Due to its low cost, environmentally friendly process, and lack of secondary contamination, the photodegradation of dyes is regarded as a promising technology for industrial wastewater treatment. This technology demonstrates the light-enhanced generation of charge carriers and reactive radicals that non-selectively degrade various organic dyes into water, CO2, and other organic compounds via direct photodegradation or a sensitization-mediated degradation process. The overall efficiency of the photocatalysis system is closely dependent upon operational parameters that govern the adsorption and photodegradation of dye molecules, including the initial dye concentration, pH of the solution, temperature of the reaction medium, and light intensity. Additionally, the charge-carrier properties of the photocatalyst strongly affect the generation of reactive species in the heterogeneous photodegradation and thereby dictate the photodegradation efficiency. Herein, this comprehensive review discusses the pseudo kinetics and mechanisms of the photodegradation reactions. The operational factors affecting the photodegradation of either cationic or anionic dye molecules, as well as the charge-carrier properties of the photocatalyst, are also fully explored. By further analyzing past works to clarify key active species for photodegradation reactions and optimal conditions, this review provides helpful guidelines that can be applied to foster the development of efficient photodegradation systems.

Mechanistic insights into photodegradation of organic dyes using heterostructure photocatalysts

Feasibility of industrial-scale treatment of dye wastewater via bio-adsorption technology

Synthesis of magnetic oxidized multiwalled carbon nanotube-κ-carrageenan-Fe3O4 nanocomposite adsorbent and its application in cationic Methylene Blue dye adsorption.

Chitosan/(polyvinyl alcohol)/zeolite electrospun composite nanofibrous membrane for adsorption of Cr6+, Fe3+ and Ni2+

Adsorptive performance of MOF nanocomposite for methylene blue and malachite green dyes: Kinetics, isotherm and mechanism.

Dye adsorption by resins: Effect of ionic strength on hydrophobic and electrostatic interactions

Adsorption of iodide ions on a calcium alginate–silver chloride composite adsorbent

In this study, the calcium alginate–potassium tetraphenylborate (Ca(ALG)2–KB(C6H5)4) composite adsorbent was synthesized using potassium tetraphenylborate (KB(C6H5)4) as the adsorption-active component and calcium alginate (Ca(ALG)2) as the matrix material. Different techniques were used for characterization of the adsorbent such as SEM, EDS, XRD, laser particle size analysis and moisture analysis. Competitive adsorption of Li, Na, K, Rb, Cs ions onto the adsorbent was investigated through kinetic curves, adsorption isotherms and column techniques at 25 °C. The equilibrium adsorption capacities were compared in the single-element and multi-element systems. The equilibrium adsorption amount was in the sequence Cs+ > Rb+ ≫ Na+ ∼ Li+, and Li and Na ions were hardly adsorbed. The separation factor was found to follow the order βCs/Li > βRb/Li > βNa/Li under both the noncompetitive and competitive adsorption conditions. In the kinetic experiments for competitive adsorption, the adsorption reached equilibrium in about 24 h. The equilibrium sorption data were described by the Langmuir and Freundlich isotherm models and the results showed that the Langmuir model with determination coefficients of 0.997 and 0.981 for Cs+ and Rb+ respectively could describe the competitive system at room temperature more correctly. Lower breakthrough ratio and higher adsorption amount were observed for Cs+ in the column experiments for competitive adsorption. Ion-exchange was deduced as the mechanism for selective adsorption of Rb+ and Cs+ ions onto the composite on the basis of EDS and XRD analysis of the adsorbent before and after adsorption. The tetraphenylborate anion (B(C6H5)4−) had different affinity to different alkali metal ions following the order Cs+ > Rb+ > K+ due to the order of the solubility product Ksp (CsBph4) < Ksp (RbBph4) < Ksp (KBph4).

Competitive adsorption of Li, Na, K, Rb and Cs ions onto calcium alginate–potassium tetraphenylborate composite adsorbent

Adsorption is one of the effective methods to recover or remove alkali metal ions from aqueous solutions. Current studies on the adsorption of alkali metal ions are mainly focused on the adsorption of one alkali metal ion. However, under natural conditions, alkali metal ions are usually coexisted. During separation processes, they compete with each other. In this study, competitive and noncompetitive adsorption of Li, K, Rb, and Cs ions onto three ion-exchange resins (D001, LSC-100, and LSC-500) of sodium form was investigated in batch experiments at 25oC. Compared with the noncompetitive adsorption, competitive adsorption of different alkali metal ions present with larger differences, in general. The adsorption from single and multiple solutions presents similar preference. Under both the noncompetitive and competitive adsorption conditions, for D001 resin, the separation factor was found to follow the order of β Cs/Li > β Rb/Li > β K/Li, on the contrary, for both LSC-100 and LSC-500 resins, it ...

Competitive adsorption of Li, K, Rb, and Cs ions onto three ion-exchange resins

Rare earth alloys can be prepared through the methods of melting, metallothermic reduction, and molten salt electrolysis Compared to the former two methods, the molten salt electrolysis method has several advantages: the production cost is lower, the composition of the rare earth alloys is uniform and easy control, and the quality of the rare earth alloys is good The rare earth alloys can be prepared easily and continuously on industrial scale In this paper, the research progress in the molten salt electrolysis preparation of the rare earth alloys of magnesium, aluminum, iron, cobalt, nickel, and copper is reviewed by considering the rare earth alloy applications in structural, magnetic, and hydrogen storage materials The prospects of the related research works are discussed

Tan Guo

Papers

Dye adsorption by resins: Effect of ionic strength on hydrophobic and electrostatic interactions

Adsorption of iodide ions on a calcium alginate–silver chloride composite adsorbent

Competitive adsorption of Li, Na, K, Rb and Cs ions onto calcium alginate–potassium tetraphenylborate composite adsorbent

Competitive adsorption of Li, K, Rb, and Cs ions onto three ion-exchange resins

Research progress in the preparation of rare earth alloys by molten salt electrolysis method