الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
This research provides a circular win-win approach for recycling rhizofiltration biomass into multifunctional engineered biochar for various environmental applications (e.g. phosphate recovery) with a potential reuse of the exhausted biochar as an enriched soil amendment. Functionalized biochars were derived from the disposals of water hyacinth (Eichhornia crassipes) plants grown in synthetic contaminated water spiked with either Fe+2 (Fe-B), Mn+2 (Mn-B), Zn+2 (Zn-B) or Cu+2 (Cu-B) comparing with the original drainage water as a control treatment (O-B). The in-situ functionalization of biochar via the inherently heavy metal-rich feedstock produced homogenous organo-mineral complexes on biochar matrix without environmental hazards (e.g. volatilization or chemical sludge formation) associated with other post-synthetic functionalization methods. Physicochemical analyses (SEM-EDS, XRD, FTIR, BET and zeta potential (ζ)) confirmed the functionalization of Fe-B, Zn-B and Cu-B due to organo-mineral complexes formation, maximizing specific surface area, lowering the electronegativity, originating positively charged functional groups, and thus improving the anion exchange capacity (AEC) comparing with O-B. In contrary, physicochemical characteristics of Mn-B was in similarity with those of O-B. Phosphate recovery by the functionalized biochar was much greater than that of the unfunctionalized forms (O-and Mn-B). Precipitation was the dominant chemisorption mechanisms for phosphate sorption onto biochar compared to other mechanisms (ion exchange, electrostatic attraction and complexation with active functional groups). The exhausted biochar showed an ameliorating effect on the low water and nutrient supply potentials of sandy soil, and thus improved fresh biomass yield and nutritional status of maize seedlings with some restrictions on its high micronutrient content.
Aim of the work : studying the effect of rich heavy metals content of water hyacinth disposals on biochar production and functionalization, evaluating and modeling phosphate recovery by the engineered biochars under kinetic and isothermal batch sorption experiments, studying mechanisms responsible for phosphate sorption by the engineered biochars, studying the effect of the exhausted biochar on water and nutrient supply potentials of sandy soil, and studying the beneficial effect of the exhausted biochar additives on maize seedlings grown in sandy soil. Conclusion: Finding from this study is providing an innovative and cost-effective technique for disposing heavy metal-rich biomass into value-added functionalized biochar.