Removal Of Heavy Metal Ion From Aqueous Solutions Using Typical Carbon-Based Materials And Their Quantification

This paper is aimed at the application of typical carbon materials in the removal of contaminants and the quantitative analysis of typical carbon materials.On the one hand,after the comparison ofremoval abilities of the polyethyleneimine modified biochar and polyethyleneimine modified graphene oxide（GO）forPb²⁺in aqueous solution,a novel method based on the modified biochar for highly efficient removalofPb²⁺was developed..On the other hand,a highly sensitive quantitative method for graphene oxide（GO）in environmental water samples was developed based on the on-line photocatalyticdegradation coupled with the point discharge atomic emission spectrometry system.Bothe biochar and GO aretypicalcarbon materials with large specific surface area,abundant surface functional groups,low price and easy industrial production,triggering extensive research,application and large-scale production potential of them.The comparison experiments demonstrated that the polyethyleneimine modified biochar was more efficient in removal of Pb²⁺in aqueous solution than the polyethyleneimine modified GO.Based on the characterization of the morphology and surface properties of the modified biochar,the effects of biochar types,pyrolysis temperature and polyethyleneimine addition were systematically investigated.Under the optimized experimental conditions,the removal efficiency of the trace concentration of lead（1 mg/L）was 94%within 90 min.The removal efficiencies of Pb²⁺in variouswater bodies such as lake water and river water were higher than 90%.Results demonstrated thatthis developed method could be successfully applied to efficiently remove Pb²⁺in actual water bodies,providing a noveltoolfor the removal of other heavy metal ions.It is confirmed that GO is one of the most toxic carbon materials.Quantitative analysis of GO is a prerequisite for scientific evaluation of its environmental risk.However,the quantitative analysis methods for GO at low concentration in the environment are currently scarce.In this study,UV photodegradation was combined with point discharge-atomic emission spectroscopy（PD-OES）to establish a quantitative analysis method for trace GO in water.The Fenton reagent and nano titanium dioxide are selected as oxidants and the photocatalyst todegrade GOinto volatile products such as carbon dioxide,alcohol and aldehyde under the irradiation of a high pressure mercury lamp.The high-purity argon gas was used to introduce the volatile products into the PD-OES system.The quantitative analysis of GO was achieved from the carbon emission intensity.This study systematicallyinvestigated the effects of oxidant components,working conditions,and sample properties on system performance.In order to further improve the sensitivity and anti-interference ability of the system,the agglomeration phenomenon of GO in high-salt and high-alkaline solution sheets was proposed for rapid separation and enrichment of GO before quantitative analysis.The detection limit of GO for this method is as low as5.2μg/L,and the precision is 4.3%(50.0μg L^-1GO,n=7).The spiked recoveries of real water samples includingake water,river water,ground water and tap water varied in the range of 92-110%,suggesting the excellent practicability of the method proposed...