جستجوی مقالات مرتبط با کلیدواژه « حذف » در نشریات گروه « مهندسی آب »

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).

Excess fluoride is one of the water pollutants in the world, which is removed from the water by chemical methods to produce sludge, and other methods such as R.O. also have problems in electricity consumption and wastewater disposal. Metal-organic complexes are one of the newest adsorbents used in the separation of anions. In this study, MOF 1 was used to remove fluoride from aqueous solution. Existing factors such as pH, contact time, adsorbent amount and temperature were examined. Based on the results, the MOF synthesized in acidic media absorbs more fluoride ions. Contact time of up to 20 minutes has a significant effect on the removal of fluoride ions and then its effect is greatly reduced. The amount of adsorbent used is up to saturation and the water environment has no significant effect on the absorption of fluoride ions. Also, the results of kinetic studies confirm the pseudo-second-order kinetic model for fluoride adsorption reactions in the presence of MOF1. Also in this research, zinc metal is used as a zebrafish as a central metal with the aim of reducing the environmental MOF.

Nowadays, provision of sanitary water is one of the main concerns of the world society, and heavy metals are one of the most important pollutants in water resources. Heavy metals, including copper, can enter the food chain and the body of living organisms and can affect humans through toxic and carcinogenic effects. Therefore, in this study, nanoporous SBA-15 functionalized with di and tetra carboxylic acid was synthesized and used for remove copper ions from aqueous solutions. The adsorbents were characterized by scanning electron microscopy, N2 adsorption-desorption measurements and infrared spectroscopy for investigation of porosity and functional groups of mesoporous silica. Flame atomic absorption spectroscopy was used for determination of ions. Effective parameters on removal process including amount of adsorbent, contact time, pH of solution and presence of other metal ions in the medium, were evaluated and optimized. The best removal efficiency with di and tetra carboxylic acid functionalized SBA-15 was obtained at pH>5 with 10 mg of adsorbent in the stirring time of 15 minutes. The recovery of copper from adsorbents was done with 20 ml solution of nitric acid (3 mol/L). Langmuir and Freundlich adsorption isotherms were evaluated for both adsorbents. According to the Langmuier model, the maximum adsorption capacity of 232.56 and 93.46 mg of copper per gram of adsorbent and correlation coefficients (R2) of 0.857 and 0.9688 for di and tetra carboxylic acid functionalized SBA-15 were obtained, respectively. But, the correlation coefficients (R2) obtained from the fitting of the data using the Friendlich isotherm were 0.991 and 0.972 for di and tetra carboxylic acid functionalized SBA-15 silicas, respectively, which indicates that this model is suitable to explaining the behavior of copper adsorption on both adsorbents. Finally, the removal of copper from real wastewater samples was performed. The results indicate that nanoporous SBA-15 silicas functionalized with di and tetra carboxylic acid are desirable adsorbents for copper ions removal.

Arsenic which is present in the underground and surface water is one of the most toxic elements threating human health and animals. Arsenic has been removed in different type of ways. In this study Arsenic removal from drinking water and its decreasing rates were investigated by NZVI (nanoparticle zerovalent iron) to standard limit (I.e. 0.01 mg/lit). The tests were conducted on reactor containing 100 ml water containing 1mg/L. Arsenic by virtue of Batch method. The mixture was executed in mixing was done an Oultrasnic device in order to have better mixture and complete distribution of nanoparticles in water. Then the arsenic was removed from the water by VATMAN paper of 0.45 Hm. The remained arsenic in the water was measured by ICP device. In this article the influence of the parameters including mixture time, PH, NZVI and arcenic doses were examined. Having perfomed many tests the results showed that 1 mg arsenic can be removed 100 percent by 0.05 g NZVI in 8 min. It is possible to remove by 98 percent arsenic in 5-10 PH range. Iron nanopaticle way is an effective and rapid way to remove arsenic from water and various conditions have not considerable effect on it.