No abstract

In this work, anodic oxidation of C.I. direct blue 21 was carried out in an electrochemical reactor at a constant temperature of 20°C.The technique was found successful in removing the color of the dye from aqueous solutions containing 0.5 M sodium sulfate. Variables studied were : initial dye concentration, solution flow rate to the reactor, anode area, current density and time duration of anodic oxidation. It was found that the rate of dye removal increased with increasing current density, duration of anodic oxidation and solution flow rate. The mass transfer coefficient was found to increase with increasing reactor current density, decreasing the area of the anode and decreasing the initial dye concentration.

The removal of phenol from a simulated wastewater effluent by adsorption on a homogeneous mixture of Maghara Coal and Activated Carbon in different proportions has been carried out in a fixed bed reactor. It was noted that the adsorption capacity of activated carbon is 12.05 fold that of Maghara Coal. Variables studied were initial phenol concentration, bed height, and type of adsorbent, namely GMC, GAC, (50%GMC+50%GAC), and (25%GMC+75%GAC). The volumetric flow rate of phenol solution and the temperature were kept at 27.5 ml/min and 27°C respectively. Also the adsorption isotherm for both PMC and PAC were studied. The equilibrium data fit well in the Freundlich model of adsorption.

Dual-phase (DP) steels consist of a ferritic matrix dispersed with some percentage of martensite, which gives the material a good combination of strength and ductility, along with the capacity to absorb energy and enhanced corrosion protection properties. The purpose of this work was to study the microstructural and corrosion behavior (mainly pitting and galvanic corrosion) of DP steel compared with that of conventional rebar. To obtain DP steel, low-carbon steels were heat-treated at 950 °C for 1 h and then intercritically annealed at 771 °C for 75 min, followed by quenching in ice-brine water. The corrosion rates of DP steel and standard rebar were then measured in different pore solutions. Macro- and microhardness tests were performed for both steels. It was found that DP steels exhibited a superior corrosion resistance and strength compared to standard rebar. The reported results show that DP steels are a good candidate for concrete reinforcement, especially in aggressive and corrosive environments.

This study is focuses on the investigation of the effect of using TiO2 short nanofibers as a reinforcement of an Al matrix on the corrosion characteristics of the produced nanocomposites. The TiO2 ceramic nanofibers used were synthesized via electrospinning by sol-gel process, then calcinated at a high temperature to evaporate the residual polymers. The fabricated nanocomposites contain 0, 1, 3 and 5 wt.% of synthesized ceramic nanofibers (TiO2). Powder mixtures were mixed for 1 h via high-energy ball milling in a vacuum atmosphere before being inductively sintered through a high-frequency induction furnace at 560 °C for 6 min. The microstructure of the fabricated samples was studied by optical microscope and field emission scanning electron microscope (FESEM) before and after corrosion studies. Corrosion behavior of the sintered samples was evaluated by both electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques (PPT) in 3.5% NaCl solution for one hour and 24-h immersion times. The results show that even though the percentage of ceramic nanofibers added negatively control corrosion resistance, it is still possible to increase resistance against corrosion for the fabricated nanocomposite by more than 75% in the longer exposure time periods.