The Corrosion Inhibition of Montmorillonite Nanoclay for Steel in Acidic Solution

The aim of this research is to study the anticorrosive behavior of a coating consisting of modified montmorillonite nanoclay as an inorganic green inhibitor. The anticorrosion protection for mild steel in 1.0 M HCl solution is studied via weight loss, electrochemical methods, SEM, and XRD. The results proved that montmorillonite nanoclay acts as a good inhibitor with a mixed-type character for steel in an acidic solution. Both anodic and cathodic processes on the metal surface are slowed down. There is a clear direct correlation between the added amount of montmorillonite nanoclay and the inhibition efficiency, reaching a value of 75%. The inhibition mechanism involves the adsorption of the montmorillonite nanoclay onto the metal surface. Weight loss experiments are carried out with steel samples in 1.0 M HCl solution at room temperature, and the same trend of inhibition is produced. SEM was used to image the surface at the different stages of the corrosion inhibition process, and also to examine the starting nanoclay and steel. XRD was used to characterize the nanoparticle structure of the coating. Montmorillonite nanoclay is an environmentally friendly material that improved the corrosion resistance of mild steel in an acidic medium.

A novel co-processed olive tree leaves biomass for lead adsorption from contaminated water

Olive farming is one of the key agricultural activities in Jordan, where nearly 70% of the cultivated land in Jordan is covered with olive trees. Olive harvesting generates massive quantities of agricultural waste which will be an environmental burden if not managed properly. The present study introduces the use of novel co-processed biomass extracted from the olive tree leaves for the adsorption of lead from contaminated water. Several biomass co-processing techniques using different concentrations of sodium hydroxide, phosphoric acid, and the Dead Sea water were investigated and their effect on the removal efficiency was demonstrated. Moreover, the effect of several parameters on the adsorption efficiency including biomass particle size, solution pH, contact time, adsorbent amount, and lead ion concentration was explored. It was inferred that biomass co-processing enhanced the adsorption capacity of lead. It was also found that the adsorption efficiency increased with decreasing biomass particle size due to the increase in surface area. The highest lead removal was attained at an efficiency value of 70% for the 0.1 mm particle size and at a maximum adsorption capacity recorded at pH 5. The foregoing had a negatively charged biomass surface which, as such, favored the cationic adsorption (pH_PZC values around 2.8-4.5). For lead biosorption, the process was a rapid process whereby most adsorption was observed within the first 20 min. Concurrently, there were no considerable changes in lead removal thereafter. Theoretically, this was attributed to the decrease in the available adsorption sites on the biomass surface. On the other hand, a continuous increase in the removal efficiency was recorded upon increasing the adsorbent amount. However, there was a continuous decline in the removal efficiency upon an increase in the initial lead concentration. The experimental data were fitted well with Langmuir isotherm (indicating a monolayer adsorption isotherm), while kinetic data showed the best fit with a pseudo-second-order kinetic model.

Sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine oxide (DDAO) in single and mixed systems as corrosion inhibitors of zinc in hydrochloric acid

The influence of surfactant synergism between sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine Oxide (DDAO) on zinc corrosion in 0.05 M hydrochloric acid (HCl) solutions at 25 °C was investigated. Firstly, solutions of SDBS and DDAO with mole fractions of 0.00, 0.25, 0.50, 0.75 and 1.00 were prepared and their surface tension and critical micelle concentration (CMC) values in water and in 0.05 M HCl were measured as a function of total surfactant concentration. The SDBS/DDAO mixed system exhibited a strong synergism in 0.05 M HCl with a highly negative interaction parameter β (average β = −23.46), according to regular solution theory. Secondly, the adsorption of single surfactants SDBS and DDAO and SDBS/DDAO surfactant mixture on 2.0% zinc powder was investigated by the depletion method to find out the role of synergism in the adsorption tendency of these surfactants on the zinc surface and thus their corrosion inhibiting effect. The adsorption tendency of single surfactant and the mixed surfactant systems onto 2.0% zinc powder followed the order: SDBS > 0.75 SDBS/0.25 DDAO ≈ 0.25 SDBS/0.75 DDAO > DDAO > 0.50 SDBS/0.50 DDAO. Finally, the corrosion of zinc was investigated using the potentiodynamic polarization technique. It was found that SDBS and DDAO act as efficient corrosion inhibitors for zinc in 0.05 M HCl solution with increasing corrosion inhibition efficiency when they are mixed. Additionally, images of scanning electron microscopy were obtained for zinc sheets in solutions containing single and mixed SDBS/DDAO surfactants in the presence and absence of 0.05 M HCl. The microscopic images show an improvement in the protection of the zinc surface against acid attack in the presence of single and mixed SDBS/DDAO surfactants.

Synergistic interaction between sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine oxide (DDAO) and their adsorption onto activated charcoal and Jordanian natural clay

Solutions of sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine oxide (DDAO) with mole fractions of 0.00, 0.25, 0.50, 0.75 and 1.00 were prepared and their surface tension was measured as a function of total surfactant concentration. The critical micelle concentration (CMC) values of these mixed solutions were also determined. The minimum area occupied by a surfactant molecule at air/water interface was calculated for single and binary surfactant mixtures. A pronounced synergistic interaction between SDBS and DDAO was detected. The surface tension and CMC-values of SDBS/DDAO mixtures are significantly lower than those of the single surfactant. The mixed system of SDBS/DDAO exhibits a highly negative interaction parameter (β = −10.6) according to regular solution model, and is found to fulfill the condition of Hua and Rosen, indicting a strong synergistic interaction between the two surfactants. The contact angle measurements show the wettability of the surfactant mixture onto polyethylene substrate is higher than of the respective single surfactant. In addition, the adsorption of SDBS and DDAO or their mixtures on 1.0% activated carbon and 5.0% Jordanian natural clay (JNC), respectively, was investigated using the depletion method. The individual surfactants were found to adsorb to a considerable extent on activated carbon, and a slightly higher adsorption tendency was even measured for mixed SDBS/DDAO surfactant systems. Although no SDBS molecules adsorbed on JNC, adsorption was observed for solutions containing DDAO and SDBS/DDAO surfactants. The improvement in wettability and adsorption of SDBS/DDAO surfactants at the air/water and solid/water interfaces is directly related to the synergistic interaction between the two surfactants.

Adsorption of Single and Mixed Surfactants onto Jordanian Natural Clay

The adsorption of sodium dodecyl sulfate (SDS) and N,N-dimethyldodecan-1-amine oxide (DDAO) and their mixtures from their solutions, onto Jordanian Natural Clay (JNC) was investigated at room temperature. The clay was firstly analyzed with X-ray fluorescence technique. The surface tension of the single and mixed surfactant solutions was then measured as a function of the total surfactant concentration and the critical micelle concentration (CMC) values of these solutions were determined. The interaction between SDS and DDAO as indicated by their interaction parameter was calculated according to the regular solution model. Adsorption of single surfactants onto 3 % wt/vol Jordanian Natural Clay, using the depletion method, was ultimately investigated. Although no absorbed SDS molecules were found onto the Jordanian Clay, but a pronounced adsorption tendency for DDAO and mixed SDS/DDAO molecules was obtained. The amounts of surfactant adsorbed onto 3 wt/vol% JNC follow the trend: SDS/DDAO > DDAO > SDS indicating the importance of synergistic interaction of surfactants on their adsorption behavior.