Environment
Behnoosh khataei; Farhad Qaderi; Farzad Mosavat
Abstract
The increase in the number of factories, the industrialization of human life, and the increasing use of industrial paints have caused an increase in dye wastewater and consequent environmental pollution. Discharging wastewater containing the dyes mentioned above, which are often carcinogenic, is a severe ...
Read More
The increase in the number of factories, the industrialization of human life, and the increasing use of industrial paints have caused an increase in dye wastewater and consequent environmental pollution. Discharging wastewater containing the dyes mentioned above, which are often carcinogenic, is a severe threat to living organisms. In this research, a photocatalytic method (as an advanced oxidation method) using zinc oxide nanoparticles was investigated to treat the colored wastewater containing methylene blue. This type of nanoparticle is cheap (based on the used synthesis method), abundant and readily available, and low in toxicity. For this purpose, an evaluation of the optimal ratio between zinc acetate and polyvinylpyrrolidone for the synthesis of zinc oxide nanoparticles was carried out. Furthermore, the simultaneous decreasing and increasing effects of independent parameters (pH, irradiation time, methylene blue concentration, zinc acetate to PVP ratio) on the efficiency of the photocatalytic process and kinetic model were evaluated. The results showed that the best pollutant removal efficiency (91.7%) was obtained using the ratio of zinc acetate and polyvinylpyrrolidone equal to 33.67 in 60 minutes of irradiation time. This result shows that the lower ratio of zinc acetate to polyvinylpyrrolidone indicates higher dye removal.
Environment
Mehdi Soleymani Gharegol; Kazem Badv; Behzad Nemati akhgar
Abstract
This paper carried out the study on removing cyanide from aqueous solutions by modified zeolite with hexadecyltrimethylammonium bromide. After determining the properties of the prepared adsorbent by the XRD, SEM, FTIR, and BET techniques, the effect of parameters such as the initial concentration of ...
Read More
This paper carried out the study on removing cyanide from aqueous solutions by modified zeolite with hexadecyltrimethylammonium bromide. After determining the properties of the prepared adsorbent by the XRD, SEM, FTIR, and BET techniques, the effect of parameters such as the initial concentration of cyanide, pH, contact time, temperature, and the ionic strength of cyanide was examined by batch tests, and the effects of bed depth and flow rate on the performance of cyanide adsorption was investigated by column process. The XRD analysis showed the presence of clinoptilolite mineral in the structure of the raw zeolite, and the surface coating of raw zeolite by surfactant was detected by the SEM method. The FT-IR results confirmed the adsorption of cationic surfactant on the surface of the modified zeolite. The Langmuir, Freundlich and Tamkin adsorption models showed an excellent ability to describe the cyanide adsorption isotherm using the studied adsorbent. The adsorption capacity of cyanide by modified zeolite was 3.97 mg/g, significantly increased compared to the maximum adsorption capacity of raw zeolite cyanide (0.54 mg/g). The pseudo-second-order model has an excellent ability to describe the adsorption kinetics of cyanide contaminants using natural and modified zeolites. Maximum cyanide uptake capacity was achieved at pH value 8. Cyanide removal decreased with increasing pH and ionic strength of the stock solution and increased with an increase in solution temperature. Column study results confirmed that the adsorption capacity increased with the increasing bed depth, and decreased with increasing flow rate. Yoon-Nelson curves are closer to the experimental curves with high R2 values.
