Commercial Phosphoric Acid Research Articles

Studies on uranium sorption from Egyptian wet-process phosphoric acid using silicone rubber modified with thiourea and methyl methacrylate composite

ABSTRACT The application of silicone rubber modified by thiourea and methyl methacrylate composite SRTM aimed at the sorption of uranium from commercial phosphoric acid is the highest objective of this examination effort. The impact of various factors on sorption efficiency for example adsorbent dose (g/ml), temperature, phosphoric acid concentration, and shaking time have remained studied. XRD, XRF, EDX, SEM, Zeta potential, BET, and FTIR analyses remained carried out to determine the properties of the produced composite. The attained results showed the sorption capacity for uranium as 25.19 mg g− 1 at the mentioned conditions; commercial phosphoric acid, 30% P2O5, 120 min, and room temperature. The investigational documents have been designated fine with pseudo-second-order kinetic scientific calculations. Balance process described by isotherm model’s Langmuir. uranium sorption thermodynamic considerations showed a spontaneous procedure and exothermic nature (ΔG (kJ/mol) = −13.8:-11.3, ∆H(kJ/mol) = −34.9, ∆S (J/mol K) = −70.9). Mechanism and reusability sorption were studied and Desorption efficiencies of about 95% for U (VI) were achieved using 1.0 M sulphuric acid solution.

Recycling waste polymer packaging materials as effective active carbon porous materials for uranium removal from commercial phosphoric acid

Abstract Plastic packaging waste is considered a serious threat to the environment due to its non-biodegradable nature. Transforming plastic waste into active carbons using pyrolysis methods could be a valuable option to solve the challenge of plastic waste. Synthesized active carbon was differentiated using zeta potential, particle size, SEM, BET, and DSC. This study also investigates the use of obtained active carbons for U(VI) removal from commercial phosphoric acid. The kinetics of adsorption were found to follow the pseudo-second-order model and intra-particle diffusion as one of the controlling mechanisms. Langmuir, and Freundlich, isotherms were employed to explore the equilibrium data. Furthermore, thermodynamic investigations revealed that uranium uptake is an endothermic, feasible, and spontaneous process. The present study concludes that plastic waste-based activated carbon could be employed as a low-cost alternative to commercial activated carbon for uranium removal from phosphoric acid and the production of green fertilizers.

Kaolinite/thiourea-formaldehyde composite for efficient U(VI) sorption from commercial phosphoric acid

Abstract Uranium removal from wet phosphoric acid is a vital process for food and environmental security. The incorporation of thiourea-formaldehyde into the kaolinite networks was performed to obtain an effective and acid-resistant sorbent. The prepared composite was applied for U(VI) uptake from crude phosphoric acid. X-ray diffraction, EDX, scanning electron microscopy, and Fourier transform infrared analyses were carried out to explore the properties of the yield composite. The sorption characteristics, i.e., capacity, kinetic, isotherm, and thermodynamic were investigated. The anticipated data declare that the reaction is fast whereas 60 min is sufficient to reach the equilibrium state. The experimental results obeyed to Pseudo second-order kinetic model and Langmuir isotherm model. The maximum sorption capacity was about 5.8 mg g−1. Thermodynamic parameters displayed that the sorption process is endothermic, feasible, and spontaneous. The displayed results demonstrate that the prepared composite could be used as the proper material for producing eco-friendly fertilizers.

The influence of intrinsically proton conductive electrode binder materials on HT-PEMFC performance

High temperature proton exchange membrane fuel cells (HT-PEMFCs) typically employ either acid-absorbing or hydrophobic electrode binders in their catalyst layers (CLs). A recently introduced alternative is the ionomeric binder PWN, poly(2,3,5,6-tetrafluorostyrene-4-phosphonic acid). In literature, PWN with a phosphonation degree of 70% was shown to remarkably improve HT-PEMFC performance. Here, we investigate the influence of the phosphonation degree (40–95%) of this ionomeric binder on HT-PEMFC performance. PWN is employed in the cathode CL and compared to the commonly used polytetrafluoroethylene (PTFE) binder. The electrochemical behavior is tested at 180 °C at ambient pressure under H2/air conditions using a commercial phosphoric acid (PA)-doped PBI-membrane. HT-PEMFCs with PWN generally outperform fuel cells (FCs) with PTFE after a full break-in regarding peak power density (PPD), activation overpotential (as studied by Tafel analysis), and reproducibility in the mass transport region. Further, PWN-electrodes show higher electrochemically active surface areas (ECSAs) than PTFE-electrodes after completing the break-in. We find that the phosphonation degree has a substantial impact on the PPD, with PWNs with lower phosphonation degrees (40–60%) outperforming highly phosphonated PWNs (70–95%). Taken together, PWN as an ionomeric electrode binder in HT-PEMFCs shows remarkable improvements in performance, but a precise adjustment of the phosphonation degree is required to obtain optimal results.

Kinetic and equilibrium studies for U(VI) and Cd(II) sorption from commercial phosphoric acid using C100H resin

Kinetic and equilibrium studies for U(VI) and Cd(II) sorption from commercial phosphoric acid using C100H resin

Sorption Extraction of Rare Earth Metals from Wet-Process Phosphoric Acid

When apatites and phosphorites are processed, up to 30% of rare earth metals are converted into wet-process phosphoric acid. Wet-process phosphoric acid from the phosphorite treatment process differs from apatite one by impurity composition, i.e. the iron content is by 3.5 times, and calcium is by 5.0 times more. The complex composition of the wet-process phosphoric acid from the phosphorite treatment process requires additional researches to select optimal ion exchangers and technological parameters of sorption. Various aspects of sorption have been studied to select the optimal ion exchangers and technological parameters, and technological modes for desorption of rare earth metals from a cation exchanger to obtain a concentrate of rare earth metals have been completed. The method enables to extract rare earth metals without changing the composition of commercial wet-process phosphoric acid directly in the production process of the enterprises engaged in the phosphorite treatment process.

Investigation of Phosphate based geopolymers formation mechanism

In the present research, phosphate-based geopolymers were prepared from metakaolin and commercial phosphoric acid H3PO4. The paper aims to observe and identify the different chemical early steps of the material formation mechanism, as well as the kinetics of each step. To achieve this goal, an investigation upon the reaction with respect to time has been fulfilled, using different techniques such as atomic absorption measurements, in situ quasi-isothermal Differential Scanning Calorimetry (DSC), pH-metry measurements, Scanning Electron Microscope (SEM) with Energy-dispersive X-ray (EDX) analysis, X-ray diffraction, magic angle spinning Nuclear Magnetic Resonance (MAS-NMR) and Fourier Transform Infrared spectroscopy (FTIR). As a result, a composite structure composed of amorphous aluminum phosphate phases and amorphous silica phases dispersed in a geopolymeric amorphous structure of (-Si-O-Al-O-P-) units with the presence of some terminal-Si-O-P units, was observed. Furthermore, the techniques combination suggested a geopolymeric mechanism composed principally of three great processes: the first one stands for the dealumination process. It was proved that this process is divided into two elementary overlapping steps. The second one corresponds to the condensation process. It was proved that this process is divided into four types of condensation, according to the chemical nature of the reactant units as well as that of the obtained ones. Eventually, the last one represents the polycondensation step, resulting in the finally polymerized 3D structure. In addition, this work monitored the duration and the kinetics of each geopolymeric step.

Sorption of U(VI), Mn (II), Cu(II), Zn(II), and Cd(II) from multi-component phosphoric acid solutions using MARATHON C resin.

Crude phosphoric acid is a vital component used in making phosphate fertilizers. Depending on the processes used in producing the crude phosphoric acid, it usually contains organic and inorganic contaminants. To make environmentally friendly phosphate fertilizers, these contaminants must be removed from the crude phosphoric acid stock used in making fertilizers. In this paper, commercially available strong cation exchange resin, Marathon C, was used to study the adsorptive removal of U(IV), Mn(II), Cd(II), Zn(II), and Cu(II) from synthetic multi-component phosphoric acid solutions and commercial crude phosphoric acid. Important parameters on the adsorption process such as the effects of contact time, initial metal ion concentration, sorbent dose, and concentration of phosphoric acid were investigated. The results suggested that the adsorption process reached equilibrium within 240min for the five metal ions studied and the resin had adsorptive affinity for the metal ions in the order of U(IV) > Zn(II) > Cu(II) > Mn(II) > Cd(II). The results from the kinetics and isotherm models from the studies are very consistent with pseudo-second-order kinetic and Langmuir isotherm models. Simultaneous adsorptive removal of metal ions from the crude phosphoric acid strongly suggests that the Marathon C resin could be used in removing toxic metal ions from crude phosphoric acids used in making phosphate fertilizer.

Uranium Separation from Phosphoric Acid Using Metallic Carbonaceous Structures as Efficient Adsorbents: an Experimental and Kinetic Study

The possibility of removing uranium species from commercial phosphoric acid using metal-modified biocarbon was examined. The biocarbon was prepared from a solid residue by pyrolysis and was activated by chemical precipitation. The structural characteristics and morphology of the composite prepared were determined, and it was tested in U separation. The influence of various factors such as shaking time, adsorbent dosage (g/mL), temperature, mechanical stirring speed, and phosphoric acid concentration on the uranium adsorption was examined. The results obtained show that the U adsorption process is applicable to both concentrated and dilute phosphoric acid, but is more efficient in the case of the dilute acid. The adsorption kinetics was described by the Lagergren first-order and pseudo-second-order models. The process was applied to uranium adsorption from commercial phosphoric acid (23.5% P2O5).

Scrambled Eggs or How Eggshells Become Phosphates

As part of the training activities planned for the Chemical Engineering degree, in 2016, a group of students from the Chemical Engineering Laboratory course was challenged to face a plausible reuse of discarded eggshells. A straightforward methodology to synthesize phosphates such as calcium pyrophosphate or fluoroapatite among others was developed using commercial phosphoric acid and discarded eggshells as starting materials. Throughout the development of this activity, topics such as recycling and reuse of discarded materials, guided-inquiry instruction, self-learning, and soft-skills development were successfully covered. The strategy proposed in this work encourages students to make connections between science and life and provides an excellent linkage between chemical research and recycling without neglecting those basics required by the official curriculum.

HDEHP-Impregnated Kaolinite for Adsorption of Uranium from Dilute Phosphoric Acid

Impregnation of kaolinite with di(2-ethylhexyl) hydrogen phosphate (HDEHP) improves the uranium adsorption from commercial phosphoric acid. The uranium adsorption was studied as a function of conditions: contact time, solid/liquid ratio, temperature, mechanical stirring speed, and phosphoric acid concentration, and the optimum conditions were determined. The adsorbent was characterized by the X-ray fluorescence and FTIR spectroscopy. The results show that 92% of uranium was adsorbed from commercial phosphoric acid (30% P2O5) onto impregnated kaolinite at room temperature after 30-min contact. The adsorption kinetics was analyzed by the pseudo-first- and pseudo-second-order models, with the pseudo-second-order model giving better fit. The thermodynamic functions (ΔH0, ΔS0, and ΔG0) of the uranium adsorption show that the process is exothermic and spontaneous.

Phosphoric acid doped high temperature proton exchange membranes based on comb-shaped polymers with quaternized graft architectures

A series of poly(arylene ether ketone)-g-quaternized 4-vinylbenzyl chloride copolymers (PAEK-g-QVBC-x) containing locally and densely quaternized side chains were synthesized. The PAEK-g-QVBC membranes were obtained by solution casting from their reaction mixture and then doped with phosphoric acid (PA) to be used as advanced anhydrous high temperature proton exchange membranes. Compared to the commercial PA doped polybenzimidazole membrane and other main-chain-type quaternized hydrocarbon polymer membranes with the similar proton conductivity, these PA-PAEK-g-QVBC-x membranes possess much lower PA doping level, extremely lower volume swelling ratio, and higher dimensional and oxidative stability. Among them, PA-PAEK-g-QVBC-6.4 membrane with the PA doping level in weight of 101.7% has the highest proton conductivities of 31 mS cm−1 at 120 °C and 65 mS cm−1 at 200 °C, respectively. Surprisingly, its volume swelling ratio is only 7.8%, which is far less than other reported PA doped membranes. The preliminary fuel cell test shows that PA-PAEK-g-QVBC-6.4 membrane has the peak power density of 53 mW cm−2 at 100 °C without any humidification. The results indicate that the anhydrous proton exchange membranes based on comb-shaped polymers with quaternized graft architectures have the potential to resolve the dilemma between demand of high PA doping levels to achieve high proton conductivity and the dimensional and mechanical stability of largely swollen membranes for high temperature fuel cells.

Uranium sorption from commercial phosphoric acid using kaolinite and metakaolinite

Uranium sorption from commercial phosphoric acid was carried out onto kaolinite and metakaolinite. The different factors affecting uranium adsorption have been investigated. The obtained results show that, the sorption process is applicable for the high strength phosphoric acid, 40% P2O5, and diluted phosphoric acid, 20% P2O5, but it preferred to the diluted phosphoric acid. The kinetic models applied to the sorption rate data were evaluated for Lagergren first order and the pseudo second order models. From the results, the uranium sorption from commercial phosphoric acid, 40% P2O5, onto kaolinite and metakaolinite was found to occur through physical sorption process.

Development of Novel and Cost Effective Techniques for Purification of Commercial Grade Phosphoric Acid for Fertilizers, Food and Pharmaceutical Industries

AbstractCultivation of 1.5 millions Faddens is one of the major projects for securing food supply to the ever increasing population; therefore, expansion of the fertilizer industry becomes a must.Phosphate ores from New Valley and Nile Valley are chemically processed by sulphuric acid to produce phosphoric acid intermediate by the dihydrate process. Two plants are already inoperation at “Abu Zabaal” and “Fayoum” and another two plants are under establishment, onealong the Red Sea Coast at El-Sokhna and the other at the “New Valley”. Two major problems are facing the industry, namely, the low filtration rate of the acid from solid gypsum and the second is the high level of impurities which decreases the P2O5 water solubility of the produced fertilizers. The filtration rate has been doubled by utilization of surface active agents(Surfactants) to modify the gypsum crystals. On the other hand, novel technique is being developed to decrease the impurities especially iron from 4% to < 1% leading to increasing the P2O5 water solubility of the produced fertilizer. Further decrease of Fe content of the fertilizer grade acid to < 0.1% is achieved through application of a novel membrane technology. The purified acid could be used for food and pharmaceutical industries, thus the economics of the acid production units greatly improve. The paper reviewed the results obtained so far which will improve significantly the value added products. The effects of the different parameters such as oxalic acid dose, temperature and concentration of phosphoric acid on Fe2O3 removal efficiencyhave been studied. Increasing the oxalic acid dose up to 7.5 g/100g of 28% P2O5 (80oC, 100 rpm) raised the removal efficiency of Fe2O3 to 90.8%. Increasing the dose of oxalic acid to 10 g/100g led to slight increase in the removal efficiency of Fe2O3 to 91.6%.

Influence of the molar concentration of phosphoric acid solution on the properties of metakaolin-phosphate-based geopolymer cements

Six different phosphoric acid solutions with molar concentrations 4, 6, 8, 10, 12 and 14M were prepared by dilution of commercial phosphoric acid in distilled water. The obtained phosphoric acid solutions were used for producing metakaolin-phosphate-based geopolymer cements. These geopolymer cements were obtained by adding each fresh prepared phosphoric acid solution to metakaolin with a mass ratio phosphoric acid solution/metakaolin=0.80. It was observed in the infrared spectra of phosphoric acid solutions 8, 10, 12 and 14M, the absorption bands at 875–879 and 949–972cm−1 which are assigned to H2PO4−. The SEM images of geopolymer cements exhibit the presence of berlinite (AlPO4) which is dispersed in the matrix and contributes to enhancing the strength, whereas the geopolymer cements from phosphoric acid solution with 14M are heterogeneous microstructures. The compressive strength of phosphate-based geopolymer cements was between 36.4 and 93.8MPa; it increased with increasing the concentration of phosphoric acid solutions up to 10M. It can be concluded that the most convenient concentration of phosphoric acid solution required for producing phosphate-based geopolymer cements with good mechanical properties is around 10M.

Mechanical and microstructural properties of metakaolin-based geopolymer cements from sodium waterglass and phosphoric acid solution as hardeners: A comparative study

Sodium waterglass with mass ratios SiO2/Na2O and H2O/Na2O equal to 1.5 and 10, respectively was prepared from commercial silica fume as a silica source. The phosphoric acid solution with molar concentration 10M was prepared by dilution of commercial phosphoric acid in distilled water. The ATR-infrared spectrum of alkaline hardener shows the presence of SiQ0, SiQ1 and SiQ2 units suggesting a more depolymerized solution. While the acid hardener contains H2PO4− due to the deprotonation of commercial H3PO4 indicating that the molar concentration 10M contained an appropriate amount of water necessary for the workability. The formation of H2PO4− is appropriate for the second step of geopolymerization. Metakaolin-based geopolymer cements were obtained by adding each fresh hardener to metakaolin. The results show that the compressive strength of phosphate-based geopolymer cement is 93.8MPa while the one of alkali-based geopolymer cement is 63.8MPa. The difference of the compressive strength could be related to the formation of berlinite (AlPO4) in the structure of phosphate-based geopolymer cement which acts as a filler and reinforces the structure and therefore the compressive strength of the specimen. However, the microstructures of both geopolymer cements are homogeneous and compact structure. It was typically found that phosphate-based geopolymer cement has a higher compressive strength compared to the one of alkali-based geopolymer cement. It is important to note that the hardening of metakaolin-based geopolymer cement from phosphoric acid solution required an energy gradient while metakaolin-based geopolymer cement from sodium waterglass hardens at room temperature like regular Portland cement. The purpose of this work was to compare the mechanical and microstructural properties of metakaolin-based geopolymer cements obtained in the same condition using sodium waterglass and phosphoric acid solution as hardeners. Due to their higher mechanical properties, phosphate-based geopolymer cement could be used for the construction of roads and bridges and geopolymer cements from alkaline medium could be used for building the houses.

Homogenous hydrothermal synthesis of calcium phosphate with calcium carbonate and corbicula shells

In this work, we prepared calcium phosphate by a general homogenous hydrothermal process, either from commercial calcium carbonate and phosphoric acid, or from corbicula shells and phosphoric acid. The chemical composition and properties of the resulting products were also investigated. Commercial calcium carbonate and corbicula shells reacted with phosphoric acid to produce calcium hydrogen phosphate and hydroxyapatite via a homogeneous hydrothermal process. The chemical composition of the products was influenced by both processing temperature as well as time. The compositions themselves influenced the substitution of calcium with iron and the absorption of trimethylamine gas.

REE extraction from phosphoric acid, phosphoric acid sludge, and phosphogypsum

Phosphate rock is considered a secondary source of rare earth elements (REE), which are usually found in isomorphism substitution with Ca2+ ion. It approximately assays 0·01–0·1% (100–1000 μg g−1). Large tonnages of phosphate ore are mined and processed annually to manufacture commercial grade phosphoric acid indicating that REE extraction from phosphate beneficiation and chemical processing streams may have an economic value. In this work, REE were extracted from phosphoric acid by ion exchange resin using both direct and counter current methods while REE cocrystallised with phosphogypsum (PG) was digested by a mixture of concentrated sulphuric acid and recycled phosphoric acid, followed by extraction with DEHPA solvent. It was found that Heavy Rare Earth Elements (HREE) (Y, Gd, Tb, Dy, Er, Ho, Yb, Tm, and Lu) represented more than 70% of the REE dissolved in phosphoric acid while the critical REE (CREE) (Y, Nd, Eu, Tb, and Dy) constitute 45% of the distribution. Phosphogypsum has higher acids insoluble (A.I.) and phosphate (P2O5) than phosphoric acid sludge (PAS). The main impurities in PG are P2O5, AI, and CaO, while A.I., Al2O3, and P2O5 are the main PAS impurities. Phosphoric acid sludge leaching by nitric acid was more efficient than sulphuric acid even with higher acid strength and lower solids percentage; nitric and sulphuric acid leaching efficiency was approximately 58 and 49% for nitric and sulphuric acid, respectively. Rare earth elements extraction from phosphoric acid by ion exchange resin was not significantly affected by temperature change within the range 25–82°C but approximately 18% reduction was observed when extraction temperature was increased from 10 to 25°C. It was also found that REE-extraction efficiency increased with increasing resin dosage; approximately 65 and 28% extraction efficiency were achieved with 7 and 3 kg resin/t of phosphoric acid, respectively.

Surface chemistry considerations in the flotation of bastnäsite

Bastnäsite is the chief valuable mineral in two of the world’s largest rare earth (RE) mineral deposits and is also found in a number of new RE deposits currently under development. This work used electrophoretic and electroacoustic zeta potential measurements to identify the interaction between bastnäsite and several different collectors. The results of these measurements were then compared with microflotation of bastnäsite and quartz, a common RE gangue mineral. Zeta potential measurements of bastnäsite determined the isoelectric point of bastnäsite to occur at approximately pH 6.3 (via electrophoretic measurement) and pH 8.1 (via electroacoustic measurement). Sodium oleate and Flotinor SM15 (a commercial phosphoric acid ester) are both shown to chemically adsorb onto the bastnäsite surface. Zeta potential measurements of bastnäsite with benzohydroxamic acid indicate significant adsorption, especially from pH 5 to pH 10. The microflotation results show that all three collectors were able to successfully recover bastnäsite. SM15 is the least selective collector as it floats both quartz and bastnäsite whereas benzohydroxamic acid is able to selectively float bastnäsite at pH 9. The recovery of bastnäsite using benzohydroxamic acid is also shown to be highly dependent on frother selection. The optimum pH of flotation for all three collectors occurs at pH 9.

Novel Technique for Purification of Fertilizer Phosphoric Acid with Simultaneous Uranium Extraction

A process codenamed PHOSPURIN is described for the purification of Fert Phosphoric acid with simultaneous extraction of Uranium compounds from acid. This includes maintaining the acid stream at different redox potentials for the necessary extraction of all the metals & rare earths using Solvent Extraction technique. Details are also provided on the extraction behavior of various cations and rare earths from fert acid media employing redeveloped Phosphate reagent (codenamed KROPHOS-18) in kerosene system.The effects of various parameters, such as the concentration of acid, metal ion and extractant, nature of the diluents etc., on the extraction of various cations have been investigated. Based on the extraction data, most of the cations like Fe (II) & (III), Al, Mg, Ca, Mn, Na, K, heavy metals like Arsenic / Cadmium, rare earths including Uranium etc., are all being extracted with high to very high separation factors from all molar fertilizer phosphoric acids.The practical utility of the extractant & the process has been demonstrated by tests on commercial fert phosphoric acid. It has been conclusively found that KROPHOS-18 has good properties, such as high distribution coefficient, good stability, acceptable kinetics, good phase separation etc.