Characteristics of conocarpus wastes and common reed biochars as a predictor of potential environmental and agronomic applications

Abstract

In current study physicochemical, elemental and nutriental properties of biochars produced from two types of municipal residues including conocarpus waste (CW) and common reed (CR) at three pyrolysis temperature (200, 350, and 500 °C) was to evaluate and that exploit the potentail of them as predictors of their suitability for soil and environmental amelioration purposes. The results indicated that pyrolysis temperature and feedstock types strongly influenced biochar properties. Comparison of CR and CW biochars indicated that CR biochar had greater volatile matter (10–45%), carbon contents (15–83%), anion exchange capacity (33–41%), specific surface area (15–38%), and total concentration of phosphorous (85–188%) and potassium (16–70%), while CW biochar had greater ash content (33–37%), nitrogen content (36–109%), and sulfur content (65–215%) as well as micronutrient concentration. Regardless of feedstock type, with raising pyrolysis temperature, the ash content, fixed carbon, pH, electrical conductivity, anion exchange capacity, aromatic compounds, and nutrient concentration increased. A great amount of nitrogen (0.88–1.74%), phosphorus (0.09–0.47 g kg−1), and potassium (0.43–1.50 g kg−1) concentration in biochars can be considered as a suitable source of nutrient for plants in less fertile soils. Therefore, according to the requirement, variety of biochars with different properties can be produced by selecting suitable feedstock and charring condition for agronomic and environmental uses. Application of external source of waste energy is also beneficial both financially and technologically alongside with alleviating nutrient leaching and improving soil quality and fertility state.Abbreviations CW: conocarpus waste; CR: common reed; MT: million tons; EC: electrical conductivity; CEC: cation exchange capacity; AEC: anion exchange capacity; C: carbon; O: oxygen; H: Hydrogen; Na: sodium; K: potassium; P: phosphorous; Fe: iron; Cu: copper; Zn: zinc; Mn: manganese; SSA: specific surface area BET: Brunauer–Emmett–Teller; SEM: scanning electron microscope; FT-IR: Fourier transform infrared spectroscopy

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