Analía Sicardi-Segade

Congo Red is a complex aromatic azo dye whose metabolites can be toxic due to their carcinogenicity, mutagenicity, and various associated toxic effects on flora, fauna, and humans. Different technologies have been employed to degrade this dye, including biodegradation, radiation-based degradation, and chemical degradation with catalysts and photocatalysis. Among these, the use of TiO₂-based materials combined with photocatalysis has proven to be an effective technology for its degradation. However, the wide bandgap of TiO₂ limits its efficiency under visible light, prompting the need for modifications such as doping with metals, metalloids, and organic compounds. These modifications enhance its photocatalytic performance under visible light, achieving degradation efficiencies of up to 100% under optimal conditions. This article explores recent advances (from 2020 to the present) in the degradation of Congo Red using TiO₂-based photocatalysts under visible light, focusing on their characteristics, synthesis methods, and degradation efficiencies. Additionally, it compares the TiO₂-based photocatalysis with visible light to other available technologies, emphasizing its potential as a sustainable and efficient approach while addressing the importance of monitoring degradation byproducts to prevent the generation of equally or more toxic compounds.

Methylene blue is a cationic organic dye commonly found in wastewater, groundwater, and surface water due to industrial discharge into the environment. This emerging pollutant is notably persistent and can pose risks to both human health and the environment. In this study, we developed a Surface Plasmon Resonance Biosensor employing a BK7 prism coated with 3 nm chromium and 50 nm of gold in the Kretschmann configuration, specifically for the detection of methylene blue. For the first time, laccases immobilized on a gold surface were utilized as bio-receptors for this organic dye. The enzyme was immobilized using carbodiimide bonds with EDC/NHS crosslinkers, allowing for the analysis of samples with minimal preparation. The method demonstrated validation with a limit of detection (LOD) of 4.61 mg L⁻¹ and a limit of quantification (LOQ) of 15.37 mg L⁻¹, a working range of 0–100 mg L⁻¹, and an R² value of 0.9614 during real-time analysis. A rainwater sample spiked with methylene blue yielded a recovery rate of 122.46 ± 4.41%. The biosensor maintained a stable signal over 17 cycles and remained effective for 30 days at room temperature.

Methylene blue is a cationic organic dye found in wastewater, groundwater, and surface water, due to industrial release in the environment. This emerging pollutant is very persistent and, depending on the doses, can harm human and environmental health. In this work, a Surface Plasmon Resonance Biosensor using a BK7 prism with a coating of 3 nm chromium and 50 nm of gold in the Kretschmann configuration was developed for the detection of methylene blue, using for the first time, laccases immobilized on a gold surface as bio-receptors for this organic dye. The enzyme immobilization through carbodiimide bonds, using EDC/NHS crosslinkers, and allowed to analyze samples with minimal preparation. The method was validated, achieving a LOD of 4.61 mg L-1 and LOQ of 15.37 mg L-1, a working range from 0-100 mg L-1, and a R2=0.9614 in a real-time analysis. A sample of rainwater spiked with methylene blue was analyzed, and a recovery of 122.46 ± 4.41% was obtained.

This work presents a simplified method for compensating the chromatic aberration of a digital camera lens using orthogonal fringe patterns displayed on an LCD monitor. The proposed compensation method drastically reduces the complex mathematical calculations to an arithmetic procedure of the simple rule of three. First, the implemented method is simulated, and then the experimental results confirm the simulated model. The mean squared error and standard deviation of the chromatic aberration compensation are calculated. Additionally, an arrangement is presented to avoid systematic errors when calculating the chromatic aberration of the lens to be compensated without additional digital processing.