TN428 : Experimental Studies and Numerical Modeling of Heavy mextals Removal from Acid Mine Drainage by Perlite and Diatomite Nanoparticles
Thesis > Central Library of Shahrood University > Mining, Petroleum & Geophysics Engineering > PhD > 2013
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Abstarct: In this research mineral materials consisting of diatomite, perlite and perlite-diatomite composite were used as nanoadsorbents to remove heavy mextals from acid mine drainage (AMD). Firstly, diatomite, diatomite/perlite composite and perlite nanoadsorbents were prepared from natural sources. XRD, XRF, BET, SEM, TEM, AFM and IR analyses were carried out to investigate adsorbents physical and chemical characteristics. The results show that diatomite nanoparticles are tiny and spherical with a smooth morphology. Perlite nanoparticles have a granular and ragged morphology and composite nanoparticles are characterized with a mediocre morphology according to SEM, TEM and AFM analyses. The XRD analysis shows that SiO2 is the major compound with more than 60 %. According to IR analysis, hydroxyl (OH) is a singular functional group of the adsorbents which is located at 3595-3615cm-1. SEM, TEM, AFM, XRD analyses and Scherrer equation revealed particles size of less than 100 nm. According to BET analysis, the specific area and porosity of the adsorbents are as follows from highest to lowest: nanoditomite, nanocomposite, nanoperlite, raw diatomite and raw perlite. The nanoadsorbents were used to remove Iron (II), Manganese (II), Copper (II), Cadmium (II), Nickel (II) and chromium (III) ions from synthetic aqueous solutions in both batch and continuous systems. The influence of pH, adsorbent dosage, mextal concentration, temperature and time on adsorption process was investigated in a batch system. The results show that diatomite, diatomite/perlite composite and perlite nanoadsorbents have a suitable efficiency for mextal removal and their efficiency is sorted as: nanoditomite > nanocomposite > nanoperlite. Furthermore, the order of adsorption of heavy mextal ions for the same adsorbent changes as: Copper (II) > Iron (II) > Manganese (II) > chromium (III) > Cadmium (II) > Nickel (II). Equilibrium adsorption isotherms and kinetics were investigated. The equilibrium adsorption results are fitted better with the Langmuir isotherm. In addition, the kinetic data follow pseudo-second-order model. Nanoadsorbents were packed inside in a column (a length of o.2 m and a diameter of 0.02 m) as a continuous system and the wastewater was passed with specific flow rates at optimal pH. Breakthrough curve and column saturation time were obtained for each mextal ion.
Amongst the drainages of the waste dumps at the Sarcheshmeh porphyry copper mine, the acidic drainage of dump No. 31 with a pH of 5.1 was chemically analyzed by ICP method. The concentrations of Iron (II), Manganese (II) and Copper (II) ions were 4.1, 8.3 and 10.5 ppm (above their standard values). Therefore, in the next stage, the adsorption of these three mextal ions was investigated in both batch and continuous systems using perlite and diatomite nanoparticles. Kinetic and equilibrium studies show that the adsorption of mextal ions follows the Langmuir isotherm and pseudo-second-order Kinetics models. Moreover, nanodiatomite was more efficient than nanoperlite. A numerical finite volume model is also presented to simulate adsorption of Iron (II), Manganese (II) and Copper (II) ions from the drainage of waste dump No. 31 in both batch and contiguous systems. A multi-purpose computational fluid dynamics software called PHOENICS was modified to solve model governing equation and provide codes in FORTRAN 99 and the software input (PIL) languages in order to include the extra terms in model that are not standard for PHONICS governing equation. The error values calculated using RMSE parameter were less than 10%; describing that the model is valid. The error associated with the continuous model was less than that of batch model. A sensitivity analysis was conducted to determine the effect of model parameters variability on the results of model. The sensitivity of the model to changes in the , , and (batch system) , , , , , L and V (continous system) on the adsorption process were examined by performing several simulations. It was found that the model is more sensitive to changes in , , and . The results obtained from this research can be used to design an appropriate pollution control and waste water treatment plan in a mining scale to decrease the harmful effects of mextallic pollutants.
Keywords:
#Adsorption #Nanoadsorbent #Diatomite #Perlite #Sarchechmeh porphyry copper mine #Acid mine drainage #Heavy mextals #Computational Fluid Dynamic. Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
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