Direct synthesis of single-phase α-CaSO4·0.5H2O whiskers from waste nitrate solution

Single-phaseα-CaSO4·0.5H2O whiskers were directly synthesized from waste Ca(NO3)2 solution using a hydrothermal method,and HNO3 was synchronously regenerated.The effects of reaction temperature and Ca^2+concentration on the phase composition and morphology of products were determined by X-ray diffraction and optical microscopy.On the basis of the experimental results,the formation diagram ofα-CaSO4·0.5H2O was plotted within the range of 5–35 g·L^-1 Ca^2+and 115°C–150°C.In addition,the conditions of the direct synthesis ofα-CaSO4·0.5H2O were determined.Well-crystallized,single-phaseα-CaSO4·0.5H2O whiskers with high aspect ratios(length,1785μm;diameter,10.63μm;aspect ratio,168)and HNO3(70.25 g·L^-1)were obtained at the optimal conditions of 25 g·L^-1 Ca^2+and 125°C.

Disposal of cuprous chloride waste water

The waste water system generated in the process of production of cuprous chloride was studied.The existing forms of copper in the system and the influence of temperature and pH on the existing forms of copper ion were analyzed and determined through calculating the coefficients of copper complex distribution.In the waste water system,the main forms of copper are CuSO4, Cu2 +,CuCl + ,CuCl, 2-and2- 3 CuCl.Temperature has little influence on the distribution coefficient of Cu(Ⅱ),but has significant influence on distribution coefficient of Cu(Ⅰ).With the increase of temperature,the distribution coefficient ofCuCl, 2-increases significantly while the distribution coefficient of2- 3 CuCl decreases.The pH has nearly no influence on the distribution coefficients of various Cu(Ⅰ)-compounds,but has sizable influence on the distribution coefficients of Cu(Ⅱ)-compounds.With the increase of pH,the distribution coefficient of CuSO4(aq)increases while the distribution coefficients of Cu 2+ and CuCl + decrease.According to these results,the anion resin of 201×7 OH-and the cation resin of 732 Na were chosen to dispose the waste water solution of cuprous chloride.Finally,97.9%copper in the waste water is recovered.

Highly selective adsorption of rhenium by amyloid-like protein material

Rhenium separation from molybdenum in molybdenite minerals and waste leachate has become an emerging challenge.Addressing this challenge,we prepared a set of protein-based alkylamine/alkylammonium salts complexes as extractants for selective uptake of rhenium from molybdenum,where the protein component turned into the insoluble amyloid-like structure when its internal disulfide bonds were reduced,namely phase-transition process.Among them,the phase-transited lysozyme and methyletrioctyleammonium chloride complex(PTL-N263)exhibited the most efficient adsorption at the alkaline condition for the electrostatic interaction between negatively charged metal ions with positively charged center(R_(4)N^(+))in N263,where negatively charged protein residues hindered the ion exchange of Cl^(-)in N263 for larger size Mo species(Mo_(7)O_(24)^(6-))than smaller size Re species(ReO^(4-)).The adsorption follows the Freundlich model and pseudo-second-order kinetics,which exhibits toplevel adsorption performance with a maximum adsorption capacity of 124 mg/g and a separation factor(β_(Re/Mo))of 2.78×10^(3)for Re.The adsorption capacity per unit area(57.2 mg/(g m^(2)))is 1.6–41 times higher than previously reported adsorbents,and the cost for adsorbing 1 g of Re(VII)is$1.07,indicating its industrial capability.This adsorption strategy can be applied to separating Re from Mo in binary solutions and industrial wastewater with other competing ions.