Removal of methylene blue dye from textile simulated sample using tubular reactor and TiO[2]/UV-C photocatalytic process

In this study, photocatalytic degradation of methylene blue was examined using different concentrations of TiO[2] nano-particles [diameters less than 21 nm] and ultraviolet [UV-C] radiation in a tubular reactor. Different concentrations of catalyst [0.3-1.2 g/L], different pH conditions [3, 7 and 9] and dye concentration [15, 30 and 60 mg/L] as well as sample rotation level [125 mL/min] were studied. The sample passed 1-7 times through the quartz reactor exposed to UV-C ray [constant intensity = 2.8 mW/cm[2]] [every rotation time was 8 min]. Results of this research showed clearly that methylene blue is significantly degradable by TiO[2] and UV-C radiation. Increasing dye concentration resulted in decreased efficiency and thus, as more samples passed through quarts tube, removal efficiency increased. Methylene blue with concentration of 15 mg/L and after 7 rotations in the reactor [56 min] was removed with the efficiency of 98%. Subsequent to dye removal, 47% of initial COD decreased simultaneously

[Survey of nano filtration performance for hexavalent chromium removal from water containing sulfate]

Geological situation and/or anthropogenic contamination contain an increased concentration of ions such as hexavalent chromium as well as some other dissolved components such as sulfate in the upper of the established MCLs [50microg/L]. In this paper, simultaneous removal of Cr [VI] and sulfate from water was investigated using nanofiltration as a promising method for reaching drinking water standards. For varying pressure, pH, anion and cation solution effect, Sulfate and Cr [VI] concentration which have chosen were levels found in drinking water sources [Cr=0.1- 0.5mg/L] and [SO[4][-2]= 100-800mg/L].Experiments were performed using NaCl, Na[2]SO[4],K[2] Cr[2]O[7]and anhydrous CrCl[3]. 6H[2]O which prepared with de mineralized water on procedure detailed in standard methods. All salts were purchased from Merck Corporation with purity over 99%. The results for hexavalent chromium experiments showed that when the concentration decreases, the chromate anions were given a better retention to 4 bars [96%]. But when the concentration increases, concentration polarization led to increased removal of Cr [VI] [98%]. For Cr [III] the influences of the ionic strength as well as the concentrations were strongly dependant on rejection but operating pressure were found weak. In addition, with increasing total dissolved solids, perfect rejection of chromium was seen. The effect of pH showed that better retention was obtained at natural and basic pH. This study indicates that the nature of anions and cations, driven pressure and pH have significant effect on nano filtration operation. Research findings show that it seems nano filtration is a very good promising method of simultaneous removal of Cr [VI] and sulfate from water

[Investigating the effect of gas flow rate, inlet ozone concentration and relative humidity on the efficacy of catalytic ozonation process in the removal of xylene from waste airstream]

The catalytic ozonation is an efficient process for the degradation of volatile organic compounds from contaminated air stream. This study was aimed at investigating the efficacy of catalytic ozonation process in removal of xylene from the polluted air stream and the influence of retention time [gas flow rate], inlet ozone dose and relative humidity on this performance. the catalytic ozonation of xylene was conducted using a bench scale set-up consisted of a syringe pump, an air pump, an ozone generator, and a glass reactor packed with activated carbon. Several experimental run was defined to investigate the influence of the selected operational variables. The results indicated that the efficiency of catalytic ozonation was greater than that of single adsorption in removal of xylene under similar inlet concentration and relative humidity. We found a significant catalytic effect for activated carbon when used in combination with ozonation process, leading to improvement of xylene removal percentage. In addition, the elimination capacity of the system improved with the increase of inlet ozone dose as well as gas flow rate. The relative humidity showed a positive effect of the xylene removal at the range of 5 to 50%, while the higher humidity [more than 50%] resulted in reduction of the performance. The findings of the present work revealed that the catalytic ozonation process can be an efficient technique for treating the air streams containing industrial concentrations of xylene. Furthermore, there is a practical potential to retrofit the present adsorption systems into the catalytic ozonation simply by coupling them with the ozonation system