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.
This study aims to assess methane (CH 4) and carbon dioxide (CO 2) concentrations in the ventilation systems of two coal mines (A and B) in the Santa Catarina coal deposit in southern Brazil (Paraná Basin, Bonito Formation), and estimate their greenhouse gas (GHG) emissions. The highest CH 4 levels (1.8%) were recorded in strong methane emanation areas in mine A, below the lower explosive limit (5%). The IPCCrecommended methods significantly overestimated the methane emission (up to 80%) when compared to the experimental data measured for each mine. Application of an alternative method made it possible to estimate direct CO 2 emissions, indicating that CO 2 accounted for 22 to 77% of total GHG emissions. Carbon dioxide emissions are generally not included in GHG emission inventories, indicating that the coal industry underestimates the contribution of this gas. As such, it is recommended that the methodology used for these calculations be revised and that specific emission factors be applied for each mine. In order to improve the accuracy of inventories, more sampling needs to be carried out in all operational and abandoned mines.
The objectives of this study were twofold: to assess two chromatographic methods for the analysis of greenhouse gases (GHG) and carbon monoxide, and to propose and evaluate a low-cost and reusable alternative system for their sampling and storage, using 10 different container configurations (flasks and bags). To that end, standard samples containing the gases of interest (CO 2 , CH 4 and CO) and different types of real samples were tested. Finally, procedures for the sampling, storage and analysis of CO 2 and CH 4 were evaluated and optimized. Two chromatographic methods were applied, using different analysis conditions and columns. Gas chromatography analysis of sample stability and container reusability demonstrated that borosilicate flasks with butyl rubber and PTFE/silicone septa are ideal for storing samples, allowing up to 5 successive sampling cycles with no significant loss of recovery. For larger volume samples, multilayer foil bags are the most stable for the compounds analyzed. The tests conducted with real and synthetic gas samples under optimized chromatography conditions using both methods indicated satisfactory performance for CO 2 and CH 4 quantification. However, CO analysis in the column with a polystyrene-divinylbenzene stationary phase (Method 1) produced an artifact due to the presence of oxygen in the samples, restricting its quantification.
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