Explore the vast range of titles available.

Addressing the environmental challenges posed by phosphogypsum (PG) stockpiling, this study investigates the synergistic mechanisms of a dual-functional application strategy where PG serves as both cementitious binder and aggregate. Unlike previous research limited to single-mode utilization, this study focuses on the interfacial compatibility between PG-based binders and PG aggregates (PGA). Through a comparative experimental program, the mechanical performance and microstructure of different binder–aggregate combinations were evaluated. The proposed dual-functional formulation achieved a high PG incorporation rate of 38% by mass. While the compressive strength of 39.3 MPa was lower than that of the reference ordinary concrete, it comfortably surpasses the C30 strength requirement for structural applications, validating its engineering feasibility. Comparative analysis revealed that although natural stone aggregates possess higher intrinsic strength, the PG-binder/PGA system exhibits superior interfacial bonding compared to the PG-binder/stone system. Microstructural observations indicated that this synergistic interaction facilitates the formation of interwoven ettringite and C-S-H gel networks, contributing to a structurally integrated interfacial transition zone (ITZ). These findings suggest that the dual-functional strategy offers a viable pathway for developing low-carbon building materials by balancing high-volume waste utilization with mechanical compliance.

This research focuses on phosphogypsum concrete’s compressive strength. Given phosphogypsum’s underutilization as industrial waste, the discrete element method is applied. After preparing 100mm cubic specimens and curing, a 0.3mm particle size parallel bond model is built. Results show good agreement between simulated and experimental compressive strengths. Analyses of particle displacement, force chains, crack distribution, porosity, and coordination number uncover the mechanical behavior and failure mechanism. This study provides a theoretical basis for optimizing the mix design, enhancing its application and sustainable utilization in construction, and addressing waste and resource issues.

The utilization rate of phosphogypsum (PG) is currently low, and prolonged storage poses environmental pollution. Therefore, there is an urgent need to promote resource-efficient utilization. This study investigated the alterations in the characteristics of modified PG artificial soil (MPG-soil) and their influence on buckwheat ( Fagopyrum esculentum Moench) growth using hierarchical land reclamation technique (HLRT) and integrated land reclamation technique (ILRT). The results demonstrated that MPG-soil reduced bulk density (3.8–6.9%), enhanced moisture content (up to 22%), and improved enzymatic activity. HLRT achieved superior phosphorus mineralization (7.53 U/g S-NP activity) and increased buckwheat yield by 130.6% over controls. Despite elevated soil salinity, MPG amendments restricted heavy metal accumulation in grains (BCF < 0.3), though Pb levels exceeded national standards due to background contamination. Nutrient dynamics revealed increased phosphorus availability but reduced organic matter, necessitating supplemental fertilization. The Nemerow index confirmed all treatments as “Safe and Clean”, while principal component analysis highlighted HLRT’s efficacy in balancing soil structure and fertility. Proline accumulation in high-PG treatments indicated adaptive stress responses. MPG-soil effectively contained heavy metal migration, ensuring agricultural product safety. This study assessed the potential of PG for land reclamation, and provided guidelines for its safe utilization in agriculture.

Phosphogypsum is the main industrial solid waste from wet process phosphoric acid production, which has significant potential for environmental sustainability and engineering applications when modified. In order to explore the mechanical properties of modified phosphogypsum (MG) in different loading environments, uniaxial compression tests were conducted at four loading rates: 0.03, 0.06, 0.12, and 0.6 mm/min. The test results show that MG undergoes creeping at the loading rate of 0.03 mm/min, quasi-static loading at 0.12 to 0.6 mm/min, and transition between the two states at 0.06 mm/min. As the loading rate increases, the crack initiation stress , damage stress , and peak strength gradually increase, but the increasing amplitude gradually decreases. Under quasi-static loading at 0.12 to 0.6 mm/min, and show no significant changes and remain at 0.52 and 0.81, respectively, close to the values of rock materials. As the loading rate increases from creep loading to quasi-static loading, the elastic strain energy increases slowly and steadily, while the total strain energy and dissipative strain energy decrease first and then increase slowly. With the axial stress increasing from 0 to 0.81 , the principal strain field changes from relatively uniform to a concentration band, which has a very steep angle with the horizontal direction. The research results provide an important theoretical basis for the engineering application of MG as building materials.

Nano-material of calcium hydroxyapatite (n-CaHAP), with particle size ranging from 50 to 57 nm which was prepared from phosphogypsum waste (PG), was used for the removal of lead ions (Pb (II)) from aqueous solutions. It was investigated in a batch reactor under different experimental conditions. Effects of process parameters such as pH, initial Pb ion concentration and adsorbent dose were studied. Also, various types of kinetic modeling have been studied where the lead uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) model. The Pb ions adsorption onto n-CaHAP could best fit the Langmuir isotherm model. The maximum adsorption capacity (qmax) for Pb ions was 769.23 mg/g onto n-CaHAP particles.

Phosphogypsum is a solid waste with great environmental stockpile pressure produced by the wet production of phosphoric acid. Although there are various methods to purify and utilize phosphogypsum, the means for environmentally friendly, low energy consumption, and high value-added utilization still need to be further explored. Here, CaSO4·2H2O crystal was directly purified and regulated from phosphogypsum by using the anti-solvent method. The antisolvent can be adsorbed in the c-axis direction of the crystal and further inhibit the growth rate in this direction, resulting in a change in the morphology of the crystal. By adjusting the polarity and chain length of the anti-solvent, the morphology of CaSO4·2H2O crystal can change from butterfly-like flake crystals to hexagonal prism-like crystals. When n-propanol with long chain was used as the anti-solvent, the morphology of the CaSO4·2H2O crystal showed a hexagonal prism with a specific surface area of 19.98 m2/g and a Cu2+ loading efficiency of 52.67%. The encouraging results open up new possibilities for the application of phosphogypsum.

As phosphogypsum constitutes a large amount of solid waste material, its purification treatment and comprehensive utilization have close connection with economic development and ecological environmental protection. For the moment, the storage quantity of phosphogypsum is still rising as a result of the increasing phosphate fertilizer production to meet the food demand in China. This paper summarizes the generation process, impurity removal treatment (physical method, chemical method, heat method), high-value utilization (nanometer calcium sulfate whisker, nanometer calcium carbonate) of phosphogypsum material and some existing problems. It puts forward some views on the challenges in this field and the direction of future development. It is hoped that the investigation and summary in this paper could supply some significant information for the impurity removal and high-value utilization of phosphogypsum material as a contribution to sustainability.

Phosphogypsum, a byproduct of orthophosphoric acid production, is one of the large-tonnage wastes. Since phosphogypsum mainly consists of CaSO4 2H2O, it can be considered as an alternative gypsum-bearing raw material in the production of gypsum binders. However, its features, such as particle morphology and the presence of impurities, can negatively affect the characteristics of phosphogypsum-based binders. Identification of these factors will allow us to develop methods for their minimization and increasing the efficiency of phosphogypsum use from the required source as a raw material for the production of phosphogypsum-based binders. In this regard, the manuscript contains a comprehensive and comparative analysis of phosphogypsum and natural gypsum, which makes it possible to establish their differences in chemical composition and structural and morphological features, which subsequently affect the properties of the phosphogypsum-based binder. It has been established that the key factor negatively affecting the strength of phosphogypsum-based paste (2.58 MPa) is its high water demand (0.89), which is due to the high values of the specific surface area of the particles and the presence of a large number of conglomerates with significant porosity in phosphogypsum. It has been suggested that preliminary grinding of phosphogypsum can help reduce the amount of water required to obtain fresh phosphogypsum-based paste with a standard consistency and improve its physical and mechanical properties.

This study compared the physical properties and mechanical strength development of PCBAs with water, sealed, standard, and open ambient air curing over 28 days to find a suitable curing method for the production of phosphogypsum-based cold-bonded aggregates. The types and relative amounts of hydration products, microstructural morphology and pore structure parameters were characterized utilizing XRD, TGA, FTIR, SEM and nitrogen adsorption methods. According to the results, water curing leads to rapid increases in single aggregate strength, reaching 5.26 MPa at 7 d. The standard curing condition improved the 28 d mechanical strength of the aggregates by 19.3% over others by promoting the generation of hydration products and the transformation of the C-S-H gel to a higher degree of polymerization and by optimizing the pore structure. Further, PCBAs achieved an excellent solidification of phosphorus impurities under all four curing conditions. This work provides significant guidance for selecting an optimized PCBA curing method for industrial production.

In this study, phosphogypsum waste collected from a factory dump in Kedainiai, Lithuania, was used for the first time as a starting material in the dissolution–precipitation synthesis of high-quality bioceramic calcium hydroxyapatite (Ca10(PO4)6(OH)2; CHA). The CHA powders were synthesized using the dissolution–precipitation method, employing phosphogypsum in four different conditions: untreated, dried at 100 °C, dried at 150 °C, and annealed at 1000 °C. Various phosphorus sources were used in the CHA synthesis process: Na2HPO4; a mixture of Na2HPO4 and NaH2PO4; or a combination of Na2HPO4, NaH2PO4, and NaHCO3. These mixtures were allowed to react at 80 °C for 48 h, 96 h, 144 h, and 192 h. X-ray diffraction (XRD) analysis revealed slight variations in the synthesized products depending on the specific starting materials used. Fourier transform infrared spectroscopy (FTIR) was conducted to confirm the structural characteristics of the synthesized CHA samples. The surface microstructure of the synthesized CHA samples differed notably from that of the raw phosphogypsum. All synthesized CHA samples exhibited Type IV nitrogen adsorption–desorption isotherms with H3-type hysteresis loops, indicating the presence of mesoporous structures, typically associated with slit-like pores or aggregates of plate-like particles. To the best of our knowledge, an almost monophasic CHA has been fabricated from phosphogypsum waste for the first time using a newly developed dissolution–precipitation synthesis method. A key challenge in the high-end market is the development of alternative synthesis technologies that are not only more environmentally friendly but also highly efficient. These findings demonstrate that phosphogypsum is a viable and sustainable raw material for CHA synthesis, with promising applications in the medical field, including the production of artificial bone implants.