Silver Nanoparticles Deposition On Model Environmental Surface In Aquatic Environments: Influence Of Coexistent Ions And Macromolecular

Nanotechnology,which is considered to be the new industrial revolution,not only shares the potential advantages of nanotechnology in many fields,but also brings large benefits to our daily life and manufacture.As one of the foundations and products of nanotechnology,AgNPs have outstanding catalytic,optical and electrical properties,while their strong broad-spectrum antimicrobial activity and relative low cost make it extensive used in textiles,food storage containers,personal care products,laundry additives,home appliances,and even food supplements.However,AgNPs are discharged into aquatic environments throughout the process from manufacture to disposal and adverse effects that may be produced on the environment or for humans have been found.Biological exposure is a prerequisite for biotoxicity.While deposition of AgNPs in environmental relevant surfaces can reduce their exposure in the aquatic environment.Hence,exhaustive research is needed into their deposition behavior and mechanism for AgNPs exposed to the aquatic environment.In the work described herein,quartz crystal microbalances with dissipation combined with dynamic light scattering and X-ray photoelectron spectroscopy were used to explored the effect of coexistent ions and macromolecules on deposition behavior of AgNPs in the aquatic environment.Meanwhile,aggregation and transformation behavior of AgNPs,DLVO interaction energy profiles between AgNPs and surfaces,affinity between macromolecules and surfaces were considered to reveal the influence of above factor on AgNPs deposition mechanism.The results show that the promotion of AgNPs deposition by cations in accord with the DLVO theory.Meanwhile,effects of cation valences on AgNPs deposition in agreement with Schulze-Hardy rule.The introduction of anions which interacted specifically with AgNPs into cationic system change the deposition behavior of AgNPs.At low electrolyte concentration,silver chloride precipitates on the surface of AgNPs increased the affinity of AgNPs to surfaces.Hence AgNPs deposition behavior were promoted.While at high electrolyte concentration,AgNPs deposition were inhibited due to the continuously formation of soluble Ag Cl_x^（x-1）-species.While in coexistent ions and macromolecules system,key mechanisms affecting the deposition of AgNPs depend on the macromolecular species.In the present of humic acid or sodium alginate,the transformation of AgNPs by chloride is stronger than the adsorption of humic acid/sodium alginate on AgNPs.At low electrolyte concentration,hydrophobic humic acid/sodium alginate adsorbs on the surface of newly formed Ag Cl,which inhibits the deposition of AgNPs onto hydrophilic SiO₂surfaces.While at high electrolyte concentration,the continuously formation of soluble Ag Cl_x^（x-1）-species prevent the absorption of humic acid/sodium alginate on AgNPs,hence humic acid/sodium alginate has little effect on the deposition of AgNPs in this condition.However,in the present of bovine serum albumin,the deposition of AgNPs shows different types.There are several reasons:（1）hydrophilic bovine serum albumin has a strong affinity for SiO₂,（2）bovine serum albumin produced stronger adsorption on AgNPs,which inhibits the transformation of AgNPs by chlorine,（3）chloride reduces the looseness of bovine serum albumin,which increase intermolecular repulsion,thus inhibits the deposition of AgNPs.Overall,these results provide systematically insights into the effects of coexistent ions and macromolecular on deposition behavior and mechanism of AgNPs on SiO₂ surfaces,and have significant implications for evaluating the transport potential and environmental risk of common AgNPs in aquatic environments.