Abstraction of nitrates and phosphates from water by sawdust- and rice husk-derived biochars: Their potential as N- and P-loaded fertilizer for plant productivity in nutrient deficient soil (original) (raw)

Journal of Analytical and Applied Pyrolysis, 2021

Abstract

Abstract Biochars were produced by pyrolyzing the rice husk and sawdust at two temperatures of 300 °C (low-temperature) and 700 °C (high-temperature) and tested for the removal performance for nitrates and phosphates in water via batch sorption experiments. The resulting N- and P-loaded biochars were then applied to soil to evaluate their impact on maize growth. Adsorption kinetics experiments indicated a relatively high rate of adsorption of nitrates (up to 2.469 mg g−1 h−1) onto biochars than phosphates (up to 0.456 mg g−1 h−1). The high-temperature biochar showed greater adsorption capacity (up to 95.42 mg g−1) for nitrates, while low-temperature biochar exhibited more adsorption (up to 47.18 mg g−1) for phosphates. Chemisorption was the dominant mechanism for the adsorption of nitrate onto high-temperature biochars, as indicated by the best fitting of the sorption data to the pseudo-second-order model (R2 > 0.96). Phosphate adsorption onto low-temperature biochars was mainly governed by pore diffusion and chemisorption, as predicted from the best fits to the intra-particle diffusion (R2 ≥ 0.96) and pseudo-second-order (R2 ≥ 0.84) models, respectively. The results of plant growth experiments indicated positive effects on maize productivity in soils amended with N- and P-loaded biochars, which was confirmed by the increase in the fresh and dry biomass weights (up to 803 and 733 %, respectively) and greater uptake of essential nutrients (Zn up to 554 %, Mn up to 954 %, Fe up to 325 %, Ca up to 537 % and Mg up to 531 %) in maize plants as compared to the control.

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