Adsorption Kinetics of Toxic Heavy Metal Ions from Aqueous Solutions onto Grafted Jute Fibers with Acrylic Acid by Gamma Irradiation

Jute fibers were used as an adsorbent substrate for Hg²⁺ and Pb²⁺ metal ions as toxic pollutants from their aqueous solutions after graft copolymerization with polyacrylic acid under the effect of gamma irradiation. The treated jute fibers were characterized by using of Fourier-Transform Infrared Spectroscopy. The effects of solution pH, contact time, temperature, and the dissolved metal ions’ concentration on the adsorption efficiency were investigated. The adsorption kinetics and the used adsorption isotherm were also investigated. From the results, it was concluded that the adsorption process conformed the second-order kinetic reaction and followed the Langmuir adsorption isotherm model, and the higher adsorption capacities were at pH 5 and 6 for Pb²⁺ and Hg²⁺ metal ions respectively.     

Synthesis and Applications of Functional Polymers from Natural Okra Fibers for Removal of Cu(II) Ions from Aqueous Solution

Functional groups (?COOCH₃ and ?NH₂) in natural okra fiber had been introduced by free radical graft polymerization of methyl methacrylate (MMA) and acrylamide (AAm) from their binary solution using ascorbic acid/H₂O₂ as a redox initiator at a temperature of 45°C for 90 min. Factors affecting the grafting of lignocellulosic fiber such as feed molarity and comonomer composition were investigated. The grafted copolymers were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM-EDX), and thermogravimetric analysis (TGA). Functional groups were tested for their potential application in the removal of copper ions from aqueous solutions. Batch experiments were performed to evaluate the adsorption capacity of the maximum grafted cellulosic fibers toward the Cu (II) ions. Pseudo-first-order and pseudo-second-order kinetic models were studied to analyze the Cu²⁺ adsorption process and results showed that the pseudo-second-order model was more suitable than the pseudo-first-order model. Further, Langmuir, Freundlich, and Tempkin models were also applied to describe the adsorption isotherm of Cu²⁺ by different fiber adsorbents. The results indicate that the Langmuir model fitted the adsorption equilibrium data better than other two models. The maximum monolayer capacity q_m calculated using the Langmuir isotherm for raw and MMA+AAm grafted fiber were 4.89 and 33.05 mg/g, respectively.