Mg modified nanobiochar from spent coffee grounds: Evaluation of the phosphate removal efficiency and its application as a phosphorous release fertilizer

Abstract

Phosphate enrichment of the aquatic system often impacts their aesthetic and ecological values. Hence, phosphate recovery is essential to maintain the quality of aquatic systems and ensure sustainable use of phosphorous. Herein, Mg-modified nanobiochar from spent coffee grounds (Mg/NBC) is proposed as an efficient adsorbent for phosphate recovery, and as a phosphorous-release fertilizer. The nanobiochar was obtained by acid digestion of the biochar resulting from pyrolysis. The effect of parameters viz pH, contact time, the dose of adsorbent, and initial concentration on the adsorption was investigated in batch experiments. Results indicated that phosphate adsorption on Mg/NBC is favored in acidic conditions with maximum adsorption (95%) at pH 1. Mg/NBC showed a 12.84% improvement in the adsorption efficiency than the pristine nanobiochar. Characterizations of the adsorbent before and after adsorption suggested that phosphate is involved in both physisorption and chemisorption. Adsorption of phosphate followed pseudo-second-order kinetics with an equilibrium constant (K2) of 0.029 g/mg.min. The Langmuir adsorption isotherm model is better fitted to the equilibrium data with a maximum adsorption capacity of 100 mg/g suggesting uniform monolayer adsorption. Results of the pot test showed that phosphate-laden Mg/NBC improved the growth of garlic and beans by 10 and 5% respectively. The result highlights the utility of phosphate-laden Mg/NBC as a phosphorous-release fertilizer and illustrates a circular economy approach for spent coffee grounds.

Copper Oxide Nano Biochar from Spent Coffee Grounds for Phosphate Removal and its Application as an Antibacterially Active Entity

“…The process was typically allowed to finish in a fume hood after 1.0 g of the resulting biochar was put into a hydrothermal autoclave reactor holding 60.0 mL of concentrated HNO3 and H2SO4 (1:3 ratio). Finally, the product was collected, filtered, washed, and stored for further experiments (1,5). The coprecipitation of metal ions allowed for the modification of nanobiochar.…”

“…Phosphorus is necessary for the growth of plants and is essential for all living things. Rock phosphate is a finite resource that is tapped into for fertilizer production, food production, and contemporary farming (1). Phosphate accumulates in water systems due to industrial and agricultural discharge.…”

Copper oxide nanobiochar from spent coffee grounds for phosphate removal and its application as an antibacterial activity

“…At various temperatures (250, 350, and 450 o C), the cleaned spent coffee grounds were treated to gradual pyrolysis in a mu e furnace. To create uniform-sized particles, the obtained biochar was mashed in a mortar and pestle and sieved using a 150.0 m mesh (6,14). The size of the biochar particles was reduced by acid digestion in a hydrothermal autoclave reactor.…”

“…After allowing the reaction mixture to sit for 24 hrs, the precipitate was ultimately removed, cleaned, and kept for later investigations as shown in Fig. 1 (14).…”

“…Quanti cation of the residual phosphate concentration was measured by the ascorbic acid method (Method, 1978) using a calibration curve from phosphate external standards (1,12,14,15). The removal e ciency and the amount of phosphate adsorbed were determined by using equations ( 1) and ( 2…”