The synthesis of adsorbents that meet the need for large‐scale production at relatively low cost and are capable of removing anionic and cationic toxic dyes from aqueous solutions, with high sorption capacity and reusability, is urgently needed from an environmental and industrial viewpoint. In this context the identification of hydrogels that remove dyes efficiently under ambient conditions and at near‐neutral pH without the necessity of pre‐treatment is an imperative. In this study we report the preparation of two hydrogels using the redox polymerisation of acrylamide, hydroxyethylmethacrylate (HEMA) and N‐isopropylacrylamide (H1) and acrylamide, HEMA, N‐isopropylacrylamide and perylene‐5‐ylpent‐3‐yne‐2‐methylprop‐2‐enoate‐co‐2‐methyl‐2‐(prop‐2‐enoylamino)propane‐1‐sulfonic acid (PePnUMA‐co‐AMPS) (H2). These hydrogels proved to be effective for the removal of methylene blue (MB), fuchsin acid (FA) and Congo Red (CR) from aqueous solution at near‐neutral pH where their adsorption behaviour was in keeping with the Langmuir model having qmax values of 769.2 mg g−1 (MB), 1666.7 mg g−1 (FA) and 2358.2 mg g−1 (CR). The adsorption of MB and FA by these hydrogels follows pseudo‐first‐order kinetics, whilst the adsorption of CR follows pseudo‐second‐order kinetics. Detailed thermodynamic analysis indicated that the dye–adsorbent interaction is primarily one of physisorption in nature. Finally, desorption studies carried out in 1.0 mol L–1 NaClO4 indicated that these adsorbents could be recycled at least four times using a variety of dyes while maintaining their mechanical properties. © 2021 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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The adsorption behavior of Bismarck brown (BB) dye from aqueous solutions onto graphene oxide GO and graphene oxide-g-poly (n-butyl methacrylate-co-methacrylic acid) GO-g-pBCM as adsorbents was investigated. The prepared GO and GO-g-pBCM were characterized by Fourier transform infrared spectroscopy FTIR, which confirmed the compositions of the prepared adsorbents. Adsorption of BB dye onto GO and GO-g-pBCM was explored in a series of batch experiments under various conditions. The data were examined utilizing Langmuir and Freundlich isotherms. The Langmuir isotherm was seen as increasingly reasonable from the experimental information of dye on formulating adsorbents. Kinetic investigations showed that the experimental data were fitted very well to the pseudo-second-order model, and the calculated positive values of the (∆H° and ∆S°) indicated that the adsorption of BB dye onto GO and GO-g-pBCM was endothermic and increasing of the adsorption process randomness. The negative values of (∆G°) imply that the adsorption process was spontaneous.

Inhibition performance of norepinephrine was investigated as corrosion inhibitors by Gravimetric technique and carried out with mild steel samples in 1 M hydrochloric acid solution at room temperature. Norepinephrine exhibited maximum efficiency of 79% at 500 mg/L. The results of Gravimetric studies revealed that the investigated compound acted as good corrosion inhibitor and the inhibition efficiencies increased with increase in the concentrations of the inhibitor IC. The experimental data complied with the Langmuir adsorption isotherm. Thermodynamic parameters, such as ΔG˚, ΔH˚, and ΔS˚, were calculated using adsorption equilibrium constant obtained from the Langmuir isotherm. Results suggested that the norepinephrine adsorption on mild steel surface was a spontaneous and exothermic process. Scanning electron microscopy was used to investigate the mild steel surface at the highest corrosion inhibition studied concentration.

Any processing method that maintains the level of compounds known for their health benefits will be of interest to the food industries. Therefore, the effects of vacuum drying, storage and freezing on the anthocyanin content and their antioxidant properties of Iresine herbstii L. flowers were investigated. The results showed that fresh samples (AEFF) had the highest amount of total anthosyanin content (8.31 ± 0.23 mg/g dry matter, expressed as cyaniding 3-glucoside equivalents), followed by 7.17 ± 0.12 mg/g solid content, 13.72% loss of vacuum dried samples (AEDF). In comparison with fresh samples, total anthocyanins in stored samples for two weeks at 5˚C (AESF) and frozen samples during 1 (AEZF1) and 3 months (AEZF 3 ) of storage were significantly (P < 0.01) reduced to 6.43 ± 0.24 mg/g solid content, 22.63% loss, 5.65 ± 0.33 mg/g solid content, 32.01% loss and 4.71 ± 0.51 mg/g solid content, 43.33% loss, respectively. Anthocyanins from I. herbstii L. flowers exhibited a dose-dependent (AEFF > AEDF > AESF > AEZF 1 > AEZF 3 , respectively) antioxidant activity against lipid peroxidation in a linoleic acid model system as well as strong reducing power and ferrous ion chelating abilities. Moreover, the anthocyanins extracted were found to show remarkable scavenging activity on superoxide anion radicals, hydroxyl radicals, hydrogen peroxide, nitric oxide radicals and deoxyribose degradation. Based on the results obtained, we can concluded that the Iresine herbstii L. flowers may be valuable natural antioxidant sources and are potentially applicable in both pharmacy and food industry.