ABSTRACT
Background: The presence of heavy metals in aquatic and terrestrial ecosystems causes harmful effects to living organisms in the environment. This research aimed to determine the potential of activated pumice stone [APS] as a sorbent for the removal of Cd, Cu, and Zn from wastewater
Methods: This research was conducted during 2013 on a laboratory scale. The study was performed using batch experiments with synthetic wastewater having Cd, Cu, and Zn concentrations of 10, 20, 40, and 80 mg/L. Various isotherm models, including Langmuir and Freundlich, were used to evaluate the sorption data. The influence of contact time and amount of sorbent on the removal of Cd, Cu, and Zn from wastewater was studied. All experiments were done at pH = 7 and at room temperature [20 +/- 1°C]. The solution pH was adjusted using 1N NaOH or 1N HCl solutions, and the pH value was determined by a pH meter
Results: The results showed that the adsorption of Cd, Cu, and Zn approaches equilibrium after about 2 hours, while the rates of removal efficiency for Cd, Cu, and Zn at equilibrium were 91.6%, 91.8%, and 82.9%, respectively. Kinetic studies showed that the sorption of Cd, Cu, and Zn onto APS were fitted to the pseudo-second order kinetic models
Conclusion: The results indicate that the APS is a good choice, because it is a low-cost and effective sorbent. The sorption capacity of APS as a sorbent was considerably affected by the initial concentration of metal ions in the solution and by contact time
ABSTRACT
The aim of this study was to assess the effects of road deicing salt on the quality of the ground water resources in Hamadan Province during winter season. Water samples were taken monthly from thirty wells located around the Hamadan-Asadabad highway. The quality of well water was examined by measuring amount of sodium, chloride, total hardness, total dissolved solid, electrical conductivity, total fecal coliform, and total coliform in well water sample. The correlation between mineral deposits in the water samples and the distance of wells from the highway was investigated using Pearson Correlation Coefficient. It was estimated that nearly 11,000 tons salt were applied annually in this province for deicing roads and streets. There was a statistically significant negative correlation between the quality variables of well water taken from a distance less than 400 meters from highway axis in the southern side except for fecal coliform and total coliform. No statistically significant correlation was seen between the distance from the highway axis and the quality variables of well water taken from the northern side. There was a significant difference between water quality variables of the wells located in a distance less than 200 meters in the northern side of the highway, with that of the wells located in southern side in the highway [p<0.05]. A positive correlation between road dicing salt and mineral deposits in the ground water resources was indicated. Therefore, regarding the limited water resources in Hamadan Province, constraining application of road deicing salt is recommended