Study of Adsorption Properties of Bentonite Clay

The clay used in this study was the bentonite from Mostagnem, Algeria. This material is used in many fields such as drilling, foundry, painting, ceramics, etc. It can also be applied in the treatment of wastewaters from chemical industries by means of adsorption. In this chapter the physicochemical properties of bentonite were determined by using several analyses techniques such as chemical composition, XRD, FTIR and SBET. The bentonite was intercalated by aluminum poly-cations solution and cethytrimethyl ammonium bromide. The acid activation of natural bentonite was performed by treatment with hydrochloric acid at different concentrations. The surface water pollutants removed by the modified bentonites are bemacid yellow E-4G and reactive MX-4R dyes, and fungicide chlorothalinil. The Langmuir and Freundlich adsorption models were applied to describe the related isotherms. The pseudo-first order and pseudo-second order kinetic models were used to describe the kinetic data. The changes of enthalpy, entropy and Gibbs free energy of adsorption process were also calculated.

Study New Pyridine Derivatives as Corrosion Inhibitors for Mild Steel in an Acidic Media

Some new pyridinium salts, namely4-(4-bromo-benzylidene-hydrazinocarbonyl)-1-phenyl-pyridinium bromide, A1; 4-(4-bromo-benzylidene-hydrazinocarbonyl)-1-butyl-pyridinium bromide, A2; 4-(4-bromo-benzylidene-hydrazinocarbonyl)-1-phencyl-pyridinium bromide, A3; were synthesized and studied as corrosion inhibitors for mild steel in 1M H2SO4aqueous solution at 20°C by weight loss measuring for 24 hrs. The results showed that the inhibition efficiency of all pyridinium bromide derivatives had a significant in value with the highest concentration. An increase in the inhibitor concentration is accompanied by a decrease in the corrosion rate, an increase in the retarding efficiency and an increase in the degree of surface coverage. The values of the free energy of adsorption revealed the effects of spontaneously reaction of (A1, A2, and A3) and gave useful information to predict the interaction between the metal surface and the organic molecules as corrosion inhibitors.

Corrosion Inhibition Studies of Benzilic Acid-Tyrosine Ligand and their Metal Complexes

A novel amino acid ligand derived from Benzilic acid and Tyrosine and its Cr (II), Fe (III), Co (II) and Ni (II) transition metal complexes were synthesized. The structure elucidation of the ligand and its complexes were derived on the basis of various spectroscopic methods such as Infrared and electronic spectra along with the aid of CHN, magnetic and conductometric measurements1, 2, 3. The corrosion inhibition efficiency of newly synthesized amino acid-mixed ligand and their metal complexes were studied in 0.5M HCl solution. The results show that the inhibitors exhibits an inhibition efficiency of 40-67% at 200ppm.The ligand shows the maximum efficiency whereas on complexation the efficiency tend to decrease. When the concentration of the inhibitor increases, then the efficiency of the inhibitor will increase4. The adsorption studies reveal that iron complex with the mild steel is chemisorption and the thermodynamic parameters such as adsorption, equilibrium constant (K) and free energy of adsorption (∆Gads) were calculated. The curve of the adsorption fits well with Langmuir adsorption isotherm.

Adsorption Properties of Hydrocarbon and Fluorocarbon Surfactants Ternary Mixture at the Water-Air Interface

Measurements were made of the surface tension of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycols) having 10 oxyethylene groups in the molecule (Triton X-100, TX100) and cetyltrimethylammonium bromide (CTAB) with Zonyl FSN-100 (FC6EO14, FC1) as well as with Zonyl FSO-100 (FC5EO10, FC2) ternary mixtures. The obtained results were compared to those provided by the Fainerman and Miller equation and to the values of the solution surface tension calculated, based on the contribution of a particular surfactant in the mixture to the reduction of water surface tension. The changes of the aqueous solution ternary surfactants mixture surface tension at the constant concentration of TX100 and CTAB mixture at which the water surface tension was reduced to 60 and 50 mN/m as a function of fluorocarbon surfactant concentration, were considered with regard to the composition of the mixed monolayer at the water-air interface. Next, this composition was applied for the calculation of the concentration of the particular surfactants in the monolayer using the Frumkin equation. On the other hand, the Gibbs surface excess concentration was determined only for the fluorocarbon surfactants. The tendency of the particular surfactants to adsorb at the water-air interface was discussed, based on the Gibbs standard free energy of adsorption which was determined using different methods. This energy was also deduced, based on the surfactant tail surface tension and tail-water interface tension.

Systematic Studies of Sodium γ-Octyl Aspartate to evaluate its Biodegradation, Surface Parameters, Micellization Aspects and Thermodynamic Properties of its Binary Mixture using Electrolytes

γ-octyl aspartate has been synthesized with 46.2% yield. The optimized conditions for esterification of aspartic acid and n-octanol are 24 hours duration and 1:1 molar ratio of reactants (aspartic acid: n-octanol). FT-IR, 1H NMR and CHNS element analysis techniques are used for structure elucidation of γ -octyl aspartate. Surface/ interfacial studies, micellization aspects, thermodynamic parameters, biodegradability and binary salt behaviour of sodium γ-octyl aspartate have been studied. The CMC of synthesized surfactants was 0.0078 mol/L, whereas minimum surface area per surfactant molecule was calculated as 29.49 Å2m2; calculated aggregation number was 34 and micelle radius (r) found to be 1.40 nm. The degree of counter-ion dissociation (α) was determined to be 0.86. Thermodynamic parameter - standard free energy of adsorption (ΔG0ads) was calculated as -18.70 kJ/mol. The shape of micelle of synthesized surfactant was noticed to be spherical but during binary studies in some cases, it was found to be cylindrical. OECD and Winkler’s method were used to determine biodegradation of sodium γ-octyl aspartate found to be 95.1 %.

Synthesis, Characterization and corrosion Inhibition Studies on Mn (II) and Co (II) Complexes Derived from 1-{(Z)-[(2-hydroxyphenyl) imino]methyl}naphthalen-2-ol in 1M HCl Solution

Schiff base derived from the reaction of 2-amino phenol and 2-hydroxy-1-naphthaldehyde and its Co (II), and Mn (II) complexes have been synthesized and characterized by solubility test, melting point/ decomposition temperatures, molar conductance, IR and magnetic susceptibility. The number of ligands coordinated to the metal ion was determined using Job’s method of continuous variation. Their molar conductance values indicate that all the complexes are non-electrolytes. Magnetic moment values of the complexes showed that both Mn (II) and Co (II) are paramagnetic. The spectroscopic data of metal complexes indicated that the metal ions are complexed with azomethine nitrogen and deprotonated oxygen atom. Corrosion inhibition of the schiff base and Mn (II) and Co (II) complexes were evaluated using the weight loss method in a 0.1MHCl solution for copper metal. The inhibition efficiency increased with increasing inhibitors concentration. The negative values of Gibb’s free energy of adsorption (ΔGads) confirmed the spontaneity and physical adsorption of the inhibition process which is inconsistent with Langmuir adsorption isotherm.

Artichoke Extract as an Eco-Friendly Corrosion Inhibitor for Zinc in 1 M Hydrochloric Acid Solution

Artichoke extract (AE) was studied as the corrosion inhibitor for zinc in 1 M HCl utilizing chemical and electrochemical methods. The adsorption isotherm of Artichoke extract on Zn surface accords with Langmuir adsorption isotherm. The inhibition efficiency increases with increasing the extract's concentration and decreases with the rise in the medium's temperature. The inhibition efficiency reached a value of 93.2% at 300 ppm of extract. This extract may be forming a film and acts as a barrier, which minimizes the contact area between zinc surface and HCl solution. Artichoke extract acts as a mixed inhibitor in HCl solution. Thermodynamic parameters of activation and adsorption were determined and explained. The adsorption parameters also obeyed the Langmuir adsorption isotherm, and the sign of the free energy of adsorption showed a spontaneous process. The surface morphology of zinc metal was examined by employing various techniques. Also, the biological effect of the Artichoke extract was studied. Theoretical studies of quantum mechanics and molecular dynamics simulations studies were carried out on the Artichoke extract compounds, and the results agree with the experimental one. The efficiencies marked from all employed techniques were in perfect correspondence, demonstrating the validity of these procedures.

Chemical Adsorption Data’s, Temperature Effect and Structural Properties of Artemether-Lumefantrine Corrosion Inhibition Properties on Structural Steel in 0.62M NaCl

Chemical and marine components are faced with corrosion resulting from salty media in an application, which ends up in serious catastrophe. In an attempt to provide and curtail this challenge of toxic use of inorganic inhibitors, properties of Artemether/Lumefantrine was examined as a corrosion inhibitor for mild steel in 0.625M sodium chloride (NaCl) medium. The corrosion propagation under different inhibitor concentrations between 0-20 ml and the temperature difference of 298-323K was examined using linear potentiodynamic polarisation and open circuit potential. The structural pitting evolution was done using a scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDS) analyses. From the data, the activation energy of the corrosion reaction increased with increasing inhibitor concentration, suggesting that it inhibits corrosion by increasing the energy required to initiate the corrosion reaction. The Gibbs free energies of adsorption fall within the range of-10.08 and-13.87 kJ/mol, which is greater than-20 kJ/mol; thus, the artemether-lumefantrine inhibitor exhibited physical type adsorption. The values of the free energy of adsorption were all negative. The Langmuir Isotherm seems to perform exceptionally well with a correlation efficiency of 0.975 against all other isotherm fits.

Removal of Methylene Blue from Aqueous Solutions by Using Nance (Byrsonima crassifolia) Seeds and Peels as Natural Biosorbents

Contamination of effluents with chemicals is a serious problem that impacts human health. Methylene blue is a cationic dye found frequently in industrial and urban sewages. In this work, dried grinded seeds and peels of nance were used as biosorbents in aqueous solutions at pH 7 and 10 (simulating urban and textile effluents) finding that Langmuir and Freundlich isotherms adequately described the sorption. Adsorption efficiencies were larger than 98% in all cases and slightly lower at pH 7 due to the closeness with the point of zero charge (pzc) of seeds and peels of nance (5.96 and 3.42, respectively). In all cases, Langmuir adsorption was favorable (RLa < 1), and Gibbs free energy of adsorption was negative indicating spontaneity, and since these values were larger than −80 but lower than 0 kJ/mol, the MB removal process was mainly due to physical interactions, a characteristic of physical adsorption. No significant differences were found amongst bulk mass transfer coefficients for the adsorption of both sorbents, indicating that both bioadsorbents had the same hydrodynamic and driving forces as well as depicted similar MB-adsorbent affinities. Interaction of MB with adsorbents was corroborated by FTIR spectroscopy, and the sorption was evidenced by scanning electron microscopy and image analysis which indicated that both adsorbents had fractal structures.