Fe/polymer-based photocatalyst synthesized by sono-sorption method applied to wastewater treatment

Photocatalytic Properties and Chemical Durability of CaO-B2O3-V2O5 Borovanadate Glasses

The aim of this paper is to investigate the photocatalytic properties and chemical durability of the CaO-B2O3-V2O5 glasses system. The latter were synthesized by the melt-quenching technique. The amorphous nature of the prepared borovanadate glasses has been confirmed with X-ray diffraction. The chemical durability measured from their weights before and after immersion in deionized water and hydrochloric acid indicated that replacing V2O5 with B2O3 improved the chemical durability. The observed increases in chemical durability might be explained by the increase in the glass transition temperature, due to stronger bonding in the structural network. The photocatalytic performance was assessed by the degradation of methylene blue (MB) dye under irradiation, and the evolution of dye degradation was analyzed by UV-visible spectrometry. The vanadium content in the glass, the amount of catalyst, and the initial dye concentration showed a variable effect on the degradation of the MB dye. The photodegradation of methylene blue by the photocatalysts was found to follow pseudo-first-order rate kinetics. The photocatalytic activity for all the prepared photocatalysts showed a higher degradation performance, and the results indicated that 40 CaO-30 B2O3-30 V2O5 has the highest removal efficiency of about 99% in 180 min.

Characteristics and treatment of Brazilian pulp and paper mill effluents: a review

Pulp and paper industries are very important for developing the Brazilian economy. During production processes, many effluents are generated with high polluting potential. The objective of this study is to conduct an extensive literature review on the characteristics of effluents and treatment forms adopted by Brazilian mills in this industrial sector. Most consulted studies address raw (without treatment) and secondary (after biological treatment) effluents, considering their main characteristics like pH, chemical and biochemical oxygen demands (COD and BOD, respectively), color, solids, organochlorines, toxicity, estrogenic activity, and phenols. Raw effluents differ considerably in composition, depending on the type of paper produced, the pulping process employed, and other steps, like pulp bleaching. Raw effluent characteristics indicate that this effluent cannot be directly disposed of into water bodies, because it does not comply with federal and state disposal standards. Secondary effluents normally comply with Brazilian legislations, although some studies have reported COD and total phenol concentrations higher than disposal standards, suggesting that additional treatments are necessary. Treated effluent reuse was verified in some Brazilian mills, while its disposal in eucalyptus plantations has been considered a promising alternative for irrigation purposes.

Wastewater Treatment by Polymeric Microspheres: A Review

This review addresses polymer microspheres used as adsorbent for wastewater treatment. The removal of various pollutants (including dyes, heavy metal ions, and organic pollutants) is a prominent issue, as they can cause severe health problems. Porous microspheres can provide large specific area and active sites for adsorption or photo degradation. Enhancement in performance is achieved by various modifications, such as the introduction of nanoparticles, magnetic particles, and ZIF-8. Some microspheres were synthesized from synthetic polymers such as vinylic polymer and polydopamine (PDA) through a facile fabrication process. Natural polymers (such as cellulose, alginate, and chitosan) that are biodegradable and eco-friendly are also used. The adsorbents used in industrial application require high adsorption capacity, thermal stability, and recyclability. Batch adsorption experiments were conducted to investigate the optimal conditions, influence of related factors, and adsorption capacities. Insights regarding the adsorption mechanisms were given from the kinetic model, isotherm model, and various characterization methods. The recyclability is investigated through regeneration ratio, or their maintenance of their capability through repeated adsorption-desorption cycles. The high potential of polymer microsphere for the removal of pollutants from wastewater is shown through the high adsorption capacities, environmentally friendliness, and high stability.