Revealing the Effect of Anions on the Formation and Transformation of Zeolite LTA in Caustic solutions: An <i>In Situ</i> Synchrotron PXRD Study

Zeolite LTA is one of the largest industrial zeolites in both volume and market value. Natural resources or manufacturing wastes such as clay minerals, fly ash, and lithium slag are now used as raw materials for the economically and environmentally friendly synthesis of zeolites. However, soluble impurities such as inorganic anions (CO32–, SO42–, and PO43–) in these feeds have significant effects on the quality of zeolite LTA products, because these impurities enhance or inhibit the formation of other unwanted phases (amorphous zeolites or sodalite) via mechanisms that remain poorly investigated. Here we use in situ synchrotron powder X-ray diffraction to study the effects of different inorganic salts (Na2CO3, Na2SO4, and Na3PO4) on the kinetics of the sequential phase transformations in zeolite LTA during 2.5 h of reaction at 90 °C in both weakly and highly alkaline solutions. The results show that different salts have no effects on the amorphous phase formation stage but do affect the zeolite or sodalite crystallization stage. The addition of Na2CO3 increases the dissolution rate of zeolite, but it barely promotes the crystallization rate of sodalite. The addition of Na3PO4 inhibits sodalite crystallization, whereas the addition of Na2SO4 is most effective in facilitating sodalite formation and improving final sodalite particle size. Also, SO42–-bearing sodalite has a larger unit cell than other types of sodalites. These outcomes suggest that both CO32– and SO42– have negative effects on stabilizing zeolite LTA phases but PO43– has positive effects on these products

Prediction scatter plot of pH (a) and VIP scores of optimized PLSR model (b).

<p>Prediction scatter plot of pH (a) and VIP scores of optimized PLSR model (b).</p

Gender analysis of the diabetic phenotype in Ran transgenic mice.

<p>The indicated non-TG or Ran transgenic mice were analyzed for gender differences in blood glucose levels at 2 mo of age. Each point corresponds to an individual mouse.</p

Defective islet cell proliferation in Ran transgenic mice.

<p><i>A</i>, Pancreas section from non-TG or Ran-WT transgenic mice were harvested at the indicated postnatal (P) age and analyzed for Ki-67 reactivity, by immunohistochemistry. Sections from normal mouse spleen were used as control. <i>B</i>, The number of Ki-67⁺ cells/islet surface area (0.02 mm²) was quantified by morphometry. **, p = 0.0081. <i>C</i>, Pancreas section from non-TG or Ran-WT transgenic mice (P50) were analyzed for TUNEL reactivity and the numbers of positive cells was quantified. Mean±SD.</p

Descriptive statistics for heavy metal concentrations in soils by PXRF methods (mg/kg).

<p>Descriptive statistics for heavy metal concentrations in soils by PXRF methods (mg/kg).</p

Deregulated PDX-1 expression in Ran-targeted cells.

<p><i>A</i>, Pancreas sections from non-TG, Ran-WT, Ran-G19V or Ran-T24N transgenic mice were stained with an antibody to insulin or PDX-1, by immunohistochemistry. <i>B</i>, The number of insulin- or PDX-1-stained cells was quantified by morphometry in the indicated surface area. Insulin⁺ cells, non-TG (n = 2), 28.2±0.4; Ran-WT (asymptomatic, n = 3), 29.8±1.2; Ran-WT (diabetic, n = 3), 6.2±0.6, ***, p<0.0001; PDX-1⁺ cells, Non-TG (n = 2), 34.2±4.1; Ran-WT (asymptomatic, n = 3), 37.5±2.3; Ran-WT (diabetic, n = 3), 22.8±1.8, **, p = 0.007. <i>C</i>, Islets from 2 mo-old non-TG or a Ran-WT transgenic mouse were analyzed by Western blotting. <i>D</i>, Pancreatic islets isolated from non-TG mice were transduced <u>ex vivo</u> with control pAd-GFP or pAd-GFP-Ran-WT, pAd-GFP-Ran-G19V or pAd-GFP-T24N and analyzed after 48 h by fluorescence microscopy for GFP expression (<i>left</i>), or Western blotting (<i>right</i>). *, non-specific. <i>E</i>, INS-1 cells were left untreated (INS-1) or transduced with control lentivirus (pLKO) or lentivirus encoding Ran-directed shRNA (Ran, 74V1), and analyzed by Western blotting. <i>F</i>, Parental INS-1 cells or four independent clones of INS-1 cells stably transduced with Ran-directed shRNA (77V-2, 74V-1, 75V-1, 75V-2) were analyzed for changes in insulin release in the supernatant. Representative experiment out of at least two independent determinations.</p

Regression of PXRF measurements against ICP-AES analysis for trimmed datasets.

<p>The red, green and blue dotted lines represent the national standard value of heavy metals when pH <6.5, 6.5–7.5 and >7.5.</p