable for adsorption in a low pH solution than PAM-TL because of it had more negative charge?sulfo group?on the surface.The removal rate of PAM-TL@SF for Ag?I?reach 98.72%after 7 cycles and it still exhibit excellent adsorption performance in actual industrial wastewater.Therefore,PAM-TL@SF has a promising application prospect in actual industrial wastewater treatment.