Salah M. Tawfik

Biocidal and anti-corrosive activities of benzoimidazol-3-ium cationic Schiff base surfactants

Two series of cationic Schiff base surfactants, namely, 2‐(benzylideneamino)‐3‐(2‐oxo‐2‐alkoxyethyl)‐1,3‐benzoimidazol‐3‐ium bromide (IA–D) and 2‐[(4‐methoxybenzylidene) amino]‐3‐(2‐oxo‐2‐alkoxyethyl)‐1,3‐benzoimidazol‐3‐ium bromide (IIA–D) were prepared. The chemical structures of the prepared Schiff bases were recognized by elemental analysis, FTIR, H NMR, C13‐NMR and GC/MS spectra. The surface activities of the synthesized Schiff base cationic surfactants showed their tendency towards adsorption at the air/water interface. The adsorption tendency was estimated from the values of surface tension and the depression of surface tension at the critical micelle concentration. The studied surfactants were evaluated as antimicrobial agents against pathogenic and sulfur‐reducing bacteria using inhibition zone diameters and minimum inhibition concentration values. The synthesized cationic benzoimidazolium Schiff base cationic surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The synthesized compounds were tested for the activity as corrosion inhibitors against carbon steel corrosion in 0.5 M HCl at 200 and 400 ppm. The promising inhibition efficiency of these compounds against the sulfur‐reducing bacteria facilitates them to be applicable in the petroleum field as new categories of Sulfur Reducing Bacteria biocides. The inhibition efficiencies of the tested compounds showed good inhibition and protection of the carbon steel. The corrosion inhibition tendency correlated to the surface activity and chemical structure of the compounds.

Alginate surfactant derivatives as an ecofriendly corrosion inhibitor for carbon steel in acidic environments

Biopolymer alginate surfactant derivatives were synthesized and their influences as a novel corrosion inhibitor on carbon steel in 1 M HCl were studied using gravimetric, electrochemical, EDX and SEM techniques. The compounds obtained were characterized using FTIR, 1H NMR and UV-vis spectroscopy studies. The inhibition efficiency increased with the increase in concentration and reached a maximum of 96.27% for AS–Cu at 5 × 10−3 M concentration. Potentiodynamic polarization results reveal that alginate derivatives could be classified as mixed-type corrosion inhibitors with predominant control of the cathodic reaction. The extent of inhibition exhibits a positive trend with an increase in temperature. The Langmuir isotherm provides the best description of the adsorption nature of the inhibitor. The results of EIS indicate that both the charge transfer resistance and inhibition efficiency tend to increase by increasing the inhibitor concentration. The thermodynamic parameter and activation parameters were calculated to investigate the mechanism of inhibition. Also, the relationship between the chemical structure and inhibition efficiency of the inhibitor was discussed.

Preparation and characterization of chitosan-clay nanocomposites for the removal of Cu(II) from aqueous solution

In the present study, chitosan assembled on gold and silver nanoparticles were prepared and characterized by UV-vis, TEM, EDX and DLS techniques. The nanocomposites chitosan (Ch)/clay, chitosan (Ch)/AgNPs/clay and chitosan (Ch)/AuNPs/clay were prepared by solution mixing method and characterized by FTIR, XRD, and SEM techniques. The adsorption of copper(II) ions onto the prepared hybrid composites from an aqueous solution using batch adsorption was examined. The results showed that benefiting from the surface property of clay, the abundant amino and hydroxyl functional groups of chitosan, the adsorbent provides adequate and versatile adsorption for the Cu(II) ions under investigation. The batch adsorption experiments showed that the adsorption of the Cu(II) is considerably dependent on pH of milieu, the amount of adsorbent, and contact time. Batch adsorption studies revealed that the adsorption capacity of Cu(II) increased with increase in initial concentration and contact time with optimum pH in the range around neutral. The maximum uptake of Cu(II) ions by (Ch)/AgNPs/clay composite was found to be 181.5mg/g. The adsorption efficiency of Cu(II) ions by prepared (Ch)/AgNPs/clay and (Ch)/AuNPs/clay is bigger than that the individual chitosan (Ch)/clay composite which clarifies the role of metal nanoparticles in enhancement the adsorption characters. The study suggests that the (Ch)/AgNPs/clay hybrid composite is a promising nano-adsorbent for the removal of Cu(II) ions from aqueous solution.

Benzothiazol-3-ium Cationic Schiff Base Surfactants: Synthesis, Surface Activity and Antimicrobial Applications against Pathogenic and Sulfur Reducing Bacteria in Oil Fields

Two series of cationic Schiff base surfactants namely: 2-(benzylideneamino)-3-(2-oxo-2-alkoxyethyl)-1,3-benzothiazol-3-ium bromide (1-4) and 2-[(4-methoxybenzylidene)amino]-3-(2-oxo-2-alkoxyethyl)-1,3-benzothiazol-3-ium bromide (5-8) were prepared. The chemical structures of the prepared Schiff bases were recognized by elemental analysis, FTIR, and NMR spectra. The surface activities of the synthesized Schiff base cationic surfactants were showed their tendency towards adsorption at the air/water interface. The adsorption tendency was estimated from the values of surface tension and the depression of surface tension at the CMC. The studied surfactants were evaluated as antimicrobial agents against pathogenic and sulfur reducing bacteria using inhibition zone technique. The synthesized cationic pyrazolium Schiff base surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative and fungi. The promising inhibition efficiency of these compounds against the sulfur reducing bacteria facilitates them to be applicable in the petroleum field as new categories of SRB biocides.

Synthesis, characterization and anticorrosion potentials of chitosan-g-PEG assembled on silver nanoparticles

Chitosan (Ch) grafted with poly(ethylene glycol) (Ch-g-mPEG) were synthesized using mPEG with molecular weights 2000 g/mol. The synthesized Ch-g-mPEG was characterized using gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), and X-ray diffraction (XRD) techniques. Ch-g-mPEG silver nanoparticles has been synthesized and characterized by high-resolution transmission electron microscopy (HRTEM) and energy dispersive analysis of X-rays (EDAX). The synthesized Ch-g-mPEG and its nanostructure were examined as corrosion inhibitors for carbon steel in 1M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results revealed that the inhibition efficiency obtained by Ch-g-mPEG self-assembled on silver nanoparticles is greater than that obtained by Ch-g-mPEG only. Potentiodynamic polarization results reveal that the synthesized compound could be classified as mixed-type corrosion inhibitors with predominant control of the cathodic reaction. The results of EIS indicate that the both charge transfer resistance and inhibition efficiency tend to increase by increasing the inhibitor concentration.

Synthesis, characterization and antimicrobial activity of N,N-bis(hydroxymethyl)-N-[(2-mercaptoacetoxy)methyl]alkyl ammonium bromide surfactant and their Co(II), Zn(II) and Sn(II) complexes

Two-membered cationic surfactants namely: N,N-bis(hydroxymethyl)-N-[(2-mercaptoacetoxy)methyl)dodecane ammonium bromide (C12Q) and N,N-bis(hydroxymethyl)-N-[(2-mercaptoacetoxy)methyl]hexadecane ammonium bromide (C16Q) and their cobalt, tin and zinc complexes (C12QCo, C12QSn, C12QZn, C16QCo, C16QSn and C16QZn) were synthesized. The chemical structures of the synthesized compounds were confirmed using different spectroscopy tools. The surface activities of the synthesized surfactants were influenced by their chemical structures and the type of the transition metals. The synthesized cationic surfactants and their metal complexes were evaluated as biocides against Gram- positive bacteria (Bacillus subtilis and Micrococcus luteus), Gram-negative bacteria (Bordetella pertussis and Escherichia coli) and fungi (Candida albicans and Aspergillus niger), while the sulfate-reducing bacteria were tested against Desulfomonas pigra. The biological activity results showed that the cationic surfactants exhibit moderate to high efficiency against the tested microorganisms. The antimicrobial activity was strongly increased by complexation of these cationic surfactants with Co(II), Sn(II) and Zn(II) ions. The antimicrobial activity of the synthesized compounds against sulfate-reducing bacteria showed promising results in the field of biocides application.

Synthesis and antimicrobial activity of polysaccharide alginate derived cationic surfactant–metal(II) complexes

New natural polysaccharide carbohydrate derivatives of sodium alginate surfactant and its cobalt, copper and zinc complexes were synthesized. Structures of the synthesized compounds are reported using FTIR, (1)H NMR and UV-vis. The critical micelle concentration (CMC) value of the alginate surfactant and its metal complexes in aqueous solution was found out from surface tension measurements. Surface tension data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔGmic, ΔHmic, ΔSmic) and adsorption (ΔGads, ΔGads, ΔSads). The surface activities of the synthesized polymeric surfactant and its metal complexes were influenced by their chemical structures and the type of the transition metals. These compounds were evaluated against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans and Asperigllus niger). The antibacterial and antifungal screening tests of the alginate surfactant metal complexes have shown good results compared to its precursor alginate surfactant.

Protection of carbon steel against corrosion in hydrochloric acid solution by some synthesized cationic surfactants

A series of some cationic surfactants was synthesized namely: N,N,N-tris(hydroxymethyl)-2-oxo-2-(2-(2-(dodecanoyloxy)ethoxy)ethoxy)ethanaminium chloride (DDAC); N,N,N-tris(hydroxymethyl)-2- oxo-2-(2-(2-(tetradecanoyloxy) ethoxy) ethoxy) ethanaminium chloride (TDAC) and N,N,Ntris( hydroxymethyl)-2-oxo-2-(2-(2-(hexadecanoyloxy)ethoxy)ethoxy)ethanaminium chloride (HDAC). Their chemical structures were characterized using FTIR and 1HNMR spectroscopy. Corrosion inhibition performance of these compounds on carbon steel in 0.5 M HCl was studied using weight loss and potentiodynamic polarization methods. It was seen that the three synthesized cationic surfactants decreased the corrosion rate of mild steel in acidic medium due to the adsorption on the metal surface. And it was found that the inhibition efficiency increased with increasing the inhibitor concentration. The adsorption of inhibitors on the carbon steel surface obeys modified Langmuir equation which named Villamil isotherm adsorption. Polarization curves show that the synthesized inhibitors are mixed-type inhibitors in 0.5 M HCl. ΔGads0 were ranged from–31.65 to–33.40 kJ mol–1 which indicate that the adsorption process is mixture between physical and chemical adsorption.

Three Gemini cationic surfactants based on polyethylene glycol as effective corrosion inhibitor for mild steel in acidic environment

Abstract Three Gemini quaternary ammonium surfactants based on polyethylene glycol have been prepared and characterized using FTIR and 1HNMR spectra. The effect of ethylene oxide units’ number on the steel corrosion in 1.0 M HCl has been estimated using weight loss, polarization and electrochemical impedance spectroscopy. The Gravimetric technique has been done at three different temperatures 25, 40 and 55 °C. The synthesized Gemini cationic surfactants with the higher molecular weight (higher number of ethylene oxide units) showed the higher inhibition efficiency under all conditions. All the prepared Gemini inhibitors showed higher inhibition efficiency upon raising the solution temperature from 25 to 55 °C. The synthesized inhibitor G1500Br showed inhibition efficiency reach to 94% at temperature 55 °C. The Langmuir adsorption isotherm is the best-fitted isotherm concerning the tested Gemini surfactants adsorption onto steel surface. The change in the free energy of adsorption refers to physicochemical adsorption on steel surface. The synthesized materials act as a mixed-type inhibitor based on the potentiodynamic polarization results.

Performance of nonionic surfactants derived from tannic acid in preventing the acidic dissolution of carbon steel

Corrosion inhibition tendency of four modified nonionic tannic acid derivatives containing dodecyl, hexadecyl, octadecyl and oleyl chains on carbon steel was investigated using gravimetric measurements, polarization and electrochemical impedance spectroscopy (EIS). The effect of concentration and immersion time was studied. The results show that the synthesized inhibitors act as efficient inhibitor for the corrosion of carbon steel in 0.5 M H2SO4. Inhibition efficiency ( %) increases with the inhibitor concentration, and the maximum  % values at 400 ppm by weight are 94.4%-96.4% at 25 C. The adsorption of the different inhibitors on carbon steel surface obeys Langmuir adsorption isotherm. The inhibitors act as mixed-type inhibitor in 0.5 M H2SO4 and their inhibition on carbon steel is caused by physical adsorption (physisorption).EIS spectra exhibit one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. The addition of the inhibitors to 0.5 M H2SO4 solutions enhances Rt values while reduces Cdl values.