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Enhanced Arsenic Removal from Groundwater by Using an Advance Adsorbent - Ferric Oxide/Activated Rice Husk Ash Material, Nguyen Trung Thanh

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This presentation is part of the ProSPER.Net Young Researchers' School 2017 ‘Water Security for Sustainable Development in a Changing Climate’.

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Enhanced Arsenic Removal from Groundwater by Using an Advance Adsorbent - Ferric Oxide/Activated Rice Husk Ash Material, Nguyen Trung Thanh

  1. 1. Enhanced arsenic removal from groundwater by using an advance adsorbent – ferric oxide/activated rice husk ash material Dr. Trung Thanh, Nguyen
  2. 2. Contents • Effect of arsenic to human health • Mapping arsenic contamination in South East Asia • Arsenic removal technologies • Solid materials for aqueous arsenic removal • New approach for aqueous arsenic removal
  3. 3. Mapping arsenic contamination Fig. 1. Distribution of arsenic contamination in South East Asia, showing the contamination in the Mekong Delta and Red river.
  4. 4. Arsenic effect to human health The WHO guideline for safe levels of arsenic ingestion is a concentration of 10 µg/L in drinking water and a limit of 100 µg/L in untreated water prior to being processed for consumption Arsenic is known as the “king of poisons” Fig. 2. Blackfoot disease from approximately ten years of drinking 50 µg/L of arsenic contaminated groundwater
  5. 5. Arsenic removal technologies Arsenic removal engineering Combining of oxidation and precipitation engineering Nano filtration Adsorption and ion exchange Why is adsorption technology applied to remove the arsenic from groundwater? (1) Low charge for operation of arsenic removal system (2) The adsorbent could be reused. (3) no toxic products are created by adsorption. (4) This tech. can be carried out with high arsenic concentration.
  6. 6. Solid materials for aqueous arsenic removal
  7. 7. New approaches for aqueous arsenic removal
  8. 8. Motivations 1. Ferric oxide /carbon material exhibited low arsenic capacity 2. Low durability due to weak interaction between ferric oxide and carbon support. Oxide support Drawbacks Low surface area Complex synthesis procedure
  9. 9. Mechanism of arsenic adsorption on the ferric oxide surface S.E. O'Reilly, D.G. Strawn and D.L. Sparks; Residence Time Effects on Arsenate Adsorption/Desorption Mechanisms on Goethite; Soil Science Society of America Journal, Vol. 65 No. 1, p. 67-77, 1999. Fig. 3. Mechanism of arsenic adsorption on the ferric oxide surface
  10. 10. Approach 1 Ferric oxide/activated rice husk ash material for enhancing aqueous arsenic removal from groundwater
  11. 11. New idea Activated rice husk ash support Ferric oxide nanoparticle Strong interaction metal oxide support Carbon and SiO2 High surface area e- Cheap H2AsO4 - H2AsO3 - Adsorption
  12. 12. Results and discussions Fig. 1. Images of rice husk ash (RHA), activated RHA and FexOy on RHA support materials Sample color depends on the loading of ferric oxide
  13. 13. Characterizations SEM/TEM images and BET surface area Material BET surface area (m2/g) Activated RHA 433 FexOy/RHA 410 Nanomaterials with high surface area
  14. 14. Characterizations Fig. 4. FTIR patterns of original and activated rice husk ashes. Wave number (cm-1) Functional group 3404.31 -OH and Si-OH 2925.81 C-H streching of alkanes 1641.31-1737 C=O stretching of aromatic groups 1546.8-1652.88 C=C stretching of alkanes and aromatic 1461.94 CH2 and CH3 1379.01 Aromatic CH and carboxyl-carbonate 1238.21 CHOH stretching of alcohol group 1153.35-1300 CO group in lactones 1080-1090 Si-O-Si 935.41 C-C 469-800 Si-H 580-34 -OCH3 FTIR Activated RHA contains Carbon and SiO2.
  15. 15. Characterizations Fig. 5. XRD patterns of ferric oxide/RHA materials. The ferric oxide nanomaterial is a muxture of Fe2O3 and FeO FeCl3 chemical is ferric resource for ferric oxide synthesis.
  16. 16. Arsenic capacity Experimental conditions: CAs: ~ 100 µg/L Volume: 50 mL Adsorbent dosage: 50 mg pH: ~ 7.0 Room temp. Adsorption time : 20 mins Fig. 6. Arsenic capacities of various adsorbents at room temperature The 5 wt.% FeCl3-FexOy/RHA material shows highest arsenic capacity than that of others. The activated RHA is a good support of ferric oxide nanoparticles for arsenic removal ~14 mgAs/gFe ~1.2 ~5.8
  17. 17. Mechanism of Enhancing arsenic capacity of FexOy/RHA material Fig. 7. Strong interaction metal oxide support Positive charge on the iron oxide nanomaterial
  18. 18. Conclusions of approach 1 The activated RHA is good support for ferric oxide nanomaterial toward arsenic removal from groundwater. The FexOy/RHA adsorbent shows high arsenic capacity due to high BET surface area of activate RHA support and a positive charge on the ferric oxide surface by a good interaction between ferric oxide and silica of activated RHA support.
  19. 19. Approach 2 Manganese –dopped Ferric oxide/activated rice husk ash material for enhancing aqueous arsenic removal from groundwater
  20. 20. New idea Activated rice husk ash support Ferric oxide nanoparticle Strong interaction metal oxide support Carbon and SiO2 High surface area e- Cheap H2AsO4 - H2AsO3 - Adsorption Manganese oxide e- Adsorption
  21. 21. Characterization Fig. 8. XANES patterns of Fe7Mn3Oz/RHA; FexOy/RHA; and Fe (reference) materials The Fe7Mn3Oz/RHA materials is observed higher positive charge on ferric oxide surface than that of FexOy/RHA material
  22. 22. Results and discussions Fig. 9. Arsenic capacities of various adsorbents at room temperature Experimental conditions: CAs: ~ 100 µg/L Volume: 50 mL Adsorbent dosage: 50 mg pH: ~ 7.0 Room temp. Adsorption time : 20 mins The Fe7Mn3Oz/RHA material shows highest arsenic capacity than that of others. The present of manganese can enhance the arsenic capacity of ferric oxide nanomaterial. ~ 1,3 ~ 1.1
  23. 23. Conclusions of approach 2 The present of manganese can enhance the arsenic capacity of ferric oxide nanomaterial.
  24. 24. A project of arsenic removal for groundwater in Cambodia Fig. 10. a photo of arsenic removal from groundwater in Anlong Veng Prov., Cambodia-2016 40 L/h
  25. 25. Ferric oxide on activated rice husk ash material Water inlet Water outlet Sand Sand Adsorbent
  26. 26. Thank you very much for your attention!

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