| Heavy metals are one of the major pollutants in the atmosphere and pose a great threat to human health.Although the concentration of heavy metals in automobile exhaust is very low,the number of automobiles is huge,which still has a great impact on the environment.Therefore,it is of great significance to remove heavy metals from automobile exhaust.In this study,talc was used as adsorbent and characterized by X-ray diffraction?XRD?and infrared spectroscopy?IR?.Various methods of digestion of talcum powder are compared.The digestion experiment was carried out by the preferred digestion method,and the main components of talc were determined by inductively coupled plasma mass spectrometry?ICP-MS?.The theoretical value of Mg content in talc powder was 190320.00?g·g-1,while the measured value was 167483.14?g·g-1.The actual measured value was slightly lower than the theoretical value,and the results were consistent.In the study,the detection limit of each element was between 0 ng ng·mL-1 and 1.8850 ng·mL-1,the correlation coefficients were between 0.9995 and1.0000,and the linear relationship was good.The adsorption of talc on heavy metal ions in automobile exhaust was studied.The orthogonal test method is adopted to select the best adsorption condition for talc to adsorb heavy metals in the automobile under the idling state of the automobile.The amount of Al,Cr,Ni,Cu,Ag,Cd,Ba and Pb adsorbed by talc in automobile exhaust for a certain period of time was determined by inductively coupled plasma mass spectrometry?ICP-MS?.It was regarded as the total of heavy metals in automobile exhaust that the amounts of heavy metals were absorbed by excellent purity nitric acid at the same time.Adsorbability of Talc was evaluated by adsorption and adsorption rates.Experiments proved that talc has certain adsorption effect on Al,Cr,Ni,Cu,Ag,Cd,Ba and Pb in automobile exhaust.The adsorption amount of each element in 30min is between 0.02 and 94.05?g·g-1,and the adsorption rate is between 0.34 and63.85%.The adsorption effect of talc on heavy metals in gasoline vehicle exhaust and diesel vehicle exhaust was compared.The results showed that the adsorption amount of talc for heavy metals in diesel vehicle exhaust was significantly greater than that of talc for heavy metals in gasoline vehicle exhaust,and the adsorption effects of different elements were different.Moreover,the adsorption amount of talc for heavy metals in diesel vehicle exhaust would increase with the increase of adsorption time,which was proportional to the adsorption time.Talc was modified.Talc was taken as a substrate and calcined to obtain calcined talc?CT?.Taking Talc as a substrate,the Calcined Talc?CT?was obtained after calcination treatment.Sodium tetraborate modified talc?MT?,zinc oxide loaded modified talc?ZT?,EDTA modified talc?ED-T?,and EDTA modified calcined talc?ED-CT?was prepared.The talc before and after modification was detected by X-ray diffraction?XRD?and infrared spectroscopy?IR?,and the changes of talc before and after modification were compared.The adsorbability of Talc,CT,MT,ZT,ED-T and ED-CT to eight heavy metals in diesel vehicle exhaust was investigated.The results showed that the adsorption of Al and Ba in automobile exhaust by Sodium tetraborate modified talc?MT?increased by 4 times and 5 times respectively in 15 min.The adsorption of Al and Ba in automobile exhaust by zinc oxide loaded modified talc?ZT?increased nearly 3 times respectively in 15 min.Compared with talc itself,EDTA modified calcined talc?ED-CT?has significantly improved adsorption effect.The adsorption capacity for Al,Ba and Pb in automobile exhaust increased nearly 3 times,6 times and 1 time respectively in 15 min.Compared with several talc modification methods,EDTA modified calcined talc has the best adsorbability. |
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