Adsorption/desorption study of proteins onto multi-walled carbon nanotubes and amino multi-walled carbon nanotubes surfaces as adsorbents

α-Amylase Immobilized Composite Cryogels: Some Studies on Kinetic and Adsorption Factors

Stability of enzymes is a significant factor for their industrial feasibility. α-Amylase is an important enzyme for some industries, i.e., textile, food, paper, and pharmaceutics. Pumice particles (PPa) are non-toxic, natural, and low-cost alternative adsorbents with high adsorption capacity. In this study, Cu²⁺ ions were attached to pumice particles (Cu²⁺-APPa). Then, Cu²⁺-APPa embedded composite cryogel was synthesized (Cu²⁺-APPaC) via polymerization of gel-forming agents at minus temperatures. Characterization studies of the Cu²⁺-APPaC cryogel column were performed by X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), and Brunauer, Emmett, Teller (BET) method. The experiments were carried out in a continuous column system. α-Amylase was adsorbed onto Cu²⁺-APPaC cryogel with maximum amount of 858.7 mg/g particles at pH 4.0. Effects of pH and temperature on the activity profiles of the free and the immobilized α-amylase were investigated, and results indicate that immobilization did not alter the optimum pH and temperature values. k_cat value of the immobilized α-amylase is higher than that of the free α-amylase while K_M value increases by immobilization. Storage and operational stabilities of the free and the immobilized α-amylase were determined for 35 days and for 20 runs, respectively.

Synthesis of Fe3O4@chitosan@ZIF-8 towards removal of malachite green from aqueous solution: Theoretical and experimental studies

Discharges of dyes-containing wastewater from industries have created global concern. Removal of these substances from aqueous solution is very important and essential. Magnetic chitosan coated with ZIF-8 was prepared successfully and used to eliminate cationic dye malachite green in various conditions. To find the effectiveness of ZIF-8 towards malachite green removal, their surface interaction was investigated using density functional theory (DFT) calculations for the first time which the results show physisorption of malachite green on ZIF-8. The characteristics of adsorbent synthesized were evaluated using XRD, FTIR, FE-SEM, TEM and TGA analysis. In addition, the influence of different parameters on malachite green removal was investigated. The results showed that pH = 7, 40 mg of adsorbent dosage, 10 mg/L initial concentration, 40 min contact time and temperature of 25 °C were obtained as an optimum values for Fe₃O₄@chitosan@ZIF-8. The equilibrium data were in good agreement with the Langmuir model having maximum capacity (q_m) value of 3.282 mg/g. The experimental data revealed that the adsorption process obeyed to pseudo-second order kinetic model. It was concluded that Fe₃O₄@chitosan@ZIF-8 can be utilized as an efficient and effective adsorbent for removal of toxic malachite green dye from aqueous solution.

Polypyrrole-modified magnetic multi-walled carbon nanotube-based magnetic solid-phase extraction combined with dispersive liquid–liquid microextraction followed by UHPLC-MS/MS for the analysis of sulfonamides in environmental water samples

Polypyrrole modified magnetic multi-walled carbon nanotubes were prepared and applied as an efficient adsorbent for magnetic solid-phase extraction.

Removal of dye molecules from aqueous solution by carbon nanotubes and carbon nanotube functional groups: critical review

Scheme for the adsorption of dye molecules by CNTs and CNT functionality.