Adsorption of Phosphorus and Its Fertilization and Porous Sorbent Using Calcium and Dissolving Magnesium

Aims: The aim of this research was to investigate Magnesium hydroxide [Mg(OH)2] and nano calcium treatments for the utilization of spent coffee grounds (SCG) and formed waste glass. Adsorption of phosphate, potassium, and phosphate on the surface of the magnesium-modified SCG or formed waste glass was measured. The effect of the potassium magnesium phosphate formed on the SCG and nano calcium phosphate on plant growth was evaluated.

Methods: The adsorption characteristics for phosphorus and potassium were studied using a batch method to determine the effect of the magnesium concentration on the modified SCG and the side effects of nano calcium.

After adsorption, the modified SCG product and nano calcium phosphate were applied to the soil, and plant growth tests were carried out in pots.

Results: The maximum phosphate adsorption (65.89% at a phosphate concentration of 45.98 mg/g) was obtained with 2.5 M Mg(OH)2. When the post-equilibrium pH was close to 9, the ratio of the changes in the concentrations of potassium to phosphate was 1:1, and potassium magnesium phosphate formed on the surface of the modified SCG. The use of nano calcium resulted in a high adsorption capacity of 62 mg/g phosphorus. By considering separation and supporting it on foam glass, a removal rate of more than 90% was achieved for a phosphoric acid solution with an initial concentration of 100 mg/l.

Conclusion: Calcium hydroxide and nano-sized calcium with low solubility could also be supported on inexpensive porous materials to show the ability to recover phosphorus and potassium, or higher adsorption capacities. The potassium magnesium phosphate and calcium phosphate, produced per carrier, were mixed with soil and used in planting experiments, which demonstrated a discernible impact on growth. The application of a fertilizer prepared from EMSCG was observed to have a beneficial effect on the growth of R. sativus, resulting in an increase in both plant height and leaf width in comparison to the control (no treatment).