Sulfonated Magnetic Nanocomposite Based on Reactive PGMA-MAn Copolymer@Fe3O4 Nanoparticles: Effective Removal of Cu(II) Ions from Aqueous Solutions

Chelating magnetic nanocomposites have been considered as suitable materials for removal of heavy metal ions for water treatment. In this work poly(glycidyl methacrylate-maleic anhydride) copolymer (PGMA-MAn) is modified with 4-aminobenzenesulfonic acid (ABSAc) and subsequently the product reacted with modified Fe3O4 nanoparticles and 1,2-ethanedithiol (EDT) in the presence of ultrasonic irradiation for preparation of tridimensional chelating magnetic nanocomposite. Synthesized magnetic nanocomposite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), vibrating sample magnetometer (VSM), energy dispersive X-ray analysis (EDX), elemental mapping analysis (EMA), Brunauer-Emmett-Teller (BET), and thermal gravimetric analysis (TGA). The adsorption behavior of Cu(II) ions was investigated by synthesized nanocomposite in various parameters such as pH, contact time, metal ion concentration, and adsorbent dosage. The equilibrium distribution coefficient (kd) was determined and the findings prove that the kd value is approximately high in the case of all selected metal ions. The synthesized nanocomposite exhibited good tendency for removing Cu(II) ions from aqueous solutions even at an acidic pH.

Cadmium distribution coefficeints and Cd transport in structured soils

In the case of cadmium transport via soil macropores, the short-term duration of an interaction between the reactive solute in aqueous phase and soil, as well as cadmium precipitation or adsorption on particles < 10–5 m should be taken into account. Two distribution coefficients are proposed for predicting the cadmium transport in a structured soil: the matrix distribution coefficient Kdm, equal to the equilibrium distribution coefficient Kdeq and estimated using the conventional batch technique, and the macropore distribution coefficient KdM, estimated using the modified batch technique. It was found that the conventional approach (using the coefficient Kdeq only) would underestimate a penetration of the part of Cd transported in the macropores about 255-times in the loamy-sand soil in Kalinkovo, 20-times in the loam soil in Macov, and 122-times in the clay soil in Jurová in comparison with the approach proposed in this study.

Impurity Solubility and Redistribution Due to Recrystallization of Preamorphized Silicon

The use of silicon substrate preamorphization in ultrashallow junction formation has increased in recent years. The reduction of channeling during impurity implantation, coupled with higher-than-equilibrium metastable solubility levels, produces scaled junctions with low resistances. However, a number of physical phenomena arise that must be considered for proper impurity profile and device optimization.With respect to impurity solubility advanced annealing techniques such as solid-phase-epitaxial-regrowth (SPER), flash, and laser annealing, can place impurity atoms on substitutional sites in the silicon lattice to extremely high concentrations when combined with preamorphization. In this context there is a relationship between the equilibrium distribution coefficient and metastable solubility. The long-established equilibrium distribution coefficient of an impurity, extracted in the liquid to solid phase transformation, can make a prediction of metastable solubility after transformation of amorphous silicon into crystalline silicon during SPER, flash, and laser annealing.With respect to impurity redistribution the significant effects can be split into 3 categories, namely before, during, and after recrystallization. Before recrystallization impurity diffusion in the amorphous region may occur. Boron is particularly susceptible to this effect, which is very significant for the formation of p-type junctions. During recrystallization many impurities move ahead of the amorphous-crystalline (a/c) interface and relocate closer to the surface. In general redistribution is more likely at high impurity concentrations. For low-temperature SPER there is a direct correlation between the magnitude of this redistribution effect and the impurity metastable solubility. After recrystallization, with SPER, flash, and laser annealing commonly leaving residual damage in the silicon substrate, interstitial-diffusers are especially vulnerable to preferential diffusion toward the surface, where impurity atoms may be trapped, ultimately leading to a more shallow profile.

The influence of non-ideal phase flow on the extraction efficiency for the case of a linear equilibrium distribution

The influence of the fundamental parameters of non-ideal phase flow and the extraction parameters on the number of equilibrium stages - ND, theoretical stages - NT, as well as the number of stages (ND - NT), the existence of which is a consequence of the backflow in extractors, was investigated. The calculated number of stages (ND - NT) served as a measure of the influence of the denoted parameters on the extraction efficiency. The results of the investigation indicate that the number of stages (ND - NT) considerably increased with increasing backmixing coefficients and that the dependence was linear. It was established that the increase of the ratio of the flow rate of the heavy and light phase and the decrease of the equilibrium distribution coefficient, as well as the increase of the total separation factor, led to an exponential increase of the number of stages in the extractor, which consequently caused a decrease in the extraction efficiency.

Transport of Sellafield-Derived 14C from the Irish Sea through the North Channel

Since the early 1950s, the Sellafield nuclear fuel reprocessing plant in Northwest England has released radiocarbon into the Irish Sea in a mainly inorganic form as part of its authorized liquid effluent discharge. In contrast to the trend in which the activities of most radionuclides in the Sellafield liquid effluent have decreased substantially, 14C discharges have increased since 1994–95. This has largely been due to a policy change favoring marine discharges over atmospheric discharges. 14C is radiologically important due to its long half life, mobility in the environment, and propensity for entering the food chain. Current models for radionuclide dispersal in the Irish Sea are based on a reversible equilibrium distribution coefficient (kd), an approach which has been shown to be inadequate for 14C. Development of predictive models for the fate of Sellafield-derived 14C requires a thorough understanding of the biogeochemical fluxes between different carbon reservoirs and the processes controlling the net flux of 14C out of the Irish Sea, through the North Channel. In this study, both an empirical and a halving time approach indicate that close to 100% of the 14C that is discharged from Sellafield is dispersed beyond the Irish Sea on a time-scale of months in the form of DIC, with little transfer to the PIC, POC, and DOC fractions, indicating that the “dilute and disperse” mechanism is operating satisfactorily. This is consistent with previous research that indicated little transfer of 14C to Irish Sea sediments. While significant 14C enhancements have been observed in the biota of the Irish Sea, this observation is not necessarily in conflict with either of the above as the total biomass has to be taken into account in any calculations of 14C retention within the Irish Sea.