Corrosion Protection of Electro-Galvanized Steel by Green Conversion Coatings

A A cerium-based chemical conversion process was studied. First, zinc coating obtained from a free-cyanide alkaline bath, with derivative of imidazol with new brightener, was investigated, zinc-plated steel specimens were treated with a solution of 50 mmol· L^-1 Ce（NO3 ）3 The corrosion behavior of bare and treated mild galvanized steel was evaluated during exposure to 0.5 mol · L^-1 NaCl for different immersion time, using Tafel polarization curves and electrochemical impedance spectroscopy （EIS） measurements. The surface morphology of the coating was studied using scanning electron microscopy （SEM）. The composition and chemical percent of the coating were examined by X-ray dispersion energy （EDAX）. The results of these measurements showed that the newly developed cerium-based conversion coating process was a promising candidate for replacing the conventional chromate treatments used at present for galvanized steel.     

Electrochemical studies of Zn-Ni alloy coatings from non-cyanide alkaline bath containing tartrate as complexing agent

The Zn-Ni alloys have been electro-deposited from a non-cyanide alkaline bath containing tartrate as a complexing agent for Ni²⁺ ions. A water soluble polymer is used as a brightener. It was prepared by the reaction of epiclorohydrin with hexamethylenetetramine and mercaptobenzimidazol. Its effect on co-deposition process was examined. It was found that adding brightener in plating bath has a great effect on the cyclic voltammogram and galvanostatic measurements during the electrodeposition. Under the examined conditions, the electrodeposition of the alloys was of anomalous type. X-ray diffraction measurements revealed that the alloys consisted δ-phase (Ni₃Zn₂₂). The composition and morphology of the deposits were also studied by using scanning electron microscopy (SEM) and energy dispersive analysis X-ray (EDAX), respectively. The effect of optimum plating bath conditions on the corrosion resistance is studied by Tafel polarization.     

Influence of various amounts of limestone powder on performance of Portland limestone cement concretes

The benefits of limestone as a partial replacement for Portland Cement (PC) are well established. Economic and environmental advantages by reducing CO₂ emissions are well known. The paper describes the effect of various amounts of limestone on compressive strength, water penetration, sorptivity, electrical resistivity and rapid chloride permeability on concretes produced by using a combination of PC and limestone at 28, 90 and 180 days. The percentages of limestone that replace PC in this research are 0%, 5%, 10%, 15% and 20% by mass. The water/(clinker + limestone) or (w/b) ratios are 0.37, 0.45 and 0.55 having a constant total binder content of 350 kg/m³. Generally, results show that the Portland limestone cement (PLC) concretes having up to 10% limestone provide competitive properties with PC concretes.     

Formulation of Petrolatum/Clay Nanocomposite Coating and Characterization of its Corrosion Resistance Properties

Protection of Metals and Physical Chemistry of Surfaces - Montmorillonite organoclay, in different amounts (between 1 to 5 wt %), was incorporated into the petrolatum using mechanical stirring and...     

Artificial neural network (ANN) approach for modeling of Cr(VI) adsorption from aqueous solution by zeolite prepared from raw fly ash (ZFA)

In this present work, artificial neural networks (ANN) are applied for prediction of percentage adsorption efficiency for the removal of Cr(VI) ions from aqueous solution by zeolite (ZFA) prepared from raw fly ash (RFA). The off operational parameters such as initial pH, adsorbent dosage, contact time and temperature is studied to optimize the conditions for maximum removal of Cr(VI) ions. Three equations, i.e. Morris–Weber, Lagergren, and pseudo second order have been tested to track the kinetics of removal process. The Langmuir, Freundlich, Redlich–Peterson, Temkin, and D-R are subjected to sorption data to estimate sorption capacity. Thermodynamic parameters showed that the adsorption of Cr(VI) onto ZFA was feasible, spontaneous and endothermic. Artificial neural networks are effective in modeling and simulation of highly non-liner multivariable relationships. The comparison of the removal efficiencies of Cr(VI) using ANN model and experimental results showed that ANN model can estimate the behavior of the Cr(VI) removal process under different conditions.     

Investigations of the effects of temperature and initial sample pH on natural organic matter (NOM) removal with electrocoagulation using response surface method (RSM)

The removal of natural organic matter (NOM) from surface water by electrocoagulation (EC) was studied using response surface method (RSM). Factors used in the empirical model were electric charge per liter, initial pH and temperature. Relevant square and interaction terms of factors were studied. Based on analysis of variance (ANOVA), the model fitted well with dissolved organic carbon (DOC) reduction, aluminum dissolving and pH changes. UV 254 nm absorbance removal was moderately predicted. According to results, temperature affected significantly the dissolving rate of aluminum electrodes. Initial DOC concentration of the surface water was 18.35 mg/l. Maximum DOC removal of 80.4% was obtained when high electric charge per liter (144 C/l), low pH (4.3) and high temperature (295.15 K) were used. However, high DOC removal of 76.2% was predicted also when water temperature was only 275.15 K. Effect of temperature on NOM removal was minor as compared to the effects of electric charge per volume and the initial pH. EC neutralized pH during the EC treatment and had little impact on the conductivity of the water. According to the results, EC can be used for NOM removal during cold water period in Nordic countries.     

Effect of garlic consumption on total antioxidant status and some biochemical and haematological parameters in blood of rats

BACKGROUND: The effect of diet garlic supplementation on total antioxidant status (TAS), nitric oxide (NO) and routine biochemical and haematological parameters was investigated in blood of rats. A total of 30 male rats were divided equally into two groups. Each of 15 rats of treatment group was fed 600 mg kg^?1 garlic solution in distilled water by gavage and controls only received distilled water. After garlic consumption for 1 month, blood serum total antioxidant, nitrate and some biochemical and haematological tests including serum lipids parameters, blood sugar, complete blood count (CBC), and haemoglobin were measured. RESULTS: The garlic treatment group showed significantly increase in the mean level of TAS from 0.77 ± 0.10 mol L^?1 to 1.18 ± 0.11 mol L^?1 (P < 0.01) and nitrate (a NO metabolite) from 0.78 ± 0.06 µmol L^?1 to 1.44 ± 0.27 µmol L^?1 (P < 0.05) in the blood sera of rats compared with the controls. There were no significant differences between the routine biochemical and haematological parameters. CONCLUSION: Garlic consumption should have antioxidant properties and may not affect the lipids profile and total blood cell counts. Copyright © 2009 Society of Chemical Industry     

Review of the relationship between milk urea nitrogen and days in milk, parity, and monthly temperature mean in Iranian Holstein cows

The objectives of this study were to determine the relationships between milk urea N and days in milk, parity, and season in Iranian Holstein cows. Twelve Iranian commercial dairy herds participated in a 13-mo study from December 1, 2008, to December 31, 2009. All cows were milked 3 times daily, housed in freestalls, and fed a total mixed ration twice a day. Mean milk urea N over the study period was 16.0mg/dL. Mean milk urea N, categorized by 30-d increments of days in milk, paralleled changes in milk values and followed a curvilinear shape. However, milk urea N concentration reached a maximum at the fifth month of days in milk, but milk production reached a maximum at the third month. The concentration of milk urea N was lower during the first 30 d in milk category compared with all other days in milk categories. Overall mean milk urea N concentration of Holstein cows in the third and greater lactations was lower than in the first or second lactation. Milk urea N was at its lowest level in December (13mg/dL), increased in the spring and summer months, and reached a maximum in July (18.8mg/dL). From that point, milk urea N concentration progressively diminished to the autumn-winter level. In this study, milk urea N concentration was positively correlated with monthly temperature mean and may be a reason for the lower reproductive performance during the summer months. It has been recommended that milk urea N concentration should be evaluated in association with parity, days in milk, and season (or month). These variables should be considered potential sources of misinterpretation when exploring the relationship between milk urea N and nutritional management or measures of performance.     

Solid-phase extraction of ultratrace uranium(VI) in natural waters using octadecyl silica membrane disks modified by tri-n-octylphosphine oxide and its spectrophotometric determination with dibenzoylmethane

A simple and reliable method for rapid extraction and determination of uranium in natural waters using octadecyl-bonded silica membrane disks modified with tri-n-octylphosphine oxide (TOPO) and spectrophotometry with dibenzoylmethane is presented. Extraction efficiency and the influence of sample matrix, type, and optimum amount of extractant, flow rates, and type and minimum amount of organic eluent were evaluated. The maximal capacity of the membrane disks modified by 50 mg of TOPO was found to be 4033 micrograms of uranium. The limit of detection of the proposed method is 100 ng/1000 mL. The method was applied to the extraction and determination of uranium in natural waters.