scholarly journals Removal of Chromium from Aqueous Solution Using Modified Pomegranate Peel:Mechanistic and Thermodynamic Studies

2009 ◽  
Vol 6 (s1) ◽  
pp. S153-S158 ◽  
Author(s):  
Tariq S. Najim ◽  
Suhad A. Yassin
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Aqueous Solution ◽  
Adsorption Process ◽  
Batch Process ◽  
The Other ◽  
Water Molecules ◽  
Pomegranate Peel ◽  
Solution Interface ◽  
Adsorbent Surface

Modified pomegranate peel (MPGP) and formaldehyde modified pomegranate peel (FMPGP) were prepared and used as adsorbent for removal of Cr(VI) ions from aqueous solution using batch process. The temperature variation study of adsorption on both adsorbents revealed that the adsorption process is endothermic, from the positive values of ∆H˚. These values lie in the range of physisorption. The negative values of ∆G˚ show the adsorption is favorable and spontaneous. On the other hand, these negative values increases with increase in temperature on both adsorbents, which indicate that the adsorption is preferable at higher temperatures. ∆S˚ values showed that the process is accompanied by increase in disorder and randomness at the solid solution interface due to the reorientation of water molecules and Cr(VI) ions around the adsorbent surface. The endothermic nature of the adsorption was also confirmed from the positive values of activation energy, Ea, the low values of Ea confirm the physisorption mechanism of adsorption. The sticking probability, S*, of Cr(VI) ion on surface of both adsorbents showed that the adsorption is preferable due to low values of S*(0< S*< 1 ), but S*values are lower for FMPGP indicating that the adsorption on FMPGP is more preferable .

scholarly journals Utilization ofm-Phenylenediamine-Furfural Resin for Removal of Cu(II) from Aqueous Solution-A Thermodynamic Study

2010 ◽  
Vol 7 (3) ◽  
pp. 757-762
Author(s):  
Tariq S. Najim ◽  
Israa G. Zainal ◽  
Dina A. Ali
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Free Energy ◽  
Room Temperature ◽  
Adsorption Process ◽  
Sorption Process ◽  
The Other ◽  
Weak Values ◽  
Solid Liquid Interface ◽  
Solid Liquid

m-Phenylenediamine was condensed with furfural in absence of catalyst at room temperature. The producedm-phenylenediamine-furfural resin was used for the removal of Cu(II) from aqueous solution. The pH for the optimum removal of Cu(II) was 6. The negative values of Gibbs free energy at low concentration of Cu(II) (20, 30 ppm) indicative of the spontaneous adsorption process, while, at higher Cu(II) concentration (40,50 ppm) the positive and weak values of ∆G° indicate that the process is feasible but non spontaneous. The values of ∆H° were positive indicating that the sorption process is endothermic. On the other hand, the values of activation energy (Ea) were inconsistent with the values of ∆H° both are positive and lie in the range of physisorption. The entropy ∆S° of the process was positive indicative of the randomness of the Cu(II) ions at the solid / liquid interface. The values of sticking probability S* were less than one which indicate a preferable adsorption process and the mechanism is physisorption.

Investigation of Titania Addition into Tar Sands for Removal of Phenol from Aqueous Solutions

2006 ◽  
Vol 41 (1) ◽  
pp. 94-99 ◽  
Author(s):  
Lua'y Zeatoun ◽  
Munjed Al-Sharif ◽  
Abeer Al-Bsoul
Keyword(s):  
Aqueous Solution ◽  
Adsorption Process ◽  
Sorption Process ◽  
The Other ◽  
Solution Temperature ◽  
Equilibrium Isotherm ◽  
Activation Temperature ◽  
Tar Sands ◽  
Initial Concentration ◽  
Initial Phenol Concentration

Abstract Tar sands were found to remove significant amounts of phenol from aqueous solution in the presence of titania; about 70% at an initial concentration of 10 ppm. Batch sorption experiments showed that phenol uptake was increased with either an increase in initial phenol concentration, percentage of titania in the sorbent or pre-activation temperature. On the other hand, the presence of soft ions such as sodium, Na+, or potassium, K+, or the increase of solution temperature suppressed the uptake of phenol. Physical pre-activation of the tar sands influenced the adsorption process positively. The sorption process appears to be exothermic and relatively fast; the equilibrium isotherm data were well represented by either Langmuir or Freundlich models.

Adsorption of Grape Seed Procyanidins on Macroporous Adsorbent Resin: Isotherms and Thermodynamics

2011 ◽  
Vol 396-398 ◽  
pp. 571-574 ◽  
Author(s):  
Ying Hua Song ◽  
Gui Zhi Zhang
Keyword(s):  
Solid Solution ◽  
Adsorption Isotherms ◽  
Adsorption Process ◽  
Physical Adsorption ◽  
Grape Seed ◽  
Adsorption Properties ◽  
Macroporous Resin ◽  
Solution Interface ◽  
Isotherms And Thermodynamics ◽  
Langmuir And Freundlich Equations

The adsorption properties,including the adsorption isotherms,thermodynamics,of grape seed procyanidins onto macroporous resin HZ818 are investigated.Both the Langmuir and Freundlich equations can provide a good fit to the adsorption isotherms, which indicates an endothermic and a favorable process in our study.The capacities of the adsorption increase with temperature. The negative values of ΔG and values of ΔH lower than 40 kJ/mol indicate a spontaneous physical adsorption, and the positive values of ΔS show the increased randomness at the solid/solution interface during the adsorption process.

Synthesis of metastable tetragonal (t′) zirconia-calcia solid solution by pyrolysis of organic precursors and coprecipitation route

1996 ◽  
Vol 11 (6) ◽  
pp. 1410-1420 ◽  
Author(s):  
Masatomo Yashima ◽  
Masato Kakihana ◽  
Koutaroh Ishii ◽  
Yasuro Ikuma ◽  
Masahiro Yoshimura
Keyword(s):  
Solid Solution ◽  
Aqueous Solution ◽  
Axial Ratio ◽  
Chemical Processes ◽  
The Other ◽  
Ca Ions ◽  
Scattering Study ◽  
Citrate Gel Process ◽  
Organic Precursors ◽  
Coprecipitation Route

Three kinds of chemical processes, citrate gel process, acetate gel process, and coprecipitation route, have been applied to the synthesis of homogeneous metastable tetragonal (t′) and cubic solid solutions of ZrO2−X mol% CaO (X = 4–20). From a Raman scattering study, the citrate gel process based on the gelation of the aqueous solution of citric acid containing Zr and Ca ions was found to produce compositionally homogeneous samples in comparison with the other two methods. The axial ratio c/a decreases with increasing concentration of CaO and becomes unity around 8–10 mol% CaO composition.

Poly[[diaquabis(μ4-benzene-1,3-dicarboxylato)(μ3-benzene-1,3-dicarboxylato)dierbium(III)] monohydrate]

2007 ◽  
Vol 63 (11) ◽  
pp. m2826-m2827
Author(s):  
Wen-Dong Song ◽  
De-Yun Ma ◽  
Chao-Hua Zhang
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Hydrothermal Reaction ◽  
Three Dimensional ◽  
The Other ◽  
Water Molecules ◽  
Bridging Ligands ◽  
Solvent Water ◽  
Hydrogen Bonding Interactions ◽  
Dimensional Network

The title erbium coordination polymer, {[Er2(C8H4O4)3(H2O)2]·H2O} n , was obtained by the hydrothermal reaction of ErCl3 with benzene-1,3-dicarboxylic acid (1,3-BDC) in alkaline aqueous solution. Each of the two crystallographically independent ErIII ions is seven-coordinate and has a distorted pentagonal–bipyramidal geometry. One Er centre is coordinated by seven O atoms from six 1,3-BDC ligands and the other Er centre is surrounded by five O atoms from five 1,3-BDC ligands and two water molecules. The bridging ligands, which have two different coordination modes, link the metal centres to form a three-dimensional network with channels parallel to the b axis in which solvent water molecules are located. The crystal structure is stabilized by intra- and intermolecular O—H...O hydrogen-bonding interactions. One benzene ring and the solvent water molecule are independently disordered over two positions each, with occupancy ratios of 0.595 (2):0.405 (2) and 0.661 (1):0.339 (1), respectively.

Molecular Dynamics Simulation on Aqueous Solution of Calcium Carbonate System

2019 ◽  
Vol 394 ◽  
pp. 73-78
Author(s):  
Da Fang Wang ◽  
Dong Dong Meng ◽  
Feng Jun Wang ◽  
Xin Dong Cui
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Molecular Dynamics Simulation ◽  
Diffusion Coefficients ◽  
Binding Energies ◽  
The Other ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Neutral Surface ◽  
Carbonate System

Molecular dynamics simulation was used to investigate two models of aqueous solution ofcalcium carbonate system between 283K and 373K. The diffusion coefficients of water moleculesdemonstrated that both the electropositive surface (110) on Model-I and neutral surface (104) onModel-II showed interaction with the water molecules, and the surface (110) exhibited strongerelectrostatic interaction with water molecules than the latter, besides obvious anomaly appeared near343K on Model-I. On the other hand, surface (110) exhibited anomalous influences on Ca2+ andCO32- ions near 313K and 343K on Model-I, and only a broad anomaly on CO32- ions near 343K onModel-II. The binding energies between surface (110) / (104) and Ca2+ /CO32- ions demonstrated thatthe surface (104)were more favorable for the growth of the new crystal but weak for the diffusion.

Structural Study of a new Compound Based on Acid 1,4-Cyclohexanedicarboxylic (1,4-CDC)

2010 ◽  
Vol 6 (1) ◽  
pp. 891-896
Author(s):  
Manel Halouani ◽  
M. Dammak ◽  
N. Audebrand ◽  
L. Ktari
Keyword(s):  
Aqueous Solution ◽  
Water Molecules ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Compound I ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Cyclohexanedicarboxylic Acid

One nickel 1,4-cyclohexanedicarboxylate coordination polymers, Ni2 [(O10C6H4)(COO)2].2H2O  (I), was hydrothermally synthesized from an aqueous solution of Ni (NO3)2.6H2O, (1,4-CDC) (1,4-CDC = 1,4-cyclohexanedicarboxylic acid) and tetramethylammonium nitrate. Compound (I) crystallizes in the monoclinic system with the C2/m space group. The unit cell parameters are a = 20.1160 (16) Å, b = 9.9387 (10) Å, c = 6.3672 (6) Å, β = 97.007 (3) (°), V= 1263.5 (2) (Å3) and Dx= 1.751g/cm3. The refinement converged into R= 0.036 and RW = 0.092. The structure, determined by single crystal X-ray diffraction, consists of two nickel atoms Ni (1) and Ni (2). Lots of ways of which is surrounded by six oxygen atoms, a carboxyl group and two water molecules.

Temperature Effect on the Two-Dimensional Phase Transition Kinetics of Adenine Adsorbed at the Hg Electrode/Aqueous Solution Interface

2003 ◽  
Vol 68 (8) ◽  
pp. 1407-1419 ◽  
Author(s):  
Claudio Fontanesi ◽  
Roberto Andreoli ◽  
Luca Benedetti ◽  
Roberto Giovanardi ◽  
Paolo Ferrarini
Keyword(s):  
Phase Transition ◽  
Aqueous Solution ◽  
Phase Change ◽  
Temperature Effect ◽  
Transition Rate ◽  
Effect Of Temperature ◽  
Two Dimensional ◽  
Solution Interface ◽  
Phase Transition Kinetics ◽  
Kinetics Of

The kinetics of the liquid-like → solid-like 2D phase transition of adenine adsorbed at the Hg/aqueous solution interface is studied. Attention is focused on the effect of temperature on the rate of phase change; an increase in temperature is found to cause a decrease of transition rate.

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