Adsorption of Bisphenol-A by HDTMA Modified Clinoptilolite

2011 ◽  
Vol 71-78 ◽  
pp. 717-721
Author(s):  
Hong Yu Wang ◽  
Hang Li Zhang ◽  
Qian Zhao ◽  
Hui Fei Huang
Keyword(s):  
Bisphenol A ◽  
Rate Constant ◽  
Absorption Rate ◽  
Ph Value ◽  
Freundlich Isotherm ◽  
Ammonium Bromide ◽  
Solution Ph ◽  
Kinetics Of Adsorption ◽  
Modified Clinoptilolite ◽  
Kinetics Of

The adsorption of bisphenol-A (BPA) by hexadecyl trimethyl ammonium bromide (HDTMA) modified clinoptilolite was presented. In this paper, the equilibrium adsorption of BPA by HDTMA modified clinoptilolite was described by Freundlich isotherm with a correlation coefficient's square (R2) of 0.988. The kinetics of adsorption was defined by second-order kinetics with a rate constant (Kv) of 1.98 g/mg/h. The absorption rate was fast, and the liquid solid equilibrium was accomplished within 180 minutes. The effects of initial solution pH, and reaction temperatures had been estimated, showing that the adsorption was enhanced gradually by increasing pH value.

scholarly journals Preparation of a Novel Activated Carbon from Cassava Sludge for the High-Efficiency Adsorption of Hexavalent Chromium in Potable Water: Adsorption Performance and Mechanism Insight

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3602
Author(s):  
Ling Li ◽  
Yan Li ◽  
Yiqi Liu ◽  
Lei Ding ◽  
Xiaopeng Jin ◽  
...  
Keyword(s):  
Activated Carbon ◽  
High Efficiency ◽  
Freundlich Isotherm ◽  
Pore Filling ◽  
Solution Ph ◽  
Kinetics Of Adsorption ◽  
Metal Elements ◽  
Intra Particle Diffusion ◽  
Equilibrium Process ◽  
Kinetics Of

Particularly, because of the leakage risk of metal elements from sludge carbon, little attention has been focused on using sludge activated carbon as an adsorbent for the removal of Cr (VI) from contaminated water sources. Herein, a novel sludge carbon derived from dewatered cassava sludge was synthesized by pyrolysis using ZnCl2 as an activator at the optimal conditions. The prepared sludge activated carbon possessed a large BET surface (509.03 m2/g), demonstrating an efficient removal for Cr (VI). Although the time to reach equilibrium was extended by increasing the initial Cr (VI) concentration, the adsorption process was completed within 3 h. The kinetics of adsorption agreed with the Elovich model. The whole adsorption rate was controlled by both film and intra-particle diffusion. The Cr (VI) removal efficiency increased with elevating temperature, and the adsorption equilibrium process followed the Freundlich isotherm model. The adsorption occurred spontaneously with endothermic nature. The removal mechanism of Cr (VI) on the prepared sludge activated carbon depended highly on solution pH, involving pore filling, electrostatic attraction, reduction, and ion exchange. The trace leakage of metal elements after use was confirmed. Therefore, the prepared sludge activated carbon was considered to be a highly potential adsorbent for Cr (VI) removal from contaminated raw water.

Effect of Grinding Aids on the Fracture Energy of Mica

2011 ◽  
Vol 402 ◽  
pp. 503-509
Author(s):  
Ze Hong Wang ◽  
Fu Jia Yu ◽  
Shan Cai ◽  
Shan Zhi Deng ◽  
Roger Horn
Keyword(s):  
Sodium Chloride ◽  
Fracture Energy ◽  
Sodium Citrate ◽  
Ph Value ◽  
Sodium Tripolyphosphate ◽  
Experimental System ◽  
Ammonium Bromide ◽  
Solution Ph ◽  
Grinding Aids ◽  
Slurry Rheology

An extension of the classical Obriemoff experiments has been set up to measure the fracture energy of mica. This experimental system will be entirely independent of slurry rheology. CTAB (Cetyl Trimethyl Ammonium Bromide), sodium tripolyphosphate, sodium hexametaphosphate, and tri-sodium citrate are used as grinding aids in this study and the fracture energy has been measured for mica in air, water, and water with the addition of various concentrations of these grinding aids. The results show that the fracture energy of mica in water is about half of what it is in air. Grinding aids are shown to reduce the fracture energy of mica, but not dramatically. Addition of grinding aids reduces the fracture energy by a further 10-20%, with tri-sodium citrate appearing to be the most effective. For each grinding aid there appears to be an optimal concentration, typically around 10 mmol. An experiment is also done with sodium chloride at a range of concentrations to investigate the mechanism of these grinding aids, but no reduction in fracture energy (compared to water) was observed, hence the molecular-level mechanism of action of these grinding aids remains unclear. The effect of solution pH values on the fracture energy are also investigated using tri-sodium citrate and sodium chloride. The results show that the solution pH value may effect on the fracture energy of mica. So, in practice, both concentration and pH value of solution are important for getting better grinding results.

scholarly journals KINETIC STUDY ON ADSORPTION OF CHROMIUM(lIl) TO DIATOMACEOUS EARTH PRE-TREATED WITH SULFURIC AND HYDROCHLORIC ACIDS

2010 ◽  
Vol 3 (1) ◽  
pp. 32-38
Author(s):  
Nuryono Nuryono ◽  
V.V.H. Susanti ◽  
Narsito Narsito
Keyword(s):  
Rate Constant ◽  
Adsorption Kinetics ◽  
Diatomaceous Earth ◽  
Atomic Absorption Spectrophotometry ◽  
Adsorption Rate ◽  
Physical Interaction ◽  
Kinetics Of Adsorption ◽  
Pre Treatment ◽  
Sulfuric And Hydrochloric Acids ◽  
Kinetics Of

In this research, the effect of Sangiran diatomaceous earth pre-treatment with sulfuric acid (H2SO4) and hydrochloric acid (HCl) on the kinetics of adsorption for Cr(III) in aqueous solution has been studied. The research has been carried out by mixing an amount of diatomeaeous earth with HCl or H2SO4 in various concentrations for two hours at temperature of 150 - 200°C. The mixture was washed with water until neutral, and the residue was dried at 70°C for four hours. The result then was used as adsorbent. Adsorption was carried out by mixing an amount of adsorbent with Cr(III) solution in various contact times. Ion adsorbed was determined by analyzing filtrate using atomic absorption spectrophotometry. The effect of pre-treatment on adsorption kinetics was evaluated based on kinetic parameters, i.e. constant of adsorption rate by using Langmuir-Hinshelwood kinetics and using two-process kinetics (fast and slow processes). Adsorption kinetics calculated using LH equation gave negative value for adsorption rate constant of zero order (k0). On the other words, the LH kinetics might not be applied for adsorption of Cr(III) to diatomaceous earth adsorbent. Results of kinetics study approached using two processes (fast and slow) showed that adsorption of Cr(III) occurred in two processes with rate constant of fast adsorption, kc, 0.041/min, rate constant of slow adsorption, kl, 0.0089/min, and of slow desorption, k'l, 0.089/menit. Pre-treatment with HCl up to 10 M decreased either kc, kl or k'l, while pre-treatment with H2SO4 1M increased kc to 0.061/min, decreased kl to 0.00424 and k'l to 0.0139/min. On pre-treatment with H2SO4 higher than 6 M significantly decreased three constants above. Based on the Gibbs energy change (4.31 - 6.79 kJ/mole) showed that adsorption involved physical interaction.   Keywords: adsorption, chromium, diatomaceous earth, kinetics, Langmuir-Hinshelwood

Heterogeneous oxidation of diclofenac in the presence of α-MnO2 nanorods: influence of operating factors and mechanism

2015 ◽  
Vol 71 (9) ◽  
pp. 1340-1346 ◽  
Author(s):  
Jian Li ◽  
Tuqiao Zhang ◽  
Miaomiao Ye
Keyword(s):  
Ph Value ◽  
Reaction Pathway ◽  
Complete Removal ◽  
Solution Ph ◽  
Heterogeneous Oxidation ◽  
Oxidation Activity ◽  
Ph Values ◽  
Anions And Cations ◽  
Oxidation Efficiency ◽  
Kinetics Of

Diclofenac (DCF), one of the pharmaceutical and personal care products that has been widely detected in water, was selected as a model pollutant to evaluate the oxidation activity of α-MnO2 nanorods. The results showed that the heterogeneous oxidation process is highly pH dependent, with higher degradation efficiency at lower pH values. The complete removal of DCF was obtained within 80 min at the solution pH value of 2.5. The oxidation kinetics of DCF can be modeled by Langmuir–Hinshelwood equation (R2 > 0.999). The effects of various operating parameters, including initial solution pH, α-MnO2 dosage, anions, and cations, on the oxidation efficiency were investigated in detail. A possible reaction pathway for DCF was proposed. In addition, it was demonstrated that the α-MnO2 nanorods can be recycled without decreasing their oxidation activity after 10 cycles.

scholarly journals Study on Kinetics of GD Hydrolysis in HCl aqueous

2021 ◽  
Vol 267 ◽  
pp. 02060
Author(s):  
Shaoxiong Wu ◽  
Hongpeng Zhang ◽  
Ting Miao ◽  
Haiyan Zhu ◽  
Lianyuan Wang ◽  
...  
Keyword(s):  
Rate Constant ◽  
Ph Value ◽  
Negative Ion ◽  
Hydrolysis Rate ◽  
Obvious Effect ◽  
Factors Affecting ◽  
Initial Concentration ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
Positive Ion

Organophosphate neurotoxic agents like Sarin (GB) and Soman (GD) are lethal to person. Except various kinds of decontaminants, they can be also decomposed in natural environment through nucleophilic reaction, where acidic or alkaline substance was to accelerate their hydrolysis. Most of the papers were about GB hydrolysis. Information on GD hydrolysis was relatively small, especially about kinetics of GD in acidic solution. In view of possible effect of positive ion and negative ion on hydrolysis reaction, a relatively simple composes solution, HCl aqueous solutions, was selected to investigate the factors affecting GD hydrolysis rate. Results showed that GD hydrolysis was accorded with the first-order kinetics equation if pH value was kept constant. Its rate constant was independent of GD initial concentration when the amount of H+ was excess than its requested amount. The apparent hydrolysis rate constant (kobs) in pH of 0.90 was about 0.202 min-1 at 20°C, no matter what initial concentration of GD was. The concentration of H+ was the most important factor affecting its rate. The rate constant (kobs) in HCl aqueous as a function of pH value (0.90~2.80) obeyed an equation in 25°C, that is kobs =0.17×10-0.82×pH. Reaction temperature had an obvious effect on hydrolysis rate of GD. Every 10°C increase in temperature, kobs of GD hydrolysis was improved about 2.5 times. The activation energy value (Ea) of GD hydrolysis in HCl aqueous with a pH value of 0.90 was approximately 64.25 kJ/mol.

2004 Bader Award LectureMetal-ion-catalyzed acyl and phosphoryl transfer reactions to alcohols: La3+-promoted alcoholysis of activated amides, carboxylate esters, and neutral organophosphorus esters

2004 ◽  
Vol 82 (12) ◽  
pp. 1791-1805 ◽  
Author(s):  
R Stan Brown ◽  
Alexei A Neverov ◽  
Josephine SW Tsang ◽  
Graham TT Gibson ◽  
Pedro J Montoya-Pelaez
Keyword(s):  
Rate Constant ◽  
Metal Ion ◽  
Active Form ◽  
Transfer Reactions ◽  
Nucleophilic Attack ◽  
Phosphoryl Transfer ◽  
Solution Ph ◽  
Activated Esters ◽  
Neutral Ph ◽  
Kinetics Of

Unlike metal-ion-catalyzed hydrolysis processes, metal-ion-catalyzed methanolysis processes have received scant attention in the literature particularly from the standpoint of mechanistic studies. La3+, introduced into methanol solution as its triflate or perchlorate salt, is particularly effective in promoting methanolysis reactions of unactivated and activated esters, phosphate triesters, and activated amides such as acetyl imidazoles and lactams. Studies of the kinetics of methanolysis of these substrates as a function of solution pH and [La3+] indicate that the solution comprises lanthanum dimers with one to five associated methoxides (La23+(–OCH3)1–5), the most catalytically active form being La23+(–OCH3)2, which is produced at near neutral pH in methanol (8.4). Mechanisms for all the acyl and phosphoryl transfer reactions are proposed where the metal ion serves a dual role of acting as a Lewis acid to activate the C=O or P=O system to nucleophilic attack by a metal-coordinated methoxide nucleophile. In cases where direct comparisons can be made, the La23+ catalyst system is more active for the methanolysis of nonactivated substrates than for activated substrates. Another general characteristic of this system is that the catalytic rate constant for the metal complex exceeds the second-order rate constant for free methoxide, in some cases by as much as 4600-fold. Overall the catalytic effects exhibited by the La23+ system is spectacular for such substrates as paraoxon, where as little as 2 mmol L–1 La(OTf)3 in the presence of equimolar NaOCH3 accelerates the methanolysis by 109-fold relative to the background reaction at neutral pH and ambient temperature.Key words: kinetics of methanolysis, metal ion catalysis, lanthanides, methanolysis of carboxylate esters and phosphate esters.

scholarly journals Preparation of Activated Charcoal Adsorbent from Waste Tire

2012 ◽  
Vol 27 ◽  
pp. 19-25 ◽  
Author(s):  
Vinay Kumar Jha ◽  
Kiran Subedi
Keyword(s):  
Methylene Blue ◽  
Rate Constant ◽  
Activated Charcoal ◽  
Langmuir Model ◽  
Water Steam ◽  
Kinetics Of Adsorption ◽  
Waste Tire ◽  
Pseudo Second Order ◽  
Mathematical Equations ◽  
Kinetics Of

Activated charcoal was prepared from waste tire by using pyrolysis technique in three different atmospheres, viz, air, nitrogen and a combined atmosphere of nitrogen and water (steam). Methylene blue was then adsorbed on to these activated charcoals and the kinetics of adsorption was also studied. The adsorption isotherms of methylene blue were simulated by the mathematical equations of Langmuir and Freundlich. The Langmuir isotherms were found to have better fitting than that of Freundlich. The Qmax values obtained from Langmuir model were 0.032, 0.036, and 0.092 mmol/g for the activated charcoals prepared in air, nitrogen and nitrogen and water (steam), respectively. The overall reaction was found to be pseudo-second order with the rate constant of 4.2 × 10-2 L g/(mmolmin). The equilibrium adsorption value obtained from the kinetics data i.e. 0.072 (mmol/g) was found to be comparable with that obtained from Langmuir model.DOI: http://dx.doi.org/10.3126/jncs.v27i1.6437 J. Nepal Chem. Soc., Vol. 27, 2011 19-25Uploaded date: 16 July, 2012

scholarly journals Theory of reverse scan square-wave voltammetry influenced by the kinetics of reactant adsorption

2010 ◽  
Vol 8 (3) ◽  
pp. 513-518 ◽  
Author(s):  
Milivoj Lovrić ◽  
Šebojka Komorsky-Lovrić
Keyword(s):  
Rate Constant ◽  
Square Wave Voltammetry ◽  
Electrode Reaction ◽  
Peak Current ◽  
Kinetics Of Adsorption ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Reverse Scan ◽  
The Relationship ◽  
Kinetics Of

AbstractA model of electrode reaction complicated by slow adsorption of the reactant is developed for square-wave voltammetry with inverse scan direction. The relationship between the dimensionless net peak current and the logarithm of dimensionless rate constant of adsorption is a curve with a minimum and a maximum. For this reason the ratio of real net peak current and the square-root of frequency is a non-linear function of the logarithm of frequency and exhibits either a maximum or a minimum. The frequency of extreme serves for the estimation of the rate constant: log(k ads /D 1/2 ) = log(k*ads )crit + 0.5 log f crit , where (k*ads )crit is a critical dimensionless rate constant of adsorption. Square-wave voltammetry is sensitive to the kinetics of adsorption if k ads 2 cm s−1

Adsorption Characters of Mn2+ onto Palygorskites Modified by 1, 10-Phenanthroline and Triethylamine

2010 ◽  
Vol 178 ◽  
pp. 8-16
Author(s):  
Liang Dong Feng ◽  
Bo Qing Chen ◽  
Ying Ying Shi ◽  
Ying Wei Guo ◽  
Jing Huang ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Contact Time ◽  
Ph Value ◽  
Order Model ◽  
Kinetics Of Adsorption ◽  
Initial Concentration ◽  
Adsorption Capacities ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Kinetics Of

1, 10-phenanthroline and triethylamine modified palygorskites were prepared by microwave irradiation, and characterized with FT-IR technique. The effects of contact time, adsorbent dosage, and pH value of the initial solution on the adsorption characters of Mn2+ were investigated. The adsorption of Mn2+ from aqueous solutions using 1, 10-phenanthroline or triethylamine modified palygorskites were investigated. Experiment results indicated that 1,10-phenanthroline and triethylamine molecules have been successfully grafted to palygorskite. The adsorption was rapid during the first 5 minuts and equilibrium were attained within 60 minutes in the initial concentration of Mn2+ of 50 and 100 mg•L-1, and fast adsorption in the first 10 minutes and slowly increased with the contact time due to the adsorption of palygorskite. The 1, 10-phenanthroline modified palygorskites had higher adsorption capacity than triethylamine modified palygorskites. Compared with natural palggorskites, the Mn2+ ions adsorption capacities of palggorskite modified by 1, 10-phenanthroline or triethylamine were significantly improved. There were less difference in the adsorption capacity between different dasages of 1, 10-phenanthroline modified palygorskites, but the adsorption capacity of Mn2+ adsorbed onto triethylamine modified palygorskites decreased with increasing the dosages. A Lagergren pseudo-second order model best described the kinetics of adsorption of Mn2+ onto the modified palygorskites.

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