Production of zeolitic materials in pilot scale based on coal ash for phosphate and potassium adsorption in order to obtain fertilizer

Abstract

The use of different types of zeolites (X, Na-P1, and 4A) synthesized by different methods and scales were tested in this work to adsorb nutrients present in synthetic solutions and industrial effluents for later application as fertilizer. Modifications with calcium chloride were performed on the zeolite with the best performance to increase its adsorption capacity. The best performing zeolite was type X (ZXH) produced on a pilot scale by the hydrothermal process. Its adsorption capacity without modification was 149 mg P-PO 4 /g zeolite and 349 mg K/g zeolite. With the change, there was a fourfold increase in these results, which were up to threefold higher than reported in the literature. The kinetic model that best characterized the adsorption process was the intraparticle diffusion model, and the equilibrium isotherm was that of Freundlich. The adsorption tests performed with industrial effluent showed high removal of the nutrients of interest (> 90% for PO 4 3− and > 95% for K + ). The desorption tests with zeolites nutrient-loaded from synthetic solutions showed 13 to 24% PO 4 3− and 14 to 47% K + release within 24 h, while for zeolite nutrient-loaded from effluent the release were 7 and 100% for PO 4 3− and K + , respectively. The results we obtained in this work indicated the potential use of zeolites in the treatment of effluent and its application as a fertilizer.

Geopolymer Foam Reinforced with Iron Ore Flotation Tailing for Potassium Adsorption and Controlled Release in Water

“…The final potassium concentrations of these tests were analyzed by atomic absorption spectrometry (AAS), Varian equipment, and model AA240FS. The Lagergren’s integrated model of pseudo-first-order (eq ), pseudo-second-order (eq ), and the intraparticle diffusion model proposed by Weber and Morris (eq ) were applied to the data, for the initial conditions of q = 0 and t = 0. ,− q t = q e false( 1 − exp ( − k 1 t ) ) q t = q e 2 k 2 t 1 + q e k 2 t q t = k id t + C where q t is the potassium adsorption capacity (mg/g), q e is the potassium adsorption capacity at equilibrium (mg/g), t is the time (min), k 1 is the rate constant (min –1 ), k 2 is the constant of pseudo-second-order rate (g·mg –1 ·min –1 ), k id is the intraparticle diffusion rate constant (mg·g –1 ·min –0.5 ), and C is the initial adsorption capacity (intersection with the q t axis) (mg/g).…”

Zeolites synthesized from agro‐industrial residues applied in agriculture: A review and future prospects

“…Results showed that wheat and maize yield increased by 16.0% and 35.0%, respectively under the combination of the treatments, when compared to crops grown on unamended soil, irrigated with lower leaching fraction and planted using conventional methods. Bonetti et al (2021) synthesized zeolites type X from coal ash, loaded them with macronutrients such as phosphorus and potassium, and applied them as fertilizers in the cultivation of Tagetes patula. Results showed that the leaching of nutrients occurred gradually, being available during the entire period of plant development.…”

“…Bonetti et al. (2021) synthesized zeolites type X from coal ash, loaded them with macronutrients such as phosphorus and potassium, and applied them as fertilizers in the cultivation of Tagetes patula. Results showed that the leaching of nutrients occurred gradually, being available during the entire period of plant development.…”

“…Studies have verified that zeolites produced using low‐cost precursors (residues), such as coal fly ash, rice husk ash and sugarcane ash, exhibited potential as a controlled‐release fertilizer (Bonetti et al., 2021; Estevam et al., 2021; Hermassi et al., 2020; Inácio, 2016). Mallapur and Oubagaranadin (2017) presented a complete review of zeolite synthesis by using different types of residues.…”

“…The best performing zeolite was type X produced on a pilot scale by the hydrothermal process. The release of nutrients from modified zeolites X occurred slowly and gradually, which drives the use of this material as fertilizer (Bonetti et al., 2021).…”