Environment
H. Tamadon Ghareghie; M. Yazdi; D. Yousefi Kebria; H. Aminirad
Abstract
Soil contamination is considered a controversial issue in most countries. Nowadays, it is important to clearly understand how pollutants influence the soil from different sources. Today, hydrocarbons are one of the most important sources of soil contaminants, which is considered as a fundamental issue ...
Read More
Soil contamination is considered a controversial issue in most countries. Nowadays, it is important to clearly understand how pollutants influence the soil from different sources. Today, hydrocarbons are one of the most important sources of soil contaminants, which is considered as a fundamental issue at the global level. The current study aims to analyze and model the effect of simultaneous parameters (time and concentration) of phenols and naphthalene with different percentages (10, 15, 20 and 25%) together with the amount of bentonite in fine-grained sandy soil. The designed experiments made use of response surface methodology (RSM) and Design-Expert software to carry out a computer-based simulation. According to the proposed model, the amount of bentonite is most affected by the permeability of the soil. The obtained results also showed that the permeability significantly decreases in the light of increasing the percentage of phenol and naphthalene coupled with the amount of bentonite and the age of contamination. On average, an 80% reduction of permeability was observed in contaminated soil, which was found in the soil contaminated with naphthalene. According to the results of the synergistic effects of time, the considerable impacts of both the percentage of hydrocarbon pollutants and the amount of bentonite on the reduction of permeability are quite evident.
A. D. Mahmud; A. Hamza; A. Zubair; B. Mukhtar
Abstract
ZnO-ZnFe2O4 composite was applied for photocatalytic degradation of naphthalene in fresh and saline waters under visible light irradiation. The effects of initial concentration of naphthalene, ZnO-ZnFe2O4 dosage and salinity on photocatalytic degradation of naphthalene were investigated using the central ...
Read More
ZnO-ZnFe2O4 composite was applied for photocatalytic degradation of naphthalene in fresh and saline waters under visible light irradiation. The effects of initial concentration of naphthalene, ZnO-ZnFe2O4 dosage and salinity on photocatalytic degradation of naphthalene were investigated using the central composite design. Statistically significant model quadratic equation was developed for photocatalytic degradation of naphthalene using ZnO-ZnFe2O4 composite. The most significant parameter in the photocatalytic degradation is the ZnO-ZnFe2O4 dosage followed by the initial concentration of naphthalene and then salinity. The highest photocatalytic degradation of naphthalene was achieved at salinity of zero (that is in fresh water). The predicted optimum conditions for photocatalytic degradation of naphthalene using the ZnO-ZnFe2O4 composite are: initial naphthalene concentration of 16.8 mg/l, ZnO-ZnFe2O4 dosage of 0.50 g/l, and salinity of 0 ppt. The model quadratic equation was validated by performing experiments under the predicted optimum values. The experimental and the predicted values of naphthalene degradation under the predicted optimum values are 99.04 % and 98.8 %. Hence, the developed quadratic model is reliable for predicting photocatalytic degradation of naphthalene using ZnO-ZnFe2O4 composite.
