سمیه باجلان

Antibiotics considered a major problem into the environment due to their accumulation feature and drug resistance. The aim of this study was optimization of ciprofloxacin antibiotic sonochemical degradation in US/PS/nZVI process by Central Composite Design method.
In this experimental study the effects of independent variables such as pH of solution, PS and nZVI concentrations on antibiotic degradation were investigated. After optimization, the synergistic degradation and the effect of detention time was determined. Antibiotic concentration was constant at 50 mg/L for all the samples. Antibiotic concentration was measured on the basis of COD reduction according to 5220 C of Standard Methods. For characterization of prepared nZVI particle, the transmission electron microscope image (TEM) was used.
The results indicated the pH as a principal variable with the optimal value of 4.5 for this process. At initial concentration of 195 mg/L COD (equal 50 mg/L antibiotic), the optimal concentration of PS and nZVI were obtained at 1200 and 120 mg/L, respectively. At this condition removal efficiency of 57% was obtained after 60 min. At optimal conditions for US/PS/nZVI process the synergistic degradation was almost 42.55%. In investigating the effects of detention time, 94% of COD was removed after 180 min.
The results of this study confirmed the acceptable efficiency of US/PS/nZVI process in degradation of ciprofloxacin antibiotic.

Main sources of 4-Chlorophenol wastewater are petroleum industry, coal, paper and resin production. The aim of this study was to compare the performance of raw and cationic surfactant modified nanoclay in removal of 4-Chlorophenol from aqueous solutions.
The influence of contact time, initial pH of solution, adsorbent dosage and 4-Chlorophenol concentration as effective parameters in adsorption process and the influence of modification solution pH and surfactant loading rates were investigated. The modified nanoclay was characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopy. Finally, the isotherm and adsorption kinetics were investigated.
The removal efficiency of 4-Chlorophenol was increased by increasing the initial pH from 3 to 11, so that after of 120 min, the absorption efficiency at an initial 4-Chlorophenol concentration of 100 mg/L and 0.25 g adsorbate was 26 and 95.5 % at pH 3 and 11, respectively. Under the same conditions the removal efficiency for the raw nanoclay was 2 and 9% at pH 3 and 11, respectively. The FTIR and XRD analyses revealed that the nanoclay structural changed from hydrophilic to hydrophobic and the interlayer spacing was increased. The adsorption of 4-Chlorophenol on raw and modified nanoclay was consistent with Langmuir and pseudo-second-order kinetics. The maximum absorption capacity of raw and modified nanoclay was 0.5 and 25.77 mg/g, respectively
The modification of nanoclay with cationic surfactant increased the adsorption efficiency of 4-Chlorophenol.