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Copyright of Revista U.D.C.A Actualidad & Divulgación Científica is the property of Universidad de Ciencias Aplicadas y Ambientales U.D.C.A and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ingeniería y Competitividad is the property of Universidad del Valle and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ingeniería y Competitividad is the property of Universidad del Valle and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The textile industry is a global economic driving force; however, it is also one of the most polluting industries, with highly toxic effluents which are complex to treat due to the recalcitrant nature of some compounds present in these effluents. This research focuses on the removal of Chemical Oxygen Demand (COD), color, Total Organic Carbon (TOC), and Ammoniacal Nitrogen (N-NH3) on tannery wastewater treatment through an advanced oxidation process (AOPs) using sodium bicarbonate (NaHCO3), hydrogen peroxide (H2O2) and temperature using a central composite non-factorial design with a surface response using Statistica 7.0 software. All experiments used a 500 mL reactor with 300 mL of tannery wastewater from a company in Cúcuta, Colombia. The physicochemical characterization was done to determine the significant absorbance peaks about the color in the wavelengths between 297 and 669 nm. Statistical analysis found that the concentration of NaHCO3 affects the removal of color and N-NH3; however, it did not affect COD and TOC. The optimal process conditions for removing the different compounds under study were: NaHCO3 1 M, H2O2 2 M, and 60 °C, with efficiencies of 92.35%, 31.93%, 68.85%, and 35.5% N-NH3, COD, color, and TOC respectively. It can be concluded that AOPs using H2O2 and NaHCO3 are recommended to remove color and N-NH3. [ABSTRACT FROM AUTHOR]

A critical review about the evolution of different advanced oxidation processes (AOPs) implemented on environmental applications in Colombia (2000‐2020), was developed in this study by means a bibliometric analysis. This country has shown an impressive growth in the last two decades, regarding to the development of AOPs, with promising studies in wastewater treatment based on solar natural light. From this analysis, we found that the heterogeneous photocatalysis (especially the solar photocatalysis) was the most developed AOP in the country, because it was the technology with most studies at pilot‐scale and the only one with a reported real‐scale application. Other AOPs such as: Electrochemical, photo‐Fenton, ultrasound and catalytic wet peroxide oxidation (CWPO), have been reported as feasible technologies for wastewater treatment, although at lab‐scale. The bibliometric analysis also showed that the Universidad de Antioquia and Universidad del Valle are the research institutions with the most contributions on AOPs in Colombia. This last institution has the largest number of AOPs' patents registered in Colombia. In general, AOPs in Colombia have shown a notorious development in the last 20 years; however, the photocatalysis is the only one that has been used with solar energy. The combination of AOPs with biological systems (or other AOPs) show greater effectiveness to remove pollutants than the AOPs operating standalone. Despite the Colombian progress regarding to these technologies' development, the transfer of AOPs as commercial solutions has been challenging; therefore, possible solutions to these problems were presented in this study in order to achieve a synergistic and efficient evolution. [ABSTRACT FROM AUTHOR]

This study provides new insight into the implementation and synergy effect of coupling in sequences of the photocatalysis ([TiO2-UVC]), ozone (O3) and hydrogen peroxide (H2O2) applied to degradation and mineralization of a model compound such as caffeine (in synthetic solution and industrial wastewater). The system consists of an annular photoreactor coupled to two venturi valves with a continuous dosage of O3 and H2O2, the combination of binary processes such as O3/H2O2, TiO2/O3 and UVC/H2O2 was evaluated, as well as the coupling of TiO2/O3/H2O2/UVC in order to estimate all the possible synergy effects. It was found that the coupling between photocatalysis and hydrogen peroxide shows a negligible performance of caffeine treatment in both synthetic and real wastewater because the reaction rate, degradation and mineralization of caffeine does not improve considerably compared to the photocatalysis process alone. Meanwhile, the coupling between photocatalysis and ozonation shows the highest synergy effect. The coupling of all the processes evaluated TiO2/O3/H2O2/UVC achieved 100% degradation of caffeine, but the mineralization was lower than photocatalysis coupled with ozonation. This could be due to the peroxide and ozone compete by active sites of the catalyst and can also act as scavengers of oxidizing species, hindering the caffeine mineralization. The results show that the combination of photocatalysis with ozone and peroxide can make a synergy effect for industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the performance of high purity magnesium and the magnesium-aluminum-zinc alloy AZ31 as sacrificial anodes in an electrocoagulation process with polarity change for the treatment of synthetic indigo carmine solution. It was studied the effect of the main parameters such as temperature, anodic material, current density, initial dye concentration, and agitation speed on the diminishing of indigo carmine concentration and non-purgeable organic carbon. Also, image analysis was used in conjunction with zeta potential measurements to understand the mechanism of flocs formation. The best results were 80% and 96% removal for non-purgeable organic carbon and dye content respectively at room temperature, by using turbulent regime, initial dye concentration of 100 mg L−1 and 50 A m−2 as current density with AZ31 alloy as electrodes. Particularly, high purity magnesium reached 75% in non-purgeable organic carbon removal and 86% in dye removal at the conditions described above. Finally, an additional improvement of 43% in the diminishing of the organic carbon content was observed when polarity change was used, a phenomenon that was attributed to the distribution of the oxidation reaction between electrodes, avoiding the saturation of the surface with oxide and hydroxide layers. Major areas and major fractal dimension were obtained by using a polarity change. [ABSTRACT FROM AUTHOR]

The tannery industry is one of the economic sectors that contributes to the development of different countries. Globally, Europe and Asia are the main producers of this industry, although Latin America and Africa have been growing considerably in recent years. With this growth, the negative environmental impacts towards different ecosystem resources as a result of the discharges of recalcitrated pollutants, have led to different investigations to generate alternative solutions. Worldwide, different technologies have been studied to address this problem, biological and physicochemical processes have been widely studied, presenting drawbacks with some recalcitrant compounds. This review provides a context on the different existing technologies for the treatment of tannery wastewater, analyzing the physicochemical composition of this liquid waste, the impact it generates on human health and ecosystems and the advances in the different existing technologies, focusing on advanced oxidation processes and the use of microalgae. The coupling of advanced oxidation processes with biological processes, mainly microalgae, is seen as a viable biotechnological strategy, not only for the removal of pollutants, but also to obtain value-added products with potential use in the biorefining of the biomass. [ABSTRACT FROM AUTHOR]

• The highest adsorption of [Fe(CN)6]3- was obtained at the highest pH value. • The [Fe(CN)6]3- adsorption could be described by the ion-pair adsorption mechanism. • Cation atomic radius may not influence the [Fe(CN)6]3- adsorption. • A chemisorption phenomenon of [Fe(CN)6]3- on GAC can be ruled out. The influence of the addition of cations on the adsorption of [Fe(CN) 6 3− on granular activated carbon (GAC) was evaluated. The tests were performed at three pH values (3, 8.2, and 13) to determine the repulsion or electrostatic affinity between the adsorbent and adsorbate. Afterward, the cations (K+, Ca2+, and Al3+) at three pollutant-cation molar ratios (1:1, 1:10, and 1:50) were added to the system, and the influence of those was identified by the changes in the adsorption efficiency. The results show that the higher removal (%) was obtained at pH 13 without neither the presence of iron precipitates nor the liberation of HCN. The adsorption of [Fe(CN) 6 3- was enhanced by the addition of K+ at 1:10 and 1:50 mol ratio since higher removals were achieved (75.27 % and 76.81 % respectively) than those obtained in the absence of cations (64.18 %) or in the presence of Ca2+ (67.58 %) and Al3+ (65.13 %) at a 1:10 mol ratio. The behavior in adsorption in the presence of cations shows that the ion-pair adsorption mechanism can describe the physical phenomenon, showing an increase in the fraction removed and the rate of adsorption with increasing cation charge. The adsorption kinetics using K+ with a 1:10 pollutant-cation molar ratio was fitted to the Lagergren pseudo-first-order model. The GAC adsorption capacity describes the pollutant adsorption rate with the predominance of physical interactions. The experimental data were fitted by the Langmuir and Freundlich isotherms, indicating a monolayer adsorption phenomenon consistent with the previously proposed ion-pair adsorption mechanism. [ABSTRACT FROM AUTHOR]

The effectiveness of two photocatalysts, TiO2 and SnO, supported on graphene oxide (TiO2-GO and SnO-GO) on the removal of organic matter from hospital wastewater effluent was evaluated at laboratory scale. The results of the experimental design allow us to conclude that variables such as catalyst type and catalyst concentration have a significant effect on the organic matter removal efficiency of the photocatalytic process. The highest levels of removal efficiencies—for chemical oxygen demand, 85%, for phenols, 80%, and for dissolved organic carbon, 94%—were achieved using a TiO2-GO catalyst with a concentration in the wastewater of 1.5 g/L. [ABSTRACT FROM AUTHOR]

• C o C N 6 3 - can be decompose by UVC radiation. • The S 2 O 8 2 - activation by base does not contribute to the degradation of C o C N 6 3 -. • There is no increase in the removal of Co when the S 2 O 8 2 - concentration is above 0.5 g/L. • The degradation process has a better performance at N 2 atmosphere at all concentrations of S 2 O 8 2 -. • 99 % Co removal was obtained at 0.5 g/L S 2 O 8 2 - and 25 mg/L C o C N 6 3 - at N 2 atmosphere. The ultraviolet light activation of persulfate (PS) was evaluated for the degradation of cobalt cyanocomplexes, which are considered as some of the most recalcitrant compounds present in mining wastewater. The influence of the solution pH (11 and 13), initial concentration of PS (0.1, 0.3, 0.5, 0.7 and 0.9 g/L), dissolved oxygen and initial concentration of contaminant were evaluated. Photolysis results showed that C o C N 6 3 - is photosensitive to UVC radiation, while the activation of PS by alkaline pH does not contribute to the degradation of the cyanocomplex. There was no presence of C N - at both solution pH values using UVC/PS. But at pH 13, the degradation of cobalt cyanocomplexes and the pseudo-first-order rate constant increased. This was attributed to the effective conversion of S O 4 • - to H O • and to the increase in the oxidative photolysis of PS at high pH. Additional tests demonstrated better performance of UVC/PS in the absence of oxygen which may be caused by the quenching effect of O 2 to the higher energy excited state of the cyanocomplex that must be reached to initiate degradation reactions. Increasing the initial concentration of C o C N 6 3 - will increase the amount of Co removed but it represents the higher specific energy consumption. [ABSTRACT FROM AUTHOR]