Many industrial processes produce wastewaters particularly rich in heavy metals and toxic elements. High concentrations of these pollutants in water are directly responsible for the life cycles of plants, animals and humans. The removal of metals and metalloids from wastewaters is one of the main objectives of environmental remediation; there are several physic-chemical methods to remove inorganic pollutants from aqueous solutions but most of these are expensive and inadequate. Adsorption is now recognized as an effective and economic method for heavy metal wastewater treatment. The adsorption process offers flexibility in design and operation and in many cases will produce high-quality treated effluent. In recent years several researchers have studied the potential of food waste as low cost adsorbent materials. The operating conditions that they used for the adsorption experiments are very heterogeneous so it’s impossible to compare the efficiencies of the individual adsorbents. The aim of this study is to evaluate the adsorption capacities of 12 food waste, assessing their capabilities to remove more than 30 elements (for most of whom the adsorption capacities have never been evaluated) from the same polluted aqueous solutions. Maintaining consistent experimental conditions gives the possibility to make a comparison between the different adsorbent capacities and properly assesses their efficiencies. The powders of each food waste have been included in the polluted solutions in gradually increasing doses to increase the number of available active sites and to study the effects of competition between the elements. The 12 food waste (banana peels, eggplant peels, apple peels, lemon peels, potato peels, grape waste, tomato peels, orange peels, watermelon peels, carobs and coffee waste) have been dried, pulverized and washed before use. The adsorption capacities of several elements (Ag, Al, As, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, In, La, Mn, Mo, Nb, Ni, Pb, Sb, Sn, Sr, Th, Ti, Tl, U, V, W, Zn) from synthetic solutions at pH 2 and pH 5.5 have been studied. For each element the solubility curve as a function of pH has been verified to evaluate the hydroxides precipitation equilibrium and their possible interference in the adsorption processes. The adsorption percentages of elements from the contaminated solutions have been calculated from the data obtained by inductively coupled plasma optical emission spectroscopy and by inductively coupled plasma mass spectroscopy (ICP-OES, ICP-MS). As can be seen from Figure 1, the food waste can be effectively used for the removal of many elements from polluted solutions even at acid pH. Maintaining homogeneous experimental conditions gives the possibility to make a comparison between the different adsorbent capacities and to note that each of them has a propensity to adsorb in its own active sites certain elements rather than others. The statistical processing of the data obtained has allowed to group the materials examined according to the type of active sites present on the adsorbent surfaces. To refine the classification of adsorbents there are further studies in progress with electron microscopy and IR spectroscopy. The potentialities of food waste as adsorbent materials have also been verified on real polluted matrices, evaluating the removal of heavy metals from wastewater produced in a hydro-metallurgical process for the recovery of valuable elements by electronic cards (pH 5.5). The excellent efficiencies of these materials have been confirmed on real matrices.

Evaluation of the Adsorption Capacities of Elements from Polluted Aqueous Solutions By Food Waste / Massimi, Lorenzo; Canepari, Silvia; Giuliano, Antonella. - STAMPA. - (2016), pp. 1-2. (Intervento presentato al convegno ISMEC 2016 - The 2016 International Symposium on Metal Complexes tenutosi a UAB - Universitat Autonoma de Barcelona - Campus Universitary de la UAB, Bellaterra, Barcelona (Spain)).

Evaluation of the Adsorption Capacities of Elements from Polluted Aqueous Solutions By Food Waste

Lorenzo Massimi
;
Silvia Canepari;Antonella Giuliano
2016

Abstract

Many industrial processes produce wastewaters particularly rich in heavy metals and toxic elements. High concentrations of these pollutants in water are directly responsible for the life cycles of plants, animals and humans. The removal of metals and metalloids from wastewaters is one of the main objectives of environmental remediation; there are several physic-chemical methods to remove inorganic pollutants from aqueous solutions but most of these are expensive and inadequate. Adsorption is now recognized as an effective and economic method for heavy metal wastewater treatment. The adsorption process offers flexibility in design and operation and in many cases will produce high-quality treated effluent. In recent years several researchers have studied the potential of food waste as low cost adsorbent materials. The operating conditions that they used for the adsorption experiments are very heterogeneous so it’s impossible to compare the efficiencies of the individual adsorbents. The aim of this study is to evaluate the adsorption capacities of 12 food waste, assessing their capabilities to remove more than 30 elements (for most of whom the adsorption capacities have never been evaluated) from the same polluted aqueous solutions. Maintaining consistent experimental conditions gives the possibility to make a comparison between the different adsorbent capacities and properly assesses their efficiencies. The powders of each food waste have been included in the polluted solutions in gradually increasing doses to increase the number of available active sites and to study the effects of competition between the elements. The 12 food waste (banana peels, eggplant peels, apple peels, lemon peels, potato peels, grape waste, tomato peels, orange peels, watermelon peels, carobs and coffee waste) have been dried, pulverized and washed before use. The adsorption capacities of several elements (Ag, Al, As, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, In, La, Mn, Mo, Nb, Ni, Pb, Sb, Sn, Sr, Th, Ti, Tl, U, V, W, Zn) from synthetic solutions at pH 2 and pH 5.5 have been studied. For each element the solubility curve as a function of pH has been verified to evaluate the hydroxides precipitation equilibrium and their possible interference in the adsorption processes. The adsorption percentages of elements from the contaminated solutions have been calculated from the data obtained by inductively coupled plasma optical emission spectroscopy and by inductively coupled plasma mass spectroscopy (ICP-OES, ICP-MS). As can be seen from Figure 1, the food waste can be effectively used for the removal of many elements from polluted solutions even at acid pH. Maintaining homogeneous experimental conditions gives the possibility to make a comparison between the different adsorbent capacities and to note that each of them has a propensity to adsorb in its own active sites certain elements rather than others. The statistical processing of the data obtained has allowed to group the materials examined according to the type of active sites present on the adsorbent surfaces. To refine the classification of adsorbents there are further studies in progress with electron microscopy and IR spectroscopy. The potentialities of food waste as adsorbent materials have also been verified on real polluted matrices, evaluating the removal of heavy metals from wastewater produced in a hydro-metallurgical process for the recovery of valuable elements by electronic cards (pH 5.5). The excellent efficiencies of these materials have been confirmed on real matrices.
2016
ISMEC 2016 - The 2016 International Symposium on Metal Complexes
04 Pubblicazione in atti di convegno::04d Abstract in atti di convegno
Evaluation of the Adsorption Capacities of Elements from Polluted Aqueous Solutions By Food Waste / Massimi, Lorenzo; Canepari, Silvia; Giuliano, Antonella. - STAMPA. - (2016), pp. 1-2. (Intervento presentato al convegno ISMEC 2016 - The 2016 International Symposium on Metal Complexes tenutosi a UAB - Universitat Autonoma de Barcelona - Campus Universitary de la UAB, Bellaterra, Barcelona (Spain)).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1110833
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