A novel wastewater purification material was prepared by a hydrothermal method. It was mainly made from oyster shells with the merits of long service time, large surface area, high lead removal efficiency and excellen...A novel wastewater purification material was prepared by a hydrothermal method. It was mainly made from oyster shells with the merits of long service time, large surface area, high lead removal efficiency and excellent recyclable properties. The technological conditions were decided respectively based on the lead removal efficiencies. At pH = 5 and 30 ℃, for the wastewater with the initial concentration of Pb2＋ to be 5 mg/L, adsorption time 24 h, and 1 mg to 40 mL of mass ratio between adsorbent and Pb2＋, the maximum adsorption capacity can reach 0.19 mg/g. The lead removal material prepared by hydrothermal method has excellent recycle performance. The equilibrium adsorption capacity can get to 9.71 mg/g and the average Pb2＋ removal rate is as high as 66.39%. After reusing for 60 times, the SEM observation shows that the hydrates of reticular formation is formed after hydrothermal modification, which provides a good attachment position for Pb2＋, indicating the physical adsorption is dominant.展开更多
Multiwall carbon nanotubes（MWCNTs） were synthesized using a tubular microwave chemical vapor deposition technique, using acetylene and hydrogen as the precursor gases and ferrocene as catalyst. The novel MWCNT sampl...Multiwall carbon nanotubes（MWCNTs） were synthesized using a tubular microwave chemical vapor deposition technique, using acetylene and hydrogen as the precursor gases and ferrocene as catalyst. The novel MWCNT samples were tested for their performance in terms of Pb（Ⅱ）binding. The synthesized MWCNT samples were characterized using Fourier Transform Infrared（FT-IR）, Brunauer, Emmett and Teller（BET）, Field Emission Scanning Electron Microscopy（FESEM） analysis, and the adsorption of Pb（Ⅱ） was studied as a function of p H,initial Pb（Ⅱ） concentration, MWCNT dosage, agitation speed, and adsorption time, and process parameters were optimized. The adsorption data followed both Freundlich and Langmuir isotherms. On the basis of the Langmuir model, Qmaxwas calculated to be 104.2 mg/g for the microwave-synthesized MWCNTs. In order to investigate the dynamic behavior of MWCNTs as an adsorbent, the kinetic data were modeled using pseudo first-order and pseudo second-order equations. Different thermodynamic parameters, viz., ΔH0, ΔS0and ΔG0were evaluated and it was found that the adsorption was feasible, spontaneous and endothermic in nature. The statistical analysis revealed that the optimum conditions for the highest removal（99.9%） of Pb（Ⅱ） are at p H 5, MWCNT dosage 0.1 g, agitation speed 160 r/min and time of 22.5 min with the initial concentration of 10 mg/L. Our results proved that microwave-synthesized MWCNTs can be used as an effective Pb（Ⅱ） adsorbent due to their high adsorption capacity as well as the short adsorption time needed to achieve equilibrium.展开更多
基金Supported by the National Natural Science Foundation of China (No. 51102047)the Natural Science Foundation of Fujian Province (No. 2011J01291)+1 种基金"Green Future" program of China Environmental Protection FoundationScientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (SRF for ROCS, SEM)
文摘A novel wastewater purification material was prepared by a hydrothermal method. It was mainly made from oyster shells with the merits of long service time, large surface area, high lead removal efficiency and excellent recyclable properties. The technological conditions were decided respectively based on the lead removal efficiencies. At pH = 5 and 30 ℃, for the wastewater with the initial concentration of Pb2＋ to be 5 mg/L, adsorption time 24 h, and 1 mg to 40 mL of mass ratio between adsorbent and Pb2＋, the maximum adsorption capacity can reach 0.19 mg/g. The lead removal material prepared by hydrothermal method has excellent recycle performance. The equilibrium adsorption capacity can get to 9.71 mg/g and the average Pb2＋ removal rate is as high as 66.39%. After reusing for 60 times, the SEM observation shows that the hydrates of reticular formation is formed after hydrothermal modification, which provides a good attachment position for Pb2＋, indicating the physical adsorption is dominant.
基金financially supported by the University of Malaya, Ministry of Higher Education High Impact Research (UM.C/HIR/MOHE/ENG/20)
文摘Multiwall carbon nanotubes（MWCNTs） were synthesized using a tubular microwave chemical vapor deposition technique, using acetylene and hydrogen as the precursor gases and ferrocene as catalyst. The novel MWCNT samples were tested for their performance in terms of Pb（Ⅱ）binding. The synthesized MWCNT samples were characterized using Fourier Transform Infrared（FT-IR）, Brunauer, Emmett and Teller（BET）, Field Emission Scanning Electron Microscopy（FESEM） analysis, and the adsorption of Pb（Ⅱ） was studied as a function of p H,initial Pb（Ⅱ） concentration, MWCNT dosage, agitation speed, and adsorption time, and process parameters were optimized. The adsorption data followed both Freundlich and Langmuir isotherms. On the basis of the Langmuir model, Qmaxwas calculated to be 104.2 mg/g for the microwave-synthesized MWCNTs. In order to investigate the dynamic behavior of MWCNTs as an adsorbent, the kinetic data were modeled using pseudo first-order and pseudo second-order equations. Different thermodynamic parameters, viz., ΔH0, ΔS0and ΔG0were evaluated and it was found that the adsorption was feasible, spontaneous and endothermic in nature. The statistical analysis revealed that the optimum conditions for the highest removal（99.9%） of Pb（Ⅱ） are at p H 5, MWCNT dosage 0.1 g, agitation speed 160 r/min and time of 22.5 min with the initial concentration of 10 mg/L. Our results proved that microwave-synthesized MWCNTs can be used as an effective Pb（Ⅱ） adsorbent due to their high adsorption capacity as well as the short adsorption time needed to achieve equilibrium.
