Phosphogypsum (CaSO4·2H2O, PG) waste is produced in large amounts during phosphoric acid (H3PO4) production. Minor quantities are utilized in construction or agriculture, while most of the material is stockpiled, creating an environmental challenge to prevent pollution of natural waters. In principle, the gypsum waste could be used to capture several hundred megatonnes of carbon dioxide (CO2). ...

The mechanistic basis for cation amelioration of Al rhizotoxicity in soybean was investigated through a series of studies comparing protective effects of Ca and Mg against Al inhibition of root elongation in a background 0.8 mM CaSO4 solution (pH 4.3). A modified Gouy-Chapman-Stern model was used to evaluate the effect of cations on electrical potential and Al3+ activity at root plasma membrane...

Nitrate transport in excised corn (Zea mays L.) roots was inhibited by phenylglyoxal, but not by 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid (DIDS) or fluorescein isothiocyanate (FITC). Inhibition of nitrate uptake by a 1-hour treatment with 1 millimolar phenylglyoxal was reversed after 3 hours, which was similar to the time needed for induction of nitrate uptake. If induction of nitrate ...

This study aimed at examining effective sample treatments and spectral processing for an alternate method of soil nitrate determination using the attenuated total reflectance (ATR) of Fourier transform infrared (FTIR) spectroscopy. Prior to FTIR measurements, soil samples were prepared as paste to enhance adhesion between the ATR crystal and sample. The similar nitrate peak heights of soil past...

Synchrotron-based smalland wide-angle X-ray scattering (SAXS/WAXS) was used to examine in situ the precipitation of gypsum (CaSO4·2H2O) from solution. We determined the role of (I) supersaturation, (II) temperature and (III) additives (Mg2+ and citric acid) on the precipitation mechanism and rate of gypsum. Detailed analysis of the SAXS data showed that for all tested supersaturations and tempe...

The gas sulfur reduction of phosphogypsum in the acid co-production sulfoaluminate cement clinker is a new process for treating phosphogypsum. furnace this system was studied and analyzed by combining computational fluid dynamics (CFD) experimental validation. effects n(CaSO4)/n(S2), particle residence time, kiln tail flue temperature on performance were obtained. A second-order response model ...

Syngenite (K2Ca(SO4)2 ⋅ H2O) presents an effective hydration activator (accelerator) for anhydrite (CaSO4) applied in construction systems. The current synthesis relies on co-precipitation of K2SO4 and CaSO4 2H2O produces large amounts waste water holding excess potassium sulfate. Therefore, this method is deemed ineffective, uneconomical environmentally unfriendly. Moreover, it crystals (ℓ ∼5-...