Boiling Thermal Performance of TiO2 Aqueous NanoFluids as a Coolant on a Disc Copper Block

This work focuses on potential application of nano-fluids in cooling of high heat flux surfaces. For this purpose, experimental studies have been performed to quantify the heat transfer coefficient of Titana (TiO2) aqueous nano-fluids under different operating conditions. Boiling mechanism is established on a disc copper made heater at different heat flux, mass concentration of nano-fluids and sub-cooling temperatures. Results demonstrated that heat transfer coefficient of Titana nano-fluids are relatively higher than that of the base fluid. Heat and mass concentration of nano-particles can intensify the pool boiling heat transfer coefficient, while sub-cooling temperature can only have impacts on bubble formation. Also, visual study demonstrates that fouling formation of nano-particles can intensify the bubble transport due to the intensification of nucleation sites in the boiling surface.

Dried activated sludge as an appropriate biosorbent for removal of copper (II) ions

Removal of Cu (II) from aqueous solution by dried activated sludge (DAS) was investigated. Batch process for the biosorption of Cu (II) ions was performed to determine equilibrium and adsorption characteristics of DAS. Obtained results by scanning electron microscope showed DAS pretreated with 1% H2O2 was porous and also it had effective removal for Cu (II) ions from aqueous solutions. Effects of contact time, temperature, pH and DAS dosage on the biosorption of Cu (II) were studied. The maximum biosorption of Cu (II) at temperature of 20 °C and pH of 5 was obtained (85%) with the DAS dosage of 3.5 g/L, Cu (II) ion concentration of 100 mg/L and 4 h contact time. Also removal efficiency of Cu (II) decreased with increasing temperature. Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models were employed to study biosorption isotherms for removal of Cu (II). Weber–Morris, pseudo first order and pseudo second order models were applied to describe the biosorption kinetics