Removal of toxic elements from aqueous solution using bentonite modified with l-histidine

2014 ◽  
Vol 70 (12) ◽  
pp. 2022-2030 ◽  
Author(s):  
E. N. Bakatula ◽  
E. M. Cukrowska ◽  
I. M. Weiersbye ◽  
L. Mihaly-Cozmuta ◽  
H. Tutu
Keyword(s):  
Aqueous Solution ◽  
Freundlich Isotherm ◽  
Batch Mode ◽  
Operating Variables ◽  
Ph Values ◽  
Surface Areas ◽  
Rate Limiting Step ◽  
Thermodynamic Constants ◽  
Pseudo Second Order ◽  
Rate Limiting

This study proposes the use of bentonite modified with l-histidine for the removal of Cu, Co, Cr, Fe, Hg, Ni, U and Zn from aqueous solutions such as those impacted by acidic drainage. The surface areas of natural bentonite and bentonite–histidine were 73.8 and 61.2 m2 g−1, respectively. Elemental analysis showed an increase in the amount of carbon (0.258%) and nitrogen (0.066%) for the bentonite–histidine. At a fixed solid/solution ratio, the operating variables affecting the adsorption of metal ions from aqueous solution such as pH, initial concentration, contact time and temperature were studied in batch mode. The Freundlich isotherm model yielded a better fit than the Langmuir for the adsorption of Cu, Co, Ni and Zn, implying adsorption on a heterogeneous surface. Adsorption kinetics followed a pseudo-second-order model, suggesting chemisorption as the rate-limiting step. The apparent activation energy was greater than 40 kJ mol−1 for Cu, Zn, Ni, Co and U, which is characteristic of a chemically controlled reaction. Thermodynamic constants ΔG and ΔH showed that the adsorption of metals was endothermic and spontaneous. Adsorption of heavy metals onto bentonite–histidine was efficient at low pH values, meaning that the adsorbent could be useful for remediating acid mine water.

Fuchsine Adsorption from Aqueous Solution by Epichlorohydrin Crosslinked Peanut Husk

2012 ◽  
Vol 549 ◽  
pp. 362-365 ◽  
Author(s):  
Ying Hua Song ◽  
Sheng Ming Chen ◽  
Jian Min Ren ◽  
Yuan Gao ◽  
Hui Xu
Keyword(s):  
Aqueous Solution ◽  
Contact Time ◽  
Adsorption Process ◽  
Adsorption Equilibrium ◽  
Freundlich Isotherm ◽  
Order Model ◽  
Isotherm Equation ◽  
Thermodynamic Constants ◽  
Pseudo Second Order ◽  
Uptake Studies

The adsorption of fuchsine by peanut husk, which was crosslinked by epichlorohydrin was studied with variation in the parameters of contact time, pH, initial fuchsine concentration and temperature. They were used for equilibrium adsorption uptake studies with fuchsine. The results indicate that adsorption equilibrium could be well described by both the Langmuir and the Freundlich isotherm equation. The adsorption followed the pseudo-second order model. The thermodynamic constants of the adsorption process were also evaluated, which suggest an endothermic adsorption process which runs spontaneously.

Preparation of cationic starch microspheres and study on their absorption to anionic-type substance

2015 ◽  
Vol 71 (10) ◽  
pp. 1545-1553 ◽  
Author(s):  
Jie Zheng ◽  
YaNan Wang ◽  
ZuoShan Feng ◽  
ZeMin Kuang ◽  
DeZhou Zhao ◽  
...  
Keyword(s):  
Iminodiacetic Acid ◽  
Freundlich Isotherm ◽  
Isotherm Model ◽  
Cationic Starch ◽  
Order Model ◽  
Chemical Absorption ◽  
Rate Limiting Step ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Rate Limiting

Cationic starch microspheres (CSMs) were prepared from lab-made neutral starch-based microspheres using a cationic adsorbent, namely 3-chloro-2-hydroxypropyltrimethyl ammonium chloride, as the cationic etherifying agent. Detection by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and laser diffraction techniques revealed that CSMs had coarse surfaces with good sphericity and dispersibility. Differential thermal analysis showed the lower thermostability of the CSMs’ main chains. Furthermore, scores of experiments confirmed that CSMs are capable of absorption to N-(phosphonomethyl) iminodiacetic acid (PMIDA), a type of anionic substance, which is the intermediate to the preparation of glyphosate, maximally up to 95.24 mg/g. Compared with the Freundlich isotherm model, the Langmuir isotherm model can better describe the absorption process. The kinetic study showed that the pseudo-second-order model demonstrated a better correlation of the experimental data in contrast with the pseudo-first-order model. It can be therefore concluded that the rate-limiting step was the chemical absorption rather than the mass transport.

Removal of Mg from spring water using natural clinoptilolite

Clay Minerals ◽  
2012 ◽  
Vol 47 (1) ◽  
pp. 81-92 ◽  
Author(s):  
S. Tomić ◽  
N. Rajić ◽  
J. Hrenović ◽  
D. Povrenović
Keyword(s):  
Ion Exchange ◽  
Kinetic Studies ◽  
Spring Water ◽  
Zeolite A ◽  
Zeolitic Tuff ◽  
Rate Limiting Step ◽  
Intra Particle Diffusion ◽  
Pseudo Second Order ◽  
Natural Clinoptilolite ◽  
Rate Limiting

AbstractNatural zeolitic tuff from Brus (Serbia) consisting mostly of clinoptilolite (about 90%) has been investigated for the reduction of the Mg concentration in spring water. The sorption capacity of the zeolite is relatively low (about 2.5 mg Mg g-1for the initial concentration of 100 mg Mg dm-3). The zeolitic tuff removes Mg from water solutions by ion exchange, which has been demonstrated by energy dispersive X-ray analysis (EDS). The extent of ion exchange was influenced by the pH and the initial Mg concentration. Kinetic studies revealed that Lagergen's pseudo-second order model was followed. Intra-particle diffusion of Mg2+influenced the ion exchange, but it is not the rate-limiting step. Rather than having to dispose of the Mg-loaded (waste) zeolite, a possible application was tested. Addition to a wastewater with a low concentration of Mg showed that it could successfully make up for the lack of Mg micronutrient and, accordingly, enabled the growth of phosphate-accumulating bacteriaA. Junii, increasing the amount of phosphate removed from the wastewater.

scholarly journals Mechanism of d-fructose isomerization by Arthrobacterd-xylose isomerase

1992 ◽  
Vol 283 (1) ◽  
pp. 223-233 ◽  
Author(s):  
M Rangarajan ◽  
B S Hartley
Keyword(s):  
Ring Opening ◽  
Ph Dependence ◽  
Xylose Isomerase ◽  
Competitive Inhibitor ◽  
Apparent Dissociation Constant ◽  
Ph Values ◽  
Rate Limiting Step ◽  
Competitive Inhibitors ◽  
Rate Limiting ◽  
Very High

The mechanism of D-fructose isomerization by Arthrobacter D-xylose isomerase suggested from X-ray-crystallographic studies was tested by detailed kinetic analysis of the enzyme with various metal ions at different pH values and temperatures. At D-fructose concentrations used in commercial processes Mg2+ is the best activator with an apparent dissociation constant of 63 microM; Co2+ and Mn2+ bind more strongly (apparent Kd 20 microM and 10 microM respectively) but give less activity (45% and 8% respectively). Ca2+ is a strict competitive inhibitor versus Mg2+ (Ki 3 microM) or Co2+ (Ki 105 microM). The kinetics show a compulsory order of binding; Co2+ binds first to Site 2 and then to Site 1; then D-fructose binds at Site 1. At normal concentrations Mg2+ binds at Site 1, then D-fructose and then Mg2+ at Site 2. At very high Mg2+ concentrations (greater than 10 mM) the order is Mg2+ at Site 1, Mg2+ at Site 2, then D-fructose. The turnover rate (kcat.) is controlled by ionization of a residue with apparent pKa at 30 degrees C of 6.0 +/- 0.07 (Mg2+) or 5.3 +/- 0.08 (Co2+) and delta H = 23.5 kJ/mol. This appears to be His-219, which is co-ordinated to M[2]; protonation destroys isomerization by displacing M[2]; Co2+ binds more strongly at Site 2 than Mg2+, so competes more strongly against H+. The inhibition constant (Ki) for the two competitive inhibitors 5-thio-alpha-D-glucopyranose and D-sorbitol is invariant with pH, but Km(app.) in the Mg[1]-enzyme is controlled by ionization of a group with pKa 6.8 +/- 0.07 and delta H = 27 kJ/mol, which appears to be His-53. This shows that Km(app.) is a complex constant that includes the rate of the ring-opening step catalysed by His-53, which explains the pH-dependence. In the Mg[1]Mg[2]-enzyme or Co[1]Co[2]-enzyme, the pKa is lower (6.2 +/- 0.1 or 5.6 +/- 0.08) because of the extra adjacent cation. Hence the results fit the previously proposed pathway, but show that the mechanisms differ for Mg2+ and Co2+ and that the rate-limiting step is isomerization and not ring-opening as previously postulated.

scholarly journals Characterization of Residual Biomasses and Its Application for the Removal of Lead Ions from Aqueous Solution

2019 ◽  
Vol 9 (21) ◽  
pp. 4486 ◽  
Author(s):  
Candelaria Tejada-Tovar ◽  
Angel Darío Gonzalez-Delgado ◽  
Angel Villabona-Ortiz
Keyword(s):  
Aqueous Solution ◽  
Adsorption Process ◽  
High Surface ◽  
High Surface Area ◽  
Freundlich Isotherm ◽  
Mesoporous Structure ◽  
Isotherm Models ◽  
Solution Ph ◽  
Batch Mode ◽  
Suitable Alternative

The removal of water pollutants has been widely addressed for the conservation of the environment, and novel materials are being developed as adsorbent to address this issue. In this work, different residual biomasses were employed to prepare biosorbents applied to lead (Pb(II)) ion uptake. The choice of cassava peels (CP), banana peels (BP), yam peels (YP), and oil palm bagasse (OPB) was made due to the availability of such biomasses in the Department of Bolivar (Colombia), derived from agro-industrial activities. The materials were characterized by ultimate and proximate analysis, Fourier Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller analysis (BET), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Spectroscopy (EDS) in order to determine the physicochemical properties of bioadsorbents. The adsorption tests were carried out in batch mode, keeping the initial metal concentration at 100 ppm, temperature at 30 °C, particle size at 1 mm, and solution pH at 6. The experimental results were adjusted to kinetic and isotherm models to determine the adsorption mechanism. The remaining concentration of Pb(II) in solution was measured by atomic absorption at 217 nm. The functional groups identified in FTIR spectra are characteristic of lignocellulosic materials. A high surface area was found for all biomaterials with the exception of yam peels. A low pore volume and size, related to the mesoporous structure of these materials, make these bioadsorbents a suitable alternative for liquid phase adsorption, since they facilitate the diffusion of Pb(II) ions onto the adsorbent structure. Both FTIR and EDS techniques confirmed ion precipitation onto adsorbent materials after the adsorption process. The adsorption tests reported efficiency values above 80% for YP, BP, and CP, indicating a good uptake of Pb(II) ions from aqueous solution. The results reported that Freundlich isotherm and pseudo-second order best fit experimental data, suggesting that the adsorption process is governed by chemical reactions and multilayer uptake. The future prospective of this work lies in the identification of alternatives to reuse Pb(II)-contaminated biomasses after heavy metal adsorption, such as material immobilization.

scholarly journals Adsorption of As(V) from Aqueous Solution on Chitosan-Modified Diatomite

2020 ◽  
Vol 17 (2) ◽  
pp. 429 ◽  
Author(s):  
Qintao Yang ◽  
Liang Gong ◽  
Lili Huang ◽  
Qinglin Xie ◽  
Yijian Zhong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Removal Efficiency ◽  
Ph Effect ◽  
Freundlich Isotherm ◽  
Xrd Analysis ◽  
Optimal Value ◽  
Equilibrium Data ◽  
Pseudo Second Order ◽  
Adsorption Desorption ◽  
Modified Diatomite

A novel chitosan (CS)-modified diatomite (Dt) was prepared by a simple mixture in the mass ratio to remove As(V) from aqueous solution in this research. The CS-modified Dt adsorbent was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD) analysis. The parameters to influence the adsorption of As(V) ion were studied under such conditions as kinetics, adsorption isotherm, and pH effect. The results revealed that adsorption of As(V) was initially rapid and the equilibrium time was reached after 40 min. The optimal value of the pH was 5.0 for better adsorption. The equilibrium data were well fitted to the Langmuir isotherm compared to the Freundlich isotherm, and exhibited the highest capacity and removal efficiency of 94.3% under an initial As(V) concentration of 5 mg/L. The kinetic data were well described by the pseudo-second-order model. In addition, 0.1 M NaOH has the best desorption efficiency of As(V) adsorbed on CS-modified Dt, and the removal efficiency of As(V) was still higher than 90% when after six adsorption-desorption cycles. These results showed that the CS-modified Dt could be considered as a potential adsorbent for the removal of As(V) in aqueous solution.

ADSORPTION OF ACID ORANGE 7 BY CETYLPYRIDINIUM BROMIDE MODIFIED SUGARCANE BAGASSE

2016 ◽  
Vol 78 (1-2) ◽  
Author(s):  
Nik Ahmad Nizam Nik Malek ◽  
Nurain Mat Sihat ◽  
Mahmud A. S. Khalifa ◽  
Auni Afiqah Kamaru ◽  
Nor Suriani Sani
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Sugarcane Bagasse ◽  
Freundlich Isotherm ◽  
Isotherm Models ◽  
Acid Orange 7 ◽  
Cetylpyridinium Bromide ◽  
Batch Mode ◽  
Acid Orange ◽  
Adsorption Data

In the present study, the adsorption of acid orange 7 (AO7) dye from aqueous solution by sugarcane bagasse (SB) and cetylpyridinium bromide (CPBr) modified sugarcane bagasse (SBC) was examined. SBC was prepared by reacting SB with different concentrations (0.1, 1.0 and 4.0 mM) of cationic surfactant, CPBr. The SB and SBC were characterized using Fourier transform infrared (FTIR) spectroscopy. The adsorption experiments were carried out in a batch mode. The effect of initial AO7 concentrations (5-1000 mg/L), initial CPBr concentrations and pH of AO7 solution (2-9) on the adsorption capacity of SB and SBC were investigated. The experimental adsorption data were analyzed using Langmuir and Freundlich isotherm models. The adsorption of AO7 onto SB and SBC followed Freundlich and Langmuir isotherm models, respectively. The maximum uptake of AO7 was obtained by SBC4.0 (SB treated with 4.0 mMCPBr) with the adsorption capacity of 144.928 mg/g. The highest AO7 removal was found to be at pH 2 and 7 for SB and SBC, respectively. As a conclusion, sugarcane bagasse modified with CPBr can become an alternative adsorbent for the removal of anionic compounds in aqueous solution.

Study on Adsorption of U(VI) From Aqueous Solution by Activated MgO

2017 ◽  
Author(s):  
Qingqing Liu ◽  
Xiaoyan Li
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Adsorption Process ◽  
Removal Rate ◽  
Freundlich Isotherm ◽  
Batch System ◽  
15Mg Dose ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Kinetics Of

The activated MgO was synthesized by microwave homo-precipitator method and characterized by SEM, EDS and FT-IR methods. It was used to adsorption of U(VI) from aqueous solution with batch system. The paper discussed the effect of pH, temperature, contact time, adsorbent dose and initial U(VI) concentration on the adsorption. The results showed that activated MgO has good adsorption capacity for U(VI), the removal rate and equilibrium adsorption capacity reached 83.5% and 84.04mg·g−1 at pH 5.0, 15mg dose and 313K,respectively. The adsorption kinetics of U(VI) onto activated MgO were better fitted with pseudo-second-order kinetic.The adsorption isotherm data were fitted well to Freundlich isotherm model.The thermodynamic parameters showed that the adsorption process is endothermic and spontaneous.

scholarly journals Biosorption of aniline blue from aqueous solution using a novel biosorbent Zizyphus oenoplia seeds: Modeling studies

2015 ◽  
Vol 17 (3) ◽  
pp. 70-77 ◽  
Author(s):  
M. Kumar ◽  
G. Elangovan ◽  
R. Tamilarasan ◽  
G. Vijayakumar ◽  
P.C. Mukeshkumar ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Low Cost ◽  
Sorption Process ◽  
Aniline Blue ◽  
Blue Dye ◽  
Batch Mode ◽  
Before And After ◽  
Intra Particle Diffusion ◽  
Pseudo Second Order ◽  
Isotherm Equations

Abstract This article presents the feasibility for the removal of Aniline Blue dye (AB dye) from aqueous solution using a low cost biosorbent material Zizyphus oenoplia seeds. In this study, a batch mode experiments of the adsorption process were carried out as a function of pH, contact time, concentration of dye, adsorbent dosage and temperature. The experimental data were fitted with Freundlich and Langmuir isotherm equations. The feasibility of the isotherm was evaluated with dimensionless separation factor (RL). The kinetic data of sorption process are evaluated by using pseudo-first order and pseudo-second order equations. The mode of diffusion process was evaluated with intra-particle diffusion model. The thermodynamic parameters like change in enthalpy (ΔHº); change in entropy (ΔSº) and Gibbs free energy change (ΔGº) were calculated using Van’t Hoff plot. The biosorbent material was characterized with Fourier Transform Infrared (FTIR) spectroscopy and the morphology was identified with Scanning Electron Microscope (SEM) in before and after adsorption of AB dye.

Removal of Pb (II) from Aqueous Solution by Blast-Furnace Slags

2013 ◽  
Vol 726-731 ◽  
pp. 2736-2741
Author(s):  
Ming Da Liu ◽  
Ge Tian ◽  
Liang Jie Zhao ◽  
Yao Sheng Wang ◽  
Lei Guo ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Blast Furnace ◽  
Freundlich Isotherm ◽  
Kinetic Studies ◽  
Sorption Process ◽  
Second Order ◽  
Order Model ◽  
Pseudo Second Order ◽  
Solution Kinetic ◽  
Second Order Model

Five blast-furnace slags were used as adsorbents to remove Pb (II) from aqueous solution. Kinetic studies showed that the sorption process was best described by pseudo-second-order model. Among Langmuir, Freundlich and Temkin isotherms, the Freundlich isotherm had a better fit with the simulation of the adsorption of Pb (II).

Sign in / Sign up

Export Citation Format

Share Document