Nanoscale zero-valent iron (nZVI) products are highly applicable in groundwater, industrial water, and wastewater treatment due to the high reduction properties, the small size of particles in the range of nanometers, large surface area, and high reactivity on most toxic contaminants. The ultimate aim of this study is to evaluate the removal performance of 2,4-dichlorophenoxyacetic acid (2,4-D) by nanoscaled ZVI particles. Synthesized nanoscale iron particles were characterized by X-ray diffraction and scanning electron microscopy (SEM). According to SEM images of nZVI, the particle size was under 100 nm in diameter. The specific surface area was measured by the N 2 /BET method and determined as 44.7 ± 0.4 m 2 /g. The influences of nZVI dosage, initial pH and effects of different processes were examined by batch experiments. Results were compared with Fenton and photo-Fenton processes and they showed that under optimized conditions, degradation by nZVI is more effective than Fenton and photo-Fenton reactions and a promising candidate for 2,4-D remediation.

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In this study, the decolorization, dearomatization, and mineralization efficiencies of different advanced oxidation processes (AOPs; namely O 3 , O 3 /Fe(II), O 3 /Fe(II)/UVA, and O 3 /TiO 2 /UVA) were investigated for the azo dye C.I. Reactive Red 194 (RR194). The effects of pH (3-11), amount of TiO 2 (0.05-1 g/L), and concentration of Fe(II) (0.1-1.6 mM) were investigated for the applied methods. The decolorization and mineralization efficiencies of the photocatalytic ozonation system (O 3 /TiO 2 /UVA) were increased by decreasing the pH of the dye solution in contrast to the ozonation system (O 3 ). Decolorization of RR194 was increased in the photocatalytic ozonation system with an increasing amount of catalyst however, a decreasing was occurred for the homogeneous catalytic system (O 3 /Fe(II)) when increasing the concentration of catalyst. The decolorization efficiency of the homogeneous catalytic system (O 3 /Fe(II)) was enhanced when combined with UVA light. In our study, the most efficient method for dearomatization and mineralization was the O 3 /TiO 2 /UVA among the applied AOPs.

The objective of this study is to compare the performances of catalytic ozonation processes of two activated carbons prepared from olive stone (ACOS) and apricot stone (ACAS) with commercial ones (granular activated carbon-GAC and powder activated carbon-PAC) in degradation of reactive azo dye (Reactive Red 195). The optimum conditions (solution pH and amount of catalyst) were investigated by using absorbencies at 532, 220 and 280 nm wavelengths. Pore properties of the activated carbon (AC) such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N(2) adsorption. The highest BET surface area carbon (1,275 m(2)/g) was obtained from ACOS with a particle size of 2.29 nm. After 2 min of catalytic ozonation, decolorization performances of ACOS and ACAS (90.4 and 91.3%, respectively) were better than that of GAC and PAC (84.6 and 81.2%, respectively). Experimental results showed that production of porous ACs with high surface area from olive and apricot stones is feasible in Turkey.