Utilizing low-cost purple coneflower (Echniacea purpurea) marc for competitive sorption of 152+154Eu(III), 60Co(II) and 134Cs(I) radionuclides.

Echinacea purpurea marc (EPM), a residual of echinacea herb after the extraction process, was used as a natural low-cost sorbent for competitive sorption of 152+154Eu(III), 60Co(II) and 134Cs(I) radionuclides. The EPM was ground to prepare it for use in the sorption process. The variables influencing the sorption process were assessed, including pH, contact time, concentrations of metal ions, and temperature. EPM was characterized by different analytical instruments such as FTIR, SEM, XRD, and DTA/TGA. pH 4.0 was selected as the ideal pH value for competitive sorption of the studied ions. Adsorption kinetics data found that the sorption followed a pseudo-second-order model. The adsorption isotherm data was significantly better suited by the Langmuir isotherms in the case of Eu(III) ions while following Freundlich in the case of Co(II) and Cs(I) ions. Positive ΔHo values confirm the endothermic character of metal ion sorption onto EPM. The loading efficiencies of Eu(III), Co(II), and Cs(I) ions in the EPM column were 66.67%, 9.59%, and 4.81%, respectively. The EPM is a cost-effective and efficient separation of Eu(III) ions more than Cs(I) and Co(II) ions. Therefore, in the future, it will be a starting point for the separation of trivalent elements of lanthanide ions.

Radiation synthesis and characterization of starch-acrylic acid-nanohalloysite composite for the removal of Co(II) ions from aqueous solutions.

In this study, gamma rays were used as an initiator to prepare starch-acrylic acid/nanohalloysite, P(Stc-AA/NHal) composite for the removal of Co(II) from aqueous solutions. The characteristic peaks of P(Stc-AA/NHal) composite was confirmed by Fourier transform infrared spectroscopic analysis (FTIR). The morphological structure was examined using a scanning electron microscope (SEM). Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were also used to characterize the composite and demonstrate its high thermal stability. Using a batch sorption technique and 60Co as a radiotracer, the P(Stc-AA/NHal) composite was evaluated for Co(II) ions removal from aqueous solutions. The effect of pH, contact time, metal ion concentration, and temperature on Co(II) ions sorption were studied. The kinetic data of adsorption fit accurately with the pseudo-second-order adsorption model. Finally, the equilibrium adsorption results fitted the Langmuir isotherm model very well. The highest adsorption capacity measured was 103.6 mg g-1.

Gamma radiation induced preparation of polyampholyte nanocomposite polymers for removal of Co(II).

A series of polyampholyte nanocomposite biopolymers, poly(N,N-diallyldimethylammonium chloride-co-acrylamide) grafted on carboxymethylcellulose/iron(III) oxide [P(DADMAC-AAm)CMC/Fe2O3] and poly(N,N-diallyldimethylammonium chloride-co-sodium acrylate) grafted on carboxymethylcellulose/iron(III) oxide [P(DADMAC-SA)CMC/Fe2O3], was prepared with different molar ratios of anionic groups to cationic groups using gamma irradiation. The grafting properties and swelling behavior were investigated as a function of grafting conditions such as DADMAC, AAm, SA, and CMC concentrations and absorbed dose. Fourier transform infrared spectroscopic analysis (FTIR) confirmed the graft copolymerization. Scanning electron microscope (SEM) was employed to check the morphological structure of CMC, P(DADMAC-AAm)CMC/Fe2O3, and P(DADMAC-SA)CMC/Fe2O3. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) further characterized the grafted copolymers and showed their high thermal stability. Using batch sorption experiments and 60Co as a radiotracer, P(DADMAC-AAm)CMC/Fe2O3 and P(DADMAC-SA)CMC/Fe2O3 were evaluated for Co(II) removal from aqueous solutions. Experimentally, P(DADMAC-AAm)CMC/Fe2O3 and P(DADMAC-SA)CMC/Fe2O3 show high sorption capacity of Co(II), i.e. 69.67 mg g-1 and 75.17 mg g-1, respectively, which makes them potential sorbents for Co(II) removal from water/wastewater. Finally, the Co(II) sorption was examined using sorption isotherm and kinetic models. Cobalt sorption was best fitted to Langmuir model which suggests the sorption is of chemisorption type. On the other hand, the sorption kinetics was best represented by the pseudo-first-order kinetic model.

Chitosan­g­maleic acid for effective removal of copper and nickel ions from their solutions.

Pollution of the environment associated with discharging the toxic heavy metals in water makes us focus the light to solve this problem. In continuation of our efforts, we aim in this work to utilize the graft copolymer (chitosan­g­maleic acid) to purify water from copper and nickel ions. The graft copolymer has been synthesized using gamma radiation and the grafting conditions have been optimized by studying the influence of acetic acid concentration (0.5-10% V/V), monomer concentration (5-17.5% w/v), chitosan concentration (0.25-2.5% w/v) and absorbed dose (0.5-5 kGy). FT-IR and TGA have been employed to characterize the graft copolymer. The metal ions uptake by the prepared graft copolymer was investigated and the influence of contact time, solution pH, polymer concentration, and metal ion concentration was studied. Adsorption kinetic models (pseudo-first-order, pseudo-second-order, and intra-particle diffusion equations) and adsorption isotherms (Langmuir, Freundlich, and Temkin equations) were also studied. It was found that the adsorption kinetics and isotherm agreed well with pseudo-second-order and Langmuir equations, respectively, indicating that the adsorption was chemisorption. The adsorption capacities of CTS­g­MA were 312.4 mg g-1 and 70.1 mg g-1 for Cu2+ and Ni2+, respectively. Effect of co-existence of other cationic ions on the adsorption capacity was also investigated.