Diffusive Gradients In Thin Film Based On Ceric Oxide For In-situ Measurement Of Inorganic Arsenic And Dissolved Phosphorus

In recent years,increasing arsenic and phosphorus pollution in waters has aroused wide public concerns.Inorganic arsenic is highly cancerogenic and can result in direct damages to human.Excessive phosphorus in waters can result in eutrophication of natural waters.Therefore,the measurement of inorganic arsenic and phosphorus in waters is of significance for protecting environmental ecology and human health.The diffusive gradients in a thin films?DGT?sampling is an in-situ,passive sampling technique.DGT can achieve the time-weighted-average?TWA?concentration of analytes in the sampling period and is available for bioavailability of analytes.Here we prepared a new binding gel based on ceric oxide?CeO₂?and then developed CeO₂-DGT for in-situ measurement of inorganic arsenic and dissolved phosphorus in natural waters.The detailed contents include:CeO₂ material was successfully synthesized by a facile one-step co-precipitation method.The prepared CeO₂ material was characterized by scanning electron microscopy,N₂adsorption/desorption isotherm experiment and Zeta potentiometric analysis.The results showed the obtained CeO₂ material was nanoparticle,with an average particle size of 20-30nm.The Brunauer–Emmett–Teller?BET?surface area was 82.3 m²/g,with an average pore size of 3.54 nm.The measurable isoelectric point?pI?was 5.4.The nanoparticle showed excellent dispersibility and stability in water.CeO₂ nanoaprticles-based binding gel was prepared for uptake of arsenic.The CeO₂binding gel presented a maximum adsorption capacity of 661.40?g and 371.30?g per disc toward As^III and As^V,respectively.The CeO₂ binding gel was used for DGT measuremt of arsenic,there was a linear relationship between the accumulated masses of As^III and As^V versus time with DGT deployment up to 72 h?R²=0.99?.The changes of pH?4.20⁹.05?and ionic strength?10 nmol/L⁰.5 mol/L?did not have obvious influence on the analysis.The limit of detection for As^III and As^V were 0.032?g/L(As^III)and 0.064?g/L?As^V?,respectively,by CeO₂-DGT deployment and on-line hydride generation atomic fluorescence spectrometry?HG-AFS?analysis.The method was successful applied to the measurement of arsenic in one resvior and seawater in Dalian.The results showed that the concentration of total inorganic arsenic was 1.38±0.09?g/L in the revisor and 0.45±0.06?g/L in seawater.The CeO₂ binding gel presented a maximum adsorption capacity of 596.05?g per disc.The CeO₂ binding gel was used for DGT measuremt of dissolved phosphorous in water.There was a linear relationship between the accumulated masses of dissolved phosphorous versus time with DGT deployment up to 72 h?R²=0.99?.pH?4.22⁹.32?and ionic strength?10 nmol/L⁰.5 mol/L?did not have obvious influence on the analysis.The limit of detection for dissolved phosphorous was 47.03?g/L by CeO₂-DGT deployment and phosphoantimonylmolybdenum blue method analysis.The method was successful applied to the measurement of dissolved phosphorous in one resvior and seawater in Dalian.The results showed that the concentration of dissolved phosphorus was 337.97±17.57?g/L in fresh water and 174.91±10.25?g/L in seawater.A new CeO₂ binding gel with a high capacity and fast uptake toward As^III and As^V and good storage stability was developed for DGT measurement of arsenic and phosphorus.The CeO₂-DGT coupled with a HG-AFS was examined and used successfully for the measurement of inorganic arsenic and dissolved phosphorus in resvior and seawater,with satisfactory results.The developed method provided a powerful tool for in-situ measurement of inorganic arsenic and dissolved phosphorus in natural waters.