Enhanced Electrochemical Properties of Na0.67MnO2 Cathode for Na-Ion Batteries Prepared with Novel Tetrabutylammonium Alginate Binder

Both the binder and solid–electrolyte interface play an important role in improving the cycling stability of electrodes for Na-ion batteries. In this study, a novel tetrabutylammonium (TBA) alginate binder is used to prepare a Na0.67MnO2 electrode for sodium-ion batteries with improved electrochemical performance. The ageing of the electrodes is characterized. TBA alginate-based electrodes are compared to polyvinylidene fluoride- (PVDF) and Na alginate-based electrodes and show favorable electrochemical performance, with gravimetric capacity values of up to 164 mAh/g, which is 6% higher than measured for the electrode prepared with PVDF binder. TBA alginate-based electrodes also display good rate capability and improved cyclability. The solid–electrolyte interface of TBA alginate-based electrodes is similar to that of PVDF-based electrodes. As the only salt of alginic acid soluble in non-aqueous solvents, TBA alginate emerges as a good alternative to PVDF binder in battery applications where the water-based processing of electrode slurries is not feasible, such as the demonstrated case with Na0.67MnO2.

Enhanced removal of phosphate from wastewater by precipitation coupled with flocculation

Eco-friendly flocculants of alginic acid, NaHCO3 and CaCl2.2H2O with advantages of strong gelation characteristics were prepared for supporting the removal of phosphate in synthetic wastewater using CaO and Ca(OH)2 as precipitants. The effects of weight ratios of each component in flocculants, dosage of flocculants and initial phosphate concentration were investigated through batch of experiments. The results showed excellent flocculation performance with the weight ratio of alginic acid:NaHCO3 and CaCl2.2H2O at 1:0.3:0.02 and the dosage of flocculants at 0.0050 g/25 mL of phosphate solution in the range of initial phosphate concentration from 50 to 1000 ppm. Comparing to the sample without flocculants, the phosphate removal efficiency using CaO and Ca(OH)2 with the addition of flocculants increased from 19 and 20% to 97% at the initial phosphate concentration of 50 ppm, respectively by filtration of filter paper 2.7 μm.

Fabrication and Characterization of Xanthan Gum-cl-Poly(Acrylamide-co-Alginic Acid) Hydrogel for Adsorption of Cadmium Ions from Aqueous Medium

The present research demonstrates the facile fabrication of xanthan gum-cl-poly(acrylamide-co-alginic acid) (XG-cl-poly(AAm-co-AA)) hydrogel by employing microwave-assisted copolymerization. Simultaneous copolymerization of acrylamide (AAm) and alginic acid (AA) onto xanthan gum (XG) was carried out. Different samples were fabricated by changing the concentrations of AAm and AA. A sample with maximum swelling percentage was chosen for adsorption experiments. The structural and functional characteristics of synthesized hydrogel were elucidated using diverse characterization tools. Adsorption performance of XG-cl-poly(AAm-co-AA) hydrogel was investigated for the removal of noxious cadmium (Cd(II)) ions using batch adsorption from the aqueous system, various reaction parameters optimized include pH, contact time, temperature, and concentration of Cd(II) ions and temperature. The maximum adsorption was achieved at optimal pH 7, contact time 180 min, temperature 35 °C and cadmium ion centration of 10 mg·L−1. The XG-cl-poly(AAm-co-AA) hydrogel unveiled a very high adsorption potential, and its adsorption capacities considered based on the Langmuir isotherm for Cd(II) ions was 125 mg·g−1 at 35 °C. The Cd(II) ions adsorption data fitted nicely to the Freundlich isotherm and pseudo-first-order model. The reusability investigation demonstrated that hydrogel retained its adsorption capacity even after several uses without significant loss.

Catalytic Reduction Performance of Carboxylated Alginic Acid Derivatives

In this study, the catalytic reduction behavior of carboxylated alginic acid derivatives has been investigated against the harmful organic dyes including Methyl Orange (MO) and Congo Red (CR). Alginic acid was firstly oxidized through an easy addition of KMnO4 as an oxidizing agent. A carboxylated alginic acid (CAA) has been interacted with selected metal ions (Sn, Fe, Ni, and Zr) through coordination bonds at the value of pH = 4 to form the corresponding metal complexes namely: Sn-CAA, Fe-CAA, Ni-CAA and Zr-CAA. The consistency of the coordination was confirmed by several spectroscopic techniques including FT-IR, XRD, SEM, and EDX. The catalytic reduction of these metal ion-based products was carried out against MO and CR in the presence of NaBH4 as a reducing agent under UV irradiation. All catalysts based metal complexes showed enhanced catalytic reduction against CR compared to MO. Among all those mentioned metal complexes Sn-CAA showed the best catalytic reduction of these dyes. The time taken by the Sn-CAA for CR, and MO is 5 and 7min respectively. Ni-CAA was classified as the second efficient product against both dyes, where the reduction process took 20 and 9 min respectively. The other two catalysts took a long time for CR and MO reduction. Zr-CAA showed more than 80 % reduction of only CR dye within 20 min. Whereas, Fe-CAA did not show any significant sign of reduction against both the dyes after the same time. The order of higher catalytic reduction was illustrated as: Sn-CAA > Ni-CAA > Zr-CAA = Fe-CAA.