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The effect of different prepared magnesium sources including MgCl2 (ZN-THF), metallic magnesium powder (ZN-O), and MGE (ZN-MGE) as the support of titanium-based Ziegler-Natta catalysts on behaviors of gas-phase ethylene/1-hexene copolymerization was investigated. These catalysts reacted with TEA presented higher catalytic activity than using TnOA. This is due to TEA had higher reducing power. Moreover, it revealed that ZN-MGE exhibited the highest activity among other catalysts because ZN-MGE had the highest distribution of titanium contents measured by EDX, and then generated more active sites. The average particle sizes of these catalysts were around 35 µm, which was suitable for commercial application. Considering copolymer size, the size of EH-ZN-O-TEA and EH-ZN-MGE-TnOA (ca. 420 µm) displayed the largest particle size. The large size of EH-ZN-MGE-TnOA was expected due to the agglomeration and steric hindrance of the catalyst reacted with TnOA. For the particle size distribution, only EH-ZN-O-TEA showed the bimodal distribution meaning that both fragmentation and no fragmentation occurred. Other copolymers showed positive-skewed distribution. Typically, the morphologies of copolymer were spheroidal lump without fine particles. The roles of comonomer content on thermal behaviors were presented by melting temperature, C7-soluble content, and crystallinity. It was found that although all catalysts with TEA exhibited higher activity than TnOA, the use of TnOA perhaps tended to facilitate the comonomer insertion. It revealed that steric hindrance of TnOA cocatalyst may retard the copolymer chain attachment. As the result, the comonomer insertion of EH-ZN-MGE was the highest among other catalysts.

In order to study the performance and feasibility of magnesia‐alumina spinel (MgAl2O4) ceramics for thermal storage in solar thermal power generation, MgAl2O4 was prepared by theoretical composition using α‐Al2O3 as aluminium source, fused magnesia, magnesite, and light burned magnesia as different magnesium sources and kaolin as additive. The effects of magnesium source and the additive on sintering properties, thermal shock resistance and thermal properties of MgAl2O4 ceramics were researched. The results shown sample A1 (with fused magnesia) sintered at 1670°C possessed the optimum comprehensive properties, the bending strength increased by 7.71% after 30 thermal shock times (room temperature‐1000°C, air cooling), the specific heat capacity was 1.05 J/ (g·K). Therefore, the MgAl2O4 ceramics exhibited great potential in high‐temperature thermal storage material. [ABSTRACT FROM AUTHOR]

Precipitation of phosphorus (P) as a struvite product from wastewater and local magnesium (Mg) sources is considered as a high economical prudent venture, as it has shown to bring down the cost of producing the product. However, there is a significant concentration of calcium (Ca) in these Mg and most wastewater sources. The presence of Ca in wastewater and Mg sources during struvite precipitation has been shown to negatively affect the quality of the struvite produced. The low struvite quality greatly impedes its use as a fertiliser given the economic value of the product as an alternative P fertiliser. This review paper provides an understanding of how the presence of Ca affects the purity, crystal size, and morphology of the struvite. Different methods that have been used to mitigate the effect of Ca on struvite quality have been reviewed. The factors that affect the recovery of P and the percentage recoveries of P by different Mg sources have also been reviewed. This paper serves as a basis for further research where the possibility of removing Ca from wastewater and Mg sources is explored. When Ca is removed before struvite precipitation is carried out, the quality of the product will be greatly improved. HIGHLIGHTS Trend analysis of impact of Ca on struvite quality has been done.; All methods for the mitigation of the negative impact of Ca have been reviewed.; Nutrient removal efficiencies of Mg sources have been compared.; Molar ratios that affect struvite quality have been identified.; Research gap for improving struvite quality has been identified.;

Strongly weathered phyllite is a metamorphic soft rock widely distributed in the central and western regions of China. Due to its inadequate engineering properties, the direct use of this material as a roadbed filler is not feasible and requires improvement. In this paper, calcium acetate Ca(CH 3 COO) 2 , magnesium acetate Mg(CH 3 COO) 2 and calcium chloride CaCl 2 are prepared to improve the filler by microbially induced carbonate precipitation (MICP). The effects of different calcium and magnesium sources on porosity, water absorption, uniaxial compressive strength, crack propagation time and failure patterns are investigated. The results show that CaCl 2 and Ca(CH 3 COO) 2 exhibit the most significant enhancement effect in reducing porosity and water absorption, increasing the uniaxial compressive strength by over 30%, delaying the time of failure occurrence and reducing the number of tensile cracks significantly. X-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size distribution analyses reveal disparities among the rock samples. CaCl 2 and Ca(CH 3 COO) 2 have greater efficacy than Mg(CH 3 COO) 2 in terms of improvement, as they generate relatively many carbonate precipitates to bind the phyllite filler and reduce the size and quantity of pores. To avoid the corrosion of Cl- ions when adding reinforcement bars in actual engineering, Ca(CH 3 COO) 2 is an ideal calcium source for improving the strongly weathered phyllite filler. • The physical and mechanical properties of strongly weathered phyllite filler can be improved after modification. • The physical properties and strength of modified sample have a relationship with carbonate content and crystal morphology. • Calcium acetate is suggested for use as the calcium source to improve the strongly weathered phyllite filler. [ABSTRACT FROM AUTHOR]

Phosphorus recycling and recovery has received special attention due to its non-replaceable and non-renewability. Phosphorus recovery from human urine in the form of struvite crystals is a potential alternative source. In this work, the efficiency of struvite precipitation from source separated human urine and struvite crystals size were analyzed using three different Mg 2+ sources (MgCl 2 , Mg(OH) 2 and MgO), individually evaluated using a statistical design of experiments to assess the combined effect of Mg 2+ :P molar ratio (1:1, 1.5:1 and 2:1) and stirring speed (30, 45 and 60 rpm). Formation of struvite crystals was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS). Using the optimal conditions determined, MgO as Mg 2+ source at 2:1 molar ratio and a stirring speed of 30 rpm, 99% of P was recovered as struvite crystals with a size of 50–100 μm. [ABSTRACT FROM AUTHOR]