Removal of heavy metals onto KOH-activated ash-rich sludge

Transcription

1 Removal of heavy metals onto KOH-activated ash-rich sludge adsorbent Muhammad Abbas Ahmad Zaini et al. Centre of Lipids Engineering g and Applied Research (CLEAR) UNIVERSITI TEKNOLOGI MALAYSIA

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4 To highlight g the benefits of simple treatment on valueless ash-rich local sludge into valuable adsorbent for heavy metals removal

5 Outline Why palm oil mill effluent (POME) sludge? Preparation of adsorbents Characterization of adsorbents Adsorption of heavy metals Mechanisms of removal

6 Why POME sludge? Solid residue resulted from anaerobic pond at palm oil mill Produces bad odours and is a source of surface and ground pollution affect the environment and public health Generally used as fertilizer, dumped at landfill or burned into ash by incineration Adsorbent is a new route of utilizing sludge

7 About m 3 of effluent is generated from palm oil industry in Malaysia every year. Of this, about 48,000 mg/l is solids known as palm oil mill effluent sludge

8 Synthesis of sludge adsorbent KOH impregnation: dissolve, homogenize, ratio of 0.25 air free, 500 o C, 1h Wash in HCl solution followed dby distilled ill d water Adsorbent SA

9 Ash adsorbent Adsorbent SA 850 o C, 2h Adsorbent ASA

10 Surface morphology SA ASA Rough and dense surface of SA indicates the presence of organic combustibles that partly covering the ash. It also suggests that ash is evenly distributed in the material matrix.

11 Properties of POME sludge and sludge adsorbent POME sludge SA C, % H, % N, % O, % Ash, % Moisture, % Yield, % - 69 S BET, m 2 /g Solution ph

12 Elemental composition Surface Ash Elemental composition (%) Sample area content (m 2 /g) (%) Mg Al Si S K Ca Fe Cu SA ASA KOH-activation increases the surface area of sludge from 8.7 to 68m 2 /g. But, the surface area deceases to 7.3m 2 /g upon pyrolysis. SA reveals high ash content of 71%, where the main oxides are Al, Si, Mg and Fe.

13 Adsorption Adsorbate Adsorbent

14 Heavy metals poisoning

15 Removal of Pb(II) and Cu(II) uptake (mmol/g g) Lead(II) q Copper(II I) uptake (mmo ol/g) SA ASA Equilibrium i concentration ti (mm) SA ASA Equilibrium concentration (mm)

16 Trends of adsorption Specific surface area enhances the removal of lead(ii) at lower initial concentration. ASA also displays considerable role in the removal of lead(ii), while copper(ii) uptake is surface textural sensitive. Removal of heavy metals onto ASA may arise from the interaction between metal aqua ions and oxides of ash constituents. Only small non-stoichiometric-equivalent leached Mg at almost consistent ph was recorded at equilibrium, suggesting that ion-exchange is not the removal mechanism.

17 Isotherm model Heavy metal Lead(II) Copper(II) Adsorbent Langmuir model Q b SSE R 2 SA ASA SA ASA Adsorption can be described as monolayer coverage on homogeneous surface sites. High specific surface area could be the reason for greater adsorption affinity, b towards heavy metals. Comparable performance to that of commercial F400 activated carbon.

18 Conclusion It has been proven that POME sludge can be converted into adsorbents for heavy metals removal with comparable performance to that of commercial activated carbon.

19 Bibliography Zaini MAA, Okayama R, Machida M. Adsorption of aqueous metal ions on cattle-manure-compost based activated carbons. J Hazard Mater 2009;170: Zaini MAA, Zakaria M, Mohd-Setapar SH, Che-Yunus MA. Sludge-adsorbents from palm oil mill efluent for methylene blue removal. J Eviron Chem Eng 2013;1: Zaini MAA, Cher TY, Zakaria M, Kamaruddin MJ, Mohd-Setapar SH, Che-Yunus MA. Palm oil mill effluent sludge ash as adsorbent for metylene blue dye removal. Desal Water Treat doi: /

20 Acknowledgements

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