Synthesis Of Amidoxime Group Modified Carbon Nanotubes And The Adsorption Characteristic Of Uranium And Lead

Due to the rapid development of industry and agriculture, the higher contents of heavy metals which were threw in water has reach the point can not be ignored.Because uranium has double hazards which include radioactivity and chemical toxicity,how to effectively treat the waste water pollution of uranium has attracted the attentions of most scientists.For another heavy metal element-lead(Pb),compared with uranium, although it has no radiation toxicity,the potential toxicity(such as carcinogenicity,teratogenicity,mutagenIcity)of Pb also can not be ignored.Especially with the frequent occurrence of Pb incidents in recent years,people aware that finding the effective treatment of the waste water of Pb is extremely urgent.The multi-walled carbon nanotube was used as raw material,firstly be transformed by carboxylation,acylation,amidation,then obtained the amidoxime modified carbon nanotubes(AO-MWNTs) by cyanation and amine oximation.The product was characterized by fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM),and transmission electron microscope(TEM),the adsorption experiments were carried out,different factors(such as p H,contact time,temperature,dosage)were considered to research the adsorption properties of modified carbon nanotube on uranium and Pb.The kinetic and thermodynamic of the adsorption process were respectively analyzed,and explored their adsorption mechanism through the means of SEM and FTIR.The experimental results showed that:when p H was 5,the adsorptive property of uranium on raw-MWNTs and AO-MWNTs reached the best,while the carboxylated carbon nanotubes(COOH-MWNTs) and amino functionalized carbon nanotubes(NH2-MWNTs) reached the best adsorption property of uranium when p H was 6.With the increase of adsorption time and initial concentration of uranium,the adsorption capacities of uranium on the four kinds of adsorption material increased gradually,the sequence of the adsorption capacity of uranium was AO-MWNTs>NH2-MWNTs>COOH-MWNTs>rawMWNTs,and with the increasing of adsorbent dosage,the adsorption capacity decreased.The removal of uranium was great influenced by anions of carbonate and sulfate,but less affected by cations of zinc and Pb. Kinetic fitting results showed:adsorption processes of the four materials were consistent with pseudo-second-order,and the adsorption capacity can be described by Langmuir model.When the initial concentration of Pb was 10mg/L,temperature was 25℃,p H=6,adsorbent dosage was 0.025 g,the adsorption capacity of Pb on the AO-MWNTs reached 17.24mg/g,but the adsorption capacity of raw-MWNTs could only reach 8.3mg/g in the same conditions.The pseudo-second-order matched the adsorption of Pb on AO-MWNTs better,and the Freundlich model could better describe the process.