A Sustainable Solution to Obtain P-K-Mn Glass Fertilizers from Cheap and Readily Available Wastes

Abstract

The sustainable economy framework imposes the adoption of new ways for waste reuse and recycling. In this context, this paper proposes a new alternative to obtain glass fertilizers (agriglasses) by reusing two cheap and easily available wastes, wood ash and manganese rich sludge resulting from drinking water treatment processes for groundwater sources. Glasses were obtained using different amounts of wastes together with (NH4)2HPO4 and K2CO3 as raw materials. The P-K-Mn nutrient solubilization from the obtained glasses was investigated using a citric acid solution. The kinetics of the leaching process was studied after 1, 7, 14, 21 and 28 days, respectively. The intraparticle diffusion model was used to interpret kinetic data. Two distinct stages of the ion leaching process were recorded for all of the studied compositions: first through intraparticle diffusion (the rate-controlling stage) and second through diffusion through the particle–medium interface. The fertilization effect of the obtained agriglasses was studied on a barley crop. The specific plant growth parameters of germination percentage, average plant height, biomass and relative growth rate were determinate. The positive impact of the agriglasses upon the plants biomass and relative growth rate was highlighted. The effects of agriglasses can be tuned through glass compositions that affect the solubility of the nutrients.

Solid-state synthesis of cesium manganese halide nanocrystals in glass with bright and broad red emission for white LEDs

“…There is a broad absorption peak from 400 nm to 700 nm for all samples, corresponding to Mn 3+ . 34,39 The broad absorption peak gradually weakens with increasing Br/Mn molar ratio, indicating the decrease of Mn 3+ content. The reason for the decrease of Mn 3+ content is probably that Br − is more easily oxidized than Mn 2+ .…”

Structure and Properties of the Xerogels Based on Potassium Silicate Liquid Glass and Urea

“…The raw material mixtures were prepared by introduction of different quantity (100, 200, and 300 g) of powdered urea (Russian standard GOST 6691-77, purity of 99%) into 1 dm 3 (1280 g) of the 55% aqueous solution of the potassium silicate (commercial potassium silicate liquid glass SIL-EX (PSLG) characterized with the silicate modulus equal to 3.1). The above-mentioned doses of urea were selected to obtain the final products containing, in terms of dry residue, about 5–20% of nitrogenous compound, taking into account that such concentrations are recommended for slow and controlled release fertilizers [ 1 , 2 , 3 , 4 ] as optimal ones. The obtained dispersion was homogenized by stirrer until the total dissolution of urea.…”

“…The best way to solve this problem involves an introduction of the traditional nitrogenous fertilizer (KNO 3 , urea) into an oxide matrix. This approach would significantly increase the efficiency of fertilizers, reduce the amount of them applied to the soil and, as a result, decrease air and groundwater pollution [ 1 , 2 , 3 , 4 , 5 , 6 ].…”

“…Some complex vitreous fertilizers based on alkali silica and phosphate glasses forming a matrix to incorporate different nutrients are known [ 3 , 6 , 7 ]; however, it was impossible to introduce nitrogen in their structure due to high levels of their fusion temperature (T > 1000 °C) promoting thermal decomposition of nitrogen-containing compounds (ammonium salts, nitrates, or urea). An introduction of nitrogenous compounds in the porous matrix of silica–phosphate glasses [ 8 , 9 ] does not allow for resolving the above-mentioned problem and has a high cost.…”