Dye-contaminated Wastewater Research Articles

Lab scale evaluation of biomineralization-assisted decolourization of reactive blue 4 and toxicity analysis

The process of microbial mineral precipitation has proven to be highly effective in addressing a wide range of pollutants in different environments. The objective of this study is to utilize the mineralization abilities of microbial strains found in the Noyyal River basin, which is home to a significant textile center in India, in order to both remove the color from reactive blue 4 and promote biomineralization. Promising results were obtained from the microbial isolates Streptomyces sp., Rhodococcus ruber, and Bacillus sp., and their consortium which demonstrated the ability to induce biomineralization and decolorize reactive blue 4. Characterization of the obtained biominerals through X-ray diffraction and FT-IR analysis showed the presence of well-crystallized polymorphs of calcium carbonate, along with other organic compounds. SEM-EDX analysis of biominerals formed during biomineralization-assisted decolourization of RB4 revealed distinct morphologies and elemental composition of the biominerals produced by microbial interactions with dye molecules. Further, to assess the safety and efficacy of these biominerals, zebrafish embryo toxicity tests were conducted by comparing biominerals produced during dye decolourization with the pure reactive blue 4 dye. Zebrafish embryos treated with biominerals exhibited normal developmental patterns, whereas those exposed to reactive blue 4 displayed mortality and abnormal hatching rates. The heart rates of the Zebrafish embryos were normal for controls and biomineral groups, but lower for RB4-exposed embryos. In conclusion, this study underscores the potential of biomineralization in remediating dye-contaminated wastewater, offering circular solutions for waste reduction and resource utilization.

1 T/2 H mixed phase MoS2 nanosheets decorated with Ag nanoparticles for effective photocatalysis of organic dyes for wastewater treatment

The rapid industrialization and urbanization have led to the proliferation of organic dyes in wastewater, necessitating the development of efficient and sustainable treatment technologies. We report here a novel photocatalyst based on 1 T/2 H mixed-phase molybdenum disulfide nanosheets (1 T/2 H-MoS2 NSs) decorated with silver (Ag) nanoparticles for the enhanced photodegradation of both cataionic and anionic organic dyes under natural sunlight. Hydrothermally synthesized silver nanoparticles decorated 1 T/2 H MoS2 nanosheets (Ag-1 T/2 H MoS2 NSs) are characterized through X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Raman spectroscopy, UV–vis spectroscopy, and Photoluminescence (PL) spectroscopy. FESEM results reveal that MoS2 NSs of thickness 17 nm clustered into nanoflowers where Ag nanoparticles are embedded in them. XRD results show the characteristic diffraction peaks at 2ϴ value 9.80 and 32.380 for (002) and (100) planes respectively. Photocatalytic performance has been evaluated by the degradation of Crystal Violet (CV) and Methyl Orange (MO) under direct sunlight irradiation. Nanocomposites exhibit a significant improvement in degradation efficiency i.e. 97 % for both (CV) and (MO) in 15 minutes and 25 minutes respectively compared to pure MoS2. The superior activity of the Ag-1 T/2 H MoS2 composite is attributed to the synergistic effects of the mixed-phase MoS2 structure and the charge transfer phenomenon provided by Ag nanoparticles. This work highlights the potential of Ag-1 T/2 H MoS2 NSs as an effective photocatalyst for the treatment of dye-contaminated wastewater.

Ingenious development of bandgap engineered MIL-101(Fe) core-shell supported on SnO2/ZnO heterojunction and its photocatalytic activity towards azo dye degradation: Process optimization and mechanistic insight

Water pollution is a pressing global concern, exacerbated by industrial effluents containing hazardous azo-dyes such as Trypan blue (TB) and Methyl orange (MO), which contaminate water bodies and threaten ecosystems. The scarcity of pure water intensifies the urgency to develop effective remediation strategies to tackle the toxic dye pollutants. In the present work, an attempt has been made to fabricate and utilize a novel ternary MOF-based SnO2/ZnO@MIL-101(Fe) photocatalyst for the removal of TB and MO dyes from an aqueous medium. The photocatalyst was characterized using various analytical techniques, like XRD, FTIR, UV–vis DRS, PL, SEM, TEM, and XPS, which provide insights into the composites’ crystal structure, morphology, and optical properties, which are crucial for understanding their photocatalytic behavior. The photocatalytic performance of the heterojunction was investigated under various reaction parameters such as catalyst dosage, initial concentration of dyes, and light irradiation time. The results demonstrated the superior performance of the SnO2/ZnO@MIL-101(Fe) composites in degrading the mono-azo and di-azo dyes under visible light irradiation via a photo-fenton process. The maximum degradation efficiency of 97.44 % and 98.8 % were obtained for TB and MO within 30 and 55 min, respectively. Furthermore, the change in the total organic carbon (TOC) was monitored to verify the degree of mineralization of the azo dyes. The extremely high dye degradation activity and TOC removal can be attributed to the formation of a suitable heterojunction interface between the components of the photocatalyst, leading to effective charge carrier transport and the generation of active radicals. Finally, based on the radical scavenging experiments, ESR, and VB-XPS analysis, a plausible mechanism for the photodegradation process was derived. This research contributes to the advancement of sustainable water treatment technologies by providing insights into the design, fabrication, and utilization of novel composites for efficient remediation of dye-contaminated wastewater.

Biodecolorization and Biodegradation of Sulfur Black by the Strain Aspergillus sp. DS-28

The textile industry significantly contributes to environmental pollution through its use of synthetic dyes, especially sulfur black, known for its toxicity and resistance to degradation. This research focuses on a fungal strain, Aspergillus sp. strain DS-28, isolated from activated sludge, which exhibits an exceptional ability to biodegrade sulfur black dye. This study systematically assessed the biodegradation capacity of this strain through a series of experiments conducted over a 7-day period. Analytical techniques including high-performance liquid chromatography time-of-flight mass spectrometry (HPLC-TOF/MS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) were employed to monitor the degradation process. SEM showed a significant reduction in particle size, with surfaces becoming smoother and flatter post treatment. XRD indicated a decrease in the intensity of several chemical bonds, and FTIR analysis demonstrated the enhanced vibrational absorption peaks of benzene ring bonds, with the disappearance of -C-S- and -C-S-S-C- groups. The results demonstrate that Aspergillus sp. DS-28 degrades sulfur black by initiating the oxidative breakdown of its complex structures into simpler forms. This study not only elucidates the biodegradation pathway facilitated by Aspergillus sp. DS-28, but also highlights its potential application in developing eco-friendly waste management strategies for treating dye-contaminated wastewater.

Design and characterisation of activated magnetic zeolite 4A from naturally occurring kaolin clay of Cameroonian origin for optimised dye removal by Fenton-like degradation

ABSTRACT The transformation of local clay material of Cameroonian origin into magnetic zeolite (Fe@Zeo-4A) for the degradation of acid-blue 90 in solution was investigate herein. The insertion of magnetic iron oxide particles into the zeolitic framework of Zeo-4A was achieved via hydrothermal synthesis. FT-IR spectroscopy, XRD and SEM confirmed the transformation of the clay into zeolite while EDX analysis and elemental mappings confirmed the presence of iron in the magnetic zeolite. Fe@Zeo-4A was strongly attracted to an external magnetic field. N2 adsorption-desorption studies revealed a considerable decrease in specific surface area and pore volume from the zeolite to the magnetic zeolite, suggesting the occupation of the pores of the zeolite by magnetite. The central composite design of the response surface methodology was used as optimisation approach for four parameters affecting the efficiency of degradation: solution pH, H2O2 concentration, initial dye concentration and time of stirring. ANOVA results revealed good correlation between the experimental and predicted results as well as the suitability of the linear regression model for describing the dye degradation process. An adjusted correlation coefficient of 85.17% was obtained for the dye degradation model. An optimal degradation percentage of 95.2% was obtained experimentally under optimal conditions of 7.6 for pH, 20 mg/L for dye concentration, 15.0 mol/L for [H2O2] and 15 min for time, in close agreement with a theoretical response of 96.6% predicted by the model. The magnetic zeolite was found to exhibit good stability over a wide pH range and lost only about 18% of its catalytic efficiency after five cycles of degradation experiments. Therefore, the novel magnetic zeolite-based material is an efficient Fenton catalyst for treating dye-contaminated wastewater.

Effective degradation of dyes using silver nanoparticles synthesized from Thunbergia grandiflora leaf extract

Motivated by the urgent need to address dye-related environmental pollution, this study explores the green synthesis of silver nanoparticles (AgNPs) using Thunbergia grandiflora leaf extract for its simplicity, affordability, and eco-friendliness. UV–Vis spectroscopy reveals a distinctive signal at 441 nm, while Dynamic Light Scattering shows a zeta potential charge of −18.2 mV, indicating nanoparticle stability. The study demonstrates the catalytic activity of AgNPs in degrading industrial dyes Acid Red 88 and Methylene Blue, showcasing first-order kinetics with kinetic constants of 0.18 min−1 and 0.14 min−1, respectively. Moreover, Scanning Electron Microscopic images reveal predominantly spherical nanostructures, while X-ray diffractometry analysis portrays a face-centered crystalline structure. These findings underscore the potential of AgNPs synthesized from T. grandiflora leaf extract in nanoremediation efforts, offering a sustainable solution to the pressing challenge of dye-contaminated wastewater, thereby contributing to environmental protection.

Adsorption of Methylene Blue using Bottom Ash: Experimental Design, Isotherm Analysis, and Optimum Conditions

<p><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:107%"><span style="font-family:"Times New Roman",serif"><span style="color:black">This study investigated the removal of methylene blue (MB) via adsorption using waste bottom ash.  The bottom ash, sourced from a waste storage site in the Çorlu district of Tekirdağ province, Thrace Region, was utilized as the adsorbent. The research examined the impact of several variables on MB removal, including bottom ash dosage, pH, contact time, and agitation speed. It was found that all parameters had a single-variable effect, while pH exhibited a quadratic effect on MB removal in a model-based analysis. The optimization of the model for maximum MB removal identified the optimal conditions as 0.978 g bottom ash dosage, pH 3, 15 minutes of adsorption time, and 50 rpm agitation speed. Under these conditions, the model predicted an MB removal efficiency of 71%, which was experimentally confirmed to be 72.5%. The adsorption process was found to fit with the Freundlich isotherm, indicating a multilayer adsorption mechanism on the heterogeneous surface of the adsorbent. This research not only highlights the feasibility of using bottom ash from coal combustion as an economical adsorbent for dye-contaminated wastewater but also underscores its potential to inform and inspire future studies on waste recycling and wastewater treatment. </span></span></span></span></p>

Visible light responsive SiO2/g-C3N4/BiOBr/Bi heterojunction photocatalyst for degradation of rhodamine B

For the purpose of alleviating the negative influence of rhodamine B (RhB) abuse on the environment, it is imperative to design a green and efficient photocatalyst for tackling organic dye-contaminated wastewater. Herein, a novel SiO2/g-C3N4/BiOBr/Bi (denoted as Si/CN/BiOB/Bi) photocatalyst with enhanced photodegradation activity has been successfully created. The influence of variable parameters including Bi doping amount, initial concentration of RhB, photocatalyst dosage, and reaction temperature on the photocatalytic performance of Si/CN/BiOB/Bi under visible light illumination are analyzed in detail. Results indicated that the degradation rate constant of RhB over Si/CN/BiOB/Bi-0.5 is 25.1, 18.1, and 2.2 times higher than that of CN, Si/CN, and Si/CN/BiOB, respectively. The Si/CN/BiOB/Bi-0.5 photocatalyst displayed high photocatalytic performance after 5 recycled runs. The improved photocatalytic performance can be attributed to the novel morphology as well as the excellent synergetic effects of Si/CN, BiOBr, and Bi, which enables the catalysts to accelerate the separation of photogenerated carriers. In brief, a new Si/CN/BiOB/Bi photocatalyst has a great application perspective for the purification of RhB wastewater.

Photodegradation, kinetics and non-linear error functions of methylene blue dye using SrZrO3 perovskite photocatalyst

The degradation of methylene blue dye-contaminated wastewater via photocatalysis is an efficient approach towards environmental remediation. The SrZrO3 perovskite photocatalyst was synthesized using the modified Pechini sol-gel method, and characterized using XRD, FESEM, FTIR, and UV–visible spectrophotometer. Crystallite size obtained by the Scherrer and Williamson-Hall methods were 45.56 and 44.50 nm, respectively. The sample exhibited an orthorhombic crystal structure. The optical bandgap was estimated to be 5.31 eV. Kinetic study for the degradation of methylene blue dye using SrZrO3 in the presence of H2O2 showed complete decontamination of the methylene blue dye in the time interval of 90–120 min under visible light irradiation. The degradation efficiency was above 80.1 % under illumination and less than 40.1 % in dark. Kinetic studies were performed by varying the dose of photocatalyst and initial concentration of methylene blue. It was observed that higher dose of the photocatalyst and lower concentration of the contaminant produced higher rate of degradation. The solution pH 3 and catalysts dosage of 200 mg yielded the highest rate of degradation. The experimental data fitted best into the Psuedosecond order kinetic model with the highest R2 value, indicating a strong linear relationship. The experimental data was subjected into nonlinear error functions, where the Psuedo-second order kinetic model demonstrated lower values of error functions. The results suggest that the prepared SrZrO3 photocatalyst coupled H2O2 is a promising photocatalyst for the decontamination of methylene blue dye under visible light irradiation.

Surfactant-modified coconut coir powder (SMCCP) as a low-cost adsorbent for the treatment of dye-contaminated wastewater: parameters and adsorption mechanism.

The dye-contaminated wastewater discharged from various industries such as dye manufacturing, paint, textile, paper, and cosmetic is a prime source of surface water pollution having serious detrimental effects on both the environment and human beings. These hazardous dyes when exposed to water obstruct the penetration of sunlight into the water and thus restrain aquatic plants from generating photosynthetic compounds. Moreover, some dyes are potential cancer-causing and also negatively impact the human nervous and respiratory systems. In this current study, modification of coconut coir powder (CCP) was carried out through cationic surfactant treatment and was successively utilized as the adsorbent for decoloring anionic dye (acid blue 185 (AB 185)) containing waste stream. Further, a comparative investigation of the dye removal efficiency of raw CCP and surfactant-modified coconut coir powder (SMCCP) as the adsorbent was studied. On surfactant treatment, using a very minimal SMCCP dosage of 8.3g/L, a very high percentage dye removal of 98.4% is possible, whereas with raw CCP, even after using a higher dosage of 14g/L, only 70.1% dye removal can be achieved. Characterization of SMCCP adsorbent was done by Fourier transform infrared, thermogravimetric, X-ray, and scanning electron microscope analyses. Furthermore, the optimization of critical operating parameters was investigated for the effective adsorption of AB 185 dye in batch mode. The adsorption of AB 185 onto SMCCP was a thermodynamically spontaneous endothermic process, following the Langmuir isotherm and pseudo-second-order kinetic model. Moreover, regeneration of exhausted SMCCP by 0.1 (M) NaOH was achieved with a satisfactorily high recovery of 97% in the first cycle. Subsequently, SMCCP can be successfully reutilized for five consecutive cycles with a loss of 17.6% in the total adsorption capacity. With all such advantages, the present study delivers a new paradigm to utilize the novel adsorbent SMCCP as a promising eco-friendly adsorbent aided by its advantage of regeneration and reusability for the treatment of dye-contaminated wastewater.

SnS thin films deposited at room temperature – Efficient and reusable dark catalyst for water remediation at ambient conditions

This study describes the dark catalytic degradation of cationic, anionic, and commercial dyes by SnS thin films under dark ambient conditions without the assistance of any external stimuli. The thin films were deposited by a modified SILAR (Successive Ionic Layer Adsorption and Reaction) method at room temperature and characterised using XRD, XPS, FESEM, TGA, and UV–visible spectrophotometers. The dark catalytic degradation of methylene blue (MB) dye was investigated using a spectrophotometer and validated by LCMS analysis and an adsorption desorption test. Within 15 min, 48 % of the MB dye (original concentration: 10 mg/l) had been degraded by the catalyst, and by 90 min, the degeneration was almost complete. The ROS (reactive oxygen species) scavenger test and indicator test confirmed the role of the hydroxyl radical in the degradation process. The influence of initial dye concentration, magnetic stirring, and the composition of the catalyst on the degradation efficiency was also studied. The same catalyst was used five times in succession to test its reusability, and it was then structurally and thermally characterised to test its stability. This study emphasises the possible use of SnS thin film as an effective, reliable, and reusable around-the-clock catalyst for the degradation of dye-contaminated waste water without the assistance of light or any chemical additives.

3D-Printed Sr-doped TiO2 / biowaste / polymeric structures for mitigating dye contamination in water

Wastewater laden with synthetic dyes from the textile industry poses a threat to natural water sources, the environment, and human health, contravening Sustainable Development Goals (SDGs). Addressing this challenge requires innovative solutions focusing on contaminant removal in wastewater treatment. This study explored the application of 3D-printed polymeric structure incorporating Sr doped TiO2 and biowastes as photocatalysts and adsorbents to eliminate Methylene Blue (MB) from water. X-ray diffraction (XRD) analysis verified that the Sr doped TiO2 powder synthesized by solution combustion technique predominantly exhibited the anatase phase. Transmission Electron Microscopy (TEM) showed that the average particle sizes for TiO2 doped with 1 mol% and 5 mol% Sr were 19.45±2.6 nm and 10.32±1.9 nm, respectively. The Brunauer–Emmett–Teller (BET) analysis determined the specific surface area as follows: 1 mol% Sr doped TiO2 at 39.7 m²/g, 5 mol% Sr doped TiO2 at 86.8 m²/g, SiO2 from sugarcane leaves at 168.2 m²/g, and bagasse ash at 8.5 m²/g. Over 24 hr in the dark, the 3D polymeric structure and the one incorporating Sr doped TiO2/bagasse ash absorbed approximately 48 % of the MB dye. For the structure containing Sr doped TiO2/silica from sugarcane leaves, a 66 % dye adsorption was observed. Exposure to UV light for 8 hr further enhanced dye removal in the Sr doped TiO2/silica/polymeric structure, surpassing 84 %. Reusability experiments over 10 cycles demonstrated the structures' stable performance, with dye degradation efficiency consistently exceeding 70 %, and statistical analysis confirming no significant decline in efficiency across cycles. This study underscores the efficacy of 3D-printed Sr doped TiO2/biowaste/polymeric structures as a promising technology for mitigating water pollution, providing a viable solution to the environmental and health challenges arising from dye-contaminated wastewater in the textile industry.

Metal complexes with thiosemicarbazone derivative and isatine: A promising new class of materials for biomedical and environmental applications

Metal complexes with thiosemicarbazones and isatine have been shown to exhibit a wide range of biological activities, including antibacterial, antifungal, and anticancer activity. These complexes have also been shown to be effective photocatalysts for degrading dyes, making them a subject of significant interest. This article presents the synthesis and characterization of mixed ligand complexes of isatine-thiosemicarbazones to explore their biological activity and potential for photocatalytic applications. In this study, we synthesized mixed ligand complexes of isatine-thiosemicarbazones with various metal ions, including Cu(II), Cd(II), and Fe(III). Characterization techniques such as elemental analysis, infrared (IR), mass spectrometry (MS), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) were utilized to understand their structural composition and morphological properties. The complexes exhibited remarkable antibacterial activity against Escherichia coli, Staphylococcus aureus, Streptococcus mutants, and antifungal effects on Candida albicans. Notably, the Fe-complex demonstrated the highest activity, followed by the Cu-complex and Cd-complex. Strong anticancer effects were observed against human liver HepG2 and breast MDA cancer cells, with the Fe-complex displaying the highest activity. Additionally, the complexes displayed significant photocatalytic activity in the decomposition of rose bengal dye using ultraviolet light irradiation, with the Cu-complex showing the highest degradation efficiency. The results indicate that these mixed ligand metal complexes have potential therapeutic applications as antibacterial, antifungal, and anticancer agents. Moreover, they suggest their prospective utility as photocatalysts for the remediation of dye-contaminated wastewater.

Rational design of NiO nanoflakes and porous GCN nanocomposite for synergic effectiveness on photocatalytic degradation of industry effluents and biological activity

Nanotechnology can alter matter at the nanoscale and generate new materials, gadgets, and technologies with unique features and functions, revolutionizing medicine, energy, electronics, and materials science. This study synthesizes nickel oxide nanoflowers utilizing Strychnos potatorum seed extract as reducing and stabilizing agents in an eco-friendly way. The porous GCN and NiO nanocomposite enhances NiO for multifunctional capabilities. UV–Vis, FTIR, EDX, XRD, and FESEM were used to synthesize and characterize NiO nanoflowers. Further synthesized bimetallic nanoparticles were tested for antibacterial, antioxidant, and catalytic properties. It showed increased antioxidant activity, CV and RB dye degradation, and antibacterial activity against S. aureus and E.Coli. Scavenging was enriched with nanoparticles. The highest degradation rate was 98.2 % for CV dye in 90 min. Nanoparticle concertation at 100 µl/mL inhibited E.Coli the most (18 mm). NiO nanoflowers and NiO-GCN nanocomposite synthesized from Strychnos potatorum seed extract may be a novel antioxidant, antibacterial, and catalytic agent for industrial dye-contaminated wastewater.

Efficient wastewater decontamination using magnetic bentonite-alginate beads: A comprehensive study of adsorption dynamics, regeneration, and molecular interactions

This study enhances wastewater treatment methodologies by developing magnetic bentonite-alginate beads (MBent-A beads) for adsorbing methylene blue (MB) from aqueous solutions. Experimental and computational analyses were employed to evaluate the beads' adsorption efficiency, utilizing characterization techniques including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), point of zero charge (pHpzc), Brunauer-Emmett-Teller method (BET), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) to examine the composite’s morphology and chemistry. Findings reveal a significant adsorption capacity with the beads' specific surface area at 3.94 m2/g and a maximum adsorption capacity of 774.32 mg/g. Adsorption kinetics adhered closely to the pseudo-second-order model, indicating a rapid adsorption process, while Langmuir isotherm analysis confirmed a uniform monolayer adsorption and temperature-dependent capacities. Thermodynamic analysis showed the adsorption process to be spontaneous and exothermic, reflecting a strong affinity between MB molecules and the bead surface. The beads demonstrated durability with more than 90% removal efficiency after five regeneration cycles, highlighting a minimal decrease from 98.54% to 90.60%. In-depth theoretical investigations using density functional theory (DFT), frontier molecular orbital (FMO), reduced density gradient (RDG), and quantum theory of atoms in molecules (QTAIM) analyses identified van der Waals forces and hydrogen bonding as primary interactions driving the adsorption. The synthesis of MBent-A beads and their confirmed efficacy in dye adsorption integrates experimental research with theoretical modeling, offering a robust solution for treating dye-contaminated wastewater and underlining the potential of MBent-A beads in environmental remediation.

In situ polymerization of acrylamide on magnetic SnFe2O4/CeO2 nanocomposite: A novel adsorbent for removing various dyes

Environmental conservation requires effective, secure, and economical treatment options for dye-contaminated wastewater. The current study comprises a novel fabrication of tin ferrite/ceria/polyacrylamide magnetic and porous ternary nanocomposite. This occurs through crosslinking polymerization of acrylamide on the SnFe2O4/CeO2 binary nanocomposite. The SnFe2O4/CeO2/PAM nanocomposite was comprehensively characterized using FTIR, TGA, XRD, TEM, VSM, EDX, SEM and N2 adsorption-desorption isotherms. The ternary nanocomposite's efficiency as a novel adsorbent for anionic (direct violet 4, DV4) and cationic (bismarck brown r, BBR) azo dyes was investigated. A range of variables were studied to optimize the effectiveness of eliminating both dyes. In an acidic medium, DV4 removal was more efficient, whereas BBR removal was higher in an alkaline environment. Non-linear regression was employed to analyze adsorption kinetics and isotherm models, using three statistical error functions to determine the best-fit models. Adsorption data for both dyes demonstrated a good conformity with pseudo-second-order and Freundlich isotherm models. The dyes' adsorption was both endothermic and spontaneous. The nanocomposite displayed notable performance throughout five reuses. Moreover, the nanocomposite shows good adsorption efficiency for various dyes (congo red, acid blue 40, methyl green, and crystal violet) as well as DV4 and BBR. Therefore, it emerges as a promising adsorbent for wastewater purification.

Enhanced photocatalytic performance of Ga2O3 hollow spheres prepared by hard template technique

Semiconductor-assisted photocatalytic treatment has been regarded as a promising technique to dispose the dye-contaminated wastewater and gained pronounced attention recently. Here, we demonstrated a kind of Ga2O3 nanometer hollow sphere photocatalysis by template-assisted technique and applied it on the degradation of Rhodamine B (RhB). It was found that the hollow spherical structure of photocatalyst can greatly enhance the photo absorption and reduce the recombination of photogenerated carriers, thus improve the photocatalytic performance. This study provides a new method for efficient photocatalytic degradation of RhB, and provides a new idea for subsequent degradation work.

Trypan blue dye decolorization by Aeromonas caviae isolated from water sewage in Jakarta, Indonesia

Abstract. Pinontoan R, Susanto TSR, Lucy J, Angelina C, Soentoro SE, Purnomo JS, Cornelia M. 2024. Trypan blue dye decolorization by Aeromonas caviae isolated from water sewage in Jakarta, Indonesia. Biodiversitas 25: 1631-1637. The textile industry generates a substantial amount of hazardous chemical waste, which requires proper treatment to mitigate negative environmental and health consequences if left untreated. Studies on the removal of Trypan Blue (TB), a widely used commercial diazo textile dye, by indigenous bacteria are limited. Therefore, this study aimed to isolate, identify, and characterize microorganisms capable of decolorizing TB in textile dye-contaminated wastewater from Jakarta. Microorganisms were initially screened for decolorization activity in solid media containing TB. Among the isolated strains, TB2 isolate exhibited the highest decolorizing potential and was selected for further analysis. The morphological, biochemical, molecular, and phylogenetic characteristics of the TB2 isolate revealed that it belonged to the species Aeromonas caviae. To examine the ability of the isolate to remove TB, various culture conditions, such as pH, temperature, and agitation, were tested. The results demonstrated that the A. caviae TB2 strain could reduce up to 77.10% of TB (0.0025% (w/v)) under static conditions, pH 7.0, and 27°C over six days. To our knowledge, this is the first study to report the ability of the Aeromonas genus to decolorize TB. These results imply the potential use of A. caviae for decolorizing dye-bearing industrial wastewater.

Use of a Clay from Southern Ivory Coast (Bingerville) for the Adsorption of Methyl Orange in Aqueous Media

Increasing levels of textile dyes being discharged into the environment as industrial waste represent a serious threat to human health, life, resources and ecological systems. It is therefore necessary to treat wastewater from textile industries before discharging it into the environment. The aim of this project is to eliminate methyl orange (MO) from textile industry wastewater using clay from Bingerville (Ivory Coast). The clay used was characterized by Scanning Electron Microscopy, Brunauer-Emmett-Teller and pH of Zero Charge. MO concentration was monitored using a UV-visible spectrophometer. Characterization of the clay by SEM and BET showed that our clay is microporous. The study showed that the surface of our clay has a pH of zero. Adsorption of methyl orange on our clay reaches adsorption equilibrium in 60 minutes. The adsorption model corresponds to the pseudo-order 2 kinetic model. Two adsorption isotherm models (Langmuir and Freundlich) are applicable to the adsorption of our dye on clay. This implies that the dye adsorption process on our clay is governed by a bimolecular process involving a collision between an active site on the clay and a dye molecule. Bingerville clay can be used to effectively treat dye-contaminated wastewater, since the maximum adsorbed quantity is equal to 58.139 mg g<sup>-1</sup>. The best adsorption rate was obtained in acid medium (pH = 2.26) with an adsorption rate of 91.84%.

Antioxidant and dye degradation activity of green synthesized silver-iron oxide (Ag-Fe2O3) bimetallic nanoparticles

This research introduces an eco-friendly method for synthesizing silver-iron oxide bimetallic nanoparticles using cabbage peel extract, serving as both reducing and stabilizing agents. The successful production of nanoparticles is comprehensively analyzed through UV-Vis spectroscopy, Fourier transformation infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The UV, XRD and EDS results indicated the elemental composition of Ag and Fe, suggesting the formation of a silver-core iron-shell bimetallic nanoparticles with a size of 22.3 nm, which was followed by an assessment of their antioxidant and catalytic properties. The findings revealed notable antioxidant capabilities, along with the efficient degradation of methyl red and phenol red dye. Remarkably, the Ag-Fe2O3 bimetallic nanoparticles exhibited good scavenging activity, reaching 63.87% at a concentration of 1000 µg/mL. The most significant dye degradation is observed for phenol red, achieving a remarkable 78% degradation within just 8 minutes. These results indicate the potential of Ag-Fe2O3 bimetallic nanoparticles derived from cabbage peels as promising agents for antioxidant and catalytic applications, especially in addressing dye-contaminated wastewater concerns.