H2SO4-H2O中硝酸铜对脱硫石膏晶须生长的影响

以处理后的脱硫石膏为原料,在H₂SO₄-H₂O体系中以Cu(NO₃)₂为晶形控制剂采用水热法制备脱硫石膏晶须,探讨了Cu(NO₃)₂对脱硫石膏晶须生长的影响机理。结果表明:Cu(NO₃)₂对脱硫石膏有明显促溶作用,其中Cu²⁺可减小溶液中各离子的活度系数,使溶液中的Ca²⁺浓度增大。NO^-₃通过静电作用在Ca²⁺周围聚集并对SO^2-₄产生屏蔽作用,导致脱硫石膏继续溶解并使Ca²⁺和SO^2-₄的浓度处于相对稳定状态,有利于半水脱硫石膏晶体的形核与生长。此外,Cu²⁺还可在晶须的生长过程中选择性吸附在晶须表面,生成CuSO₄,促进了脱硫石膏的结晶生长,最终在Cu(NO₃)₂用量为2.0%(质量分数)时制备的脱硫石膏晶须长径比约为73。     

Recycled high-density polyethylene/gypsum composites: evaluation of the microscopic,thermal, flammability,and mechanical properties

Sustainable composites comprising scraps of high-density polyethylene (HDPE) and gypsum waste in proportions HDPE/gypsum 100/0, 50/50, 40/60, and 30/70 wt% were prepared. The morphology of the injected specimens was core-shell. Thermal, flammability, water absorption, and compression resistance were also evaluated. Progressively, the presence of gypsum increased the HDPE crystallinity and T_onset. Concerning the flammability, the composite 30/70 exhibited the burning rate three times lower than HDPE, indicating that the gypsum played a role as a flame retardant. The HDPE acted as waterproofing for gypsum. The compression resistance of the composites was similar to HDPE.     

Calcium Sulfite Solids Activated by Iron for Enhancing As(III) Oxidation in Water

Desulfurized gypsum (DG) as a soil modifier imparts it with bulk solid sulfite. The Fe(III)–sulfite process in the liquid phase has shown great potential for the rapid removal of As(III), but the performance and mechanism of this process using DG as a sulfite source in aqueous solution remains unclear. In this work, employing solid CaSO₃ as a source of SO₃²⁻, we have studied the effects of different conditions (e.g., pH, Fe dosage, sulfite dosage) on As(III) oxidation in the Fe(III)–CaSO₃ system. The results show that 72.1% of As(III) was removed from solution by centrifugal treatment for 60 min at near-neutral pH. Quenching experiments have indicated that oxidation efficiencies of As(III) are due at 67.5% to HO^•, 17.5% to SO₅^•− and 15% to SO₄^•−. This finding may have promising implications in developing a new cost-effective technology for the treatment of arsenic-containing water using DG.     

Biochemical evaluation of sulfur and nitrogen assimilation potential of mustard (Brassica juncea L. Czern. & Coss.) under application of slow-release sulfur fertilizer

Pot experiments were conducted to study the efficacy of a slow sulfur-releasing fertilizer, sulfur glass fritz (SGF 1), on growth, photosynthesis, and sulfur, and nitrogen assimilation potentials of brown mustard (Brassica juncea L. Czern. & Coss. cv. Pusa Jaikisan). Growth as indicated by biomass accumulation slowed down in response to the application of sulfur glass fritz. A similar trend was observed in the case of photosynthesis rate. The activity of two marker enzymes, ATP-sulfurylase and nitrate reductase, showed very low levels of activity, indicating poor assimilation of sulfur and nitrogen by the plant under sulfur glass fritz. It is therefore concluded that the release of sulfur by sulfur glass fritz is too slow and that the initial nonavailability of sulfur to the plants could lead to suboptimization of both sulfur- and nitrogen-assimilating enzymes. These factors may contribute to low rates of photosynthesis and poor growth.     

Recovery of organic acids from fermentation broths

Rising concerns over the use of fossil resources have generated renewed interest in the production of commodity chemicals via fermentation. Organic acids are a particularly attractive target because their functionality enables downstream catalytic upgrading to a variety of compounds. In this article, we survey how common technical issues are addressed in the recovery schemes for several organic acids. We present results for the recovery of acetate using a new method based on amine complexation. Our reactive separation scheme produces a high-purity product, is energy efficient, and avoids the coproduction of a waste salt coproduct, all prerequisites for a large-scale production process.     

Properties study of anhydrite(II) prepared from waste gypsums

Anhydrites(II)- CaSO₄ were prepared from two waste gypsums (PRECHEZA Perov, FOSFA Potorná). The samples of anhydrites(II) with sulphate activators were tested on spillage, beginning and the end of setting time, bending and pressure strength. Both sodium and potassium sulphates accelerated setting of anhydrite, more impressively that prepared from Potorná gypsum. The addition of Na₂SO₄ influenced the strength of this anhydrite very favourably. On the contrary K₂SO₄ influenced favourably the strength of Perov anhydrite. Results confirm the necessity to evaluate properties of such materials with respect to their origin.     

常温高压下石膏在水中溶解及相变现象的研究

 研究常温下200~1 100 MPa压力范围内石膏的Raman光谱,原位观测了随压力升高,石膏在水中的溶解现象,其过程中伴随着石膏的相变。结果表明：压力小于407 MPa时,石膏的形态无明显变化;随着压力的升高,石膏开始溶解,溶解至一定程度,石膏发生了向半水石膏转化的相变;相变完成后,半水石膏继续溶解至消失。石膏这一溶解相变过程表明在地球内部与压力相应的深部区域内,也可能会发生矿物的溶解相变。     

Experimental study on cracking behaviour of moulded gypsum containing two non-parallel overlapping flaws under uniaxial compression

Failure of rock mass that is subjected to compres-sive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research inves-tigates the cracking behaviour and coalescence process in a brittle material with two non-parallel overlapping flaws using a high-speed camera. The coalescence tensile crack and tensile wing cracks were the first cracks to occur from the pre-existing flaws. The initiation stresses of the primary cracks at the two tips of each flaw were simultaneous and decreased with reduced flaw inclination angle. The following types of coalescence cracks were identified between the flaws: pri-mary tensile coalescence crack, tensile crack linkage, shear crack linkage, mixed tensile-shear crack, and indirect crack coalescence. Coalescence through tensile linkage occurred mostly at pre-peak stress. In contrast, coalescence through shear or mixed tensile-shear cracks occurred at higher stress. Overall, this study indicates that the geometry of preexisting flaws affect crack initiation and coalescence behaviour.     

石膏晶须的制备方法与应用

石膏晶须是一种性价比高、力学性能良好以及对环境友好的材料,可应用于复合材料、造纸、催化、可生物降解材料等领域.石膏晶须的制备大多停留在工艺参数研究上,对石膏晶须特征和应用研究不足.本文讨论了石膏晶须的结构,从产物形成过程上对石膏晶须的制备方法进行了分类和评述;对不同制备方法和不同应用领域的石膏晶须的产物特征进行了总结,讨论了制备和应用之间的相关性;并讨论了石膏晶须未来的发展方向.     

Stable Isotope Geochemistry of Antarctic Salt Efflorescences

Salt efflorescences consisting of gypsum sampled mainly in the Schirmacher Oasis have been analyzed for the isotopic composition of the water of crystallization and of the sulphate-sulphur. For comparison, a few samples from other Antarctic locations (Guettard Range, Prince Charles Mts., Insel Mts.) were included in the study. The isotopic variations of the water of crystallization of secondary gypsum and the calculated isotopic composition of the mother solution reflect the local climatic conditions during the precipitation of the efflorescences. It is therefore possible to obtain qualitative information about the climatic conditions prevailing in the studied region.