More sustainable wastewater treatment by reusing a renewable unwanted waste product - seashells

1. More sustainable wastewater treatment by reusing a renewable unwanted waste product - seashells Dr Darrell Alec Patterson Senior Lecturer (Associate Professor) in Chemical Engineering, Department of Chemical Engineering & Centre for Sustainable Chemical Technologies, University of Bath d.patterson@bath.ac.uk Jun H. Shariffuddin, Dr Mark I. Jones Department of Chemical and Materials Engineering, University of Auckland Sustainability Live/IWEX, 2014

2. Presentation Outline • Quick overview of all of my research • Bath Process Intensification Laboratory • Why Shell Waste? • Shell waste issues • Conversion to lime and hydroxyapatite • Project Objectives • Results • Pyrolysis to lime • Conversion to hydroxyapatite • Photocatalysis of methylene blue wastewater • Conclusions and Future Work • Acknowledgements

3. Overview of my research: Applications of Nanostructured and Tuneable Materials Membrane fabrication and applications Improved catalytic reactors (incl. wastewater) Application of nanostructured heterogeneous catalysts into new reactor types e.g. spinning disc reactors and mesh supported photocatalysts • Fabrication and testing of new membranes for separations not possible with current membranes. • Electrically conducting polymer films where separation properties can be changed during operation • Organic solvent resistant nanofiltration membranes for non-aqueous separations • Mixed matrix particle-polymer films for replacing chromatography separations in industry Membrane Reactors Bio-process (Enzyme) Intensification with Dr Emma Patterson (nee Emanuelsson) Attaching enzymes to new surfaces and then applying in novel reactor types for increased reaction rate and product yield e.g. The world’s first spinning cloth disc enzyme reactor for enhanced oil wastewater treatment, biodiesel production and pharma reactions. Combining reactors and membranes to improve reaction selectivity , rates, control and stability.

4. Summary of the Project Green Lipped Mussels HAP, Ca10(PO4)6(OH)2 Application in photocatalysis for degradation of pollutants

5. Why Shell Waste? • Internationally: aquaculture shell waste mainly landfilled • Example - NZ Mussel Industry shell waste: • Estimated at 12,000 tonnes to 100,800 tonnes per year • Set to increase as Government expands the industry • We are finding value-added uses of this waste…

6. Increasing pH • Shells are mainly calcium carbonate (CaCO3) • The green-lipped mussel has a layered shell. • Inner layers = aragonite and calcite (calcium carbonate) within an organic framework. • Outer green layer = protein conchin. • Heat treatment at 800-100°C burns off the organic and produces lime: • CaCO3⇌ CaO + CO2 • Dissolve the lime in water: • CaO + H2O ⇌ Ca(OH)2 ⇌ Ca2+ + 2OH- • Dose the calcium hydroxide with phosphates: • H3PO4⇌ H2PO4-⇌ HPO42-⇌ PO43- • Reaction between dissolved lime and phosphates at correct conditions, gives HAP: • 10Ca2+ + 6PO43- + 2OH- Ca10(PO4)6(OH)2 (s) Mussel Shell  Hydroxyapatite (HAP) Hydroxyapatite

7. Wide range of applications depending on the purity: Why Hydroxyapatite (HAP)? * Sigma-Aldrich, 2008 We are looking at photocatalysis for wastewater treatment in particular…

8. Photocatalysis = A photo-initiated heterogeneous catalysed reaction, ultimately forming a hydroxyl radical (HO), which unselectively oxidises any species it contacts. • Mainly used for wastewater treatment (pre-treat or polishing): • partial or complete degradation of biorecalcitrant chemicals Photocatalysis basics http://www.mosquitowhacker.com/images/slide0007_image016.jpg

9. Current Photocatalysts: problems • Currently metal oxides (mainly TiO2 and ZnO) are the favoured photocatalysts: • Powder • Thin films • Overall problem: current catalysts are: • expensive • consist of metals that have limited availability on Earth. • Using HAP overcomes these problems • contains widely available atoms, • can be made from renewable sources • waste sea shells • phosphate from wastewaters Powder TiO2 Photocatalyst TiO2 thin film on a PET resin film http://www.nims.go.jp/eng/news/nimsnow/Vol3/No1/image/p1-1.jpg ZnO DC Magnetron Sputter + hydrothermal deposition

10. Project Objectives • Characterise the feasibility of using HAP synthesised from mussel shells as a renewable photocatalyst for the remediation of recalcitrant pollutants in wastewaters. • Initial model wastewater = methylene blue (azo dye) • Eventual targets = pharmaceuticals, pesticides and hormones http://en.wikipedia.org/wiki/File:Reflections_in_a_flask_of_Methylene_Blue.jpg

11. Crushing, Ring Grinding, Sieving Green Lipped Mussels Raw Shell Powder Shell Preparation and Pyrolysis P. canaliculus Pyrolysis in Furnace (900oC) Pyrolysed Shell Powder = Lime (CaO)

12. Conversion of Shells to Lime • Pyrolysis of mussel shells: CaCO3 CaO + CO2 1Total percentage of mass loss includes the organic material. 2 Total percentage of transformation is after taking in to consideration the mass loss due to organics.

13. Phosphate removal using the lime • Pyrolysed shells (CaO): • A rapid 95% reduction in phosphate concentration regardless of the different particle sizes or pyrolysis conditions • Phosphate concentration reduced to less than 0.5 mg L-1 within 5 min. • Non-pyrolysed shells: • Little reaction = phosphate removal by adsorption only. Phosphate removal using shell derived lime Forms hydroxyapatite  can synthesis HAP from phosphate-rich wastewater • ABEYNAIKE; WANG; JONES, PATTERSON, 2011, Asia Pacific Journal of Chemical Engineering, 6(2), 231-24.

14. Synthesis of HAP Formation of Ca(OH)2 Formation of HAP • 10Ca(OH)2 + 6 KH2PO4  Ca10(PO4)6(OH)2 + 6KOH + 12 H2O

15. Characterization of HAP Powder Commercial HAP • FTIR and XRD analysis confirmed that HAP was formed. Shell-HAP 900 Commercial HAP Shell-HAP 800 Shell-HAP 900 Shell-HAP 800 XRD patterns FTIR spectra • FTIR spectra show peaks characteristic of HAP : PO43- and OH-1 • FTIR and XRD match commercial (Sulzer Metco) HAP

16. Photocatalysis Set Up • Lab-scale batch photoreactions at 254nm UV • Degradation of methylene blue model wastewater monitored by: • UV-Vis – decolouration of the azo dyes • HPLC – degradation of methylene blue and reaction intermediates

17. MB and its azo dye intermediates were photocatalytically degraded by HAP. HAP800 had a highest reaction rate. Due to increased CaCO3 content, which reacts non-photocatalytically Photocatalytic Degradation by HAP UV UV Oxidised Intermediates + H2O CO2 O2 + HAP HAP

18. Detailed experiments confirmed UV photocatalysis was occurring. Photocatalytic Degradation by HAP • CONTROL: HAP alone (no UV) was not sufficient for the Methylene blue removal with an overall adsorption removal of only 1.8% . • UV PHOTOCATALYSIS: Under oxygen limited conditions, the decolorisation of methylene blue was 39% after 6 hours. No further increase with longer durations. • UV PHOTOCATALYSIS: For the oxygen rich conditions, decolorisation during the initial 6 hours was approximately 54% and increased to 62% after 24 hours. • photocatalysis in oxygen rich conditions photocatalysis under oxygen limited conditions adsorption experiments Fig: Comparison of percent decolorationof azo dye compounds from Methylene Blue using HAP800. Oxygen rich conditions with HAP @ 2.0g/L.

19. Reaction Intermediates and Products • Mineralisation not achieved • Not necessary, just need to make MB more bio-compatible • Four main reaction intermediates formed and degraded • Azure A (AA) • Azure B (AB) • Azure C (AC) • Thionin (Th)

20. Photocatalysis is occuring! • Reaction intermediate spectrum matches that found for TiO2 and ZnO photocatalysis • Further indicates HAP is photocatalytically degrading the MB! Ali, Emanuelsson, Patterson, 2011, Applied Catalysis B: Environmental, 106, 323– 336.

21. Effect of reaction on HAP • FTIR analysis of the post-reaction HAP as shows surface PO43- group absorbance intensity decrease • HAP is normally insoluble at the conditions used • This may indicate that PO43- groups are being photo-dissolved • Work is continuing to determine the stability/dissolution operating envelope before photocatalytic reaction after photocatalytic reaction Fig.: FTIR spectra for the HAP powder before and after photocatalysis.

22. Conclusions/Summary • Results show it is possible to use the mussel shells as a calcium source in the formation of hydroxyapatite (HAP) with a quality comparable to commercial HAP. • Shell-derived HAP can be used as photocatalyst with an acceptable photocatalytic activity • Methylene blue was 54% degraded within 6 hours and 62% within 24 hours (oxygen rich conditions; HAP concentration, 2.0g/L). • The reaction appears to be either product inhibited and/or affected by catalyst deactivation. Further work is looking to address this. • Overall, these results indicate that the HAP derived from the mussel shells is a promising greener, renewable photocatalyst for the photocatalytic degradation of wastewater components.

23. Current/Future Work • Finding industrial partners • Scale-up of HAP production • Looking at ways to synthesize HAP on a larger scale • Photocatalysis of other model wastewaters • dehydroabietic acid – a resin acid found in pulp and paper industry wastewaters • Pharmaceuticals, pesticides and hormones • Photocatalysis of real wastewaters • Photocatalysis in an annular (industry type) flow reactor ibuprofen naproxen

24. Scholarships: • Ministry of Higher Education, Malaysia and Universiti Malaysia Pahang for the PhD scholarship for Jun H. Shariffuddin • Support for the experimental work done: • Sanford Limited (NZ) for donating the mussel shells used in this work. • University of Auckland Chemical Engineering Department. • Additional researchers: • Sean Dillon, Haneen Barakat, Bridget Hanley • Thank you to the technical teams at the Chemical Engineering Departments at the Universities of Auckland and Bath. Acknowledgements

25. CSCT places fundamental concepts of sustainability at the core of research, training and outreach in applied chemical sciences www.bath.ac.uk/csct/ go.bath.ac.uk/membranes