S. Montes

University of Santiago, Chile, CiudadSantiago, Santiago Metropolitan, Chile

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Publications (9)6.47 Total impact

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    ABSTRACT: Natural sorbents have been thoroughly assessed to determine their adsorption capabilities to remove pollutants from industrial wastewaters. Among them, pine bark has demonstrated potential for carrying out the removal of contaminants, particularly heavy metals, at the level of traces present in dissolved state. Nevertheless, to move towards the wastewater treatment implementation at large scale, the handling and processing requirements of pine bark to optimise the adsorption of heavy metals must be fully assessed. This research study presents a new mathematical model to evaluate the impact of acid pretreatment of pine bark on heavy metals adsorption at different pine bark-aqueous solution pulp densities. A diffusion-reaction mixed model was developed and applied to the case study of copper(II) adsorption onto pine bark. The low binding energy inferred from analysing the adsorption isotherms suggested that a diffusive mechanism is governing the whole process. The mixed diffusion-reaction kinetic model indicated that the activation increases the rate at which metal ions are adsorbed, but it reduces the maximum achievable adsorption which in turn restricts its usefulness to relatively high pulp densities (above 10 g/L). The latter constitutes the first step towards optimising the use of bark pine for treating wastewater polluted with heavy metals and for establishing rules for scaling-up the process.
    Environmental Earth Sciences 09/2014; 72(5):1625-1631. DOI:10.1007/s12665-014-3066-3 · 1.77 Impact Factor
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    ABSTRACT: Arsenic is the most important contaminant of the environment in northern Chile. Soil samples and plant organs from three native plant species, Pluchea absinthioides, Atriplex atacamensis and Lupinus microcarpus, were collected from arid zones in order to determine the total and bioavailable arsenic concentrations in soils and to assess the bioconcentration factor (BCF) and transport index (Ti) of arsenic in the plants. Total arsenic concentrations in soils (pH 8.3-8.5) where A. atacamensis and P. absinthioides were collected, reached levels considered to be contaminated (54.3 ± 15.4 and 52.9 ± 9.9 mg kg⁻¹, respectively), and these values were approximately ten times higher than in soils (pH 7.6) where L. microcarpus was collected. Bioavailable arsenic ranged from 0.18 to 0.42% of total arsenic concentration. In the three plant species, arsenic concentration in leaves were significantly (p ≤ 0.05) higher than in roots. L. microcarpus showed the highest arsenic concentration in its leaves (9.7 ± 1.6 mg kg⁻¹) and higher values of BCF (1.8) and Ti (6.1), indicating that this species has a greater capacity to accumulate and translocate the metalloid to the leaf than do the other species.
    Bulletin of Environmental Contamination and Toxicology 06/2011; 86(6):666-9. DOI:10.1007/s00128-011-0269-0 · 1.22 Impact Factor
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    ABSTRACT: Electrochemical processes involving particle suspensions are still ill understood. Electro-flotation is process through which particles or ions can be selectively separated. Although the technique has been widely studied, not much is known about the effect of the chemistry of suspended particles on the process performance which constitutes the aim of the present research work.A column-type cell was designed to carry out electro-flotation experiments and standard air flotation experiments. Two minerals, Merensky reef and UG2, were tested.The classic air-flotation operation gave higher recoveries and grade of collected material compared to electro-flotation only when using Merensky reef ore. However, in the case of UG2 ore, the electro-flotation reached similar performance to that of the classic operation. It was found that the electrodes readily interact with the mineral pulp reducing the efficiency to generate bubbles. That efficiency depends significantly on the ore composition. Further electrochemical studies concerning how the voltage is used throughout the process was performed. The conductivity of the pulp formed using UG2 ore increased around 5 times compared to that observed when using Merensky reef ore. Under identical experimental conditions, the froth formed with Merensky reef ore was shallow and precarious compared to the thick and stable froth formed in the case of UG2 ore.
    Powder Technology 12/2010; 204(1):1-10. DOI:10.1016/j.powtec.2010.06.024 · 2.27 Impact Factor
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    ABSTRACT: Mineral floatability is strongly connected with mineral structure and composition. The complexity of mineral surfaces has meant that few attempts have been made to understand the effect of impurities(trace elements) on the flotation process. Zeta potential technique has been extensively used to evaluate the surface charge of mineral particles. Nevertheless, those measurements consider only anaverage of mineral particles surface charge. The presence of fine particles and inclusions covering a mineral may influence the local reagent adsorption process, which will ultimately be reflected in the subsequent global response of the mineral froth flotation efficiency. The current work assesses the iron oxide mineral, haematite (Fe2O3). Zeta potential and streaming potential techniques were used to determine the surface charge of fine and coarser particles of haematite. Further analysis was performed to determine the point of zero charge (PZC) of the mineral. In addition, adsorption isotherms of alkylammonium chloride reagents with different lengths of carbon chains were carried out. It was found haematite floatability depends strongly on the isoelectric point (IEP) value, which is affected by other mineral species present at the mineral surface. Haematite floatability became significant only at relatively high tetradecyl ammonium chloride collector concentrations (concentration greater than 4 10-4 M), which does not happen with other oxides such as quartz. Unlike quartz, haematite develops a low surface charge over a wide range of pH, disabling all long-range attractive interactions between the mineral and the collector. Therefore, hydrophobic chain interaction is probably the most likely mechanism acting to promote collector adsorption and enhance further floatability. Diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to suggest a possible mechanism to understand the sequence of collector adsorption and the effect of trace species on it.
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    ABSTRACT: No abstract available.
    Bulletin of Environmental Contamination and Toxicology 02/2006; 76(1):171-8. DOI:10.1007/s00128-005-0904-8 · 1.22 Impact Factor
  • S. Montes, E. Valero, G. Montes
    01/2002; 47(4). DOI:10.4067/S0366-16442002000400016
  • S. MONTES, E. VALERO, R. SCHMIDT
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    ABSTRACT: En este trabajo se estudia el mecanismo de adsorción de cloruros de alquilamonio de cadena larga sobre cuarzo de alta pureza, mediante ensayos de potencial de flujo e isotermas de adsorción. Los primeros muestran la importancia de las moléculas de alquilaminas a valores de pH cercanos a la neutralidad, cuya presencia en la fase adsorbida explicaría la existencia de puntos de inversión de carga (PCR) en las curvas potencial zeta-pH, condiciones en las cuales la microflotabilidad es máxima. Las isotermas de adsorción muestran la elevada afinidad electrostática ion alquilamonio-cuarzo, con formación de multicapas, a concentraciones del colector inferiores a la concentración micelar crítica correspondiente. La isoterma de Frumkin-Fowler explica la posición relativa de las isotermas de adsorción experimentales, al aumentar el largo de cadena hidrocarbonada del colector a pH constante.así como también la relación inversa concentración de equilibrio-pH, para un mismo colector hidrocarbonado.
    01/2000; 45(1). DOI:10.4067/S0366-16442000000100005
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    ABSTRACT: Radiata bark pine has arisen as one of the possible heavy metals extracting agent from aqueous solutions. This innocuous treatment pathway, example of the so-called clean technology, has been studied for numerous authors nevertheless some issues, like global mechanism, are still not well described. This work is devoted to determine the effect of initial-normal heavy metal content present in radiata bark pine over its own ion extraction capability. Separate batch experiences at different conditions of both Cu(II) and Pb(II) adsorption were performed. Many authors have demonstrated that pulp density affect largely the bark pine extraction capability. In equilibrium conditions, the solid/liquid ratio itself defines the adsorption capacity independently of both heavy metal concentration and bark surface state. FTIR, PIXE and SEM analysis corroborated these facts and also proved the existence of different adsorption energy sites. Further kinetic analysis was performed to understand the different adsorption behavior of Cu(II) and Pb(II).