共查询到20条相似文献,搜索用时 31 毫秒
1.
Mohammad Kavand Tahereh Kaghazchi Mansooreh Soleimani 《Korean Journal of Chemical Engineering》2014,31(4):692-700
This study investigates optimization of various competitive adsorption parameters for removal of Cd(II), Ni(II) and Pb(II) from aqueous solutions by commercial activated carbon (AC) using the Taguchi method. Adsorption parameters such as initial metal concentration of each metal ion (C0,i ), initial pH (pH0), adsorbent dosage (m) and contact time (t) in batch technique were studied to observe their effects on the total adsorption capacity of metals onto activated carbon (q tot ). The adsorbent dosage has been found to be the most significant parameter. Interactions between C0,Cd ×C0,Ni , C0,Cd ×C0,Pb and C0,Ni ×C0,Pb have been considered for simultaneous metal ions adsorption. The optimum condition for adsorption of metal ions were obtained with C0,i =100 mg L?1, pH0=7, m=2 g L?1 and t=80 min. Finally, experimental results showed that a multi-staged adsorptive treatment would be necessary to reach the minimal discharge standards of metal ions in the effluent. 相似文献
2.
K. Seehamart T. Nanok R. Krishna J.M. van Baten T. Remsungnen S. Fritzsche 《Microporous and mesoporous materials》2009,125(1-2):97
Configurational-Bias Monte Carlo simulations of the adsorption isotherm of ethane in Zn(tbip) (H2tbip = 5-tert-butyl isophthalic acid), a representative of metal-organic frameworks, show an inflection at a loading, qi = 6 molecules per unit cell. This inflection causes the inverse thermodynamic factor, 1/Γi, to display a minimum at qi = 6, along with a maximum at qi ≈ 10. Molecular Dynamics (MD) simulations of the self-diffusivity Di,self, taking account of the framework flexibility of Zn(tbip) show that the Di,self − qi dependence follows that of 1/Γi − qi, with a minimum at qi = 6. Remarkably, MD simulations assuming a rigid framework yield significantly lower values of the self-diffusivities, and show a monotonic decrease of Di,self with qi. 相似文献
3.
M.R. Prez I. Pavlovic C. Barriga J. Cornejo M.C. Hermosín M.A. Ulibarri 《Applied Clay Science》2006,32(3-4):245-251
Hydrotalcite-like compound [Zn2Al(OH)6]2edta·nH2O(ZnAl-edta) was obtained from the precursor [Zn2Al(OH)6]NO3·nH2O (ZnAl-NO3), by the anion exchange method, with the aim of uptake Cu2+, Cd2+ and Pb2+ from the aqueous solutions by chelating process between edta and metal cations. The amount of Cu2+, Cd2+ and Pb2+ adsorbed was monitorized by atomic absorption technique at different contact time, pH and metal concentrations. The results indicate the very fast adsorption of the metal cations by ZnAl-edta reaching the equilibrium of the uptake reaction in two hours for Cu and Pb and 24 h for Cd. The shape of the adsorption isotherms suggests specific interaction and high host–guest affinity. At pH 5.5 and initial concentration Ci = 10 mM, the amount adsorbed was Cs = 1117, 375 and 871 μmol/g for Cu2+, Cd2+ and Pb2+, respectively. 相似文献
4.
Erhan Demirbas Mehmet Kobya Mehmet Salim Oncel Emrah Şık Aysegul Yagmur Goren 《分离科学与技术》2019,54(5):775-785
In this study, influences of seven process variables such as initial pH (pHi), applied current (i), operating time (tEC), initial As(III) concentration (Co), diameter of Fe ball anode (dp), column height in the electrocoagulation (EC) reactor (h) and airflow rate (Qair) for removal of As(III) from groundwater by a new air-fed fixed-bed EC reactor were evaluated with a response surface methodology (RSM). The proposed quadratic model fitted very well with the experimental data for the responses. The removal efficiencies and operating costs were determined to be 99% and 0.01 $/m3 at the optimum operating conditions (a pHi of 8.5, 0.05 A, 4.94 min, dp of 9.24 mm, h of 7.49 cm, Qair of 9.98 L/min for 50 µg/L). This study clearly showed that the RSM in the EC process was a very suitable method to optimize the operating conditions at the target value of effluent As(III) concentration (10 µg/L) while keeping the operating cost to minimal and maximize the removal efficiency. 相似文献
5.
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7.
Song Zhang Qingfang Xu Rong Tu Takashi Goto Lianmeng Zhang 《Journal of the American Ceramic Society》2014,97(3):952-958
Highly oriented <111> and <110> β‐SiC films were prepared on Si(100) single crystal substrates by laser chemical vapor deposition using a diode laser (wavelength = 808 nm) and HMDS (Si(CH3)3–Si(CH3)3) as a precursor. The effects of laser power (PL), total pressure (Ptot), and deposition temperature (Tdep) on the orientation, microstructure, and deposition rate (Rdep) were investigated. The orientation of the β‐SiC films changed from <111> to random to <110> with increasing PL and Ptot. The <111>‐, randomly, and <110>‐oriented β‐SiC films exhibited dense, cauliflower‐like, and cone‐like microstructures, respectively. Stacking faults were observed in the <111>‐ and <110>‐oriented films, and aligned parallel to the (111) plane in the <111>‐oriented film, whereas they were perpendicular to the (110) plane in the <110>‐oriented film. The highest Rdep of the <111>‐oriented β‐SiC film was 200 μm/h at Ptot = 200 Pa and Tdep = 1420 K, whereas that of the <110>‐oriented film was 3600 μm/h at Ptot = 600 Pa and Tdep = 1605 K. 相似文献
8.
José Antonio Gárate María de los Ángeles Valenzuela María Pilar Gárate Andrés F. Olea 《Journal of surfactants and detergents》2009,12(3):231-236
The solubility and aggregation process of polyethoxylated non-ionic surfactants, of general formula C
i
H2i+1–(O–CH2–CH2)
j
–OH with i = 6, 8, 10 and j = 3–6 (C
i
EO
j
), in heptane were studied. The aggregation of C
i
EO
j
surfactants in heptane was investigated by using methylene blue (MB) as an absorption probe. In solutions of MB in the presence
of these surfactants in heptane, at concentrations larger than the re-dissolution concentration, the UV bands associated to
free MB (A
1) and MB–EO complex (A
2) were detected. The ratio of these intensities A
2/A
1, was used to study the kinetics of the complex formation in pure surfactant. The value of A
2/A
1 depends on the surfactant structure and the media wherein MB is dissolved, being larger in the pure surfactant than in heptane
solutions. These results are explained in terms of solvent effect and aggregate structures on the complex formation.
相似文献
Andrés F. Olea (Corresponding author)Email: |
9.
Fast preparation of (111)‐oriented β‐SiC films without carbon formation by laser chemical vapor deposition from hexamethyldisilane without H2
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Qingfang Xu Peipei Zhu Qingyun Sun Rong Tu Song Zhang Meijun Yang Qizhong Li Ji Shi Haiwen Li Lianmeng Zhang Takashi Goto Mingxu Han Jiasheng Yan Shusen Li Hitoshi Ohmori 《Journal of the American Ceramic Society》2018,101(4):1471-1478
(111)‐oriented β‐SiC films were prepared by laser chemical vapor deposition using a diode laser (wavelength: 808 nm) from a single liquid precursor of hexamethyldisilane (Si(CH3)3–Si(CH3)3, HMDS) without H2. The effects of laser power (PL), total pressure (Ptot) and deposition temperature (Tdep) on the microstructure, carbon formation and deposition rate (Rdep) were investigated. β‐SiC films with carbon formation and graphite films were prepared at PL ≥ 170 W and Pto ≥ 1000 Pa, respectively. Carbon formation strongly inhibited the film growth. β‐SiC films without carbon formation were obtained at Ptot = 400‐800 Pa and PL = 130‐170 W. The maximum Rdep was about 50 μm·h?1 at PL = 170 W, Ptot = 600 Pa and Tdep = 1510 K. The investigation of growth mechanism shows that the photolytic of laser played an important role during the depositions. 相似文献
10.
Hoi-Lun Kwong Wing-Leung Wong Chi-Sing Lee Chi-Tung Yeung Pang-Fei Teng 《Inorganic chemistry communications》2009,12(9):815-818
A new fluorescence macrocyclic receptor based on the Zn(II) complex of a C2-terpyridine and a crown ether has been developed for molecular recognition of zwitterionic amino acids in water/DMF solution with remarkable selectivity towards l-aspartate (K = 4.5 × 104 M−1) and l-cysteine (K = 2.5 × 104 M−1). 相似文献
11.
Hydrogels for absorbing metal ions in wastewater have attracted more attentions in the environmental field especially for recent years. The removal efficiency of hydrogel adsorbents for eliminating metal ions is highly related with the effective contact between adsorbents and adsorbates. However, poor water absorption capacity of the hydrogel adsorbents would restrict on the expose of adsorption sites to the targeted subjects, causing undesirable removal ratio (RR) especially for metal ions at trace level. Thereby, the reported hydrogel adsorbents mainly focus on the removal of high content but not the trace level of metal ions so far. In this work, poly(acrylamide) (PAM)/poly(acrylic acid) (PAA)/Ca(OH)2 composite hydrogel is applied to adsorb trace metal ions. Swelling ratio of such PAM/PAA/Ca(OH)2 gel reaches 2,530 g/g, resulting in effective exposure of active sites and further expected RR for trace metal ions. The RRs of such adsorbent for Cu2+ (initial concentration C0 = 0.064 mg/L), Al3+ (C0 = 0.27 mg/L), Co2+ (C0 = 0.59 mg/L), Cr6+ (C0 = 0.52 mg/L), Mn2+ (C0 = 0.55 mg/L), Ni2+ (C0 = 0.59 mg/L), Zn2+ (C0 = 0.65 mg/L), Ag+ (C0 = 1.08 mg/L), and La3+ (C0 = 1.39 mg/L) are 56.6, 80.8, 41.3, 29.3, 34.6, 44.6, 55.9, 45.8, and 35.5%, respectively. This work broadens the application of hydrogel adsorbent for eliminating trace metal ions from polluted water. 相似文献
12.
A number of new anilido-imine–Al complexes ortho-C6H4(CHNAr1)(NAr2)AlMe2 [Ar1 = C6H5, Ar2 = C6H5 (2a); Ar1 = 2,6-Me2C6H3, Ar2 = 2,6-Me2C6H3 (2b); Ar1 = 2,6-Et2C6H3, Ar2 = 2,6-Et2C6H3 (2c); Ar1 = 2,6-iPr2C6H3, Ar2 = 2,6-Me2C6H3 (2d); Ar1 = 2,6-iPr2C6H3, Ar2 = 2,6-Et2C6H3 (2e)] were synthesized, characterized and used as initiators for the ring-opening polymerization of -caprolactone in the presence of benzyl alcohol. The effect of initiator structure and reaction conditions, such as benzyl alcohol/Al molar ratio and reaction temperature on the reactivity, and polymer molecular weight were investigated. The polymerization of -caprolactone initiated by these complexes was found to take place in an immortal fashion. 相似文献
13.
《Applied Clay Science》2008,38(3-4):221-225
This paper studied the influence of copper concentration, pH, temperature, and the ratio of solid to solution on desorption of Zn in the kaolin from Suzhou, China in a background solution of 0.01 M CaCl2 by batch extraction experiments. At 0, 5, 50, 100 mg/l Cu concentration, for each 0.5 increase in pH between about 1.80 and 3.04% desorption decreases 3.80, 13.87, 9.97, and 7.65%, respectively. The pH50 (pH at 50% Zn desorption) is found to follow the sequence: Cu (5 mg/l, pH50 = 2.60) < Cu (50 mg/l, pH50 = 2.70) < Cu (100 mg/l, pH50 = 2.95) < Cu (0 mg/l, pH50 = 10.65). The free energy change (ΔG) values, the values of enthalpy change (ΔH), and entropy change (ΔS) have been calculated. There were no large differences in the desorption of Zn from 25 to 50 °C. The concentration of Zn in solution after desorption equilibrium increases and percent desorption decreases when the solid to liquid ratio increases from 0.025 to 0.2. The kaolin possibly cannot be used for the landfill clay liner. 相似文献
14.
Highly ordered SBA-15 and Sn-SBA-15 mesoporous molecular sieves with Si/Sn = 80, 60, 40 and 10 have been prepared through direct synthesis route under milder acidic conditions, which were used for the in situ high temperature X-ray diffraction (HTXRD) studies in the temperature range 298–1573 K for the first time in the literature. SBA-15 is found to be thermally stable up to 1473 K and appearance of α-cristobalite was observed at 1573 K also supported by the thermogravimetric (TG) data. A strong negative thermal expansion was observed on heating from 298 to 1573 K (αa = −4.3 × 10−6 K−1). Sn containing samples (Si/Sn = 80 and 60) showed a positive thermal expansion (6.75 × 10−6 K−1 and 9.04 × 10−6 K−1, respectively). On the other hand, the samples with Si/Sn = 40 and 10 showed a strong negative thermal expansion (−4.12 × 10−6 K−1 and −7.56 × 10−6 K−1) similar to SBA-15. The linear thermal expansion coefficient varied in the order: Si/Sn = 60 > 80 > 40 > 0 > 10. Sn4+ ions exhibit both tetrahedral and octahedral coordination depending upon the location of these ions either on the walls of the silica (Si/Sn = 80 and 60) or in the corona region of the structure (Si/Sn = 40 and 10), respectively. The thermal decomposition of the samples (TG data) is correlated to the thermal expansion behavior (HTXRD data). The decomposition behavior of template ions located within the pores is strongly influenced by the presence of Sn in the framework and a ‘soft’ interaction probably exists between the template ions and the Sn sites. 相似文献
15.
《分离科学与技术》2012,47(5):1239-1259
Abstract The present study aims to evaluate the influence of various experimental parameters viz. initial pH (pH 0), adsorbent dose, contact time, initial concentration and temperature on the adsorptive removal of furfural from aqueous solution by commercial grade activated carbon (ACC). Optimum conditions for furfural removal were found to be pH 0 ≈ 5.9, adsorbent dose ≈ 10 g/l of solution and equilibrium time ≈ 6.0 h. The adsorption followed pseudo‐second‐order kinetics. The effective diffusion coefficient of furfural was of the order of 10?13 m2/s. Furfural adsorption onto ACC was found to be best represented by the Redlich‐Peterson isotherm. A decrease in the temperature of the operation favorably influenced the adsorption of furfural onto ACC. The positive values of the change in entropy (ΔS 0); and the negatived value of heat of adsorption (ΔH 0) and change in Gibbs free energy (ΔG 0) indicated feasible, exothermic, and spontaneous nature of furfural adsorption onto ACC. 相似文献
16.
Saturated fatty acid adsorption by acidified rice hull ash 总被引:3,自引:0,他引:3
Rice hull ash (RHA) was treated with 1.0 M HNO3 (RHA-A1) and another batch was treated with 14.0 M HNO3 (RHA-A14). RHA-A1 and RHA-A14 had a pH of 6.58 and 6.13, respectively. Adsorption of saturated fatty acids (C8, C10, C12, C14, C16, and C18) was carried out on RHA-A1 and RHA-A14 at 32±1°C. The adsorption data conformed to the Langmuir isotherm. The specific surface
area of RHA-A1 was 183.84 m2 g−1 while that of RHA-A14 was 174.67 m2 g−1. The specific pore volume of RHA-A1 was 0.216 cm3 g−1 while that of RHA-A14 was 0.234 cm3 g−1. The acid-treated ash, RHA-A14 (q
m
=0.43±0.03 mmol g−1 where q
m
is the amount of adsorbate adsorbed to form a monolayer coverage on the ash particles) showed a twofold increase in the adsorption
of fatty acid per gram ash compared to RHA-A1 (q
m
=0.25±0.03 mmol g−1). The free energy of adsorption, ΔG°
ads, was determined to be −7.06±0.10 and −6.75±0.11 kcal mol−1 for RHA-A1 and RHA-A14, respectively. The reduced ΔG°
ads values observed for RHA-A14 were attributed to the electrostatic repulsion of the hydrophobic chain of the fatty acid adsorbed
on adjacent sites and brought into close proximity of each other. The ΔG°
ads values showed that the process of adsorption took place through physisorption on both RHA. 相似文献
17.
Yue Jia Rong Wang Anthony G. Fane 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,155(1-2):155-160
Part I of this study presents a theoretical method combined with experiments to determine the adsorption kinetics of powdered activated carbon (PAC) in the hybrid PAC-submerged membrane (SM) system with air bubbling for trace organics removal. The homogeneous surface diffusion model (HSDM) was applied to describe the kinetics of the adsorbate uptake. The differences between the model solutions and the corresponding experimental results were minimized by means of Levenberg–Marquardt algorithm so that two kinetic parameters DS and kf involved in HSDM were obtained simultaneously. The DS was found to be 1.14 × 10−16 m2/s and the kf value was correlated with the bubbling rate (Qb) and carbon dosage (Cc), which are required in the modeling of the hybrid PAC-SM system presented in Part II of this study. The kf was enhanced from 1.18 × 10−4 to 4.18 × 10−4 m/s when the bubbling intensity increased in the intermittent bubbling tests, suggesting that from energy consumption point of view, the high intensity intermittent bubbling is more efficient in improving the liquid film mass transfer than continuous bubbling with the same net bubbling rate. 相似文献
18.
Electrolytic oxidation of cuprocyanide electroplating waste waters under different pH conditions 总被引:1,自引:0,他引:1
The main purpose of this work was to investigate the electrolytic oxidation of cuprocyanide solution with various total cyanide to copper molar ratios ranging from 2.8 to 20 and under different pH conditions. In strong alkaline solution (pH12), cuprocyanide ions Cu(CN)
n
/(n–1)–
, wheren=2, 3 or 4, are directly electroxidized, and copper oxide precipitates on the anode. Cyanate ions, as well as nitrogen gas, were detected as the products and 0.30–0.43 g mol of total cyanide was destroyed per Faraday. For less alkaline solutions (pH<12), cuprocyanide ions first dissociated to free cyanide ions and then electroxidized. At a pH of 10.5–11.7, cyanate ion and brown azulmin polymer were produced in the anolyte. In the neutral solution (pH=7.0–8.6), carbonate and ammonium ions and azulmin were formed and 0.52–0.56 g mol of total cyanide was destroyed per Faraday. In weak acidic solution (pH=5.2–6.8), oxalate and ammonium ions and white oxamide were produced and 1.01–1.18 g mol of total cyanide were destroyed per Faraday.Nomenclature
C
CN
molar concentration of total cyanide (kmol m–3)
-
C
Cu
molar concentration of total copper (kmol m–3)
-
C
d
equivalent concentration of cyanide destroyed due to the formation of cupric oxide (kg m–3)
-
C
f
concentration of cyanide destroyed by dissociation of complex ion to free cyanide ion and then electroxidized (kg m–3)
-
C
i
initial concentration of total cyanide (kg m–3)
-
C
t
change of total cyanide concentration during electrolysis (kg m–3)
-
F
Faraday constant (96 487 C mol–1)
-
K
1,K
2,K
3
formation constant of dicyanocuprate, tricyanocuprate and tetracyanocuprate ions
-
R
molar ratio of total cyanide concentration to total copper concentration (i.e.C
CN/C
Cu)
-
W
weight of precipitates on electrodes or in anolyte (kg)
-
angle of incidence 相似文献
19.
Rongfeng Zhu Jing Zhao Fei Liu Zhang Zhang Bijun Fang Jianwei Chen Haiqing Xu Xi’an Wang Haosu Luo 《Journal of the American Ceramic Society》2020,103(4):2575-2586
The [111]-oriented rhombohedral Mn-doped 0.15Pb(In1/2Nb1/2)-0.55Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (Mn:PIMNT(15/55/30)) crystal and the [001]-oriented tetragonal Mn-doped 0.29Pb(In1/2Nb1/2)-0.29Pb(Mg1/3Nb2/3)O3-0.42PbTiO3 (Mn:PIMNT(29/29/42)) crystal were poled under different conditions. The pyroelectric performance of the two crystals as a function of poling temperature, as well as the relationship with ferroelectric domain configuration and phase structure was investigated systematically. The pyroelectric properties of the two crystals enhance with rising the poling temperature, which can be attributed to the improvement of the single state. And for the rhombohedral Mn:PIMNT(15/55/30) crystal locating near morphotropic phase boundary (MPB), the increase of tetragonal phase induces the deterioration of pyroelectric properties. Due to more residual tetragonal phase, the pyroelectric coefficient of the Mn:PIMNT(15/55/30) crystal poled at 150°C is lower than that poled at 100°C. In general, both the crystals poled above TC achieve nearly single state, exhibiting the best pyroelectric properties with relatively high Curie temperature (TC), where P = 9.71 × 10−4 C m−2 K−1, Fi = 3.88 × 10−10 m V−1, Fv = 0.068 m2 C−1 and Fd = 29.7 × 10−5 Pa−1/2 for the rhombohedral Mn:PIMNT(15/55/30) crystal (TC = 171°C) and P = 6.78 × 10−4 C m−2 K−1, Fi = 2.71 ×10−10 mV−1, Fv = 0.1 m2 C−1, Fd = 23.54 × 10−5 Pa−1/2 for the tetragonal Mn:PIMNT(29/29/42) single crystal (TC = 251°C), meeting the stable operation of infrared detector at relatively high environmental temperatures. 相似文献
20.
Md Lutfor Rahman Zhi Jian Wong Mohd Sani Sarjadi Mohd Harun Abdullah Maria A. Heffernan Md Shaheen Sarkar Emmet O'Reilly 《应用聚合物科学杂志》2021,138(2):49671
Heavy metals pollutants are nonbiodegradable and their bioaccumulation results in detrimental environmental consequences. Therefore, it is important to effectively remove toxic heavy metal waste from industrial sewage. Thus, the main goal of this research is to synthesize an ideal cellulose-based adsorbent from palm-based waste materials (agro waste) in order to be utilized in real-life practical applications with low cost as such removing common toxic heavy metals from industrial effluents. A poly(methyl acrylate) grafted palm cellulose was synthesized via a free-radical initiation process, followed by an oximation reaction to yield poly(hydroxamic acid) ligands. The adsorption capacity (qe) of poly(hydroxamic acid) ligands for metal ions such as copper (Cu2+), iron (Fe3+), and lead (Pb2+) were 325, 220, and 300 mg g−1, respectively at pH 6. In addition, the X-ray photoelectron spectrometry results are to be proved the binding of metal ions, for instance, Cu(II) ions showed typically significant BEs of 932.7 and 952.0 eV corresponding to the Cu2p3/2 and Cu2p1/2 species. The heavy metal ions adsorption followed a pseudo-first-order kinetic model pathway. The adsorption capacity (qm) is also derived from the Langmuir isotherm linear plot, which does not showed good correction coefficients. However, the results were correlated to the Freundlich isotherm model, where the R2 value showed significance (>0.98), indicating that multiple layer adsorption occurs on the synthesized ligand. The synthesized polymeric ligand is an excellent adsorbent for the removal of heavy metals from the industrial wastewater. In addition, the metal analysis results showed that about 98% removal of copper and iron ions from electroplating wastewater including lead, nickel, and chromium can be removed up to 85–97%. 相似文献