دانلود رایگان مقاله انگلیسی حذف فلزات سنگین و آلاینده های آلی توسط شن و ماسه غنی از اکسید آهن - اشپرینگر 2018

Abstract

The aim of this work is to evaluate an efective fltration technique for residual organic pollutants and heavy metals removal using two types of sand rich in iron oxide as a massive flter (sieved and gross sand). X-ray difraction, X-ray fuorescence (XRF), scanning electron microscopy, energy dispersive spectroscopy (EDS) and specifc surface area BET were investigated to characterize the sand. Experimental results showed that the BOD5 removal was found to be 93% for gross sand (GS) and 96% for sieved sand (SS). The COD removal was equal to 98.9 and 99.7% for GS and SS, respectively. The hydrogen bonding, complexation/precipitation process, ions exchanges and electrostatic interactions are the main phenomena proposed to describe residual organic pollutants removal. For heavy metals adsorption, results show a great efciency removal between 90 and 100% for both cases. The adsorption mechanism was proposed based on zero-point charge, FTIR analysis, fuorescence (XRF) and EDS. The fxation of heavy metals onto the sand could be referred to hydrogen bonding, electrostatic interaction, ion exchange and electron donor–acceptors.

Conclusion The use of two types of rich sand in iron oxide (RSIO) as a massive flter for wastewater treatment has demonstrated its efectiveness on a pilot scale to remove heavy metals and organic pollutants from industrial wastewater. The results obtained in terms of physicochemical analyses of treated wastewater show a good reduction of the organic load (COD: 98.9% and BOD5: 93.1%) by the GS and (COD: 99.7% and BOD5: 96.1%) by SS. The results obtained for heavy metals removal show an improved performance: 99.7% [Cr(II)), 98.5% (Pb(II)), 85.1% (Cu(II)) for GS and 95.9% (Cr(II)), 95.7% (Pb(II)], 85.3% (Cu(II)) for SS. These values are in line with the Moroccan water standards used for irrigation. According to FTIR, XRD and EDS, a possible mechanism of heavy metals removal onto sand rich in iron oxide was proposed, referring to:

• Interactions between hydrogen bonding functions (OH–) and Cu(II), Cr(II), Pb(II).

• Ion exchange process.

• Electrostatic interaction.

• Complexation and precipitation process.

• Other biological interactions.