Background: The purpose of the present study was to assess the efficiency of ultrasound/hydrogen peroxide processes and ultrasound/hydrogen peroxide/ZnO nanoparticles in the removal of blue cat 41 dye from aqueous solutions. Methods: ZnO nanoparticles were prepared using the hydrothermal method. Variables including pH, concentration of ZnO nanoparticles, initial dye concentration, concentration of hydrogen peroxide, and contact time were investigated. Results: H 2 O 2 alone is not effective in dye removal. In conditions of H 2 O 2 = 20 mg/L and US = 30 kHz, removal efficiency rates of 6.5%, 23.5%, 30%, 51.8%, and 55%, respectively, were obtained. The maximum removal efficiency rate was obtained at the nanoparticle concentration of 3 g/l. Also, removal efficiency was reduced when the initial dye concentration was increased. Conclusion: The combination of nanoparticles and US and H 2 O 2 is very effective in removing blue cat 41 dye. As a result, photo catalytic processes can be considered to effectively remove environmental pollutants.

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The present paper aims to investigate water purification of phenol by walnut green hull adsorbent.The surface characteristics of the adsorbent were studied using Fourier transform infra-red (FTIR), scanning electron microscope, and X-ray diffraction (XRD) techniques. The presence of functional groups such as hydroxyl and carbonyl onto walnut green hull surface was proved by FTIR analysis. . Also, the adsorption kinetics of phenol on the adsorbent were studied. The rates of sorption were found to conform to pseudo-second-order kinetics with good correlation.

The present study evaluates the reduction of antibiotic COD from wastewater by combined coagulation and advanced oxidation processes (AOPS). The reduction of Azithromycin COD by combined coagulation and Fenton-like processes reached a maximum 96.9% at a reaction time of 30 min, dosage of ferric chloride 120 mg/L, dosages of Fe0 and H2O2of 0.36mM/L and 0.38 mM/L, respectively. Also, 97.9% of Clarithromycin COD reduction, was achieved at a reaction time of 30 min, dosage of ferric chloride 120 mg/L, dosages of Fe0 and H2O2 of 0.3 mM/L and 0.3mM/L, respectively. The results of kinetic studies were best fitted to the pseudo first order equation. The results showed a higher rate constant value for combined coagulation and Fenton-like processes [(kap = 0.022 min-1 and half-life time of 31.5 min for Azithromycin) and (kap = 0.023 min-1 and half-life time of 30.1 min for Clarithromycin)].

In this study, the degradation of humic acid was studied using advanced photochemical oxidation by exposing humic acid aqueous solution with low-pressure mercury vapor lamp as a UV light source after the addition of hydrogen peroxide. The effect of different parameters such as H 2 O 2 dosage, pH, and initial concentration of humic acid on the removal effi ciency of UV/H 2 O 2 was evaluated and investigated in detail. Increase of initial H 2 O 2 dosage (up to optimum dosage) and also increase of humic acid concentration resulted in the decrease of humic acid degradation. The residual concentrations of humic acid were measured for assessing the process performance and understanding the process reaction behavior. The results showed that humic acid was degradable in the presence of hydrogen peroxide under UV irradiation. In the absence of H 2 O 2 , the degradation effi ciency was very negligible. The results show 91% humic acid removal in 60 min of reaction time when 30 mmol L-1 of H 2 O 2 aqueous solution was added to the solution compared with only 20% of removal in similar conditions and in the absence of H 2 O 2. Investigation of the kinetics of the UV/H 2 O 2 process demonstrated that the semi-log plot of the humic acid concentration versus time was linear, which suggested a fi rst order reaction.