共查询到20条相似文献,搜索用时 15 毫秒
1.
A natural smectite clay sample from Serra de Maicuru, Pará State, Brazil, had aluminum and zirconium polyoxycations inserted within the interlayer space. The precursor and pillarized smectites were organofunctionalized with the silyating agent 3-mercaptopropyltrimethoxysilane. The basal spacing of 1.47 nm for natural clay increased to 2.58 and 2.63 nm, for pillared aluminum, SAl/SH, and zirconium, SZr/SH, and increases in the surface area from 44 to 583 and 585 m2 g−1, respectively. These chemically immobilized clay samples adsorb divalent copper and cobalt cations from aqueous solutions of pH 5.0 at 298±1 K. The Langmuir, Redlich-Peterson and Toth adsorption isotherm models have been applied to fit the experimental data with a nonlinear approach. From the cation/basic center interactions for each smectite at the solid-liquid interface, by using van’t Hoff methodology, the equilibrium constant and exothermic thermal effects were calculated. By considering the net interactive number of moles for each cation and the equilibrium constant, the enthalpy, ΔintH0 (−9.2±0.2 to −10.2±0.2 kJ mol−1) and negative Gibbs free energy, ΔintG0 (−23.9±0.1 to −28.7±0.1 kJ mol−1) were calculated. These values enabled the positive entropy, ΔintS0 (51.3±0.3 to 55.0±0.3 JK−1 mol−1) determination. The cation-sulfur interactive process is spontaneous in nature, reflecting the favorable enthalpic and entropic results. The kinetics of adsorption demonstrated that the fit is in agreement with a second-order model reaction with rate constant k2, varying from 4.8×10−2 to 15.0×10−2 and 3.9×10−2 to 12.2×10−2 mmol−1 min−1 for copper and cobalt, respectively. 相似文献
2.
在HCl介质中,12-钨磷酸(TP)分别与盐酸氯丙嗪(CPZ)和盐酸异丙嗪(PMZ)反应形成离子缔合物,导致溶液的共振瑞利散射(RRS)显著增强,并产生新的RRS光谱.它们的最大RRS峰位于359 nm (TP-CPZ)和346 nm (TP-PMZ),并且在一定范围内,CPZ和PMZ的浓度与散射强度呈线性关系,据此提出流动注射-共振瑞利散射 (FIA-RRS) 联用技术测定CPZ和PMZ的新方法,CPZ和PMZ的检出限分别为1.7和3.0 μg/L.实验优化了流动注射(FIA)参数和反应条件,并以灵敏度较高的CPZ为例,考察了共存物质的影响.本方法具有良好的选择性和重复性;用于药片和猪肝中CPZ的测定,结果满意. 相似文献
3.
荧光分光光度法直接测定盐酸异丙嗪片剂及注射液的含量 总被引:6,自引:0,他引:6
以0.0001mol/L盐酸的溶剂,303nm为激发波和nm为发射波和散荧光分光光度法直接测定盐酸异丙嗪片剂及注射液中盐酸异丙嗪的含量。盐酸异丙嗪在0.1~10.0μg/mL浓度范围呈良好线性。片剂及注射液的测定平均变异系数分别为0.31%和0.45%,回收率分别为99.9%和99.6%。 相似文献
4.
Gereli G Seki Y Murat Kuşoğlu I Yurdakoç K 《Journal of colloid and interface science》2006,299(1):155-162
This study presents the adsorption of cationic drug, promethazine hydrochloride from aqueous solution onto K10 montmorillonite. The effects of pH and temperature on adsorption process were investigated. Maximum adsorption pH was obtained to be about 7.5. Thermodynamic parameters found in this study depict the exothermic nature of adsorption. The process was favorable and spontaneous. From kinetic studies, it was found that adsorption process obeyed the pseudo-second-order kinetic model. The Langmuir, Freundlich, Dubinin-Radushkevich (DR) models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The fit of the Langmuir and DR models appeared to be good. Physisorption mainly controls the whole adsorption process but chemisorption also shows a particular contribution. 相似文献
5.
This study explored the adsorption behavior of Cu2+ onto iron oxide coated eggshell powder (IOESP) from aqueous solution. The effect of various operational parameters such as pH, contact time, initial adsorbate concentration, surfactant, and temperature on adsorption of Cu2+ ions was investigated using batch adsorption experiments. The optimum pH for Cu2+ adsorption was found to be 6.0. Kinetics of adsorption was found to follow the pseudo-second-order rate equation. The suitability of Langmuir and Freundlich adsorption models to the equilibrium data was investigated. The adsorption was well described by the Freundlich isotherm model indicating the presence of heterogeneous sites for Cu2+ adsorption. The adsorption of Cu2+ was increased in the presence of anionic surfactant (SDS) while cationic surfactant (CTAB) shows no significant change in adsorption capacity. Thermodynamic parameters showed that the adsorption of Cu2+ onto IOESP was feasible, spontaneous, and exothermic. Regeneration studies were performed using HCl, HCOOH, EDTA, and NaOH as eluting agent for Cu2+ desorption from saturated IOESP and the maximum regeneration was observed with HCl. 相似文献
6.
《Arabian Journal of Chemistry》2020,13(4):5050-5059
Amberchrom CG-300m, a styrene acrylic ester polymer resin, was studied for the first time as sorbent for metal ion sorption in a solid-phase extraction system. The polymer sorbent was modified via impregnation with dithizone to improve its efficiency. Efficiency of the modified sorbent improved by more than 47%. The loading capacity of the resin is 3.2 mg dithizone per gram of sorbent. The mechanisms of Cd(II) sorption from aqueous solutions are presented. Capacity of the modified resin for Cd(II) was investigated in batch experiments as a function of pH, initial metal ion concentration, temperature and time. Maximum capacity of 0.551 mg Cd(II) per gram of sorbent was achieved. The dimensionless separation factor, 0 < RL < 1, associated with the Langmuir isotherm (at T = 294 K) signifies sorption of Cd(II) was favorable, as do negative values of free energy of sorption (ΔG) at temperatures exceeding 293 K. Sorption was endothermic (ΔH > 0) while ΔS > 0 reflects the affinity of the sorbent towards Cd(II). The pseudo-second order model proved to be the best fit model for Cd(II) sorption kinetics data. Particle-diffusion models suggest sorption follows film as well as pore diffusion mechanisms. 相似文献
7.
稳定回归法用于复方氯丙嗪片的测定 总被引:1,自引:1,他引:1
本文应用稳定回归法用于紫外重叠光谱的分析。以复方氯丙嗪为例,不经分离,测定了盐酸氯丙嗪和盐酸异丙嗪的含量。与最小二乘回归法比较,提高了测定结果的准确度和精密度。结果满意。 相似文献
8.
Chloroquine phosphate and promethazine hydrochloride are two main components in compound reserpine tablets. It is difficult to separate the two compounds with capillary electrophoresis (CE). Heuristic evolving latent projections (HELP) is a chemometric algorithm which is suitable for resolving overlapped peaks from CE and HPLC. In this paper, HELP was applied to resolving the completely overlapped peaks of chloroquine phosphate and promethazine hydrochloride from CE. Mathematical separation and satisfactory quantification results can be achieved easily without too much time involved in the procedure. 相似文献
9.
10.
《Journal of Saudi Chemical Society》2023,27(5):101706
In our current research, an intriguing magnetic nano sorbent Fe3O4@Zr-MOF was synthesized in the lab. We used this adsorbent for successfully removing tetracycline (TC) from water. We performed a number of experiments and studies to further support this, including the following: vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller surface area (BET). Our studies have determined that the Fe3O4@Zr-MOF boasts a considerable surface area of 868 m2/g with the highest adsorption capacity (qmax) of 942.12 mg/g. Study the factors that effect on adsorption process such as pH, TC concentration, adsorbent dose, and temperature. The adsorption isotherm was fitted to the Langmuir equation, whereas the kinetic isotherm to the pseudo-second-order equation. The adsorption process was chemisorption as well as the adsorption energy was 20 kJ/mol. Adsorption thermodynamics indicated that the adsorption process was both endothermic and spontaneous. As temperatures increased, the amounts of materials absorbed also increased. The Fe3O4@Zr-MOF has magnetic properties as it easily to remove from the solution after adsorption process. The adsorbent was used for five cycles with high efficiency and without change in the chemical composition as well as the XRD was the same before and after reusability. The mechanism of the interaction between Fe3O4@Zr-MOF and TC was expected on: Electrostatic interaction, π-π interaction, hydrogen bonding, and pore filling. The adsorption results were optimized using Box Behnken-design (BBD). 相似文献
11.
Modified Sorrel’s cement was prepared by the addition of ferric chloride. The modified cement (MF5) was analyzed and characterized
by different methods. Adsorption of Gd(III) and U(VI) ions in carbonate solution has been studied separately as a function
of pH, contact time, adsorbent weight, carbonate concentration, concentration of Gd(III) and U(VI) and temperature. From equilibrium
data obtained, the values of Δ H, Δ S and Δ G were found to equal −30.9 kJ ⋅ mol−1, −85.4 J ⋅ mol−1 ⋅,K−1, and −5.4 KJ ⋅ mol−1, respectively, for Gd(III) and 18.9 kJ ⋅ mol−1, 67.8 J ⋅ mol−1 K−1 and −1.3 KJ ⋅ mol−1, respectively, for U(VI). The equilibrium data obtained have been found to fit both Langmuir and Freundlich adsorption isotherms.
The batch kinetic of Gd(III) and U(VI) on modified Sorrel’s cement (MF5) with the thermodynamic parameters from carbonate
solution were studied to explain the mechanistic aspects of the adsorption process. Several kinetic models were used to test
the experimental rate data and to examine the controlling mechanism of the adsorption process. Various parameters such as
effective diffusion coefficient and activation energy of activation were evaluated. The adsorption of Gd(III) and U(VI) on
the MF5 adsorbent follows first-order reversible kinetics. The forward and backward constants for adsorption, k
1and k
2 have been calculated at different temperatures between 10 and 60∘C. Form kinetic study, the values of Δ H
* and Δ S
* were calculated for Gd(III) and U(VI) at 25∘C. It is found that Δ H
* equals −14.8 kJmol−1 and 7.2 kJmol−1 for Gd(III) and U(VI), respectively, while Δ S
* were found equal −95.7 Jmol−1K−1 and −70.5 Jmol−1K−1 for Gd(III) and U(VI), respectively. The study showed that the pore diffusion is the rate limiting for Gd(III) and (VI). 相似文献
12.
《Arabian Journal of Chemistry》2020,13(6):5553-5563
Modification of raw flax fiber by acetylating process and microwave energy was useful in the application of oil spill cleanup. The change in fibers was characterized by scientific analysis(FTIR, SEM, XRD and contact angle). The results indicate that the modified fibers by the acetylating process have extra hydrophobic properties than both microwave radiation and raw fibers. Oil/Artificial seawater(3.5% salinity by NaCl) system (O/W-S) was used as a liquid phase operation system. Fast oil sorption was reached at 6 min and attained(equilibrium) at 10 min. Acetylated fiber(ACF)has higher oil sorption capacity(24.54 g/g) than both raw(13.75 g/g) and microwave fiber(17.42 g/g) with exothermic effect. The sorption kinetics and isotherms indicate that the oil sorption onto ACF agreement with pseudo second-order kinetic model and Freundlich isotherm model. Also, the economic reusing of fiber was evaluated. The process of acetylation demonstrated the ability to improve the absorptive properties of the fibers, which makes them able to compete with synthetic fibers in the oil spill cleanup and industrial applications, as well as cheap and eco-friendly due to their biodegradation. 相似文献
13.
For the first time, promethazine hydrochloride chemiluminescence emission was monitored. The paper describes a new, specific and highly sensitive flow injection (FI) method for the determination of promethazine hydrochloride using both a peristaltic and a syringe pump. The method was based on the chemiluminescence emission intensity produced as a result of its oxidation reaction with permanganate in sulfuric acid medium. Reaction variables were thoroughly investigated employing chemometrical methods with few number of experiments. The optimum system and chemical conditions were 2.1519×10−4 mol l−1 permanganate in 0.01 mol l−1 sulfuric acid when operating the peristaltic pump at a flow rate of 45 μl s−1 and injecting the drug by a syringe pump operated at a speed of 40 μl s−1. The method was found to be applicable in the concentration range of promethazine hydrochloride between 1.558×10−5 and 1.8697×10−3 mol l−1 with a linear calibration plot of 0.992 correlation coefficient and the following equation: I=92.74+0.08048C. The method adopted proved to be highly suitable for the assay of promethazine hydrochloride in drug formulations without fear of interferences in dosage form. 相似文献
14.
《Journal of Saudi Chemical Society》2022,26(2):101417
In the present work, a cost-effective Indian jujube seeds derived activated carbon (IJSAC) prepared via o-phosphoric acid chemical activation, is studied for the sequestration of acriflavine (AF) and Victoria blue B (VB) from the aquatic environment. The activated carbon is characterized by Fourier transform infrared spectroscopy, N2-adsorption/desorption isotherm, scanning electron microscopy techniques and point of zero-charge measurement. The specific surface area (SBET) of 571 m2/g with a pore radius of 22.45 Å specifies mesoporous nature of the IJSAC. The implication of operational conditions on the adsorption of both dyes onto IJSAC assessed by batch methodology, establish the optimal conditions as dosage (1.5 and 2.5 g/L), contact time (60 min), pH (8 and 10), and initial concentration (130 and 140 mg/L) for AF and VB uptake, respectively. The Freundlich adsorption isotherm model (R2 = 0.99) appropriates the equilibrium data suggesting multilayer adsorption onto heterogeneous surface sites, while pseudo-second order (R2 = 0.95–0.99) is the best fit kinetic model. The liquid film and intraparticle diffusion modelling demonstrate that the adsorption process of these dyes is governed by both the steps. Maximum Langmuir adsorption capacity is 113.6 mg/g for acriflavine and 92.78 mg/g for Victoria blue B. Thermodynamic studies indicate endothermic and spontaneous adsorption of dyes. The adsorption mechanism for the uptake of AF and VB by IJSAC most probably involves hydrogen bonding, electrostatic and π-π interactions. Based on its high adsorption capacity, relatively faster kinetics, and reusability, IJSAC can be perceived as a proficient and effective adsorbent for cationic dyes removal from the liquid waste. 相似文献
15.
Rabii Mahboub Yassine El Mouzdahir Abdellah Elmchaouri Ana Carvalho Moiss Pinto Joo Pires 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,280(1-3):81-87
Characterization of the textural and structural properties of a sodium form of a delaminated calcic montmorillonite, and of aluminium pillared materials prepared with and without amine pre-adsorption, was made using the adsorption of different probe molecules (nitrogen, toluene, methyl ethyl ketone and 1,1,1-trichloroethane). Due to the delaminated character of the prepared solids, the characterization by X-ray diffraction of the pillared materials was not possible. In this context, the adsorption of probe molecules revealed to be informative since, although the prepared materials were mainly mesoporous solids in consequence of their delaminated nature, when the amine pre-adsorption was used before the pillaring, microporosity was also formed. 相似文献
16.
17.
Fluoride occurs in some drinking water sources at levels that are hazardous to health. Tests were conducted to assess the
ability of a mineral-based adsorbent to take-up fluoride ion. Consequently, in search of novel adsorbent media, crystalline
and hydrous iron(III)-zirconium(IV) hybrid oxide (IZHO) was synthesized, and tested to determine its capacity and kinetics
for fluoride adsorption. The Fourier Transform Infrared (FTIR) spectrum of IZHO indicated the presence of Fe–O–Zr linkage
which showed hybrid nature of the synthetic oxide. The optimum pH range for fluoride adsorption was ranged between 4.0 and
7.0. The analyses of the isotherm equilibrium data using the Langmuir and the Redlich–Peterson model equations by linear and
non-linear methods showed that the data fitted better with latter model than the former. Thermodynamic analysis showed spontaneous
nature of fluoride adsorption, and that took place with the increase of entropy. The kinetic data obtained for fluoride adsorption
on IZHO at pH 6.8 (±0.1) and room temperature (303±2 K) described both the pseudo-first order and the reversible first-order
equations equally well (r
2= ∼0.98–0.99), and better than pseudo second order equation (r
2= ∼0.96–0.98) for higher concentrations (12.5 and 25.0 mg/dm3) of fluoride. The kinetics of fluoride adsorption on the mixed oxide took place with boundary layer diffusion. External mass
transport with intra-particle diffusion phenomena governed the rate limiting process, which has been confirmed from the Boyd
poor non-linear kinetic plots. 相似文献
18.
The objective of this work was to study the efficiency of activated carbon prepared from agricultural waste (olive stones; OS) on diclofenac (DCF) adsorption in aqueous solutions. The prepared charcoals were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM)/Energy Dispersive X-Ray Analyser (EDX), and Brunauer–Emmett–Teller (BET) analysis techniques. The results show that DCF adsorption is favorable in acid medium and low temperature. The adsorption kinetics follows a pseudo-second-order kinetic model. The adsorption was found to be spontaneous (ΔG°?0) for OS600°C, whereas the negative values of the enthalpy (ΔH°) suggest an exothermic adsorption for both adsorbents. 相似文献
19.
Daniela Suteu Carmen Zaharia Teodor Malutan 《Central European Journal of Chemistry》2012,10(6):1913-1926
The sorptive potential of some lignocellulosic agro-industrial wastes (sunflower seed shells and corn cob) for Basic Blue 9 cationic dye removal from aqueous solutions was examined using the batch technique. The Freundlich, Langmuir, and Dubinin-Radushkevich isotherm models were used in order to determine the quantitative parameters of sorption. The Langmuir isotherm model indicated a maximum sorption capacity for these materials in the range of 40–50 mg dye per g (25°C), slightly higher for corn cob than for sunflower seed shells. The values of the thermodynamic parameters showed that the retention of cationic dye is a spontaneous and endothermic process. The application of pseudo-first order and pseudo-second order intraparticle diffusion models, and a Boyd — Reichenberg model for kinetic data interpretation suggested that sorption of Basic Blue 9 dye onto the studied materials is a process where both surface sorption and intraparticle diffusion contributed to the rate-limiting step. These lignocellulosic wastes can be used with good efficiency for dye removal from aqueous effluents. 相似文献
20.
Shivaji Sircar 《Adsorption》2006,12(4):259-266
An analytical mathematical model is used to investigate the influence of minute adsorbent temperature changes on the kinetics
of sorption of a gaseous adsorbate from mixture with a carrier gas using a differential closed loop recycle method. Isothermal
operation may not be achieved even when a very high gas circulation rate is used. Very small changes in the adsorbent temperature
during the process can cause substantial departure from isothermal uptake behavior. It is shown that the kinetic process can
be assumed to be isothermal only for trace adsorbate concentrations. A criterion for validity of isothermal data analysis
is proposed. 相似文献