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Nuclear-grade Spent Organic Resin (SOR) contains high concentrations of radioactive nuclides and metal contaminants, while phosphate sludge contains high amount of fine clayey particles and CO

The leaching of rare earth elements (REEs) from secondary resources is exponentially increasing to supply the widespread range of high-tech applications of these elements including phosphors lighting materials, catalysis and permanent magnets. Phosphate fertilizer byproducts including phosphogypsum (PG) were identified as a potential alternative resource of REEs, not only to face the expansion of market demand, but also to achieve a sustainable management of REE resources. This study reports the leaching of REEs from PG using methanesulfonic acid (MSA) as a green organo-sulfonic acid in comparison with other acids such as

In this investigation, the effect of sodium hexafluorosilicate addition on the mechanical and microstructural properties of metakaolin-based geopolymers cured at ambient temperature was evaluated. The geopolymers were manufactured using metakaolin as a raw material with Sodium hexafluorosilicate Na2SiF6 powder as an additive, and a mixture composed of NaOH, KOH, and sodium silicate together as an activating solution. The amount of Na2SiF6 ranged from 1 to 5%, a (SiO2 / (Na2O + K2O)) modulus of 1.3 and a Si/Al ratio varied between 1.60 and 1.70. Geopolymer specimens cured at room temperature under air for 28 days were characterized, using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (ATG-DTG), scanning electron microscopy (SEM), and compressive tests to assess the microstructure-compressive strength dependency. The findings indicate that the addition of 2% Na2SiF6 improves the compressive strength by 28%, but beyond this value, the resistance progressively decreases, this observation was explained by the fact that this additive rises the Si/Al ratio, which led to an increase in the amount of strong Si-O-Si bonds. The reduced RC has been related to the excess amount of Na in the blend that promotes the formation of efflorescence, leading to crack formation, which negatively affects the mechanical properties.

Polysaccharides extracted from seaweeds can function as plant biostimulants. The aim of this study was to assess the effects of Polysaccharide Enriched Extracts (PEEs) obtained from 17 Moroccan seaweeds, on tomato seed germination and plant growth. Three concentrations (0.02, 0.05 and 0.1 mg mL−1) of PEEs were applied to tomato seeds to evaluate their effect on 3 germination parameters: germination percentage (GP), germination speed (GS) and mean germination time (MGT). Metabolomic analysis by GC–MS was subsequently performed on seedlings. In the second experiment, four PEEs concentrations (0.02, 0.05, 0.1 and 0.2 mg mL−1) were used as foliar spray or as soil application to tomato plants. Their growth parameters (number of leaves, shoot length, fresh and dry weight of stem and roots) and biochemical parameters (chlorophyll a and b) were measured. Results indicated a significant increase of GP and GS associated with a significant reduction of MGT of tomato seeds treated with 0.02 mg mL−1 of PEEs obtained from Gigartina sp., Gigartina pistillata, Chondracanthus acicularis, Gelidium crinale, Schizymenia dubyi, Cystoseira. foeniculacea and Fucus spiralis. Similar results were also obtained by application of higher PEEs concentration (0.1 mg mL−1) extracted from Ulva rigida, Codium tomentosum, Codium decorticatum and Bifurcaria bifurcata. Metabolomic analysis on seedlings detected the presence of some metabolites which could possibly be involved in seed germination enhancement or inhibition. The results of the second experiment showed that the same PEEs cited above at the same concentrations enhanced plant dry weight and chlorophyll a content except Gigartina sp., C. foeniculacea and C. decorticatum. Furthermore, soil application of PEEs was more effective in improving plant growth parameters than foliar application. The study shows the potential of PEEs from Moroccan seaweed to be used as biostimulants for a sustainable agriculture.

Phosphoric acid sludge is one of the prominent problems in the phosphate industry. Its production co-occurs with large losses of P2O5 that affect the process performance. Management and valorization of this waste is a key issue. For the industrial application in solid-liquid separation, selecting the suitable technique for an efficient separation is a fundamental factor. Most of the separation processes fail because of insufficient development effort in the laboratory phase and misunderstanding of separation objectives. The aim of this work is to deal with the P2O5 losses by studying their recovery from phosphoric sludge using a physical solid-liquid separation technique. Hence, laboratory tests have been conducted using vacuum filtration, centrifugation, and press filtration. The comparison was based on three requirements: the liquid recovery rate for each method, the amount of P2O5 recovered, and the solid content remaining in the recovered acid. Results showed that press filtration gave the higher performance of P2O5 recovery, up to 88.90%, followed by vacuum filtration with 69.81% and then centrifugation with 80.91%.

International audience; Thermal energy storage (TES) has been identified as a breakthrough concept in development of renewable technologies. However, the main challenges are related to the development of competitive heat storage materials. Despite the number of studies on heat storage materials, the determination of new alternatives for next generation technologies is still open. In this regard, this paper presents the results of an experimental study of the physical, thermal and mechanical properties of SiC-doped ceramics as potential materials for TES applications. Two kinds of SiC additives (high and low densities) were incorporated with different percentages into the clay matrix in order to produce ceramics via the extrusion process. The addition of low-density SiC (true density 3.16 g cm−3) led to the increasing of porosity with large pore sizes and the decreasing of bulk density. Therefore, the thermal and mechanical properties are decreased up to − 50% for flexural strength and − 15% for thermal conductivity when 20 mass% of low-density SiC was used. On the other hand, when high-density SiC (true density 3.42 g cm−3) was used, properties of the clay ceramic were strongly improved: i.e., increase in the bulk density, decrease in the porosity, increase in the thermal conductivity and increase in the flexural strength. The best material was found with the addition of 20 mass% of high-density SiC which had a thermal conductivity of 1 W m−1 K−1, a specific heat capacity of 0.62 kJ kg−1 K−1 and a mechanical strength of 19.6 MPa. It also showed a high thermal stability after 20 successive heating/cooling cycles. Hence, this study provided a useful insight into how the SiC modified the microstructure and properties of fired clay ceramics. Thus, the current results suggest that clay ceramics with high-density SiC addition are promising materials for thermal energy storage applications

Background: Seaweed-derived extracts have gained popularity in agriculture as bioproducts with phytostimulatory effects on plant growth and development. Methods: This study assessed the effect of polysaccharide-enriched extracts (PEEs) derived from six Moroccan seaweeds on tomato growth, yield, and fruit quality. PPEs were applied to tomato plants as soil drench in a greenhouse experiment. Growth parameters including plant height (cm) and number of leaves, flowers, and flower buds were recorded every 15 days. Yield and quality parameters of the harvested fruits were also recorded after each harvest. Results: The obtained results showed that all PEEs improved the growth, yield, and fruit quality of treated tomato plants. According to principal component analysis, the presence of SO4, galactose, glucose, and maltose in the characterized polysaccharides was closely associated with their effect on plant growth, yield, and fruit quality parameters. Conclusions: PEEs obtained from Gelidium crinale,Schizymenia dubyi, Fucus spiralis, and Bifurcaria bifurcata exhibited the highest biostimulant effects and could be used as bioproducts for improved tomato yield and fruit nutritional quality.

Rising global population and affluence are increasing demands for food production and the phosphorus (P) fertilizers needed to grow that food. Essential are new approaches for managing the growing amount of phosphogypsum (PG) that is a by-product of phosphoric-acid production from phosphate rock. Today, only ~15% of the worldwide production of PG is recycled, mainly for agriculture and road construction. This review addresses microbial valorization of PG through strategies that apply sulfur-transforming bacteria: sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB). The focus is on recovering elemental sulfur (S

Fluosilicic acid is a by-product of the chemical phosphate industry, mainly during the manufacture of phosphoric acid and triple super phosphate (TSP). To ensure the accurate measurement of the H2SiF6 mass fraction in this by-product, method validation is required, which needs a certified reference material (CRM) with its traceability to the International System of Units (SI). This work describes the development of a certified reference material of fluosilicic acid, which is commercially unavailable. Details of all steps, such as sample preparation, homogeneity and stability studies, value assignment, establishment of metrological traceability, and uncertainty estimation of the certified reference material, are fully described. The H2SiF6 mass fraction in the CRM was quantified by two analytical methods, i.e., UV-VIS as a primary method of analysis and flame mode atomic absorption spectroscopy (AAS) as a second method. It is worth noting that the results obtained from each method were in good agreement. The CRM certified value and corresponding expanded uncertainty, obtained from the combined standard uncertainty multiplied by the coverage factor (k = 2), for a confidence interval of 95%, was (91.5 &plusmn, 11.7) g&middot, kg&minus, 1. The shelf life of the developed CRM is determined to be 1 year, provided that storage conditions are ensured. The developed CRM can be applied to validate analytical methods, improve the accuracy of measurement data as well as to establish the meteorological traceability of analytical results.

The presence of organics materials in phosphate ores generates foam during the manufacture of phosphoric acid, thus affecting the production performance and the quality of the products. Today, in the phosphate industry defoamers are used to reduce the negative impact of foam phosphoric production. In the present work, we focusedon root cause evaluation for foam generation during the phosphoric acid production process, we evaluatedthe effect of phosphate rock quality in terms of organic carbon (OC) and carbonate content, on foam generation using a laboratory protocol for foaming ability evaluation. The results show that there is a relationship between the volume of the foam generated and the values of those impurities, while the volume of foam generated is higher when the concentration of OC and Carbonate is high. In our work, we confirm that the foaming ability of the phosphate rock can be avoided if the concentration of organic carbon less than 0.1% and less than 3% for carbonate.

International audience; Up-to-date, solar salt (a mixture of 60 mass% NaNO3 and 40 mass% KNO3) is practically the only media for thermal energy storage (TES) in concentrated solar power (CSP). This commercial product’s utilization is limited below 550 °C to avoid an irreversible thermal decomposition. The development of new performing TES materials is decisive for the deployment of CSP technology. Our recent work reported promising results obtained with mono-alkali polyphosphate (M-PO3) as TES materials. These materials can work up to around 900 °C, but their melting point is still high, which is at least 628 °C. In order to lower their melting point, binary and ternary mixtures of alkali polyphosphates are investigated in this work. Dif- ferent mixtures made of two or three alkali polyphosphates were prepared and studied using thermal analysis methods. The most promising mixture found in this work was the ternary Li-Na-K-PO3, which contained 33.3% (mol%) of each alkali metal. This mixture can be used as a liquid TES material in the temperature range of 398 to 900 °C. The results open new prospects for the development of the thermal energy storage field.

Various techniques have been used to “clean-up” industrial phosphoric acid: precipitation, flotation, activated charcoal or clay treatment. To address membrane processes potential in phosphoric acid clarification process, this study explores the advantage of membrane techniques as new route for phosphoric acid clarification in an eco-efficient way through the use of “regenerated spent membrane”. Regeneration of the spent membranes was performed on of 0.15 m2 active area regeneration. These membrane samples were used to study the phosphoric acid clarification at a laboratory scale. They were immersed in an oxidizer for at most seven days. The samples were characterized systematically before immersion in an oxidant media. In this study, the potential to regenerate spent membranes and application of this media to clarify the 29% P2O5 phosphoric acid was demonstrated. This study shows, by tests that the reverse osmosis (RO) membranes achieve an abatement of 70% and 65% for solids and organic materials, respectively. These positive results will pave the way for implementing these membranes phosphoric acid treatment process. Moreover, besides being economically advantageous, the use of the spent membrane is likely an environmentally friendly route (no waste, no organic solvent and effluent to be regenerated later on).

The coating of fertilizers by polymers is one of the most efficient tools for their slow and control release into soil. This strategy avoids excessive use of the fertilizers and increases their availability to the crops needs. In the present paper, hydro-soluble diammonium phosphates (DAP) fertilizer was double coated following the dip-coating process by chitosan-clay composites as inner coating and paraffin wax as an outer coating. The chitosan composite preparation and characterization were deeply investigated. The montmorillonite (MMT) clay incorporation as filler improves the water barrier diffusion, mechanical properties, and thermal stability of the composite. The combination of the swelling behavior of the chitosan-clay composite (inner coating) and the hydrophobic property of paraffin wax (outer coating) was confirmed by the water holding capacity evaluation and the phosphorus release essays in water and soil. Indeed, the phosphorus dissolution from the coated DAP granules was significantly delayed compared to the uncoated DAP. Moreover, the biodegradation study of composite material in soil and the biochemical oxygen demand (BOD) tests revealed that the coating system proposed could be considered as a carbon source for microorganisms after the fertilization process, which confirms its sustainability.

Various techniques have been used to “clean-up” wet-process phosphoric acid such as precipitation, flotation and adsorption. To address the potential of membrane processes in the phosphoric acid clarification process, this study explores the benefits of membrane techniques as a green separation technique for phosphoric acid clarification in an eco-efficient way through the use of recycling spent reverse osmosis membrane. Regenerated membrane was used to study the phosphoric acid clarification at a laboratory scale. They were immersed in an oxidizer for at most seven days. The samples were characterized systematically before immersion in an oxidant media. In this study, the potential to regenerate spent membranes and application of this media to clarify the 29% P2O5 phosphoric acid was demonstrated. This study shows, through experiments, that the reverse osmosis (RO) membranes could achieve a rejection of 70% and 61% for suspended solid and organic matter, respectively. These promising results will pave the way for implementation of these membranes in phosphoric acid treatment. Moreover, besides being economically advantageous, the use of the spent membrane is likely an environmentally friendly route (no waste, no organic solvent and effluent to be regenerated later on).

Upcycling phosphate mining sludges to produce a green cementitious binder, called geopolymer, has recently been implemented; although interesting, a thermal activation has been required to increase their reactivity, in detriment of the energy consumption, environmental footprint and costs. This paper provides an innovative approach to phosphate sludge disposal without any thermal activation, through a dual-alkali activation of NaOH–KOH for designing sustainable geopolymer coating binder of metakaolin with up-to 50 wt% replacement by un-calcined phosphate sludge (UPS). RSM-based statistical design was undertaken to optimize and understand the influence of design factors of activator modulus (MS), ageing time and thermal curing on compressive strength, apparent porosity and water absorption as targeted properties, through polynomial models. Optimal geopolymer testing included measurements of initial-final setting time and durability against 5% NaCl, 5% Na2SO4 and 2% HCl attack up to 3 months, through the visual examination, weight loss and flexural strength.The microstructures of the optimal binder highlighted significant changes in the geopolymeric network, including the formation of hybrid type gels (N,K)-A-S-H or (C,N,K)-A-S-H, silica gel and C-A-S-H/C–S–H co-existing with an inactive filler material exerted by unreacted particles. The optimal binder with RSM methodology reached in a high compressive strength of 49.78 ± 0.30 MPa at 26 days of curing, which obviously confirmed in terms of the microstructural features. A thermal curing (50C°) looks effective to maintain a suitable setting time while achieving excellent mechanical and chemical stability in aggressive environments. In these blends, the UPS chemistry is effective to improve both the mechanical and the durability properties where it acts basically as a barrier (chemical and/or physical) owing to the dual-alkali cations (MS = 1.32) in the activation solution. This study confirms the promise of using the elaborated UPS-MK based geopolymers as sustainable coating materials, which could substantially promote a cleaner production in the construction sector and phosphate mines.

In the present work we investigate the possibility of reusing phosphate sludge, which is considered as a mining by-product from beneficiation plants of the Moroccan phosphate rocks (OCP, Youssoufia), through the geopolymerization process. This process allows to evaluate the alkaline behaviour of thermally untreated phosphate sludge (UPS) as a partial replacement of metakaolin. The geopolymers were synthesized with various activator modulus (Ms = 1.40, 1.30, 1.24, 1.20, and 1.15) made from a mixture of different alkaline (NaOH and KOH) solutions and sodium silicate. The effect of 0–60% untreated sludge (UPS) powder in metakaolin based geopolymer materials cured at 60 °C was investigated. Compressive strength and apparent porosity were determined after 28 days of curing and the reaction products were tested by different techniques including: X-Ray Diffraction (XRD), Fourier Transformed Infrared spectroscopy (FTIR), thermal gravimetric analyses (TGA) and Electron microscope scanning coupled with energy dispersive spectroscopy (SEM-EDX). For up to 50% of UPS, physical properties of the hardened products are induced, especially when the activator modulus (Ms = 1.30) is used. In these blends, the presence of UPS is favorable to ensure the better connectivity between grains in the system. In fact, the sludge has been suggested to have a dual role, it has a filler effect and/or a small precipitation of Ca-bearing phases co-existing with (Na, K)-A-S-H-type gel.

International audience; The monitoring of the physical properties of fertilizers presents a lot of interest at different levels. All the problems related to the behavior of the granules (segregation, spreading, granulation, hardness…) need a better characterization of the fertilizers in order to understand and/or predict them.The scientific community is led to develop a variety of modeling approaches for, on the one hand, the understanding of the dynamics of impurities originating from phosphoric acid during the manufacture of fertilizers, and on the other hand, the evaluation of the effectiveness of measurements and data monitoring from production and the fluctuations in the physical quality of the fertilizers that follow. In this investigation of the influence of elements such as Fe, Al, Mg, F-, Si, Na, K and Cl on fertilizer quality, we gathered and followed-up data from production lines of Ammonium phosphate fertilizers for several months. The aim of the current work is the statistical study and modeling of the phosphoric acid impurities effect on the physical quality of fertilizers such as granulation yield, grain size, and the average diameter of granules D50, based on the analysis of data from different production lines by applying the Artificial Neural Network (ANN) approach. In addition models, were constructed using Multiple Linear Regression (MLR) and Principal Components Analysis (PCA).

International audience; Fertilizer producing entity, OCP group.SA, Jorf lasfar, BP118 – 24025 El Jadida, Maroc Ammonium phosphate fertilizer is produced by simple reaction (neutralization) between ammonia and phosphoric acid resulting in the formation of the basic salt.The knowledge of the physical properties of fertilizers presents a lot of interest at different level. All the problems dealing with the behavior of the particles (segregation, spreading, granulation, hardness…) need a better characterization of the fertilizers in order to understand and/or predict them.Several works were carried out to define and control the effect of impurities from phosphoric acid on the physicochemical properties of ammonium phosphates fertilizers. In the investigation of the influence of elements such as Fe, Al, MgO, F-, SiO2, Na2O, K2O and Cl- on fertilizer quality, we followed the production lines of Ammonium phosphate fertilizers for several months, even more than a year.The aim of the current work is the statistical study and modeling the effect of phosphoric acid qualities on the physical quality of fertilizers such as granulation yield, grain size, and the average diameter of granules D50, based on the analysis of data from different production lines by applying the Principal Components Analysis (PCA). In addition models were constructed using Multiple Linear Regression (MLR) and Artificial Neural Network (ANN).