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Green remediation method for soils polluted with some heavy metals Reda R. Shahin Reda R. Shahin*, N.H. Abdel-Kader and H.A. Khater Soils Department,

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Presentation on theme: "Green remediation method for soils polluted with some heavy metals Reda R. Shahin Reda R. Shahin*, N.H. Abdel-Kader and H.A. Khater Soils Department,"— Presentation transcript:

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2 Green remediation method for soils polluted with some heavy metals Reda R. Shahin Reda R. Shahin*, N.H. Abdel-Kader and H.A. Khater Soils Department, Faculty of Agriculture, Cairo University, Giza, Egypt. *Corresponding author: dredashahin@gmail.comdredashahin@gmail.com

3 Background The remediation of heavy metals contaminated soils is still recognized as the most difficult problem to be solved due to its high expenses. EDTASoil washing with synthetic chelating agents such as EDTA seem to be most popular. persistent low biodegradability EDTA is quite persistent in the environment due to its low biodegradability (Masakazu et al., 2008). eco-friendlyThere is a need for an eco-friendly washing material.

4 green leaves extracteco-friendly materialTo evaluate the use of the green leaves extract as an eco-friendly material instead of EDTA in the remediation of the heavy metals polluted soils. OBJECTIVE

5 Materials

6 Three Soil Types Soil Type pH (1:1) EC dS/m (1:1) Pb (mg/kg)Cd (mg/kg)Co (mg/kg)Cr(mg/kg) Aqua - Regia DTPAAqua- Regia DTPAAqua- Regia DTPAAqua- Regia DTPA Sandy 8.010.41134102744.5334.65165.723.97854.4189.1 Loamy 8.215.01421100852.7131.65229.318.62878.2153.8 Clay 8.216.4148898854.0923.13346.17.70938.067.2 Soil texture Particle size fraction (g/kg)pH (1:2.5 EC dS/m OM g/kgCaCO 3 g/kg CEC Cmol/kg SandSiltClay Sandy7481441087.791.141.511.69.4 Loamy4603781627.831.9411.3 22.033.6 Clay424904867.553.6626.6 3.2648.1

7 Hibiscus and Eucalyptus leaves Extract EDTA 0.01 M Control (Distilled water) + Surfactant Sodium dodecyl sulfate (SDS) )

8 Hibiscus Enriched with phenoles

9 Eucalyptus Enriched with aromatics

10 Green Leaf Extraction

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12 Infra-red Examination Of the Green Leaf Extract

13 Hibiscus

14 Eucalyptus O - H - NH2 CO - OH CO -N H 2 -C H3 C=O - H

15 GroupBond typeFrequency Cm-1 GroupFormulaFrequency Cm-1 C–H bending 985–1472amides-NH21575 C–H stretching 2845– 2909aromatic754–762 O–CH31475C–O–C stretching 1164 ketoneC=C,1575– 1748phenols1271– 3627 carboxylic-COOH1319–1717 IR -results

16 high amounts as carboxyl, phenol, amino metal complexationThe slurry of the leaves of both Hepescus and Eucalyptus were found to contain high amounts of active groups such as carboxyl, phenol, amino as well as other legends susceptible for metal complexation IR -results

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18 Surfactant Chemical Structure Organic compounds that are amphiphilic, contain both *hydrophobic groups (their tails) *hydrophilic groups (their heads). Groupings Allow For Surface Interaction With Many Contaminants

19 Surfactants also have a part in removing heavy metals (HMs) from soil surfaces, probably through the formation of complexes, micelles and ion exchange processes (Gao,2007). Under acidic or alkalic condition, surfactants have removed heavy metals from soil through direct complexation followed by solubilization (Herman et al,. 1995, Mulligan et al., 1999, Abidin and Yeliz, 2005 and Mulligan, 2005). Role of Surfactants

20 Leaching Columns and sampling

21 Soil 12cm 3 cm 3 Cm 1PV Time : 2 4 8 16 32 64 128 256 days 1PV = 8 PV R= 5 cm

22 Results

23 Soil-pH changes PV Sandy (1:2.5) = 8.00 Cont. W + S E E + S P p + S 17.447.167.327.286.286.13 87.397.157.317.255.315.11 PV Clay (1:2.5) = 8.44 Cont. W + S E E + S P p + S 18.428.118.017.897.447.16 87.657.397.157.015.485.54

24 Soil Salinity Changes PV Sandy (1:2.5) =10.4 dS/m Cont.W + SEE + SPp + S 111.010.610.09.99.89.7 82.612.832.112.512.882.81 PV Clay (1:2.5) =26.4 dS/m Cont.W + SEE + SPp + S 126.425.624.424.023.522.9 82.532.323.902.172.003.09

25 The cumulative curves of the leached amounts of Pb (mg/column) Sandy L Clay

26 Sandy L Clay The cumulative curves of the leached amounts of Cd (mg/column)

27 The cumulative curves of the leached amounts of Co (mg/column) Sandy L Clay

28 The cumulative curves of the leached amounts of Cr (mg/column) Sandy L Clay

29 Conclusions Sandy loam showed the highest amounts of the leachable metals while the lowest amount was recorded for the clay one. The washing with EDTA extracted higher amounts of Pb and Cd as compared to the plant slurry in sandy loam or clay soils. The surfactant enhanced leaching of all the studied metals and soils. In Cobalt, plant slurry (P and P+S) was superior or equal to EDTA (E and E+S)

30 Calculating Retardation (R) from the model breakthrough curve (BTC)

31 Retardation factor (R) Retardation factor (R) which represent the number of pore volumes which leached (Mn) 50% of the total leached amounts (Mt) of each metal (Mn/Mt = 0.5)

32 The cumulative amounts of the leached Pb and Cd (mg/column)

33 The cumulative amounts of the leached Co and Cr (mg/column)

34 Breakthrough (BTC) Retardation of Pb, Cd, Co and Cr ions in the investigated soils using different leaching solutions. SoilMetalEE+SPP+S SandyPb3.1003.0003.4003.200 Cd1.6001.2001.5601.600 Co2.2002.1003.3502.250 Cr2.1001.9003.0002.300 ClayPb6.2006.1006.8006.600 Cd3.2003.1003.5003.400 Co4.2004.1004.4004.250 Cr3.1002.9003.3003.100

35 Retardation Brief Pb > Co > Cd >CrPb > Co > Cd >Cr Clay >> SandyClay >> Sandy For all the leached metalsFor all the leached metals

36 Downward Metal Distribution

37 Soil 12cm 3 cm 3 Cm Total pore volumes = 8 PV R= 5 cm At the end of leaching, soil column was sectioned every 3 cm and DTPA extracted metal was measured

38 Clay Sandy L Downward distribution of DTPA extractable Pb in the soil columns at the end of the leaching experiment

39 Downward distribution of DTPA extractable Cd in the soil columns at the end of the leaching experiment Sandy L Downward distribution of DTPA extractable Cd in the soil columns at the end of the leaching experiment Clay

40 Sandy L Downward distribution of DTPA extractable Co in the soil columns at the end of the leaching experiment Clay

41 Sandy L Downward distribution of DTPA extractable Cr in the soil columns at the end of the leaching experiment Clay

42 Remediation Efficiency

43  In conclusion, the slurry of the leaves of both Hepescus and Eucalyptus were found to contain high amounts of active groups such as carboxyl, phenol, amino as well as other legends susceptible for metal complexation.  The enormous amount of the active ligands with the slightly acidic reaction (pH= 6.5) may facilitate the metals washing from the polluted soil columns even more efficiently than EDTA in some cases.

44 Thank you


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