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Biochar and enhanced phosphate capture: Mapping mechanisms to functional properties
Jessica G Shepherd1, Stephen Joseph2, Saran P Sohi1
1School of GeoSciences, University of Edinburgh, Alexander Crum Brown Road, Edinburgh, EH9 3FF, UK; UK Biochar Research Centre, University of Edinburgh, Alexander Crum Brown Road, Edinburgh, EH9 3FF, UK.
Chemosphere
|April 2, 2017
Summary
This study reveals that iron minerals are key to phosphorus capture in biochar derived from wastewater sludge and ochre. Optimizing feedstock and pyrolysis conditions can enhance biochar
Area of Science:
- Environmental Science
- Materials Science
- Sustainable Chemistry
Background:
- Wastewater phosphorus recovery is crucial for sustainable agriculture.
- Biochar from secondary organic resources offers potential for phosphorus (P) capture.
- Understanding P capture mechanisms in biochar is vital for optimizing its use as a fertilizer.
Purpose of the Study:
- To identify the mechanisms of phosphorus capture in biochar.
- To inform the optimization of biochar as a sustainable phosphorus fertilizer.
- To investigate the influence of feedstock composition and pyrolysis temperature on P capture.
Main Methods:
- Multi-technique analysis including LA-ICP-MS, X-ray diffraction, XPS, and SEM-EDX.
- Pyrolysis of sewage sludge (PAD) and sludge-ochre blend (POCAD) at 450°C and 550°C.
- Exposure of biochars to phosphate solutions and characterization of P-exposed samples.
Main Results:
- Iron (Fe) minerals were generally important for P capture.
- Lower oxidation state Fe2p3 bonding and stronger Fe-S covariation observed in POCAD550 suggest Fe/S compounds impact P capture.
- Aluminium, calcium, and silicon also showed potential roles in P capture.
Conclusions:
- Multiple mechanisms concurrently facilitate P capture in biochar.
- Biochar functionality for P capture can be tailored by manipulating feedstock and pyrolysis conditions.
- This research provides insights for developing enhanced biochar-based phosphorus recovery systems.