Activated Carbon from Agricultural Wastes for Adsorption of Organic Pollutants

Agricultural waste materials (strawberry seeds and pistachio shells) were used for preparation of activated carbons by two various methods. Chemical activation using acetic acid and physical activation with gaseous agents (carbon dioxide and water vapor) were chosen as mild and environmentally friendly methods. The effect of type of raw material, temperature, and activation agent on the porous structure characteristics of the materials was discussed applying various methods of analysis. The best obtained activated carbons were characterized by high values of specific surface area (555–685 m2/g). The Guinier analysis of small-angle X-ray scattering (SAXS) curves showed that a time of activation affects pore size. The samples activated using carbon dioxide were characterized mostly by the spherical morphology of pores. Adsorbents were utilized for removal of the model organic pollutants from the single- and multicomponent systems. The adsorption capacities for the 4-chloro-2-methyphenoxyacetic acid (MCPA) removal were equal to 1.43–1.56 mmol/g; however, for adsorbent from strawberry seeds it was much lower. Slight effect of crystal violet presence on the MCPA adsorption and inversely was noticed as a result of adsorption in different types of pores. For similar herbicides strong competition in capacity and adsorption rate was observed. For analysis of kinetic data various equations were used.

On the Guinier law for spin-echo small-angle neutron scattering

It is shown that Guinier analysis of spin-echo small-angle neutron scattering (SESANS) data is dependent on the instrumental setup, in particular the range of scattering vectors accessible by the detector. In the case that Guinier analysis is permissible, the length scale obtained is proportional to the average width of the density autocorrelation function of the scattering particle, and not its radius of gyration.

Anomalous Small-Angle X-Ray Scattering Characterization of Model Pressure Vessel Alloy Microstructures

Anomalous small-angle x-ray scattering (ASAXS) experiments were performed at energies near the Mn-K and Fe-K absorption edges on an Fe-0.9 Cu wt.%-1.0 Mn wt.% alloy subjected to either annealing at 450°C, 24 hrs or irradiation with 10 MeV electrons to 0.5 mdpa at 300°C. A Guinier analysis of the net scattered intensity revealed scatterers with radii of 16.5.16.8 Å and 16.4.17.3 Å for the irradiated and annealed foils, respectively. The variation in net scattered intensity with photon energy in the annealed sample was consistent with scattering contrast variations expected for Cu-rich, Cu-Mn precipitates. Minimal variation in net intensity (scattering contrast) with energy determined that Cu-Mn precipitates were not detected in the irradiated sample.