No abstract

Corrosion inhibition effect of Sesbania sesban extract (SSE) on the carbon steel in 1M HCl solution was investigated by potentiodynamic polarization and weight loss techniques. The corrosion rate of carbon steel was decreased in the presence of SSE. The corrosion inhibition efficiency was found to increase with SSE concentration to attain 91.08% with 2.00 g/l at 25 . The polarization studies showed that SSE acts as mixed type inhibitor. The effect of temperature, acid concentration and immersion time on the corrosion rate of carbon steel in HCl solution in the absences and presence of SSE was also studied. Values of corrosion inhibition efficiency calculated from weight loss technique were in good agreement with those obtained from potentiodynamic polarization test. The results showed that the adsorption of the extract on the carbon steel surface obeys Langmuir isotherm. The activation parameters, apparent activation energy (E a , the enthalpy of activation (ΔH a ) and entropy of activation (ΔS a ) for the corrosion of carbon steel in 1M HCl in the absence and presence of SSE were calculated and discussed.

Phenol is one of the common contaminants observed in many wastewater industries. It is toxic, hazardous, carcinogenic and listed as a priority pollutant by the Environmental Protection Agency (EPA). This research aimed to establish the efficacy of activated carbon derived from walnut shell in extracting phenol from aqueous solutions using a fixed-green bed column adsorption system. The effect of parameters affecting the adsorption process including the initial concentration of phenol, bed ratio, and flow rate, was studied. The results showed that the highest percentage of phenol removal by the activated carbon is 86.2% at pH 7, initial concentration of phenol 0.001M, bed ratio 1:3 sand/activated carbon, and flow rate 10 ml/min. The breakthrough behavior of the fixed-bed adsorption process was studied. It was observed that the adsorption process equilibrium is practically reached after 105 minutes. The adsorption column dynamic behavior was investigated using three numerical models. The results confirmed that Thomas and Yoon-Nelson models are found more fitted to the adsorption experimental results. Moreover, modeling and interpretation of the column adsorption isotherms predicted that the Freundlich isotherm model is better than Langmuir isotherm model to describe the column adsorption data indicating that the phenol adsorbed molecules are not restricted to monolayer formation and the mechanism of adsorption is chemo-sorption. Briefly, the results of this study pointed out that the activated carbon derived from the walnut shell is not only a low-cost green adsorbent but also has high performance in the removal of phenol from aqueous solutions.

A wide range of batch experiments were carried out for estimation of the key process parameters in competitive biosorption of Pb 2+ , Hg 2+ , Cr 3+ and As 5+ from simulated of wastewater onto dry activated sludge in batch adsorber. Eleven isotherm models were used for single component and five models for multi-component systems. The Langmuir model gave the best fit for the data of single component, while the binary, ternary and quaternary systems were fitted successfully with extended Langmuir model. The biosorption capacity for single metal decreased by 11-51 %, 53-88 % and 79-94 % in the binary, ternary and quaternary systems respectively at the optimum agitation speed 600-800 rpm. An order of metal biosorption capacity onto dried activated sludge was the same in the case of . FT-IR analysis was carried out before and after biosorption to determine which functional groups were responsible for binding the heavy metals. Kinetic study showed that pseudo-second order model was well fitted for all metals ions. R 2 used to enhance the justification analysis for each used model.

No abstract