certain negative environmental impacts. 45−47 Overall, decisive action is needed to ensure safe and sufficient N fertilizer supply under turbulent times, and sustainable chemistry and engineering have to play a significant role. This is substantiated by the fact that the population is projected to increase to ∼9.8 billion by 2050, while the N-rich protein diet is also expected to increase as 99% of the population growth from 2020 to 2050 is projected to occur in Asia and Africa, currently on a low-protein diet. 48 We hope that this editorial will stimulate and seed creative thinking in obtaining sustainable synthesis routes of efficient and stable N fertilizers from widely available waste, rather than utilizing natural gas.
To maintain high production and growing rates of plants, synthetically obtained fertilizers are commonly used. Excessive amounts of fertilizers damage the natural ecosystem and cause various environmental problems. In relation to the environment and its sustainability, another great environmental, economic, and social issue is food loss and waste. This paper aims to evaluate the impact of spent coffee grounds (SCG) on soil properties, rye growth, and their possibilities to be used as the biodegradable and organic material in the production of organic bulk fertilizer. This study demonstrated that spent coffee grounds contain primary nutrients; moreover, SCG could increase the content of soil organic matter. The addition of 4 wt% to 8 wt% SCG increased the number of spore-forming bacteria from <103 colony forming units/g soil (CFU/g soil) to 3 × 104 CFU/g soil, along with nitrogen assimilating bacteria (plain soil resulted in 5.0 × 105 CFU/g, and addition of SCG increased the value to 5.0 × 107 CFU/g). Since spent coffee grounds have a relatively high porosity and absorbance (25.3 ± 3.4 wt% in a water vapor environment and 4.0 ± 0.6 wt% in the environment of saturated sodium nitrate solution), they could be used to reduce the amount of water required for irrigation. To fully exploit their nutritional value for plants, spent coffee grounds were mixed with green algae biomass along with urea, and, during the research, higher value products (organic bulk fertilizer) were obtained.
Phosphate minerals play an important role in the natural cycle of phosphorous, both in the solid form used in agricultural applications and as aerosolized apatite mineral particles. Mineral surface aging processes, such as organic acid processing, have a significant effect on the phosphate particle physicochemical properties, particularly, their hygroscopicity. In this study, hydroxyapatite was used as a model for low solubility apatite phosphate minerals and subjected to acid processing with formic acid (FA) vapor to simulate the atmospheric processing caused by volatile organic compounds present in the troposphere. Hydroxyapatite particles were shown to react with the FA vapor to form Ca(HCOO) 2 on the particle surface, resulting in a heterogeneous microparticle surface, as evidenced by spatially resolved Raman spectroscopy. Due to the more soluble nature of the Ca(HCOO) 2 formed on the surface, the hygroscopicity of the acid-processed particle surfaces was shown to increase using dynamic vapor sorption studies. The maximum water uptake at 95% RH was shown to increase from 0.4 to 0.82% and 3.26% after 24 and 48 h of laboratory acid exposure, respectively. Conventional adsorption models, including Brunauer−Emmett−Teller and Freundlich, were used to fit the adsorption data. The heat of sorption values of the 48 h acid-exposed sample was shown to converge to the heat of condensation of water at higher coverage values compared to untreated and 24 h processed hydroxyapatite.
Urea cocrystal materials have recently emerged as high nitrogen (N) content fertilizers with low solubility capable of minimizing N loss and improving their use efficiency. However, their effects on crop productivity and N2O emissions remain underexplored. A greenhouse study was designed to evaluate sorghum (Sorghum bicolor (L.) Moench) yield, N uptake, and N2O emissions under six N treatments: C0 (without fertilizer), UR100 (urea), UC100 (CaSO4⋅4urea cocrystal) at 150 kg N ha−1, and CaSO4⋅4urea cocrystal at 40%, 70%, and 130% of 150 kg N ha−1 (UC40, UC70, and UC130, respectively). The results demonstrated that UR100, UC100, and UC130 had 51.4%, 87.5%, and 91.5% greater grain yields than the control. The soil nitrate and sulfur concentration, N uptake, and use efficiency were the greatest in UC130, while UR100 had significantly greater N2O loss within the first week of N application than the control and all the urea cocrystal treatments. UC130 minimized the rapid N loss in the environment as N2O emissions shortly after fertilizer application. Results of this study suggest the positive role of urea cocrystal in providing a balanced N supply and increasing crop yield in a more environmentally friendly way than urea alone. It could be good alternative fertilizer to minimize N loss as N2O emissions and significantly increase the N use efficiency in sorghum.
The main purpose of this thesis was to determine chemical and physical properties of spent coffee grounds (SCG) and evaluate their application in organic fertilizers industry. During the experiment, some physical properties, like particle size distribution and pH level of spent coffee grounds solutions of different concentration, were determined. Two different methods have been chosen to determine carbon content in coffee grounds. Also, several instrumental analysis methods have been used to analyse coffee grounds. The results show that spent grounds are not very acidic, values of 10% solution vary between 5.2–5.8. The concentration of organic carbon is quite high and varies between 4.75–5.74%. The TGA and DSC curves show three-stage decomposition. Above 400℃ spent coffee grounds fully decompose. The total mass loss of SCG varies between 97–98%. Functional groups (such as O–H, C=O) were determined by using FTIR spectroscopy. It is clear from XRD that spent coffee grounds are amorphous material. The SEM results show that particles of coffee grounds have high porosity. A drum granulator was used to make granular fertilizers by using water and phosphoric acid solution, but no pellet was obtained without an additional binder.
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