Currently, azo dye Carmoisine is an additive that is widely used in the food processing industry sector. However, limited biodegradability in the environment has become a major concern regarding the removal of azo dye. In this study, the degradation of azo dye Carmoisine (acid red 14) in an aqueous solution was studied by using a sequenced process of electro-oxidation–plasma at atmospheric pressure (EO–PAP). Both the efficiency and effectiveness of the process were compared individually. To ascertain the behavior of azo dye Carmoisine over the degradation process, the variations in its physical characteristics were analyzed with a voltage–current relationship, optical emission spectra (OES) and temperature. On the other hand, chemical variables were analyzed by finding out pH, electrical conductivity, absorbance (UV/VIS Spectrophotometry), chemical oxygen demand (COD), cyclic voltammetry (CV), energy consumption and cost. The sequenced process (EO–PAP) increased degradation efficiency, reaching 100% for azo dye Carmoisine (acid red 14) in 60 min. It was observed that the introduction of small quantities of iron metal ions (Fe²⁺/Fe³⁺) as catalysts into the plasma process and the hydrogen peroxide formed in plasma electrical discharge led to the formation of larger amounts of hydroxyl radicals, thus promoting a better performance in the degradation of azo dye. This sequenced process increased the decolorization process.

The decolorization of the Basic violet I (BVI) dye when interacted with a corona discharge is studied in the present work, taking in account two systems, batch and flux. The current and voltage were measured during the whole process in which a corona plasma was generated, with an applied power of 51.9 and 167.72 W where the transport gas was air. A batch reactor and a flow reactor were used, where 500 and 5000 mL of samples were treated, respectively. Optical emission spectra (OES) were measured where the oxidizing species ·OH were at wavelengths of 307.597 and 310.148 nm, associated with the A²∑⁺ - X²Π transition. The absorption spectra for the batch system showed a discoloration of 85.7% in the first 10 min, while in the flow system, the absorption was 93.9% at the same time and 4.5% at the same time by conventional heating. Characteristics of the final sample included an acidic solution with an electrical conductivity of 449.20 ± 55.44 and 313.6 ± 39.58 μS/cm, a dissolved oxygen concentration of 7.74 ± 0.2 and 6.37 ± 0.23 mg/L, an absorbance of 0.04 ± 0.01 and 0.03 ± 0.01 au, with turbidity measuring 1.22 ± 1.59 and 10.34 ± 4.96 NTU, and an energy cost of 1.1 × 10^-1 and 6.3 × 10^-1 g/kWh in the batch and continuous flow systems, respectively. The interaction of the corona plasma with water promoted the production of reactive species, resulting in the discoloration of the Basic Violet I dye.

The discharge of industrial wastewater with dyes into natural tributaries has serious environmental consequences on aquatic ecosystems and the health of living beings. Atmospheric plasmas have proven to be very useful for the degradation of organic contaminants in water; in this context, corona type discharge, owing to its physical characteristics, is capable of degrading and even mineralizing dyes dissolved in water. In this work, zeolite was used as a catalyst in the degradation of the textile azo dye Direct Orange 39 (DO39) through interaction with plasma generated at atmospheric pressure. The zeolite was characterized by microscopic analysis, scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). Microscopic analysis was carried out to determine the roughness and grain size of the zeolite, and scanning electron microscopy and energy-dispersive spectroscopy were carried out to understand the morphology and chemical composition of this material, respectively. The initial concentrations were 1.0 mM for the dye and 4.0 g/L for zeolite, in an initial volume of 250 mL. The results indicate that the coloration of the samples was reduced depending on the treatment time, which was verified by the absorption spectrum in the UV/vis range. The mineralization of the dye after 120 min, using zeolite, was 95%. In addition, the removal percentages in relation to chemical oxygen demand were greater than 96%. Notably the zeolite did not undergo chemical changes during its use as a catalyst in the plasma treatment.

This study introduces a hybrid computational framework combining Monte Carlo simulations with partial differential equations (PDEs) to model gallium nitride (GaN) quantum dot (QD) formation during plasma-enhanced chemical vapor deposition (PECVD). The Monte Carlo approach captures stochastic particle deposition and nucleation on a 100 × 100 nm ² grid, incorporating energy-dependent sticking probabilities, electrostatic repulsion, and a log-normal QD size distribution (mean 4 nm, σ = 0.2). The PDE model describes surface diffusion and nucleation dynamics, linking stochastic outcomes to deterministic physical mechanisms. Experimental parameters include a deposition rate of 0.05 particles/(s·nm ² ), substrate temperature of 700 K, plasma pressure of 0.2–1.0 Torr, particle energy of 30 eV, and plasma temperature of 30,000 K. The simulations generate spatial distribution maps and size histograms, achieving QD densities of 3.0 × 10 ¹⁰ to 1.2 × 10 ¹¹ cm ⁻² , validated against experimental data for LED applications. Results show that increasing plasma pressure enhances QD density but reduces spatial uniformity due to faster nucleation outpacing diffusion, with implications for optimizing optoelectronic device performance. This framework provides a robust tool for tailoring deposition conditions to achieve high-density, uniform GaN QD arrays for advanced optoelectronic applications.

CH₃CH₂OH-N₂ plasma mixture was used to synthesize cuprous oxide (Cu₂O) micro-particles in a pulsed DC sputtering system, using a ethanol pressure of 1.5 Torr and a current of 400 mA at a frequency of 30 kHz. The plasma mixture was used successfully to obtain the micro-particles of Cu₂O using a copper (Cu) target and a stainless steel substrate. The Cu₂O products are characterized by the scanning electron microscope (SEM), the results show that the morphology of the Cu₂O microparticles have a spherical shape which are randomly distributed on the stainless steel substrate. Raman results show that from the CH₃CH₂OH-N₂ plasma mixture it is possible to obtain one of the Cu oxidation phases which corresponds to Cu₂O due to the fact that within the sample analyzed by means of Raman it is possible to observe only the peaks that correspond to the Cu₂O phase. The analysis by energy dispersive spectroscopy (EDS) serves to determine the stoichiometric balance present in the substrate, from which the presence of the characteristic peaks of stainless steel was confirmed, along with the characteristic peaks of Cu and O which exhibit an atomic ratio of 2:1 respectively. Atomic force microscopy (AFM) was used to again determine the morphology of the microparticles, finding a spherical morphology. In addition, the value of roughness and grain size was determined, finding values of 20 nm and 45 nm respectively. The images 3-D show the presence of peaks and valleys within the substrate and an non-homogeneous distribution of spherical micro-particles on the surface of the stainless steel.

While plasma technology shows promise for wastewater treatment, its large-scale application is hindered by the challenge of defining universal treatment conditions for complex industrial effluents. This research investigates the degradation of Acid Black 52 (AB52) to overcome this barrier. We treated 250 mL of a 0.5 mM AB52 solution with atmospheric plasma, systematically varying the pH, applied voltage, and treatment time. The process was monitored by using UV–vis absorption spectroscopy, pH, and electrical conductivity measurements. Our findings reveal that plasma treatment can achieve over 80% dye removal under conditions optimized by both the Response Surface Methodology (voltage: 2.57 kV, discharge exposure time: 107.67 min, initial pH: 4.4) and a Genetic Algorithm (voltage: 2.6 kV, discharge exposure time: 107.84 min, initial pH: 4.95). Furthermore, statistical analysis confirmed that the applied voltage and treatment duration are the most influential factors. This work highlights the efficacy of atmospheric plasma and provides a framework for optimizing its use against specific organic contaminants.