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O. Rosskopfová M. Galamboš L. Pivarčiová M. Čaplovičová P. Rajec 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):459-465
The sorption of nickel on synthetic hydroxyapatite was investigated using a batch method and radiotracer technique. The hydroxyapatite samples used in experiments were a commercial hydroxyapatite and hydroxyapatite of high crystallinity with Ca/P ratio of 1.563 and 1.688, respectively, prepared by a wet precipitation process. The sorption of nickel on hydroxyapatite was pH independent ranging from 4.5 to 6.5 as a result of buffering properties of hydroxyapatite. The adsorption of nickel was rapid and the percentage of Ni sorption on both samples of hydroxyapatite was >98 % during the first 15–30 min of the contact time for initial Ni2+ concentration of 1 × 10?4 mol dm?3. The experimental data for sorption of nickel have been interpreted in the term of Langmuir isotherm and the value of maximum sorption capacity of nickel on a commercial hydroxyapatite and hydroxyapatite prepared by wet precipitation process was calculated to be 0.184 and 0.247 mmol g?1, respectively. The sorption of Ni2+ ions was performed by ion-exchange with Ca2+ cations on the crystal surface of hydroxyapatite under experimental conditions. The competition effect of Co2+ and Fe2+ towards Ni2+ sorption was stronger than that of Ca2+ ions. NH4 + ions have no apparent effect on nickel sorption. 相似文献
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M. S. Shaukat M. I. Sarwar R. Qadeer 《Journal of Radioanalytical and Nuclear Chemistry》2005,265(1):73-79
Summary The adsorption of strontium ions from aqueous solution on a Pakistani coal powder has been studied as a function of shaking time, amount of adsorbent, pH, and strontium ion concentration. Conditions for the maximum adsorption of strontium ions have been established. Results reveal that the diffusion of strontium ions into the pores of coal powder occurs during the adsorption process and intra-particle diffusion controls the kinetics of the process. The Langmuir and D-R adsorption equations are valid over the entire range of studied concentration. The influence of different anions on the adsorption of strontium ions was also studied. 相似文献
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The use of a chloride-containing synthetic hydrotalcite sol (LDHC) as adsorbent to remove thiocyanate from aqueous solution was investigated. LDHC was prepared by coprecipitation and was characterized by HRTEM, particle size, XRD, and FTIR. The experiments showed that LDHC was particularly effective in removing thiocyanate due to its small particle size and high zeta potential. The adsorption of thiocyanate on LDHC was favored when the initial solution pH was in the range 3-10, though the most effective pH range was between 4.0 and 8.0. The adsorption reached equilibrium within 150 min. The interaction between the surface sites of LDHC and thiocyanate ions may be a combination of both anion exchange and surface complexation. The pseudo-second-order model best described the adsorption kinetics of thiocyanate onto LDHC. The equilibrium isotherm showed that the adsorption of thiocyanate on LDHC was consistent with the Langmuir equation and the saturated adsorption capacity of LDHC for thiocyanate was 98.3 mg/g at 20°C. The regenerated LDHC in FeCl(3) solution can be used repeatedly in adsorption-regeneration cycles. The results showed that LDHC can be used as a new adsorbent for thiocyanate removal from aqueous solution because of its high adsorption capacity and rapid adsorption rate. 相似文献
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Adsorption and removal of tetracycline antibiotics from aqueous solution by graphene oxide 总被引:5,自引:0,他引:5
Gao Y Li Y Zhang L Huang H Hu J Shah SM Su X 《Journal of colloid and interface science》2012,368(1):540-546
Significant concerns have been raised over pollution of antibiotics including tetracyclines in aquatic environments in recent years. Graphene oxide (GO) is a potential effective absorbent for tetracycline antibiotics and can be used to remove them from aqueous solution. Tetracycline strongly deposited on the GO surface via π-π interaction and cation-π bonding. The adsorption isotherm fits Langmuir and Temkin models well, and the theoretical maximum of adsorption capacity calculated by Langmuir model is 313 mg g(-1), which is approximately in a close agreement with the measured data. The kinetics of adsorption fits pseudo-second-order model perfectly, and it has a better rate constant of sorption (k), 0.065 g mg(-1) h(-1), than other adsorbents. The adsorption capacities of tetracycline on GO decreased with the increase in pH or Na(+) concentration. The adsorption isotherms of oxytetracycline and doxycycline on GO were discussed and compared. 相似文献
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Haoying Zhai Jinshan Zou Fuming Liu Fangyuan Chen Xingrong Yan Wen‐Jun Zhou 《Surface and interface analysis : SIA》2021,53(1):76-83
An effective adsorbent for methyl violet (MV), chromium phosphovanadate (named as Cr‐PV) nanomaterials, was prepared by a simple coprecipitation strategy. The microstructure and morphology of as‐synthesized Cr‐PV were characterized by SEM, X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR), respectively, which was confirmed as nanosheet shapes. The adsorption behavior for MV from aqueous solutions was systematically investigated. The kinetic and equilibrium results indicate that the adsorption process follows pseudo‐second‐order kinetic model and Langmuir isotherm, respectively. Compared with PV and commercially available activated carbon, Cr‐PV has preferable adsorption property to MV. The maximum adsorption capacity can reach 123.81 mg g?1 at room temperature. The thermodynamic parameters such as Gibbs free energy (ΔGο), enthalpy (ΔHο), and entropy change (ΔSο) show that the adsorption of MV is an endothermic and spontaneous process. Moreover, the adsorptive behavior between Cr‐PV and MV is monolayer adsorption and electrostatic interaction mechanism. Cr‐PV, as a promising adsorbent with high adsorption capacity and fast adsorption rate, shows great potential for the removal of MV from wastewater. 相似文献
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The study has investigated the feasibility of using synthetic siderite for F− removal from aqueous solution. Batch experiments were performed to test effects of adsorbent dosage, contact time, initial F− concentration, temperature, solution pH, and coexisting anions on F− removal. Results show that the kinetic rate of F− adsorption was high in the first 2 h, and thereafter significantly decreased. The kinetic data was better fitted to the pseudo-second order kinetic model than the pseudo-first order kinetic model. In comparison with Langmuir isotherm, both Freundlich and Redlich-Peterson isotherms better described the adsorption process, which indicates that the multilayer adsorption should be involved in the process of F− removal. Thermodynamic study manifests that F− adsorption on synthetic siderite was spontaneous and exothermic in nature. The synthetic siderite had high adsorption capacity for F− removal, which was up to 1.775 mg/g in the batch with an adsorbent dosage of 5 g/L and an initial F− concentration of 20 mg/L at 25 °C. The adsorption was relatively independent on solution pH between 4 and 9. The presence of Cl− and NO3− had less impact on F− adsorption, while PO43− significantly affected F− removal from aqueous solution. Results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) suggest that the high adsorption capacity possibly arose from both coprecipitation of ferric hydroxide with F− and adsorption of F− on the fresh goethite. 相似文献
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Ion exchange of strontium on synthetic hydroxyapatite 总被引:2,自引:0,他引:2
Adsorption of strontium ions on synthetic hydroxyapatite was examined using both batch and column methods. The apatite was prepared from aqueous solutions and characterized by standard analytical methods. The sample obtained had characteristics of well crystallized stoichiometric hydroxyapatite. The experimental data for sorption of strontium can be very well fitted with Langmuir's adsorption isotherm. It was found that sorption occurs by an ion exchange reaction between strontium ions in solution and calcium ions in apatite. 相似文献
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《印度化学会志》2021,98(11):100191
Hydroxyapatite is a versatile compound resembling natural bone mineral. HAP insinuates feasibility with substitution ensuing in its application in various fields. The properties of calcium and strontium are cognate and pose as a bone-seeking trace-element that accumulates in new trabecular bone. Strontium substituted hydroxyapatite, Ca9.5Sr0.5(OH)2(PO4)6, was synthesized using citric acid as fuel and calcined 900 °C. The as-prepared product notably was characterized by powder X-ray diffraction, Fourier - Transform Infrared spectroscopy and Scanning Electron Microscope along with Energy Dispersive Spectroscopy. FT-IR analysis exhibited stretching and bending vibrations of (PO4)3- and OH− groups along without any signal of carbonate group. Studies showed that product formed is strontium substituted hydroxyapatite, and calcination temperature plays an essential role in the formation of hydroxyapatite phase. The precursors when calcined resulted in 46–50 nm of Sr substituted hydroxyapatite. 相似文献
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Wenkun Zhu Yi Li Yang Yu Tao Duan Dayun Zhou Liang Wang Jian Zhou Meng Kuang 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(2):553-560
Cotton carbon aerogel was prepared and used as a new water-insoluble adsorbent to remove strontium from aqueous solution. A comprehensive study on adsorption of strontium by cotton carbon aerogel was conducted regarding the effects of initial pH, temperature, initial strontium concentration, and contact time. The adsorbent was characterized by SEM. The results of regression analysis indicated that the adsorption process largely depends on the pH and temperature. The optimum pH range for adsorption process is 5–7. The maximum removal efficiency of strontium from aqueous solution was 60.16%. Moreover, cotton carbon aerogel adsorbent has good reusability before the fifth reuse. 相似文献
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Different types of activated carbons were prepared by changing the activation temperatures (400–700 °C) and impregnation ratio (sewage sludge: KOH; 1:1, 1:2) and the removal of Sr+2 from aqueous solution was determined. The maximum adsorption yield (12.11 mg/g) was obtained at 500 °C for 1 h carbonization conditions with impregnation ratio of 1:1. The affecting parameters were analyzed by using central composite design method. The selected parameters were initial pH, temperature, initial strontium concentration and carbon dosage. The analysis of variance was performed in 95% confidence level and checked to fitting of experimental value and predicted value. The significant F was P < 0.05 with a model F value of 19.94 which revealed that this regression is statistically significant. The results of regression analysis indicated that pH and temperature parameters were not individually statistically significant for Sr+2sorption. However, the efficiency of strontium sorption increases with the increase in carbon dosage and decreases with the Sr+2 concentration. Influences of initial pH and temperature, pH and Sr+2 concentration, temperature and carbon dosage and Sr+2 concentration and carbon dosage on the adsorption process were considered statistically significant. Adsorption of strontium was described by Freundlich isotherm as a physical adsorption (E = 7.2 kJ/mol). The adsorption reactions were calculated as endothermic, spontaneous and favorable reactions. 相似文献
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J. M. Soriano-Rodr��guez V. E. Badillo-Almaraz C. Alliot F. Monroy-Guzm��n P. Vitorge 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):645-652
The sorption of Pd(II) on hydroxyapatite (Ca10(PO4)6(OH)2) has been studied at 25 °C as a function of pH, in 0.01 M NaClO4, and 0.01 and 0.025 M Ca(ClO4)2 aqueous background electrolytes and Pd(II) concentration (9.3 to 47 ??M), trying to minimize some types of reactions, such as solid dissolution of and metal precipitation. The radiotracer palladium, 109Pd, obtained by neutron irradiation, has been used to calculate the palladium??s distribution coefficients K d between aqueous and solid phase. A mathematical treatment of results has been made by ion-exchange theory in order to interpret palladium sorption onto treated solid. For this, we take into account the existence of active sites at the hydroxyapatite surface, and the aqueous solution chemistry of palladium as well as the effect of phosphate anions from solid dissolution. The results can be explained as evidence of sorption of the species PdOH+, and of a mixed hydroxo complex of Pd2+ like (XCaO?)?CPdOH+·nH2O fixed onto {??Ca?COH} surface sites of the hydroxyapatite. 相似文献
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The role of citric acid in the demineralization of dental enamel, which is mainly constituted by hydroxyapatite, is important for periodontal regeneration and in the conditioning of enamel or dentin for bonding restorative resins. The adsorption of citric acid from aqueous solutions onto synthetic hydroxyapatite at 278, 288, 298, and 308 K and pH 4.8 has been studied by means of UV spectroscopy. The adsorption reaction, which takes place by an interaction between phosphate groups and citrate anions at the solid-solution interface, yields an adsorbate-adsorbent complex of high stability. The adsorption isotherms fit the Langmuirian shape. The proposed adsorption model, where citrate species interact in a bidentate manner (one citrate ion links two phosphate sites), is coherent with the experimental data. The activation standard heat and activation standard entropy were calculated. All the thermodynamic and kinetic parameters were in concordance with the adsorption reaction proposed in this work. 相似文献
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O. Rosskopfová M. Galamboš P. Rajec 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):715-722
The sorption of strontium on synthetic hydroxyapatite was investigated using batch method and radiotracer technique. The hydroxyapatite
samples were prepared by a wet precipitation process followed by calcination of calcium phosphate that precipitated from aqueous
solution. Also, commercial hydroxyapatites were used. The sorption of strontium on hydroxyapatite depended on the method of
preparation and it was pH independent ranging from 4 to 9 as a result of buffering properties of hydroxyapatite. The distribution
coefficient K
d was significantly decreased with increasing concentration of Sr2+ and Ca2+ ions in solution with concentration above 1 × 10−3 mol dm−3. The percentage strontium sorption for commercial and by wet method prepared hydroxyapatite was in the range of 83–96%, while
calcined hydroxyapatite was ranging from 10 to 30%. The experimental data for sorption of strontium have been interpreted
in the term of Langmuir isotherm. The sorption of Sr2+ ions was performed by ion-exchange with Ca2+ cations on the crystal surface of hydroxyapatite. Although calcined hydroxyapatite is successfully used as biomaterial for
hard tissues repair, it is not used for the treatment of liquid wastes. 相似文献
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Adsorption of fluoride from aqueous solution by graphene 总被引:3,自引:0,他引:3
Li Y Zhang P Du Q Peng X Liu T Wang Z Xia Y Zhang W Wang K Zhu H Wu D 《Journal of colloid and interface science》2011,363(1):348-354
A batch adsorption system was applied to investigate the adsorption of fluoride from aqueous solution by graphene. The adsorption capacities and rates of fluoride onto graphene at different initial pH, contact time, and temperature were evaluated. The experimental results showed that graphene is an excellent fluoride adsorbent with an adsorption capacity of up to 17.65 mg/g at initial fluoride concentration of 25 mg/L and temperature of 298 K. The isotherm analysis indicated that the adsorption data can be well described by Langmuir isotherm model. Thermodynamic studies revealed that the adsorption reaction was a spontaneous and endothermic process. 相似文献
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de Souza CA Colombo AP Souto RM Silva-Boghossian CM Granjeiro JM Alves GG Rossi AM Rocha-Leão MH 《Colloids and surfaces. B, Biointerfaces》2011,87(2):310-318
The kinetic of chlorhexidine digluconate (CHXDG) uptake from aqueous solution by hydroxyapatite (HA) was investigated by ultraviolet (UV) analysis performed in HA powder (UV-solid) after the CHX adsorption. Adsorption isotherm of chlorhexidine (CHX) uptake was modeled by a combination of Languimir and Langmuir-Freundlich mechanisms. Strong molecule-molecule interactions and positive cooperativity predominated in the surface when CHX concentration was above 8.6 μg(CHX)/mg(HA). UV-solid spectra (shape, intensity and band position) of CHX bound to HA revealed that long-range molecular structures, such as aggregates or micelles, started to be formed at low CHX concentrations (1.52 μg(CHX)/mg(HA)) and predominated at high concentrations. Grazing-incidence X-ray diffraction (GIXRD) analysis from synchrotron radiation discarded the formation of crystalline structures on HA surface or precipitation of CHX crystalline salts, as suggested in previous works. The effect of the HA/CHX association on HA in vitro bioactivity, cytotoxicity and CHX antimicrobial activity was evaluated. It was shown that CHX did not inhibit the precipitation of a poorly crystalline apatite at HA/CHX surface after soaking in simulating body fluid (SBF). Cell viability studies after exposure to extracts of HA and HA/CHX showed that both biomaterials did not present significant in vitro toxicity. Moreover, HA/CHX inhibited Enterococcus faecalis growth for up to 6 days, revealing that binding to HA did not affect antimicrobial activity of CHX and reduced bacterial adhesion. These results suggested that HA/CHX association could result in a potential adjuvant antimicrobial system for clinical use. 相似文献
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Liana Alvares Rodrigues Tiago Moreira Bastos Campos Manoel Orlando Alvarez-Mendes Aparecido dos reis Coutinho Kumiko Koibuchi Sakane Gilmar Patrocínio Thim 《Journal of Sol-Gel Science and Technology》2012,63(2):202-210
Carbon xerogel (CX) was used for phenol adsorption from aqueous solution. CX was synthesized by sol?Cgel polycondensation of resorcinol with formaldehyde using sodium carbonate (Na2CO3) as catalyst. Then, it was dried by convective drying technique and pyrolyzed under inert atmosphere. Phenol adsorption kinetics was very fast, what was attributed to the presence of open pore structure. The kinetic studies showed that the adsorption process could be fitted to a pseudo-second-order model and the particle diffusion process is the rate-limiting step of the adsorption. The phenol removal was maximum and unaffected by pH changes when the initial pH of the phenol solution was in the range of 3?C8. The optimum adsorbent dose obtained for phenol adsorption onto CX was 0.075?g/50?cm3 solution. The Langmuir model described the adsorption process better than the Freundlich isotherm model and the monolayer adsorption capacity is 32?mg?g?1. Among the desorbing solutions used in this study, the most efficient desorbent was EtOH (100?%) which released about 87?% of phenol bound with the CX. 相似文献
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Adsorption of nitrobenzene from aqueous solution by MCM-41 总被引:3,自引:0,他引:3
Adsorption of nitrobenzene onto mesoporous molecular sieves (MCM-41) from aqueous solution has been investigated systematically using batch experiments in this study. Results indicate that nitrobenzene adsorption is initially rapid and the adsorption process reaches a steady state after 1 min. The adsorption isotherms are well described by the Langmuir and the Freundlich models, the former being found to provide the better fit with the experimental data. The effects of temperature, pH, ionic strength, humic acid, and the presence of solvent on adsorption processes are also examined. According to the experimental results, the amount of nitrobenzene adsorbed decreases with an increase of temperature from 278 to 308 K, pH from 1.0 to 11.0, and ionic strength from 0.001 to 0.1 mol/L. However, the amount of nitrobenzene adsorbed onto MCM-41 does not show notable difference in the presence of humic acid. The presence of organic solvent results in a decrease in nitrobenzene adsorption. The desorption process shows a reversibility of nitrobenzene adsorption onto MCM-41. Thermodynamic parameters such as Gibbs free energy are calculated from the experimental data at different temperatures. Based on the results, it suggests that the adsorption is primarily brought about by hydrophobic interaction between nitrobenzene and MCM-41 surface. 相似文献