Volume 21 - 2019

The aim of this study was to evaluate the mercury removal from aqueous solutions by using L-Cysteine functionalized Multi-walled Carbon Nanotubes. The effect of pH, adsorbent dose, contact time and mercury concentration in removal efficiency was evaluated. Multi -walled carbon nanotubes were functionalized with L-cysteine. The Response Surface Methodology (RSM) was used to find the optimum process parameters. The results showed that an increase in contact time, pH and adsorbent dosage resulted in an increase of the adsorption rate. However, removal efficiency decreases by increasing mercury concentration. The highest and lowest removal efficiencies of mercury were 89% and 17%, respectively. The maximum adsorption rate was occurring at 120 min. It is concluded that L-Cysteine functionalized multi-walled carbon nanotubes is an effective adsorbent for removal from aqueous solutions.

In this study, the application of Sn/Sb/Ni-Ti electrodes for the treatment of waste streams were investigated which is promising for ozone production by electrolysis of water because of their stability and high potential for ozone evolution reaction. These series of anodes have a high electrochemical ozone generation potential at ambient conditions (approximately up to 40% current efficiency). But using and testing of these novel anodes for real wastewater are too limited in the literature. Titanium mesh substrate coated with Sn/Sb/Ni-Ti alloy was used as anode immersed in wastewater at room temperature with platinized titanium cathode. These electrodes used for COD and color removal from OID wastewater in Inegol, Bursa, Turkey. Five operational parameters were evaluated for electrochemical COD and color removal processes, such as pH, salt content, applied voltage/current, current efficiency and contact time. Experimental results showed that after 30 min the electrochemical oxidation efficiency of COD and color could reach up to 98% and 99% respectively at pH 8.2 and temperature of 25°C as the optimum conditions. Current density observed as the most effective parameter for COD and color removal efficiencies. The lowest energy consumption was between 10-25 mA cm-2 of current density with only 0.6 kWh gCOD−1, while the highest energy consumption was 100 mA cm-2 of current density with 9.12 kWh gCOD−1 . The optimum current density value has been found as 50 mA cm-2 with 4.05 kWh gCOD−1 . These results were also supported with ANOVA test.

The urge of environmental friendly techniques in textile processing is gaining much attention due to high risks of effluent load causing eco-imbalance. For the present study, the cotton fabric and Reactive Violet H3R dye solution were treated with microwave radiation for 2, 4, 6, 8 & 10 min. at different powers (low, medium & high). Dyeing was performed using un-irradiated (NRC) and irradiated cotton (RC) with un-irradiated (NRS) and irradiated dye solution (RS). Different dyeing parameters were optimized and ISO standard methods for color fastness were employed to rate the color change before and after irradiation. It is found that microwave irradiation for 8 min. at high power has given good colour strength. When 60 mL irradiated dye solution of 7.5pH containing 8g/L of salt as exhausting agent is used to dye irradiated fabric at 60^oC for 55 min. ISO standards for colorfastness employed at various shades have shown that microwave irradiation has improved the rating of fastness properties. It is concluded that microwave irradiation has a promising potential to improve the color strength and dyeing properties under mild conditions.

Plant nanotoxicology is an emerging and less-explored area of research for the plant stress biologists. The present study assesses the toxicity of bulk-CuO and nano-CuO (size <50 nm and surface area = 29 m² g^-1) on maize (Zea mays cv. hybrids triple white Hi Tech.) seedlings. Five successive levels of stress (25, 50, 100, 150 and 200 mg L^-1) suspensions of CuO and CuONP were imposed and seedling growth performance was studied along control at 8 days of experiment. Modulation of enzymatic antioxidants (SOD, CAT, APX and POD) and non-enzymatic antioxidants (total phenolics and total flavonoids) activities under both-CuO stresses were investigated in detail to get an overview of their-stress response of maize. Seed germination was completely stopped under 150 and 200 mg L^-1CuONP. Generally, CuONP stress was most violent and 100 mg L^-1CuONP showed the same or more drastic effect in 150 and 200 Cu bulk. Photosynthetic pigments, shoot and root lengths reduced under both stresses by about 50% of control. Soluble proteins and total antioxidants increased gradually till it reached about 200% of control at 150 mg L^-1CuO and about 200-300% at 100 mg L^-1CuONP. In addition, increased reducing power activity coupled with both stresses which reached to 400% of control at 150 mg L^-1CuO and 100 mg L^-1CuONP. Moreover, superoxide dismutase increased by 800% of control at 100 mg. L^-1CuONP.