A new metal-organic complex [Pb2（PDB）2（phen）]n·nH2O （H2PDB=pyridine-3,4-dicarboxylic acid,phen=1,10-phenanthroline） 1 has been hydrothermally synthesized and structurally characterized by elemental analysis...A new metal-organic complex [Pb2（PDB）2（phen）]n·nH2O （H2PDB=pyridine-3,4-dicarboxylic acid,phen=1,10-phenanthroline） 1 has been hydrothermally synthesized and structurally characterized by elemental analysis,IR spectrum,TG and single-crystal X-ray diffraction.The compound crystallizes in triclinic,space group P1 with a=7.2472（5）,b=10.6966（8）,c=16.2376（12）,α=98.2960（10）,β=91.6430（10）,γ=97.4810（10）o,V=1233.53（16）3,C26H16O9N4Pb2,Mr=942.81,Dc=2.538 g/cm3,μ（MoKα）=13.697 mm-1,F（000）=872,Z=2,the final R=0.0247 and wR=0.0654 for 3886 observed reflections （I 〉 2σ（I））.In the crystal structure,the Pb（1） atom is six-coordinated with four carboxylate oxygen atoms from three different PDB ligands and two nitrogen atoms from phen ligand,showing a distorted octahedral geometry;the Pb（2） atom is four-coordinated with four carboxylate oxygen atoms from four different PDB ligands,showing a distorted tetrahedral geometry.It exhibits a three-dimensional supramolecular network structure formed by hydrogen bonds and π-π interactions.展开更多
Tourmaline from Altai mine in China＇s Sinkiang was used to remove lead （II）, copper （II） from aqueous solution. The results demonstrate that tourmaline contains Na（Mg,V）3AI6（BO3）3Si6Ols （OH）4, NaFe3AI6（BO3...Tourmaline from Altai mine in China＇s Sinkiang was used to remove lead （II）, copper （II） from aqueous solution. The results demonstrate that tourmaline contains Na（Mg,V）3AI6（BO3）3Si6Ols （OH）4, NaFe3AI6（BO3）3Si6Ols（OH）4. The data show that Tourmaline from Altai mine in China＇s Sinkiang can be used natural adsorbent for lead （II）, copper （II）.It is observed that the adsorption data fitted to the Langmuir isotherm. Furthermore, both Pb （II） and Cu （II） absorbed by tourmaline and tourmaline were characterized by X-ray diffraction, Laser Raman Spectrum, Fourier transform infrared spectroscopy, X-ray energy dispersive spectrometer, Transmission electron microscopy and Zeta potential.展开更多
A novel two-dimensional lead（II） coordination polymer 1, [C11H7Cl2NO3Pb]n, has been prepared by solvothermal reaction of new bridging ligand（5-chloro-quinolin-8-yloxy）acetic acid（HL） with PbCl2, and its structur...A novel two-dimensional lead（II） coordination polymer 1, [C11H7Cl2NO3Pb]n, has been prepared by solvothermal reaction of new bridging ligand（5-chloro-quinolin-8-yloxy）acetic acid（HL） with PbCl2, and its structure was characterized by IR, elemental analysis, TG-DTA and single-crystal X-ray diffraction analysis. The crystal is of monoclinic system, space group P21/c with a = 16.7603（7）, b = 8.6907（4）, c = 8.4745（3）A, β = 101.1110（11）°, C11H7Cl2NO3 Pb, Mr = 479.27, V = 1211.25（9）A3, Z = 4, Dc = 2.628 g/cm^3, F（000） = 880, μ = 14.367 mm^-1, R = 0.0173 and wR = 0.0508. The asymmetric unit contains one lead（II） cation, one（5-chloro-quinolin-8-yloxy）acetate（L） ligand and a chloride ion. The PbII center is hepta-coordinated in a distorted pentagonal bipyramidal geometry. The coordination sphere of the Pb atom is completed by two oxygen atoms and one nitrogen atom of the same L ligand, two bridging chloride ions and two bridging oxygen atoms of two adjacent L ligands. Two PbII centers are linked by the two L ligands to form a C2-symmetric dimer unit with a planar [Pb2O2] ring. Each dimer unit acts as a secondary building unit（SBU） and links adjacent four dimer units by the chloride atoms and oxygen atoms of carboxylate groups of L, forming a two-dimensional array. Such two-dimensional layers are packed through intermolecular C–H…Cl hydrogen bonds into a three-dimensional supramolecular structure. When the dimer unit is viewed as a 4-connected node, 1 is simplified as a 4-nodal 2-D network with square lattices of the diagonal lengths to be 6.079（1）A. The fluorescence emission peak of complex 1 appears near 407 nm.展开更多
The main objective of this paper is to study the removal of Cadmium(II), Lead(II), Chromium(VI), and Mercury(II) ions by sorption onto different natural and synthetic nanoparticles. Special attention has been given to...The main objective of this paper is to study the removal of Cadmium(II), Lead(II), Chromium(VI), and Mercury(II) ions by sorption onto different natural and synthetic nanoparticles. Special attention has been given to the application of fish bone in nanoform as a useful, inexpensive and eco-friendly alternative material. A comparison between natural hydroxyapatite (fish bone), synthetic hydroxyapatite nanoparticles (HAP) and alginate-hydroxyapatite composite (Alg/Hap) to assess their removal efficiencies to remediate the selected heavy metals has been done. Surface characterization by using different techniques has also been performed to understand the influence of surface characteristics of the adsorbent materials in the removal process. Different parameters (pH, contact time, mass dose and metal ion concentration) have been examined to identify the optimum conditions for remediation of different metals from polluted water. The potential applications of the biosorbents for removal and sorption of these metal ions from seawater and wastewater samples were also investigated and evaluated.展开更多
An electrochemical method for the simultaneous determination of lead(II) and Cadmium(II) with a calix[6]arene modified carbon paste electrode (CPE) has been developed. Pb2+ and Cd2+ were accumulated at the surface of ...An electrochemical method for the simultaneous determination of lead(II) and Cadmium(II) with a calix[6]arene modified carbon paste electrode (CPE) has been developed. Pb2+ and Cd2+ were accumulated at the surface of the modified electrode via formation of chemical complexes with calix[6]arene, and reduced at 1.40 V. During the following anodic potential sweep, reduced lead and cadmium were oxidized, and two well-defined striping peaks appeared at about ?0.60 V and ?0.84 V. Compared with a bare carbon paste electrode, the calix[6]arene modified CPE greatly improves the sensitivity of determining lead and cadmium. The stripping peak currents change linearly with the concentration of Pb2+ 3.0×10?8–8.0×10?6 mol·L?1 and with that of Cd2+ 6.0×10?8–1.0×10?5 mol ·L?1. The detection limits of Pb2+ and Cd2+ are found to be 8.0×10?9 mol·L?1 and 2.0×10?8 mol·L?1, respectively. The modified carbon paste electrode was applied to determine trace levels of lead and cadmium in water samples. Comparing with that of atomic absorption spectrometry, the results suggests that the calix[6]arene modified CPE has great potential for the practical sample analysis. Key words lead(II) - cadmium(II) - calix[6]arene - differential pulse stripping voltammetry - chemically modified electrode CLC number O 657.15 Foundation item: Supported by the National Natural Science Foundation of China (60171023)Biography: JI Xiao-bo (1980-), male, Master, research direction: electroanalytical chemistry.展开更多
A lead（II） coordination polymer,{[Pb2（butca）（H2O）2]（H2O）2}n （1）,has been synthe-sized by the hydrothermal reaction of Pb（OH）2 and 1,2,3,4-butanetetracarboxylic acid （H4butca） at 160 °C.Single-crysta...A lead（II） coordination polymer,{[Pb2（butca）（H2O）2]（H2O）2}n （1）,has been synthe-sized by the hydrothermal reaction of Pb（OH）2 and 1,2,3,4-butanetetracarboxylic acid （H4butca） at 160 °C.Single-crystal X-ray analyses reveal that it crystallizes in monoclinic,space group P21/c with a=7.616（5）,b=7.584（4）,c=12.314（7）,β=105.595（12）o,V=685.0（7）3,Z=4,C8H14O12Pb2,Mr=716.57,Dc=3.474 g/cm3,μ=24.610 mm-1,F（000）=644,the final R=0.0381 and wR=0.1176 for 1465 observed reflections with I 〉 2σ（I）.The complex presents a 2D-layered structure featuring two different types of rings,and has a （4,36）topology based on Pb and butca4-nodes.In solid state,complex 1 shows photoluminescence with the maximum emission intensity at 468 nm under 286 nm excitation.展开更多
Raw Banana Stalk (RBS), Acid Activated Banana Stalk (AABS) and Base Activated Banana Stalk (BABS) prepared from banana stalk were used as biosorbents to remove Lead(II) from aqueous solution. The biosorbents were char...Raw Banana Stalk (RBS), Acid Activated Banana Stalk (AABS) and Base Activated Banana Stalk (BABS) prepared from banana stalk were used as biosorbents to remove Lead(II) from aqueous solution. The biosorbents were characterised using proximate analysis and Fourier Transform Infrared (FTIR) spectroscopy. Pb(II) of 1000 mg/L concentration was prepared from Pb(NO3)2 salt and other concentrations were obtained from this stock through serial dilution. Effects of adsorbent dose, temperature, initial metal concentration, contact time and pH on the percentage Pb(II) removal were evaluated. The Pb(II) concentrations in the solutions were analysed using Atomic Absorption Spectrophotometer. Kinetic, isotherm and thermodynamic parameters were determined. FTIR spectroscopy showed that RBS, AABS and BABS are rich in carboxyl, hydroxyl and phenolic functional groups. At an equilibrium time of 180 minutes, the percentage Pb(II) removal was 63.97%, 96.13% and 66.90% for RBS, AABS and BABS, respectively. Pseudo-second order kinetics best described the process with R2 (0.95, 0.98, 0.97) for RBS, AABS and BABS, respectively. Langmuir isotherm (AABS) has the maximum adsorption capacity (qmax) of 13.53 mg/g and R2 (0.99). Thermodynamic parameters obtained were △G0 (?18.75 kJ/mol), △H0 (12.63 kJ/mol), △S0 (0.05 kJ/mol·K) and Ea (4.37 kJ/mol). Banana stalk has viable characteristics for preparing biosorbents. Acid activated banana biosorbent is more efficient for removal of lead ions from its aqueous solution.展开更多
The objective of this study is to develop carbon, that of <i></span><i><span style="font-family:Verdana;">Acacia auriculeaformis</span></i><span style="font-family...The objective of this study is to develop carbon, that of <i></span><i><span style="font-family:Verdana;">Acacia auriculeaformis</span></i><span style="font-family:Verdana;"></i></span><span style="font-family:Verdana;"> through its activation in order to eliminate lead in an aqueous medium. A series of activated carbon has been prepared by chemical activation with phosphoric acid, sodium hydroxide and sodium chloride. The determi</span><span style="font-family:Verdana;">nation of the physico-chemical properties of the prepared carbon guided the choice of phosphoric acid activated carbon as the best adsorbent for the</span><span style="font-family:Verdana;"> elimination of lead(II) in </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">an </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">aqueous solution. Pb</span><sup><span style="font-family:Verdana;">2+</span></sup><span style="font-family:Verdana;"> adsorption tests in batch mode have shown that the adsorption capacity is influenced by various parameters such as mass, pH, concentration of Pb<sup>2+</sup> ions and contact time linked to the medium and the adsorbent. Adsorption isotherms, kinetic models and thermodynamics have been used to describe the adsorption process. The equilibrium data for activated charcoal correspond well to the model of Freundlich, </span><span style="font-family:Verdana;">Langmuir, Temkin and Kiselev. The kinetic adsorption data proved to be </span><span style="font-family:Verdana;">better described by the pseudo-second order model with </span><span style="font-family:Verdana;">external and intraparticle diffusion which are two decisive steps in the</span><span style="font-family:Verdana;"> adsorption process of Pb<sup>2+</sup> ions. Thermodynamics and adsorption isotherms predict a spontaneous exothermic surface reaction, of the chemisorption type, with ion </span><span><span style="font-family:Verdana;">retention 展开更多
The ability to modify a waste by-product precursor, maize tassel biomass using sulfuric acid as the activating agent with specific focus on Lead(II) ion from water has been proposed. The treating of maize tassel using...The ability to modify a waste by-product precursor, maize tassel biomass using sulfuric acid as the activating agent with specific focus on Lead(II) ion from water has been proposed. The treating of maize tassel using sulphuric acid is believed to enhance sorption capacity of Lead(II) ions. For this, batch adsorption mode was adopted for which the effects of initial pH, adsorbent dosage, contact time and initial concentration were investigated. Consequently, it was found that the adsorbent capacity depends on pH;since it increases up to 4.5 and then decreases. The highest percentage of Lead(II) ion removal was achieved in the adsorbent dosage of 1.2 g and at an initial concentration of 10 mg/L metal ion. In an attempt to determine the capacity and rate of Lead(II) removal, isotherm and kinetic data were modeled using appropriate equations. To this end, the adsorption data fitted best into the Langmuir model with an R2 (0.9997) while kinetically the Lead(II) adsorption followed the pseudo-second-order model. Furthermore, as a way to address issues related to sustainability, maize tassel is recommended since the process is considered to be a dual solution for environmental cleaning. From one side, it represents a better way to dispose the maize tassel which has no use after fertilization and on the other hand it is an economic source of carbonaceous materials.展开更多
The copolymer of the maleic anhydride-styrene is modified at the presence of 4-amino-2-thiouracil and formaldehyde and the new polymeric sorbate with spatial structure is received. The received sorbate is identified b...The copolymer of the maleic anhydride-styrene is modified at the presence of 4-amino-2-thiouracil and formaldehyde and the new polymeric sorbate with spatial structure is received. The received sorbate is identified by the IR-spectroscopy method. The complete static sorption capacitance was studied (CSSC<sup>+</sup>K</sub>= 7.8 mmol/g) and the ionization constants of ionic groups in a sorbate link was defined by electrometric method. Ionization constants were determined by potentiometric titration of the sorbent (). Sorption and desorption of the received sorbent with a lead ion (II) are investigated and optimum concentration conditions are defined: рН<sub>opt.</sub> = 5, ionic force μ = 0.8 pier/l, full sorption balance 4 hours, optimum eluent 5 ml of 0.5 M HCl.展开更多
This work focuses on the application of activated biomass as an alternative to conventional adsorbents for the removal of Pb^2+from wastewater.The biomass was carbonized at 800℃before chemical activation.Scanning Ele...This work focuses on the application of activated biomass as an alternative to conventional adsorbents for the removal of Pb^2+from wastewater.The biomass was carbonized at 800℃before chemical activation.Scanning Electron Microscope(SEM)and UV/VIS Spectrophotometer were used in characterizing the adsorbents.Batch adsorption studies were carried out to determine the effect of process conditions on the percentage removal.The kinetic studies were carried out using Pseudo-first order,Pseudo-second order,Elovich and Weber morris kinetic models while the thermodynamics studies were carried out using Gibbs free energy equation.SEM characterization revealed that micro porous space on the surface of the adsorbents(biomass wastes)increased significantly after activation.The composites maintained high surface area after chemical activation.pH of point zero charge revealed negative charge predominance on the surface of the adsorbents and adsorption was found to be very fast due to strong electrostatic force between Pb^2+and ion diffusion on the biomass surface.Cassava peel demonstrated highest potential for lead(II)ion removal from solution with 96.83%removal after 80 min with 50 mg/l lead concentration and adsorbent/liquid ratio of 0.3 g/30 ml at 60℃and pH of 7.6.The highest adsorption capacities recorded with cassava peels,groundnut shell and yam peel at initial concentration of 50 mg/g were 50.1 mg g,46.6 mg/g and 38.5 mg/g DH,DS and R2 values for the adsorption with cassava peels are:12762 J/mol,67.2 J/kmol.K and 0.945;for groundnut shell adsorbent,the DH,DS and R2 values are;36756 J/mol,130 J/mol.K and 0.997;while for yam peels adsorbent,the DH,DS and R2 values are 12163 J/mol,46 J/mol.K and 0.9278.Thus,the sorption process was feasible,spontaneous and endothermic.Adsorption of Pb^2+was rapid and showed high kinetic performance.The experimental data were well fitted with pseudo second order kinetic model.However,the present approach has the advantage of simplicity,less time consuming and most importantly,low cost.展开更多
基金Supported by the Science and Technology Research Projects of the Education Office of Jilin Province (No. 2007. 213)
文摘A new metal-organic complex [Pb2（PDB）2（phen）]n·nH2O （H2PDB=pyridine-3,4-dicarboxylic acid,phen=1,10-phenanthroline） 1 has been hydrothermally synthesized and structurally characterized by elemental analysis,IR spectrum,TG and single-crystal X-ray diffraction.The compound crystallizes in triclinic,space group P1 with a=7.2472（5）,b=10.6966（8）,c=16.2376（12）,α=98.2960（10）,β=91.6430（10）,γ=97.4810（10）o,V=1233.53（16）3,C26H16O9N4Pb2,Mr=942.81,Dc=2.538 g/cm3,μ（MoKα）=13.697 mm-1,F（000）=872,Z=2,the final R=0.0247 and wR=0.0654 for 3886 observed reflections （I 〉 2σ（I））.In the crystal structure,the Pb（1） atom is six-coordinated with four carboxylate oxygen atoms from three different PDB ligands and two nitrogen atoms from phen ligand,showing a distorted octahedral geometry;the Pb（2） atom is four-coordinated with four carboxylate oxygen atoms from four different PDB ligands,showing a distorted tetrahedral geometry.It exhibits a three-dimensional supramolecular network structure formed by hydrogen bonds and π-π interactions.
基金supported by the National Natural Science Foundation of China (No. 51004066)the Opening Project of the Key Laboratory for Advanced Building Materials of Sichuan Province (No. (No.09ZXXK09)Research Fund of Mianyang Normal University (No. 2011C03)
文摘Tourmaline from Altai mine in China＇s Sinkiang was used to remove lead （II）, copper （II） from aqueous solution. The results demonstrate that tourmaline contains Na（Mg,V）3AI6（BO3）3Si6Ols （OH）4, NaFe3AI6（BO3）3Si6Ols（OH）4. The data show that Tourmaline from Altai mine in China＇s Sinkiang can be used natural adsorbent for lead （II）, copper （II）.It is observed that the adsorption data fitted to the Langmuir isotherm. Furthermore, both Pb （II） and Cu （II） absorbed by tourmaline and tourmaline were characterized by X-ray diffraction, Laser Raman Spectrum, Fourier transform infrared spectroscopy, X-ray energy dispersive spectrometer, Transmission electron microscopy and Zeta potential.
基金Supported by Key Laboratory of Organic Synthesis of Jiangsu Province(KJS1308)
文摘A novel two-dimensional lead（II） coordination polymer 1, [C11H7Cl2NO3Pb]n, has been prepared by solvothermal reaction of new bridging ligand（5-chloro-quinolin-8-yloxy）acetic acid（HL） with PbCl2, and its structure was characterized by IR, elemental analysis, TG-DTA and single-crystal X-ray diffraction analysis. The crystal is of monoclinic system, space group P21/c with a = 16.7603（7）, b = 8.6907（4）, c = 8.4745（3）A, β = 101.1110（11）°, C11H7Cl2NO3 Pb, Mr = 479.27, V = 1211.25（9）A3, Z = 4, Dc = 2.628 g/cm^3, F（000） = 880, μ = 14.367 mm^-1, R = 0.0173 and wR = 0.0508. The asymmetric unit contains one lead（II） cation, one（5-chloro-quinolin-8-yloxy）acetate（L） ligand and a chloride ion. The PbII center is hepta-coordinated in a distorted pentagonal bipyramidal geometry. The coordination sphere of the Pb atom is completed by two oxygen atoms and one nitrogen atom of the same L ligand, two bridging chloride ions and two bridging oxygen atoms of two adjacent L ligands. Two PbII centers are linked by the two L ligands to form a C2-symmetric dimer unit with a planar [Pb2O2] ring. Each dimer unit acts as a secondary building unit（SBU） and links adjacent four dimer units by the chloride atoms and oxygen atoms of carboxylate groups of L, forming a two-dimensional array. Such two-dimensional layers are packed through intermolecular C–H…Cl hydrogen bonds into a three-dimensional supramolecular structure. When the dimer unit is viewed as a 4-connected node, 1 is simplified as a 4-nodal 2-D network with square lattices of the diagonal lengths to be 6.079（1）A. The fluorescence emission peak of complex 1 appears near 407 nm.
文摘The main objective of this paper is to study the removal of Cadmium(II), Lead(II), Chromium(VI), and Mercury(II) ions by sorption onto different natural and synthetic nanoparticles. Special attention has been given to the application of fish bone in nanoform as a useful, inexpensive and eco-friendly alternative material. A comparison between natural hydroxyapatite (fish bone), synthetic hydroxyapatite nanoparticles (HAP) and alginate-hydroxyapatite composite (Alg/Hap) to assess their removal efficiencies to remediate the selected heavy metals has been done. Surface characterization by using different techniques has also been performed to understand the influence of surface characteristics of the adsorbent materials in the removal process. Different parameters (pH, contact time, mass dose and metal ion concentration) have been examined to identify the optimum conditions for remediation of different metals from polluted water. The potential applications of the biosorbents for removal and sorption of these metal ions from seawater and wastewater samples were also investigated and evaluated.
文摘An electrochemical method for the simultaneous determination of lead(II) and Cadmium(II) with a calix[6]arene modified carbon paste electrode (CPE) has been developed. Pb2+ and Cd2+ were accumulated at the surface of the modified electrode via formation of chemical complexes with calix[6]arene, and reduced at 1.40 V. During the following anodic potential sweep, reduced lead and cadmium were oxidized, and two well-defined striping peaks appeared at about ?0.60 V and ?0.84 V. Compared with a bare carbon paste electrode, the calix[6]arene modified CPE greatly improves the sensitivity of determining lead and cadmium. The stripping peak currents change linearly with the concentration of Pb2+ 3.0×10?8–8.0×10?6 mol·L?1 and with that of Cd2+ 6.0×10?8–1.0×10?5 mol ·L?1. The detection limits of Pb2+ and Cd2+ are found to be 8.0×10?9 mol·L?1 and 2.0×10?8 mol·L?1, respectively. The modified carbon paste electrode was applied to determine trace levels of lead and cadmium in water samples. Comparing with that of atomic absorption spectrometry, the results suggests that the calix[6]arene modified CPE has great potential for the practical sample analysis. Key words lead(II) - cadmium(II) - calix[6]arene - differential pulse stripping voltammetry - chemically modified electrode CLC number O 657.15 Foundation item: Supported by the National Natural Science Foundation of China (60171023)Biography: JI Xiao-bo (1980-), male, Master, research direction: electroanalytical chemistry.
基金Supported by the Education Department of Jiangxi Province (No. 2007-125)the Initial Fund for Doctors from Jiangxi Normal University
文摘A lead（II） coordination polymer,{[Pb2（butca）（H2O）2]（H2O）2}n （1）,has been synthe-sized by the hydrothermal reaction of Pb（OH）2 and 1,2,3,4-butanetetracarboxylic acid （H4butca） at 160 °C.Single-crystal X-ray analyses reveal that it crystallizes in monoclinic,space group P21/c with a=7.616（5）,b=7.584（4）,c=12.314（7）,β=105.595（12）o,V=685.0（7）3,Z=4,C8H14O12Pb2,Mr=716.57,Dc=3.474 g/cm3,μ=24.610 mm-1,F（000）=644,the final R=0.0381 and wR=0.1176 for 1465 observed reflections with I 〉 2σ（I）.The complex presents a 2D-layered structure featuring two different types of rings,and has a （4,36）topology based on Pb and butca4-nodes.In solid state,complex 1 shows photoluminescence with the maximum emission intensity at 468 nm under 286 nm excitation.
文摘Raw Banana Stalk (RBS), Acid Activated Banana Stalk (AABS) and Base Activated Banana Stalk (BABS) prepared from banana stalk were used as biosorbents to remove Lead(II) from aqueous solution. The biosorbents were characterised using proximate analysis and Fourier Transform Infrared (FTIR) spectroscopy. Pb(II) of 1000 mg/L concentration was prepared from Pb(NO3)2 salt and other concentrations were obtained from this stock through serial dilution. Effects of adsorbent dose, temperature, initial metal concentration, contact time and pH on the percentage Pb(II) removal were evaluated. The Pb(II) concentrations in the solutions were analysed using Atomic Absorption Spectrophotometer. Kinetic, isotherm and thermodynamic parameters were determined. FTIR spectroscopy showed that RBS, AABS and BABS are rich in carboxyl, hydroxyl and phenolic functional groups. At an equilibrium time of 180 minutes, the percentage Pb(II) removal was 63.97%, 96.13% and 66.90% for RBS, AABS and BABS, respectively. Pseudo-second order kinetics best described the process with R2 (0.95, 0.98, 0.97) for RBS, AABS and BABS, respectively. Langmuir isotherm (AABS) has the maximum adsorption capacity (qmax) of 13.53 mg/g and R2 (0.99). Thermodynamic parameters obtained were △G0 (?18.75 kJ/mol), △H0 (12.63 kJ/mol), △S0 (0.05 kJ/mol·K) and Ea (4.37 kJ/mol). Banana stalk has viable characteristics for preparing biosorbents. Acid activated banana biosorbent is more efficient for removal of lead ions from its aqueous solution.
文摘The objective of this study is to develop carbon, that of <i></span><i><span style="font-family:Verdana;">Acacia auriculeaformis</span></i><span style="font-family:Verdana;"></i></span><span style="font-family:Verdana;"> through its activation in order to eliminate lead in an aqueous medium. A series of activated carbon has been prepared by chemical activation with phosphoric acid, sodium hydroxide and sodium chloride. The determi</span><span style="font-family:Verdana;">nation of the physico-chemical properties of the prepared carbon guided the choice of phosphoric acid activated carbon as the best adsorbent for the</span><span style="font-family:Verdana;"> elimination of lead(II) in </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">an </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">aqueous solution. Pb</span><sup><span style="font-family:Verdana;">2+</span></sup><span style="font-family:Verdana;"> adsorption tests in batch mode have shown that the adsorption capacity is influenced by various parameters such as mass, pH, concentration of Pb<sup>2+</sup> ions and contact time linked to the medium and the adsorbent. Adsorption isotherms, kinetic models and thermodynamics have been used to describe the adsorption process. The equilibrium data for activated charcoal correspond well to the model of Freundlich, </span><span style="font-family:Verdana;">Langmuir, Temkin and Kiselev. The kinetic adsorption data proved to be </span><span style="font-family:Verdana;">better described by the pseudo-second order model with </span><span style="font-family:Verdana;">external and intraparticle diffusion which are two decisive steps in the</span><span style="font-family:Verdana;"> adsorption process of Pb<sup>2+</sup> ions. Thermodynamics and adsorption isotherms predict a spontaneous exothermic surface reaction, of the chemisorption type, with ion </span><span><span style="font-family:Verdana;">retention
文摘The ability to modify a waste by-product precursor, maize tassel biomass using sulfuric acid as the activating agent with specific focus on Lead(II) ion from water has been proposed. The treating of maize tassel using sulphuric acid is believed to enhance sorption capacity of Lead(II) ions. For this, batch adsorption mode was adopted for which the effects of initial pH, adsorbent dosage, contact time and initial concentration were investigated. Consequently, it was found that the adsorbent capacity depends on pH;since it increases up to 4.5 and then decreases. The highest percentage of Lead(II) ion removal was achieved in the adsorbent dosage of 1.2 g and at an initial concentration of 10 mg/L metal ion. In an attempt to determine the capacity and rate of Lead(II) removal, isotherm and kinetic data were modeled using appropriate equations. To this end, the adsorption data fitted best into the Langmuir model with an R2 (0.9997) while kinetically the Lead(II) adsorption followed the pseudo-second-order model. Furthermore, as a way to address issues related to sustainability, maize tassel is recommended since the process is considered to be a dual solution for environmental cleaning. From one side, it represents a better way to dispose the maize tassel which has no use after fertilization and on the other hand it is an economic source of carbonaceous materials.
文摘The copolymer of the maleic anhydride-styrene is modified at the presence of 4-amino-2-thiouracil and formaldehyde and the new polymeric sorbate with spatial structure is received. The received sorbate is identified by the IR-spectroscopy method. The complete static sorption capacitance was studied (CSSC<sup>+</sup>K</sub>= 7.8 mmol/g) and the ionization constants of ionic groups in a sorbate link was defined by electrometric method. Ionization constants were determined by potentiometric titration of the sorbent (). Sorption and desorption of the received sorbent with a lead ion (II) are investigated and optimum concentration conditions are defined: рН<sub>opt.</sub> = 5, ionic force μ = 0.8 pier/l, full sorption balance 4 hours, optimum eluent 5 ml of 0.5 M HCl.
文摘This work focuses on the application of activated biomass as an alternative to conventional adsorbents for the removal of Pb^2+from wastewater.The biomass was carbonized at 800℃before chemical activation.Scanning Electron Microscope(SEM)and UV/VIS Spectrophotometer were used in characterizing the adsorbents.Batch adsorption studies were carried out to determine the effect of process conditions on the percentage removal.The kinetic studies were carried out using Pseudo-first order,Pseudo-second order,Elovich and Weber morris kinetic models while the thermodynamics studies were carried out using Gibbs free energy equation.SEM characterization revealed that micro porous space on the surface of the adsorbents(biomass wastes)increased significantly after activation.The composites maintained high surface area after chemical activation.pH of point zero charge revealed negative charge predominance on the surface of the adsorbents and adsorption was found to be very fast due to strong electrostatic force between Pb^2+and ion diffusion on the biomass surface.Cassava peel demonstrated highest potential for lead(II)ion removal from solution with 96.83%removal after 80 min with 50 mg/l lead concentration and adsorbent/liquid ratio of 0.3 g/30 ml at 60℃and pH of 7.6.The highest adsorption capacities recorded with cassava peels,groundnut shell and yam peel at initial concentration of 50 mg/g were 50.1 mg g,46.6 mg/g and 38.5 mg/g DH,DS and R2 values for the adsorption with cassava peels are:12762 J/mol,67.2 J/kmol.K and 0.945;for groundnut shell adsorbent,the DH,DS and R2 values are;36756 J/mol,130 J/mol.K and 0.997;while for yam peels adsorbent,the DH,DS and R2 values are 12163 J/mol,46 J/mol.K and 0.9278.Thus,the sorption process was feasible,spontaneous and endothermic.Adsorption of Pb^2+was rapid and showed high kinetic performance.The experimental data were well fitted with pseudo second order kinetic model.However,the present approach has the advantage of simplicity,less time consuming and most importantly,low cost.
