共查询到20条相似文献,搜索用时 15 毫秒
1.
Zhen-Guo Zhao 《中国化学》1992,10(4):325-330
The adsorption isotherms of phenylalanine from aqueous solution on active carbon andsilica gel at varying pH,and the influence of inorganic salt upon the ad rption have been studied(at 25℃).The adsorption amount of phcnylalanine on the silica gel is very low due to the strong ad-sorption of water by silica gel.The results on the active carbon show:(1)The adsorption is found to bepH-dependent,within pH 4.1—5.1 it increases with pH,within pH 5.1—11.8 it decreases with pH,atpH 5.1 the adsorption reaches its maximum;(2)The phenylalanine is adsorbed mainly in the formof zwitterion;(3)A certain amount of cations and anions of phenylalanine are also adsorbed with vander Waals interaction;(4)After adding NaCl,the adsorption of phenylalanine increases markedly. 相似文献
2.
Jovita Mendoza-Barrón Araceli Jacobo-Azuara Roberto Leyva-Ramos Ma. Selene Berber-Mendoza Rosa Ma. Guerrero-Coronado Laura Fuentes-Rubio J. Merced Martínez-Rosales 《Adsorption》2011,17(3):489-496
In this study a surfactant-modified zeolite (SMZ) was prepared by adsorbing the cationic surfactant hexadecyltrimethylammonium
(HDTMA) bromide on a clinoptilolite. The adsorption of the surfactant modified the surface properties of the clinoptilolite
and enhanced the anionic capacity of the SMZ. The adsorption equilibrium data of As(V) from the water solution on the SMZ
were obtained in a batch adsorber, and the Langmuir isotherm matched the data reasonably well. The As(V) adsorption capacity
of the SMZ was 12.5 times greater than that of the clinoptilolite. The adsorption of As(V) on SMZ was mainly due to the interactions
between the anionic sites of the SMZ and the As(V) anions in water solution. The adsorption capacity of the SMZ was dependent
on the solution pH. The adsorption capacity was increased and decreased by augmenting the pH from 5 to 7 and from 7 to 12,
respectively. This unusual behavior was due to the fact that the affinity of the As(V) for the SMZ was dependent on the As(V)
species that were present in solution. The adsorption capacity of the SMZ was slightly favored by decreasing the temperature
from 25 to 15 °C. The heat of adsorption was estimated to be ΔH
ads=−46.82 KJ/mol, indicating that the adsorption was exothermic and the As(V) was chemisorbed on the SMZ. 相似文献
3.
《Arabian Journal of Chemistry》2022,15(8):104011
Health and environmental issues associated with heavy metal ions have received serious attention from communities worldwide. This work explores the potential of coconut shell as activated carbon (CSAC), in adsorbing zinc, Zn(II) ions. This adsorbent was prepared via a single-stage microwave irradiation technique under the flow of carbon dioxide, CO2 gas. CSAC posed BET surface area of 625.61 m2/g, 513.25 m2/g of mesopores surface area, total pore volume of 0.42 cm3/g, and average pore diameter of 4.55 nm. Zeta potential distribution on CSAC was found to be ?21 mV. Response surface methodology (RSM) had suggested that the optimum values of variables were 450 W and 3.17 min for radiation power and radiation time respectively, which resulted in 69.65% of Zn(II) removal and 44.32% of CSAC’s yield. Based on F-value, radiation power (473.62) and radiation time (140.50) posed major and moderate effects on Zn(II) removal, respectively. Meanwhile, CSAC’s removal was significantly affected by radiation power (78.84) and less affected by radiation time (7.06). In a batch study, when the initial concentration of Zn(II) was increased, Zn(II) uptakes increased as well. On contrary, Zn(II) removal percentage decreased with the increase of Zn(II)’s initial concentration. Multilayer adsorption of Zn(II) onto CSAC had occurred since this adsorption system followed Freundlich isotherm the best, and the monolayer adsorption capacity, Qm for Zn(II) was revealed to be 7.87 mg/g. The kinetic data of the Zn(II)-CSAC adsorption system was best described by pseudo-first-order (PFO) which indicated the role of physisorption. In the regeneration study, CSAC’s mass and Zn(II) adsorption uptakes had reduced from 100% to 37% and 77%, respectively, after 6 regeneration cycles. 相似文献
4.
Pengou Martin Ngassa Guy Bertrand Piegang Boutianala Michèle Tchakouté Hervé Kouamo Nanseu-Njiki Charles Péguy Ngameni Emmanuel 《Journal of Solid State Electrochemistry》2021,25(4):1183-1195
Journal of Solid State Electrochemistry - Pb2+ ions were detected on a carbon paste electrode modified with a geopolymer cement. The X-ray pattern and the infrared spectrum of the geopolymer... 相似文献
5.
The adsorption and desorption characteristics of some phenoxy herbicides (CPA 2,4-D, and MCPA) from an aqueous solution on the active carbon materials (GAC, F-400) were studied. Adsorption equilibrium capacities of the phenoxy herbicides increased with a decrease in pH of the solution. Adsorption equilibrium isotherms were represented by the Sips equation. Kinetic parameters were measured in a batch adsorber to analyze the adsorption rates of the phenoxy herbicides. The internal diffusion coefficients were determined by comparing the experimental concentration curves with those predicted from the surface diffusion model and the pore diffusion model. The adsorption model based on the linear driving force approximation (LDFA) was used to simulate the adsorption behavior of the phenoxy herbicides in a fixed bed adsorber. Over 95 percent desorption of the phenoxy herbicides was obtained using distilled water. 相似文献
6.
C. Moreno-Castilla M. A. Fontecha-Cámara M. A. Álvarez-Merino M. V. López-Ramón F. Carrasco-Marín 《Adsorption》2011,17(3):413-419
Removal of amitrole from water was studied by adsorption on an activated carbon cloth and by oxidation with hydrogen peroxide
using the same activated carbon cloth as catalyst. Study variables included the solution pH, ionic strength, and temperature
in the adsorption process and the solution pH and the surface chemistry of the activated carbon cloth in the oxidation process.
Results showed that amitrole adsorption on activated carbon cloth was not adequate to remove amitrole from water due to the
high solubility and low aromaticity of the herbicide, which reduced its adsorption on the carbon. A higher amitrole removal
rate was obtained with the activated carbon/H2O2 system. The best results were obtained on basic activated carbon surfaces at pH 7–10, when hydroxyl radical formation is
favored, achieving the removal of 35–45% of the AMT, compared with 20–25% under the best adsorption conditions. Importantly,
oxygen fixed on the carbon surface during AMT oxidation must be removed by heat treatment in order to regenerate the surface
basicity of the carbon before its reutilization in another oxidation cycle. 相似文献
7.
The current paper presents a novel Pb(II) ion-imprinted silica-supported organic–inorganic hybrid sorbent functionalized with Schiff base by coupling a surface imprinting technique with a sol–gel process for the selective removal of Pb(II) ions from aqueous solution. Fourier transmission infrared spectroscopy, scanning electron microscopy, N2 adsorption–desorption isotherms and thermogravimetric analysis were used to characterize the Pb(II)-imprinted hybrid sorbent. The adsorption equilibrium was finished with 30 min. The experiment value of maximum adsorption capacity was found to be 54.9 mg g?1. There were not significantly influence on the adsorption capacity of Pb(II) in the range of pH 3.5–6.5. The equilibrium data were fitted very well to the Langmuir isotherm model and pseudo-first-order kinetics model. Under competitive adsorption conditions, the Pb(II)-imprinted hybrid sorbent was 3.09, 4.73, 3.34 and 4.96 times more selective than the corresponding non-imprinted sorbent for the systems of Pb(II)/Cu(II), Pb(II)/Cd(II), Pb(II)/Ni(II) and Pb(II)/Zn(II), respectively. The thermodynamic results demonstrated that the adsorption of Pb(II) onto the Pb(II)-imprinted hybrid sorbent took place by a spontaneous and endothermic process with further increase in the degree of freedom at the solid–solution interface. 相似文献
8.
A study was conducted concerning the preparation and application of a novel synthetic oxide adsorbent of MgO-SiO2 type. The material was prepared via a sol–gel route, utilizing magnesium ethoxide and tetraethoxysilane as precursors of magnesium oxide and silica respectively, and ammonia as a catalyst. The powder was comprehensively analyzed with regard to chemical composition (EDS method), crystalline structure, morphology, characteristic functional groups, electrokinetic stability and porous structure parameters (BET and BJH models). The synthesized oxide adsorbent is amorphous, with irregularly shaped particles, a relatively large surface area of 612 m2/g, and negative surface charge over almost the whole pH range. Comprehensive adsorption studies were performed to investigate the adsorption of Cd(II) and Pb(II) ions on the MgO–SiO2 oxide adsorbent, including evaluation of adsorption kinetics and isotherms, the effect of pH, contact time and mass of adsorbent. It was shown that irrespective of the conditions of the adsorption process, the synthesized MgO–SiO2 adsorbent exhibits slightly better affinity to lead(II) than to cadmium(II) ions (sorption capacity of 102.02 mg(Pb2+)/g and 94.05 mg(Cd2+)/g). The optimal time for removal of the analyzed metal ions was 60 min, although adsorption reached equilibrium within 10 min for Pb(II) and within 15 min for Cd(II) ions, which was found to fit well with a type 1 pseudo-second-order kinetic model. Additionally, adsorption efficiency was affected by the pH of the reaction system—better results were obtained for pH ≥7 irrespective of the type of metal ion. 相似文献
9.
10.
Huijun Liu Caixia Qi Zhiyuan Feng Lanlin Lei Shanxia Deng 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(3):1607-1618
The adsorption of thorium(IV) was studied using a novel supramolecular polyrotaxane based on β-cyclodextrin derivatives. The effects of pH, contact time, Th(IV) initial concentration and adsorbents dosage on the adsorption of thorium(IV) by polyrotaxane were optimized using Box–Behnken design of response surface methodology. Analysis of variance and correlation coefficients showed that the predicted model was consistent with the experimental data well. The adsorption best fitted to the Langmuir model indicated that the adsorption process happened on homogeneous surface. The thermodynamic parameters (?G 0 < 0, ?H 0 > 0, ?S 0 > 0) demonstrated that the adsorption of Th(IV) ions onto polyrotaxane was spontaneous and endothermic. 相似文献
11.
P. Senthil Kumar V. SathyaSelvaBala K. Ramakrishnan P. Vijayalakshmi S. Sivanesan 《Russian Chemical Bulletin》2010,59(10):1859-1864
The feasibility of using granulated activated carbon for adsorption removal of copper from aqueous solution was studied. The
influence of pH, amount of the adsorbent, contact time, and copper concentration on adsorption of copper was investigated.
The single-component equilibrium data on copper adsorption were analyzed using the Langmuir, Freundlich, Redlich—Peterson,
Temkin, and Toth adsorption isotherms. The adsorption process was followed by two simplified kinetic models including pseudo-first-
and pseudo-second-order equations. Kinetic parameters, rate constants, equilibrium sorption capacities, and the corresponding
correlation coefficients were calculated and examined for each kinetic model. It was shown that copper adsorption can be described
by the pseudo-second-order equation. 相似文献
12.
Activated carbon from coconut shells (ACCS) was synthesised and used for the removal of metal ions (manganese, iron, nickel
and copper) from aqueous solutions. Two different adsorption models were used for analysing the data. Adsorption capacities
were determined: copper ions exhibited the greatest adsorption on activated carbon obtained from coconut shells because of
their size and pH conditions. Adsorption capacity varied as a function of the pH. Adsorption isotherms from aqueous solutions
of heavy metals on ACCS were determined and were found to be consistent with Langmuir’s adsorption model. Adsorbent quantity
and immersion enthalpy were studied. The results were compared with other adsorbents used in a prior study. 相似文献
13.
A commercial activated carbon was functionally modified by silylation with 3-aminopropyltriethoxysilane (APTES). The silylation led to the fixation of weakly basic functional groups, –NH2, on the surface as indicated by pH titration, Boehm titration, N $_{2^{-}}$ BET analysis and X-ray photoelectron spectroscopic (XPS) analysis. Despite reducing the specific BET area and the pore volume, silylation improved the H2S removal capacity so that APTES modified activated carbon (APTES-AC) was 3.55 times more effective than the original activated carbon. XPS results indicate that H2S removal may be associated with the amino (–NH2) group and the presence of sulfur in the four oxidation states S2?, S0, S4+ and S6+. The effects of moisture, oxygen content and temperature on the performance of APTES-AC for H2S removal were investigated. The presence of moisture in the gas stream was found to have an adverse effect on the H2S removal, whilst the presence of oxygen favored the removal of H2S by APTES-AC. The higher removal capacity of APTES-AC relative to the original activated carbon indicates that APTES-AC is a potential candidate for the removal of H2S from gas streams. The H2S removal efficiency of APTES-AC was proved be superior to that of Na2CO3-impregnated AC by the pilot-scale test of purification H2S containing industrial waste gas, yellow phosphorus off-gas. 相似文献
14.
A. Wahby Z. Abdelouahab-Reddam R. El?Mail M. Stitou J. Silvestre-Albero A. Sepúlveda-Escribano F. Rodríguez-Reinoso 《Adsorption》2011,17(3):603-609
The textural characterization of a series of activated carbons prepared from olive stones, by carbonization at different temperatures
(400, 550, 700 and 850 °C) and thermal activation with CO2, has been investigated using N2 adsorption at −196 °C and CO2 adsorption at 0 °C. The effect of pre-oxidation of the carbonized precursor has also been studied, using temperature-programmed
decomposition (TPD), to evaluate the effect of oxygen content of the chars in the performance of the obtained activated carbons
for mercury removal. The adsorption of Hg(II) cations from aqueous solutions at room temperature by the prepared activated
carbons was studied. Experimental results show that all samples exhibit a large microporosity (pore diameter below 0.56 nm).
The amount of surface oxygen groups increased after pre-oxidation treatment, this enhancing the Hg(II) uptake (up to 72%).
It can be concluded that these groups make the support more hydrophilic, thus providing a more efficient adsorption of Hg(II).
The formation of a great amount of surface oxide groups such as carboxyl, phenol and lactone alters the surface charge properties
of the carbon, this enhancing the surface-Hg(II) interaction. 相似文献
15.
Xiaogang Gu Yandi Wang Zhouwei Miao Shuguang Lu Zhaofu Qiu Qian Sui Xuhong Guo 《Research on Chemical Intermediates》2017,43(1):1-13
In this study, an environmentally friendly complexing agent, S,S′-ethylenediamine-N,N′-disuccinic acid (EDDS), was applied in Fe(III)-mediated activation of persulfate (PS), and the degradation performance of trichloroethylene (TCE) was investigated. The effects of PS concentration, Fe(III)/EDDS molar ratio, and inorganic anions on TCE degradation were evaluated, and the generated reactive oxygen species responsible for TCE removal were identified. The results showed that nearly complete TCE degradation was achieved with PS of 15.0 mM and a molar ratio of Fe(III)/EDDS of 4:1. An increase in PS concentration or Fe(III)/EDDS molar ratio to a certain value resulted in enhanced TCE degradation. All of the anions (Cl?, HCO3 ?, SO4 2?, and NO 3 ? ) at tested concentrations had negative effects on TCE removal. In addition, investigations using radical probe compounds and radical scavengers revealed that sulfate radicals (SO 4 ·? ), hydroxyl radicals (·OH), and superoxide radical anions (O 2 ·? ) were all generated in the Fe(III)–EDDS/PS system, and ·OH was the primary radical responsible for TCE degradation. In conclusion, the Fe(III)–EDDS-activated PS process is a promising technique for TCE-contaminated groundwater remediation. 相似文献
16.
《Arabian Journal of Chemistry》2020,13(5):5474-5486
Iron oxides in general and especially hematite, α-Fe2O3 have been proved promising materials for efficient removal of various organic pollutants. Herein, we report a successful preparation of hematite (α-Fe2O3) by a facile precipitation method and its potential application in the removal of phenol from wastewater. The prepared material was subjected to extensive characterization using a variety of techniques such as scanning electron microscope coupled with energy-dispersive X-ray spectroscopy (SEM/EDX), X-ray diffraction (XRD), and the Brunauer Emmett Teller (BET) method. The operating conditions were optimized to improve the adsorption process efficiently. The adsorption analysis showed an adsorption capacity of 16.17 mg g−1 towards phenol at 30 °C. The reaction kinetics and potential rate-limiting steps were studied by Lagergren's pseudo-first-order and pseudo-second-order models, and it was found that the pseudo-second-order accurately described the adsorption kinetics. Freundlich and Langmuir adsorption isotherms models were applied, and the quality of the fittings clearly shows that the Langmuir model well describes the phenol adsorption on the hematite. The interaction mechanism between phenol and α-Fe2O3(0 0 1) surface was further addressed by Density Functional Theory (DFT) calculations and molecular dynamics (MD) simulations. Experimental and theoretical results indicate that there is strong evidence for the decisive effect of π–π interactions and H-bonds on the adsorption capacity. 相似文献
17.
Cigarette smoke is an ever changing and extremely complex mixture of over 5000 chemicals. When the cigarette burns, thousands
of chemical substances are generated, and these are distributed between the gas phase and the particles which constitute the
smoke aerosol.
Activated carbon when used in a filter can selectively remove a number of the vapour phase compounds to varying degrees of
efficiency.
Carbons of different activities (50–60% CTC and 90–100% CTC) have been characterised using nitrogen adsorption and also the
sorption of a number of different vapours with different properties, using a dynamic gravimetric adsorption technique.
Surface areas, pore volumes, diffusivities and heats of adsorption were calculated using nitrogen, benzene, heptane, ethyl
acetate and water as the probe molecules.
Smoke chemistries were measured using a screening approach on the characterised carbons as filter additives. It was seen that
the higher activity carbon results in increased retention in the majority of the measured vapour phase smoke constituents. 相似文献
18.
The development of economic and environmentally friendly extractants to recover cobalt metal is required due to the increasing demand for this metal.In this study,solvent extraction of Co(Ⅱ) from aqueous solution using a mixture of N,N’-carbonyl difatty amides(CDFAs) synthesised from palm oil as the extractant was carried out.The effects of various parameters such as acid,contact time,extractant concentration,metal ion concentration and stripping agent and the separation of Co(Ⅱ) from other metal ions such as Fe(Ⅱ),Ni(Ⅱ),Zn(Ⅲ) and Cd(Ⅱ) were investigated.It was found that the extraction of Co(Ⅱ) into the organic phase involved the formation of 1:1 complexes.Co(Ⅱ) was successfully separated from commonly associated metal ions such as Fe(Ⅱ),Ni(Ⅱ),Zn(Ⅲ) and Cd(Ⅱ).Co(Ⅱ) stripping from the loaded organic phase was studied in aqueous solution.These results are useful to recover Co(Ⅱ) from aqueous solution utilising(CDFAs) as an extractant. 相似文献
19.
Shuhong Hu Xiaoyan Lin Wenhui Zhao Xuegang Luo 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):223-235
Core–shell nanoscale zero-valent iron@alginate/carboxymethyl cellulose sodium composite loaded with calcium (nZVI@SA/CMC-Ca) beads were synthesized in this study using coaxial electronic injection method. The adsorbent structure was characterized via FT-IR, SEM, EDX and XPS. The adsorption behavior of U(VI) and Cu(II) on core–shell nZVI@SA/CMC-Ca beads was studied under various experimental parameters like pH, contact time and temperature. The isotherm and the kinetic data, pertaining to the adsorption of U(VI) and Cu(II) by core–shell nZVI@SA/CMC-Ca beads obeyed both the Langmuir and Freundlich isotherms model and the pseudo-second-order kinetics model, respectively. The thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption. The experiment of regeneration and reusability suggested core–shell nZVI@SA/CMC-Ca bead was a regenerated material. 相似文献
20.
Shuai Peng Yi Liu Zhiyong Xue Weiyan Yin Xiaocong Liang Ming Li Jie Chang 《Cellulose (London, England)》2017,24(11):4793-4806
Pyromellitic dianhydride-modified nanoporous magnetic cellulose–chitosan microspheres (PNMCMs) were designed and synthesized to introduce abundant carboxyl groups onto the basic microstructure. The novel microspheres were studied by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). Subsequently, a batch technique was applied to investigate various environmental parameters that could affect the adsorption behavior of the PNMCMs. Due to its nanoporous structure and large quantity of carboxyl groups, the cellulose/chitosan-based bioadsorbent exhibited excellent adsorption performance for removal of Pb(II) ions and methylene blue (MB) from aqueous solution, with maximum adsorption capacity of 384.6 and 833.3 mg/g, respectively. Furthermore, the adsorption kinetics and isotherms of Pb(II) ions and MB on PNMCMs obeyed the pseudo-second-order and Langmuir isotherm models, and the rate of adsorption was found to be controlled by film diffusion. Finally, the PNMCMs with adsorbed Pb(II) and MB could be easily regenerated using HCl, retaining removal capacity of almost 89% after six repeated uses. 相似文献