Preparazione/attivazione di un nanomateriale a base di ilmenite e valutazione della sua efficienza nell'immobilizzazione di metalli pesanti in un suolo (multi)contaminato

Responsabili di progetto

Eliana Lanfranca Tassi, Majlinda Vasjari

Accordo

ALBANIA - MoES - Ministry of Education and Sport of the Republic of Albania

Bando

CNR/MOES biennio 2018-2019 2018-2019

Dipartimento

Scienze del sistema terra e tecnologie per l'ambiente

Area tematica

Scienze del sistema Terra e tecnologie per l'ambiente

Stato del progetto

Nuovo

Proposta di ricerca

Toxic levels of heavy metals (HMs) in soils are deleterious to the environment, impacting particularly soil biota, plants, water resources and humans. The number of contaminated sites in the European Union and the area affected by different kinds of pollution, of which the remediation would cost EUR17.3 billion annually(1), underlines the extent of the problem in the continent.
However, HM-contaminated sites are notoriously difficult to remediate, still need suitable and effective technologies to solve the task with reduced costs and low impact. This is particularly relevant for Italy and Albania, where mining activities, more than two hundred years of industrialization and intensive farming to support population growth, have contributed to increase the level of toxic HMs in soils.
Typical remediation techniques for HMs in soil are extraction and immobilization. Considering the limitations of both ex-situ (soil washing) and in-situ (phytoextraction, electroctrokinetic extraction) extractive methods, immobilization processes are generally preferred. Suitable binders (hydroxyapatite, zeolites, Ca and Mg-rich materials, phosphates, organic amendments, biochar, etc.) have been studied to reduce toxic metals leachability by soil pH modification or increasing adsorption, ionic exchange and precipitation of contaminants. Generally, immobilization treatment processes are made in wet conditions, forming secondary effluents, which need treatment, entailing additional costs. Therefore, treatment under dry and water-free conditions should also be considered.
Taking advantage of the high surface area and the reactivity of nanomaterials as binders, recent studies have been investigated the use of natural-based nanomaterials for the remediation of HMs contaminants in waters(2,3), however few studies have yet been made for contaminated soils(4).
Moreover, the use of a natural-based magnetic nanomaterial in soil can be a remarkable option for the separation and the concentration of HMs in a minor fraction without use of hazardous extractants or necessity of secondary wastewater treatment and the worsening shortage of landfill sites. Furthermore, HMs concentrated in a minor fraction can be suitable for a further recovery.
Although the re-use of remnants of processing minerals are of utmost interest in the concept of a circular economy, the evaluation of the impact of nanoparticles in the environment(5) is required. Thus, an ecotoxicological approach that reveals and predicts the effects of such nanomaterial within the context of all other environmental factors is necessary. Phyto- and genotoxicity studies(6) may indicate the actual state of decontamination, the bioavailability of the pollutants at various stages of the process and the impact of soil amendment.

This proposal deals with the study, at laboratory scale, of a remediation step in a HM multi-contaminated soil using an ilmenite-based nanomaterial (IbNM). Soil treatment conditions will be approached by different rates and methods: low and high amendment dose (LA and HA, respectively) and dry/water-free and wet conditions (DC and WC, respectively). Experiments will be performed to evaluate the HMs' immobilization and to reveal the immobilization mechanism, as well as the verification of the dangerousness of soil treatments using a target plant species.

Project tasks:

1-Preparation of the IbNM from the remnant mineral damps of a former factory of quartz sand processing plant in Durres, Albania. Activation of the processed material will be done to improve the adsorption properties. The obtained material (IbNM) will be characterized by X-ray Fluorescence (XRF), Transmission Electron Microscopy (TEM) and Laser Granulometer;
2-Screening of HMs' affinity for the IbNM through batch experiments using HMs in aqueous phase;
3-Soil collection and preparation of the IbNM-amended soils using different methodologies and conditions will be employed and their main characteristics monitored;
4-Leaching experiments through soil columns will permit to determine the reduction of HMs' mobility/availability in treated soils;
5-Soil chemical fractionation using a sequential extraction procedure (SEP)(7) to obtain information on the mechanism of HMs' immobilization in soils and determine its efficiency;
6-Soil physical fractionation in magnetic and non-magnetic fractions: both will be evaluated for the HMs' availability;
7-XRF analysis on the magnetic and non-magnetic fractions to validate the immobilization mechanism hypothesized;
8-Ecotoxicity tests to evaluate the impact of the IbNM in seedlings germinated in the amended soils through the monitoring of physiological (germination, root and shoot elongation) and cytogenetic (mitotic index, chromosomal abnormalities, presence of micronuclei) endpoints.

The analyses of heavy metals in soils and extractants (after appropriate sample preparation) will be performed using the equipments available at ISE-CNR and University of Tirana: Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), Advanced Mercury Analyser (AMA254), Atomic Absorption Spectroscopy - Flame, Gas Furnace and Hydride Generation (AAS), depending on the kind and concentration level of HMs.

References:
1)CEC, 2006 COM(2006)231 Final (SEC(2006)1165)
2)Broli 2010 Determination of the adsorbent properties of the azide-magnetite ore to Cu(II), University of Tirana - MSc. Thesis
3)Broli and Vasjari 2011 The study of the adsorption of Cu2+ on ilmenite material surfaces-Proceedings at the National Conference 'Chemistry and the Development of the Country', Tirana-Albania
4)Taosha Ou et al. 2017 J Soils Sediments 17, 2202-2213
5)Tassi et al 2017 Plant Physiol Biochem, 110, 50-58
6)Ruffini Castiglione et al. 2016 Environ and Exp Bot, 130, 11-21
7)Rauret et al. 1999 J Environ Monit, 1, 57-61

Obiettivi della ricerca

The overall goal of the project is to test the special properties, mainly due to the nanoscale, of an Ilmenite-based innovative nanomaterial for the remediation of heavy metal contaminated soil, using low impact and low cost approaches. Moreover, the production of a natural ilmenite nanomaterial and the establishment of soil remediation conditions with the possibility of contaminants' recover will represent an example of circular economy.
Other goals of the project are: a) the identification of the best conditions to prepare and activate the IbNM for use as metal adsorbent, b) the identification of heavy metals with highest affinity for the proposed nanomaterial, c) to evaluate the capacity and efficiency of immobilization of HMs in a multicontaminated soil, d) to hypothesize the main mechanism of the remediation action, e) to evaluate the impact of IbNM in the treated soils, f) to improve the exchange of ideas and techniques between the two research groups that has complementary expertise in analytical chemistry and environmental soil sciences, g) the training of students and young researchers of the partnership in an international environment, who may then will contribute to promote the transfer of knowledge connected to the nanotechnology and the soil remediation processes, h) to establish a strong collaboration for the formulation of further joint proposals at international European programs such as H2020, Life, EraNet, etc.

Ultimo aggiornamento: 13/12/2024