Post-irradiation physicochemical features of polymer composite for the removal of Co(II) and Nd(III) from aqueous solutions.

The scientific impact of this work is the protection of the environment from hazardous pollutants. Gamma irradiation was employed for the preparation of a new composite polymer by irradiating a mixture containing polyvinyl pyrrolidone (PVP), hydroxyethyl methacrylate (HEMA), and tannic acid (TA) to produce PVP-HEMA-TA. The sorption efficiency and capacity of PVP-HEMA-TA were evaluated by studying some factors affecting the sorption of Nd(III) and Co(II) from aqueous solutions. The results demonstrated that the maximum uptake was 92.4 and 75.3% for Nd(III) and Co(II), respectively. From the kinetic studies, the pseudo-second-order equation could better fit the data than the pseudo-first-order for the sorption of both ions. The sorption isotherm investigations illustrated that the Langmuir equation fits the gained data better than Freundlich equation. The Langmuir capacity was 64.5 and 60.8 mg/g for neodymium and cobalt ions, respectively. The applicability of Langmuir equation is strong evidence that the process is limited by a chemisorption mechanism. Findings of the work highlight the potential utilization of PVP-HEMA-TA as an effective and recyclable material for the elimination of Nd(III) and Co(II) from the aqueous phase.

Ni-alginate hydrogel beads for establishing breakthrough curves of lead ions removal from aqueous solutions.

The scientific impact of this work is the protection of the environment from hazardous pollutants using a column technique. Besides its higher stability at working pH and its time persisting, Ni-alginate has a higher ability to remove lead ions compared to the other prepared beads (Sr-alginate, Co-alginate, and Ca-alginate). Also, Ni-alginate possessed a higher removal percent, 93.3%, toward Pb2+ than the other ions, taking the sorption order of Pb2+ > Sr2+ > Co2+ > Cd2+ > Zn2+. Therefore, this study focused on using Ni-alginate as a selective sorbent for lead ions. Fixed-bed column was employed for the sorption process. The results for that efficiency are presented as breakthrough curves in view of the impact of various parameters; influent flow rate (1.5, 3.0, and 5.0 mL/min), lead concentration (100, 150, and 200 mg/L), and bed depth of sorbent (3.0, 5.0, and 7.0 cm). Breakthrough modeling including Thomas and Yan models was employed. The outcomes indicated that Thomas theory is more applicable. The overall outcomes indicated that Ni-alginate is recommended for selective removal of Pb2+ from waste solutions.

Utilization of Modified Attapulgite for the Removal of Sr(II), Co(II), and Ni(II) Ions from Multicomponent System, Part I: Kinetic Studies.

Radionuclide sorption by natural and modified clays is extensively accepted to be an important process from the radioactive waste point of view. This work focused on modification of natural attapulgite with a layered double hydroxide to produce a novel chemisorbent for Sr2+, Ni2+, and Co2+ removal from multicomponent solution. The structural and surface characteristics of both attapulgite (ATP) and modified attapulgite (LDH-ATP) were investigated using XRD, FTIR, SEM, and thermal analysis. Comparison of sorption features of Sr2+, Ni2+, and Co2+ onto ATP and LDH-ATP was achieved; the results indicated that LDH-ATP was the most efficient sorbent for Sr2+, Ni2+, and Co2+. Kinetic studies established that the sorption is fast and reaching >90% within 30 min. The sorption of Sr2+, Ni2+, and Co2+ are well defined by non-linear pseudo-second-order model and controlled by an intra-particle diffusion mechanism. The diffusivity was determined using homogeneous surface diffusion (HSDM) model and found in the order 10-13 m2/min; this confirmed that the sorption of the three ions is chemisorption process. LDH-ATP can be employed as a candidate chemisorbent for the removal of some metal ions from waste solution.