Adsorptive removal of Congo red dye from wastewater by mixed iron oxide–alumina nanocomposites

Nanocomposites composed of mixed iron and aluminium oxide (Fe₂O₃–Al₂O₃), have been synthesized by hydrothermal method, and further used as adsorbent for the adsorptive decolorization of Congo red dye from an aqueous system. The as-prepared nanomaterials were sintered at 500 °C and 1000 °C, to obtain pure Fe₂O₃–Al₂O₃ mixed composites. The XRD studies confirmed the formation of pure and crystalline FeOOH–AlOOH (as-prepared), γ-Fe₂O₃–Al₂O₃ at 500 °C and α-Fe₂O₃–Al₂O₃ phases at 1000 °C. The morphology and size of the obtained nanocomposites were characterized by SEM and TEM. Effects of pH, contact time, initial concentration of adsorbate have been studied. The optimum pH for maximum removal of Congo red in all the three phases of nanocomposites was found to be 7. The maximum removal capacity was 498 mg/g for γ-Fe₂O₃–Al₂O₃ phases. Among the three different adsorbents, γ-Fe₂O₃–Al₂O₃ shows complete removal within 15 min of contact time.     

Optimization of weld bonding process parameters of austenitic stainless steel 304L and low carbon steel sheet dissimilar joints

Weld bonding is a hybrid joining process used to produce weld joints between similar or dissimilar metallic materials. In this work, a systematic study has been undertaken to investigate the effect of the input process parameters on the weld joint quality of dissimilar materials i.e. austenitic stainless steel 304L and low carbon steel sheet, in terms of joint strength. Experiments were planned on the basis of response surface methodology technique with three control factor and their three levels of process parameters. Experimental results were used to develop a mathematical model to predict the tensile shear strength and peel strength of the weld joint. A mathematical model, correlating the process parameters and their interaction on responses, was also established. The developed model was validated with the confirmation test case experiment, and it has been observed that the developed model is capable to evaluate weld joint strength within the range of process parameters being used. Numerical optimization technique was applied to find out the optimal set of input parameters.     

NEW STRATEGIES IN SEPARATION OF CLOSE BOILING(SOLID)MIXTURES : EXTRACTION INTO MICELLAR AND MICROEMULSION MEDIA

Aqueous solutions of various surfactants, such as, sodium lauryl sulphate, lauryl alcohol-7-ethoxylate, cetyl pyridinium chloride, cetyl trimethylammonium bromide, etc., at concentrations above their critical micelle concentration values, known as micellar solutions, and microemulsion solutions consisting of these surfactants and a co-surfactant, n-butanol, have been used successfully to separate mixtures of isomeric/non-isomeric close boiling substances like o-nitrochlorobenzene/ p-nitrochlorobenzene, o-nitrotochlorbenzene, p-nitrotoluene, 2,6-xylenol/ p-cresol, -2,4-dichloro-phenol/2,4,6-trichlorophenol, o-isopropylphenol/ p-isopropylphenol, from their solid mixtures. Exceptionally high values for the separation factor have been realized and these novel methods appear to be promising for industrial utilization.     

Lubricated wear of PTFE and graphited PTFE

Tribological behaviour of PTFE and graphited PTFE have been evaluated under lubricated conditions and compared with dry wear. The stress selected is in the range of 0.44 to 1.64 MPa, and the data generated are relevant to conformal contacts. Mineral oil lubrication can reduce wear of PTFE by one to two orders of magnitude. With graphited PTFE the lubricant effect is lower in comparison to that observed with PTFE. Specific wear rates are plotted on a histogram.