| Carbon materials have been extensively investigated as promising candidates for pollutant removal due to their high surface areas,large pore volumes,good thermal stability and great mechanical strength.In this work,three kinds of amino functional adsorbents?AC@SiO2-NH2,MWCNTs@SiO2-NH2 and PCM@SiO2-NH2?were successfully synthesized via surface functional modification and utilized for the removal of heavy metals such as Pb???,Cu???in wastewater.Characterization techniques were employed to investigate these composite materials.The effects of reaction time,loading ratios of amino groups,initial concentration of pollutant,pH and coexisting substances on adsorption were also investigated.AC@SiO2-NH2,MWCNTs@SiO2-NH2 and PCM@SiO2-NH2 exhibited good adsorption performance towards Pb???and the maximum adsorption capacities were 135.1,147.1 and 138.9 mg·g-1,respectively.The adsorption of Pb???on three amino functionalized adsorbents calculated by the Langmuir model,representing that the adsorption process occurred on a homogeneous surface by monolayer adsorption.Maximum removal efficiency was recorded at pH 5 and the common cations?K+,Na+,Mg2+?and organic compounds?SA,HA?in water have little effect on Pb?II?removal.On this basis,this paper selected activated carbon and biomass carbon as two research objects.?1?A novel functional adsorbent AC/Fe3O4@SiO2-NH2 was prepared by a one-pot synthesis process onto magnetic activated carbon matrix and applied for the removal of Pb?II?.Fe3O4 loading ratios,reaction time,initial pH values,temperature,Pb???initialconcentration and co-existing interferences were studied to explore the effect on Pb???removal.Characterization techniques including TEM,SEM,Maping,FTIR,BET,XRD,Zeta,XPS were applied to investigateits structural properties and the possible adsorption mechanism between modified magnetic activated carbon and Pb???.?2?Trace complexed Cu???in aqueous solutions were removed by amino-functionalized pig carbonization material.Analytical techniques like SEM,EDX,Maping,FTIR,TGA and XPS were employed to investigate PCM@SiO2-NH2-Adsorbent dosage,initial concentration,temperature,reaction time and competitive ions were also extensively investigated.The removal mechanism were analyzed in details,providing a theoretical basis for the further utilization of carbonized materials.Results demonstrated that AC/Fe3O4@SiO2-NH2?mass ratio of AC to Fe3O4 was 1:0.25?with specific surface area?48.9 m2·g-1?showed higher adsorption capacity for Pb?II?.Kinetics study revealed that the adsorption reach equilibrium within 20 h and the maximum adsorption capacity was 104.2 mg·g-1 under pH 5.2.The removal capacities towards four divalent metal ions calculated by the Langmuir model were found to be in the order of Pb???>Ni???>Cu???>Cd???.Furthermore,?G0 decreased from-1.6 to-3.1 kJ·mol-1 with increased in temperature from 293 to 333 K illustrating that the adsorption was spontaneous and an endothermic process.Complexation adsorption mechanism was found prominent in FTIR and XPS analyses between Pb???and AC/Fe3O4@SiO2-NH2 due to the presence of amino groups.Compared with PCM,PCM@SiO2-NH2 revealed higher removal efficiency towards Cu???-Cit and Cu???-NH3,which overcomed low efficiency of the complexed heavy metal ions by common adsorbents.PCM@Si02-NH2 with specific surface area?62.2 m2·g-1?showed the maximum adsorption capacity of 5.6 mg·g-1 and 6.7 mg·g-1 on Cu???-Cit and Cu???-NH3,respectively.The adsorption data of Cu???-Cit and Cu???-NH3 were fitted well to the Langmuir isotherm model.The adsorption mechanism of Cu???-Cit and Cu???-NH3 included complexation adsorption,electrostatic attraction and ion-exchange.Complexation adsorption mechanism was found prominent in FTIR and XPS analyses between Cu???and PCM@SiO2-NH2 due to the presence of amino groups. |
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