جستجوی مقالات مرتبط با کلیدواژه "pb (ii)" در نشریات گروه "مهندسی آب"

Considering lead’s toxicity and its characteristics as a serious environmental pollutant, to protect the human population’s health and the ecosystem it is necessary to stop this heavy metal from entering water resources and the environment through industrial wastewater. Therefore, the present study was carried out to manage lead elimination from aqueous solutions using NiO nanocomposites immobilized on graphene. To determine the effective factors in the elimination process, some parameters including contact time (20, 30, 15, 5, 10, 3 min), adsorbent dosage (0.1, 0.05, 0.2, 0.01g), initial concentration of the lead solution (5, 10, 20, 50, 100, 200, 300, 800, 1000 mg/L) and pH (2, 4, 5, 6, 7) were investigated at room temperature, 40 ˚C and 55 ˚C. Based on the results, the amount of lead eliminated by graphene-immobilized nickel oxide nanoparticles reached its maximum value under the optimum conditions of 20 min contact time, 0.05g adsorbent, 5ppm initial concentration, and 55 ˚C temperature. In addition, the experimental data were analyzed using Langmuir, Freundlich, and Dubinin-Radushkevich isotherms of the adsorption process and the results indicated maximum compliance with the Langmuir isotherm, with a maximum adsorption capacity of 2000 mg/g. These findings show that lead absorption is an endothermic reaction. The graphene/NiO magnetic nanocomposite made in this way has many pores and a high specific area (196.5 m2/g), which makes it an ideal adsorbent for removing lead(II) ions from aqueous solution. The maximum absorption capacity obtained from the said adsorbent was 2000 mg/g, which is much higher than other common adsorbents. Among the advantages of this method, we can point out the very high absorption capacity, the simplicity of separating the adsorbent from the solution, and the fast duration of the absorption equilibrium (up to 20 min).

The problem of toxic-metal-contaminated water has become a great environmental concern and presents significant hazards to the public health and economy. In this study, drinking water treatment sludge was activated and used as an efficient, cheap and cost effective sorbent in the removal of Pb (II) ion from water samples. The prepared material was characterized by Fourier transfer infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), surface analysis (BET method) and X-ray fluorescence (XRF) analysis. The effects of various parameters such as the solution pH, adsorption time, adsorbent dosage, and initial metal ion concentration upon adsorption were investigated. Equilibrium isotherm studies were carried out with different initial concentrations of Pb (II), and three models (Langmuir, Freundlich and Temkin isotherms) were utilized to analyze the equilibrium adsorption data. The best adsorption performance was obtained at the following conditions: pH of sample, 7.5; contact time, 15 min; adsorbent dosage, 0.3 g; intitial concentration of Pb (II), 20 mg/L; agitation speed, 200 rpm. The results revealed that the adsorption process obeyed the Langmuir model, with the maximum monolayer capacity (qmax) and the Langmuir constant (KL) calculated as 54.9 mg/g and 0.973 mg/L, respectively. Kinetic studies indicated that the adsorption process followed a pseudo-second-order model based on the obtained R2 values. Comparison study with the other natural adsorbents revealed that the activated sludge has the highest adsorption capacity and provides the lowest adsorption time. Desorption study exhibited that the Pb (II) ions can be desorbed from the adsorbent by 0.25 mol/L HCl solution with a recovery percentage of 98%. The results exhibited that activated sludge is an efficient and cost-effective material for the adsorption of Pb (II).