Ultrasound-Assisted Synthesis of Humic-Silica Composites by the Isolation of Humic Substances from Peat and Lignite.

The aim of the presented study was to evaluate an integrated, direct procedure for the synthesis of humic-silica composites (HSiC) by the isolation of humic substances (HS) from peat and lignite by the use of sodium silicate solution as an extractant. The obtained materials, because of the presence of humic functional groups, may potentially be used for removing contaminants from aqueous solutions. The quantitative assessment was based on experiments designed according to the Box-Behnken plan. The statistical analysis of the results allowed to determine the optimal conditions of the process tested, for which the isolation efficiency of humic substances (HS) was greater than 50 % for both raw materials. This made it possible to synthesize humic silica composites with a high content of HS, which have been qualitatively evaluated. This step was focused on the analysis of the humic structure using elemental analysis, spectroscopic methods, and differential thermal analysis coupled with thermogravimetry. On the basis of them, the presence of structures characteristic for HS in the HSiC tested was observed. Moreover, the results of the thermal analysis pointed to the higher thermal stability of the synthesized compounds, compared to the HS isolated with the use of a traditional extractant.

Thermal Characteristics of Selected Phosphate Ores and the Effect of Inorganic Salts on Their Calcination.

Calcination of phosphate ore is one of the methods of ore processing, i.e., increasing the phosphorus content (P2O5) in the ore. However, this process is very energy-intensive and not economically justified in most cases. It can be improved by using additives to lower the required calcination temperature. In this work, several samples of phosphate ores were subjected to thermal analysis using thermogravimetry coupled with mass spectrometry (TG-MS) to study their behavior during the calcination process. Then, selected phosphate ore from the Tunisian deposit was mixed with NaCl, KNO3, or Na2CO3 and calcined in various regimes (temperature and time). Uncalcined samples, together with obtained calcinates, were also subjected to thermal analysis by TG-MS. Temperature ranges in which the mass loss occurred were defined and discussed. Appropriate models of sample weight loss were derived and visualized by using the response surface methodology. Explanations of possible processes observed during the heating of phosphate ore samples with inorganic salt addition were proposed.

Ultrasound-Assisted Extraction of Humic Substances from Peat: Assessment of Process Efficiency and Products' Quality.

Results of efficiency of obtaining humic substances (HSs) from peat in traditional alkaline extraction (TAE) and ultrasound-assisted alkaline extraction (UAAE) are presented. The influence of the duration of the process and ultrasound intensity on the efficiency of extraction of humic acids (HAs) and fulvic acids (FAs) extraction was determined. The composition of the fulvic acid fraction was examined depending on the type of eluent used. Fulvic acids were divided into fractions using columns packed with DAX-8 resin. For this process, 0.1 M NaOH and 0.5 M NH3∙H2O were used as eluents. For the quality assessment of specific fulvic acids fractions, spectroscopic methods (UV-Vis and FTIR) were used. Ultrasound had a positive effect on HS extraction efficiency, especially in increasing the amount of a desired hydrophobic fraction of fulvic acids (HPO). However, a negative effect of the excessive prolongation and ultrasound intensity (approximately 400 mW∙cm-2) on the extraction efficiency of HPO eluted with 0.1 M NaOH solution was observed. Using peat as a raw carbon material for the HS extraction process can be used as an alternative industrial application of peat. UAAE may be considered as an alternative method to TAE, which provides a higher efficiency in HS isolation from peat.

Anti-Caking Coatings for Improving the Useful Properties of Ammonium Nitrate Fertilizers with Composition Modeling Using Box-Behnken Design.

Granular fertilizers (especially those based on ammonium nitrate (AN)) tend to agglomerate during storage. The aims of this research were to develop effective anti-caking coatings for ammonium nitrate fertilizers while improving the quality of fertilizers and to optimize the composition of effective anti-caking coatings. The influence of the composition of the prepared organic coatings on the effectiveness of preventing the caking of fertilizers was studied by response surface methodology (RSM) using Box-Behnken design (BBD). Additionally, the effect of the developed anti-caking agents on the quality of fertilizers was determined by measuring the crushing strength of the granules. The prepared coatings included fatty amine, stearic acid, surfactant, and paraffin wax. Gas chromatography-mass spectrometry (GC-MS) was used to analyze these coatings. The morphology of the fertilizers were examined by scanning electron microscopy (SEM). Composition studies, based on statistical assessment, showed the coating components had a varying influence on preventing the caking of fertilizers after granulation and after 30 days of storage. The results demonstrated that increasing the content of fatty amines and reducing surfactant in the composition of coating had positive effects on caking prevention. In this study, more effective and economically viable anti-caking coatings were developed. In addition, the present work could serve as a basis to further improve anti-caking coatings.

Chemical Stability of the Fertilizer Chelates Fe-EDDHA and Fe-EDDHSA over Time.

In application conditions, the influence of environmental parameters on used fertilizer chelates and their distribution over time is important. For this purpose, the changes in the content of micronutrient ions and Fe-EDDHA and Fe-EDDHSA chelates in an aqueous medium at different pH values were studied. In the assumed time, changes in the ions content were analyzed using the voltammetry method at pH 3, 5 and 7. The content of isomers and chelate forms was analyzed by ion pair chromatography at pH 3, 5 and 7. These studies allowed us to determine the effect of pH on the stability of iron chelates over time.

Pig manure treatment by filtration.

A study of new pig manure treatment and filtration process was carried out. The advantage of the worked out technology is the method of incorporation of crystalline phase into solid organic part of manure. The obtained new solid phase of manure contains about 50% of crystalline phase forming a filtration aid that enables high effectiveness of manure filtration. The filtration rate of manure separation into solid and liquid fractions with pressure filter may achieve 1300-3000 kg/m(2)/h. The method makes it possible to maintain an overall average pollutant removal performance 90% for the chemical oxygen demand COD, > 99% for the suspended solids SS, to 47% for the total nitrogen content. The obtained results showed that the proposed technology being efficient and simple offers a possible solution to pig manure problems.