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Engineered Biochar Reclaiming Phosphate from Aqueous Solutions: Mechanisms and Potential Application as a Slow-Release Fertilizer

Author:
Yao, Ying, Gao, Bin, Chen, Jianjun, Yang, Liuyan
Source:
Environmental Science & Technology 2013 v.47 no.15 pp. 8700-8708
ISSN:
1520-5851
Subject:
aqueous solutions, biochar, chemical reactions, crystals, grass seed, magnesium, mathematical models, phosphates, phosphorus fertilizers, seed germination, slow-release fertilizers, soil, sorption, tissues, tomatoes
Abstract:
This work explored the potential application of an engineered biochar prepared from Mg-enriched tomato tissues to reclaim and reuse phosphate (P) from aqueous solution. Findings from batch sorption experiments suggested that, although sorption of P on the biochar was controlled by relatively slow kinetics, the maximum P sorption capacity of the biochar could reach >100 mg·g–¹. Mathematical modeling and postsorption characterization results indicated that the sorption was mainly controlled by two mechanisms: precipitation of P through chemical reaction with Mg particles and surface deposition of P on Mg crystals on biochar surfaces. Most of the P retained in the engineered biochar was bioavailable and could be released equally at multiple successive extractions. In addition, the P-laden biochar significantly stimulated grass seed germination and growth. These results suggested the postsorption biochar can be cycled back directly to soils as an effective slow-release P-fertilizer.
Agid:
5347419