Study On Adsorption Removal Method Of Silver Nanoparticles (Ag NPs) From Water

Nanomaterials were widely uesd in research, medicine and commercial purposes owing to its interesting properties.Silver nanoparticles (Ag NPs), due to its antimicrobial property, are extensively used in consumer products industrial applications. The present production of AgNPs is estimated to500tonnes/year worldwide. A large amount of nanoparticles will be disposed into environment with the increasing application of nanoparticles. The release of Ag NPs to the sewage treatment plants was estimated to be270tonnes/year. The nanoparticles in the environment could enter human body through food chain. The nanoparticles have adverse effects on human health even possess health hazard to humans due to its smaller size and large surface area. Herein, three simple materials were used as adsorbents to adsorption removal of silver nanopartilces from aqueous solution.1. Eggshell membrane (ESM) was used to adsorption removal the AgNPs from aqueous solution. The factors that might influence the adsorption performance of AgNPs such as pH, ion strength, humic acid and capping agents of AgNPs were investigated. The results demonstrate maximum adsorption of AgNPs could be reached when pH=6. The ion strength promotes the adsorption but the humic acid has obstruction effect on the adsorption of AgNPs. The adsorption kinetics showed a pseudo-second-order model for the adsorption of AgNPs. The adsorption isotherm of Ag NPs tits the Langmuir isotherm model better. The maximum adsorption capacity towards citrate capped Ag-nanoparticles was30.5mg/g. The ESM has a good adsorption ability and could be used to adsorptive removal of AgNPs. 2. The magnetic multiwalled carbon nanotube/iron oxide composite was prepared by chemical co-precipitation. The results showed that the composite has a good performance on the adsorption removal of AgNPs. Factors which may affect the adsorption performance of AgNPs such as pH value, ion strength, humic acid and capping agents of AgNPs were investigated. The results demonstrate maximum adsorption of AgNPs obtained at alkaline condition. The ion strength promotes the adsorption and the humic acid has obstruction effect on the adsorption of AgNPs. The adsorption kinetics showed a pseudo-second-order model for the adsorption of AgNPs. The represented parameters fitted using Langmuir and Freundlich adsorption models indicated that the Freundlich model effectively describes the adsorption data with larger R2, suggesting that the Freundlich isotherm fits with the experimental data better compared to the Langmuir isotherm. The maximum adsorption capacity towards citrate capped Ag-nanoparticles was483mg/g. In addition, the adsorbent can be separated from the aqueous solution under extra magnet filed easily. The magnetic material has a good adsorption capacity and could be used to adsorptive removal of AgNPs as an ideal material.3. The magnetic activated carbon/iron oxide composite was prepared by chemical co-precipitation method. The factors that might influence the adsorption performance of AgNPs such as pH, ion strength, humic acid and capping agents of AgNPs were taken into account and discussed. The adsorption kinetics and adsorption isotherm were also investigated. The results showed maximum adsorption of AgNPs obtained when pH=6. The ion strength promotes the adsorption behaviour but the humic acid block the adsorption of AgNPs. The adsorption kinetics showed a pseudo-second-order model for the adsorption of AgNPs. The adsorption isotherm of AgNPs fits the Freundlich isotherm model well. The maximum adsorption capacity towards citrate capped Ag-nanoparticles was25mg/g. What’s more, the adsorbent can be separated from the aqueous solution under extra magnet filed easily. The magnetic activated carbon/iron oxide composite has a good adsorption ability and could be used to adsorptive removal of AgNPs.