Efficiency of ozonation process with calcium peroxide in removing heavy metals (Pb, Cu, Zn, Ni, Cd) from aqueous solutions

Heavy metal ions have deadly effects on all forms of life, and through the disposal of industrial wastewater, they enter water resources and, eventually, the food chain. Advanced oxidation processes can remove hazardous and non-degradable organic pollutants in aqueous solutions. Variables examined were initial concentrations of calcium peroxide and heavy metals, contact time, pH, and ozonation rate. Maximum removal rate of heavy metals by ozonation with calcium peroxide under optimal conditions (contact time = 90 min, pH = 3, heavy metal concentration = 25 mg/L, calcium peroxide concentration = 0.025 mg/L and ozonation rate = 1 g/min) in synthetic and real samples were respectively 89.8 and 64.6 for Pb, 92.1 and 73.9 for Cu, 90.4 and 69.7 for Ni, 86.9 and 59.1 for Cd, and 93.4 and 78.8 for Zn. Maximum COD removal rates in synthetic and real samples were 88.1 and 69.9, respectively. Removal rates of heavy metals and COD under optimal conditions on wastewater from the Isfahan electroplating industry and steel company were determined. The use of the ozonation process with calcium peroxide can be recommended as a good, coefficient method for the removal of heavy metals in wastewater treatment. © 2020, Springer Nature Switzerland AG

Ciprofloxacin removal from aqueous solutions by ozonation with calcium peroxide

Ciprofloxacin (CIP) belongs to the fluoroquinolones group and is widely applied in therapeutics. The presence of fluorine in CIP increases its stability in the environment. Advanced oxidation processes are among the most effective methods used to remove hazardous and resistant pollutants in the environment. This study aimed to determine the efficiency of the ozonation process with calcium peroxide for the removal of CIP from aqueous solutions. The removal efficiency of CIP and chemical oxygen demand under optimal conditions, that is, pH = 3, CIP concentration = 5 mg/L, concentration of CaO2 = 0.025 mg/L, temperature = 25°C, ozonation rate = 1 g/min and contact time = 50 min, was obtained 95.6 and 80.1 as well as 85.4 and 73.6, in synthetic and simulated wastewater samples (municipal wastewater + CIP), respectively. Thermodynamic studies have shown that CIP decomposition with ozonation and CaO2 is an endothermic process. The kinetics of CIP decomposition followed the pseudo-first-order equation. The use of the ozonation process with calcium peroxide is an efficient method for CIP removal. © 2020 Desalination Publications

Evaluation of antimicrobial activities of powdered cuttlebone against klebsiella oxytoca, staphylococcus aureus, and aspergillus flavus

Background: The presence of medicines in the environment is considered as a serious threat to the human health. The entrance of these substances into the water sources causes soil pollution, which eventually leads to the environmental pollution and it creates some problems for the public health. Also, increasing antibiotic resistant bacteria has attracted the attention of researchers to the use of natural resources such as marine products, for producing new antibiotics. The aim of this study was to evaluate antimicrobial activities of powdered cuttlebone against Klebsiella oxytoca, Staphylococcus aureus, and Aspergillus flavus. Methods: At first, cuttlebones were washed, dried, and powdered. Then, the powdered cuttlebone was characterized. In the next step, its antimicrobial activities were evaluated using agar well diffusion technique, and minimum inhibitory concentration (MIC) was calculated. Results: The powdered cuttlebone was found to be effective against K. oxytoca (24 mm, MIC: 10-1 mg/mL), but no antimicrobial response was found against S. aureus. Also, the powdered cuttlebone antifungal activity and MIC against A. flavus were recorded 23 mm and 10-1 mg/mL, respectively. Conclusion: The obtained results suggest antimicrobial activities of powdered cuttlebone, which are concentration dependent. Furthermore, cuttlebone can be used as an accessible natural source to provide novel, low cost, and safe antimicrobial agents. © 2021 The Author(s). Published by Kerman University of Medical Sciences

Synthesis, characteristics, and photocatalytic activity of zinc oxide nanoparticles stabilized on the stone surface for degradation of metronidazole from aqueous solution

Background: The presence of antibiotics such as metronidazole in wastewater even at low concentrations requires searching for a suitable process such as advanced oxidation process (AOP) to reduce the level of pollutants to a standard level in water. Methods: In this study, zinc oxide (ZnO) nanoparticles were synthesized by thermal method using zinc sulfate (ZnSO4 ) as a precursor, then, stabilized on stone and was used as a catalyst, in order to degrade metronidazole by photocalytic process. Effective factors on the removal efficiency of metronidazole including the initial metronidazole concentration, contact time, pH, and 0.9 gL-1 ZnO stabilized on the stone surface were investigated. Results: The X-ray diffraction (XRD) studies showed that the synthesized nanomaterials have hexagonal Wurtzite structure. Also, scanning electron microscopy (SEM) analysis revealed that the average crystalline size of the synthesized ZnO particles was in the range of 1.9-3.2 nm. The spectra represented a sharp absorption edge at 390 nm for ZnO nanoparticles corresponding to band gap of 3.168 eV. The BET-BJH specific surface area of the synthesized ZnO nanoparticles was 25.504 m2/g. The EDS spectrum of ZnO nanoparticles showed four peaks, which were identified as Zn and O. The maximum removal efficiency was 98.36 for the synthetic solution under a specific condition (pH = 11, reaction time = 90 minutes, ZnO concentration = 0.9 gL-1, and the initial concentration of metronidazole = 10 mgL-1). The photocatalytic degradation was found to follow pseudo-first-order degradation kinetics. Conclusion: Therefore, the ZnO nanoparticles synthesized by thermal decomposition are suitable and effective photocatalytic materials for degradation of pharmaceutical contaminants. © 2021 The Author(s). Published by Kerman University of Medical Sciences