Acid Orange Research Articles

Assessment of simultaneous removal of salt and dye by utilizing capacitive deionization and UV-electro oxidation hybrid process in saline wastewater treatment

In this research, the goal was simultaneous elimination of salt (NaCl) and dye (C·I Acid Orange 7 or AO7) through integration of capacitive deionization (CDI) technique with UV-based electrochemical advanced oxidation process (UV-EAOP). To optimize salt adsorption capacity (SAC) of MnO2 electrode, Taguchi's experimental design methodology was employed to fine-tune synthesis parameters, including bath temperature, current density, and precursor concentrations. BiOCl was synthesized and implemented as an anode to bolster AOP's effectiveness. Several experiments were conducted to analyze the effects of applying the combined AOP and CDI. The findings revealed that parameter optimization improved SAC, and the application of UV irradiation decreased electrode's SAC. Furthermore, it was observed that AO7 could enhance SAC while lowering salt adsorption rate (SAR). More importantly, the combined application of CDI and AOP resulted in superior pollutant removal efficiency and improved SAC, despite reduced SAR. Finally, color was entirely eliminated after 90 min, and the generated species were recognized by GC–MS. Additionally, a possible pathway for AO7 degradation was suggested based on the generated species.

Natural Vanadium–Titanium Magnetite Activated Peroxydisulfate and Peroxymonosulfate for Acid Orange II Degradation: Different Activation Mechanisms and Influencing Factors

Persulfate-based advanced oxidation processes have emerged as a promising approach for the degradation of organic pollutants in aqueous environments due to their ability to generate sulfate radicals (SO4−·) within catalytic systems. In this study, peroxydisulfate (PDS) and peroxymonosulfate (PMS) were investigated with the natural vanadium–titanium magnetite (VTM) as the activator for the degradation of acid orange II. The degradation efficiency increased with higher dosages of VTM or persulfate (both PDS and PMS) at lower concentrations (below 10 mM). However, excessive PMS (higher than 10 mM) in the PMS/VTM system led to the self-consumption of free radicals, significantly inhibiting the degradation of acid orange II. The VTM-activated PDS or PMS maintained an effective degradation of acid orange II in a wide pH range (3~11), suggesting remarkable pH stability. The SO4−· was the main active species in the PDS/VTM system, while hydroxyl radical (·OH) also contributed significantly to the PMS/VTM system. In addition, PMS exhibited better thermal stability during VTM activation. Coexisting ions in an aqueous environment such as bicarbonate (HCO3–), carbonate (CO32–), and hydrogen phosphate (HPO42–) had obvious effects on persulfate activation. Our study systematically investigated the different activation processes and influencing factors associated with PDS and PMS when the natural VTM was used as a catalyst, thereby providing new insights into the persulfate-mediated degradation of organic pollutants in aqueous environments.

WS2-Assisted Electrochemical Activation of Peroxymonosulfate for Eliminating Organic Pollutant in Water

Advanced oxidation process based on heterogeneous activation of peroxymonosulfate (PMS) has received significant attention in wastewater remediation. Herein, a facile and effective electrochemical method was introduced in a tungsten sulfide (WS2)-activated PMS process for the removal of a typical azo dye Acid Orange 7 (AO7) in aqueous solution. It was found that the electrochemical activation could remarkably promote the removal of organic pollutants by coupling with WS2/PMS system. The elimination of AO7 in the electro-assisted WS2-activated PMS (E/WS2/PMS) system achieved 95.8% of AO7 removal in 30 min, with the optimal conditions of 1.0 g/L WS2, 1.0 mM PMS, current density of 1.0 mA/cm2 and initial pH of 6.5. Based on quenching experiments and EPR techniques, mechanistic studies confirmed that hydroxyl radical (•OH) and singlet oxygen (1O2) are the primary reactive oxygen species for the oxidation of pollutants. In addition, the influences of pH, WS2 dosage, PMS concentration, current density, common anions and humic acid on the AO7 removal are also investigated in detail. Furthermore, the system exhibited resistance to aqueous matrices, verifying the accepted applicability in real water (i.e., Yangtze River water and Shahu Lake water). In summary, this study demonstrates a green system for the effective removal of contaminants in water, holding significant implications for practical application.

Efficient photodegradation of acid orange 7 in water using a facile ultrasound-assisted microwave-combustion synthesized Ag-ZnAl2-xFexO4 solid-solution photocatalyst

This study explores the development of Ag-ZnAl2-xFexO4 solid-solution photocatalysts for Acid Orange 7 (AO7) degradation under visible light irradiation. The microwave auto-combustion method was employed to synthesize these photocatalysts, allowing for the investigation of the influence of Fe substitution (x) on their properties and performance. Characterization techniques revealed a trade-off between Fe content, surface area, pore size, and light absorption capacity. The Ag-ZnAlFeO4 variant achieved an optimal balance, demonstrating exceptional photocatalytic activity for AO7 degradation. This optimized photocatalyst achieved a removal efficiency of 99.3 % under neutral pH conditions, highlighting its effectiveness and potential for practical applications. Interestingly, the mineralization efficiency of AO7 reached 85.2 % after 160 minutes of reaction time. Kinetic studies supported the superior performance of Ag-ZnAlFeO4, attributing its success to its favorable morphology, high surface area, strong light absorption, and minimal electron-hole pair recombination. The proposed degradation mechanism involves light absorption, generation of electron-hole pairs, and their subsequent reactions with water and oxygen molecules to degrade AO7. This work establishes Ag-ZnAl2-xFexO4, particularly Ag-ZnAlFeO4, as a promising visible-light photocatalyst for the efficient degradation of organic pollutants.

Sustainable Activated Carbon from Agricultural Waste: A Study on Adsorption Efficiency for Humic Acid and Methyl Orange Dyes

In this study, porous activated carbon was produced from coffee waste and used as an effective adsorbent for the removal of humic acid (HA) from seawater and methyl orange (MO) dye from aqueous solutions. Phosphoric acid H3PO4 was used as an activating agent for the chemical activation of these agricultural wastes. The characterization of the activated carbon obtained using a scanning electron microscope (SEM), Fourier-transform infrared (FTIR) spectroscopy analysis, X-ray diffraction (XRD) and the Brunauer–Emmett–Teller (BET) method revealed that the activated carbon products exhibited high porosity and the formation of various functional groups. The effects of different parameters were examined using batch adsorption experiments, such as the adsorbent masses, pH, initial pollutant concentration and contact time. The results show that the performance increased with an increased adsorbent mass (up to 0.25 g/L) and decreased initial concentration of the adsorbent tested. On the other hand, this study clearly showed that the adsorption efficiency of the MO on the raw spent coffee grounds (SCGs) waste was around 43%, while no removal was observed for the humic acid. The experiments demonstrated that the activated carbon synthesized from the used coffee grounds (the efficiency was compared with commercial activated carbon (CAC) with a difference of 13%) was a promising alternative to commercially available adsorbents for the removal of humic acid from seawater. To understand and elucidate the adsorption mechanism, various isothermal and kinetic models were studied. The adsorption capacity was analyzed by fitting experimental data to these models. The experimental data for methyl orange dyes were analyzed using Langmuir and Freundlich isothermal models. The Freundlich isotherm model provided a superior fit to the equilibrium data, as indicated by a higher correlation coefficient (R2) than that of the Langmuir model. The maximum adsorption was observed at pH 3. The Freundlich adsorption capacity was found to be 333 mg/g adsorbent. The PAC showed a high adsorption capacity for the MO and HA. The PAC showed the highest adsorption capacities for the HA and MO compared with the other adsorbents used (SCGs and CAC) and would be a good material to increase the adsorption efficiency for humic acid removal in the seawater pretreatment process. In addition, the prepared AC BET surface area was 520.40 m2/g, suggesting a high adsorption capacity. This makes the material potentially suitable for various applications that require a high surface area. These results indicate that high-quality sustainable activated carbon can be efficiently produced from coffee waste, making it suitable for a wide range of adsorbent applications targeting various pollutants.

Co-N3 site activated peroxymonosulfate for rapid degradation of ciprofloxacin: Synergistic effect of free radicals and nonfree radicals

Nitrogen-doped metal-organic framework (MOFs)-derived carbon materials (denoted as Co-MOF-74@N-T-x) were successfully fabricated by calcinating Co-MOF-74, utilizing the green precursor of melamine. Among these materials, Co-MOF-74@N-500-2 demonstrated superior catalytic performance in activating peroxymonosulfate (PMS), achieving over 95 % degradation of ciprofloxacin (CIP) within 15 min, with a rate constant that was 1.25 times greater than that of Co-MOF-74-500. The primary active species identified in this study were sulfate radicals (SO4•−) and singlet oxygen (1O2), with the latter playing an important role in the degradation of CIP in the Co-MOF-74@N-500-2/PMS system. Theoretical calculations confirmed that the enhanced catalytic activity primarily stemmed from the Co-N3 configuration, which was more effective in activating PMS than the other configurations were. Co-MOF-74@N-500-2/PMS showed excellent performance in oxidizing CIP across a broad pH range (3.0–9.0) and demonstrated stability over five cycles, along with impressive degradation performance capabilities for a wide range of pollutants including metronidazole (MNZ), oxytetracycline (OTC), nitrofurantoin (FNT), methylene blue (MB), and acid orange (OG). This study presents a viable strategy for developing efficient and durable catalytic systems aimed at degrading organic pollutants via PMS.

Selective removal of organic dyes via polymer inclusion membrane containing a perbenzylated β-cyclodextrin derivative

Organic dyes threaten aquatic ecosystems due to carcino/mutagenic properties, and their removal from wastewater is a crucial issue. The novel PIM (Polymer Inclusion Membrane) containing perbenzylated β-cyclodextrin (CD) derivative was designed as an effective material for the selective removal of organic dyes because the CD characterizes strong affinity to these compounds via inclusion complex formation. The PIM was obtained through standard solvent casting from CTA as a matrix, o-NPOE as a plasticizer, and perbenzylated β-CD as the carrier. The membrane transport was evaluated towards two different types of dyes, cationic (Methylene Blue) and anionic (Acid Orange 7), where the optimal concentration for dye removal was 50 and 75 mg/L, respectively. The efficiency of this process was around 83–90 % after 8 h, when the pH of the source/receiving phase induced the formation of non−/ionic forms of dyes, respectively. The optimal membrane composition based on mass ratio was 11.1:72.2:16.7 for CD:o-NPOE:CTA with a membrane thickness of 0.053 mm. The PIM was characterized by high selectivity dependent on both the pH of each phase used in the transport and the chemical character of the dyes. The molecular mechanism of the removal process was mostly based on the complex inclusion of dyes inside the CD cavity. The activation energies were 8.73 and 13.93 kJ/mol for MB and AO7, respectively. The dyes transport was limited by diffusion. This study provides information about novel PIM with an effective and selective carrier, the perbenzylated β-CD derivative, towards organic dyes.

Light switchable radical and non-radical periodate activation by Fe3O4/g-C3N4 for efficient organic contaminant elimination

Although the heterogeneous activation of periodate (PI) has recently garnered significant attention for organic pollutant degradation, regulating the non-radical and radical reaction pathways remains a challenge. Herein, a Z-scheme Fe3O4/g-C3N4 heterojunction (FCN) was developed to achieve controllable radical and non-radical PI activation using a light switch. In the dark, the interaction between FCN and PI gave rise to metastable surface-activated PI complexes (PI*) via the non-radical pathway, which served as the dominant reactive species for organic elimination. Upon light irradiation, FCN acted as an electron donor for PI activation via the radical pathway, forming iodate radicals (IO3•) for pollutant destruction. Consequently, the FCN/PI/VIS system achieved complete removal of acid orange 7 in 30 min, with a pseudo-first order reaction rate about 3.5 times higher than that of FCN/PI system. The involved reactive species were validated by scavenging tests, electron paramagnetic resonance (EPR) analysis, Raman spectra and electrochemical measurements. Moreover, the light switchable FCN-based PI activation system exhibited high recyclability and practicability for the treatment of various organic pollutants in water. This study provides new insights into the PI activation-mediated wastewater treatment processes.

Selective adsorption of cationic dye by κ-carrageenan-potato starch bio-hydrogel: Kinetics, isotherm, and thermodynamic studies

An eco-friendly κ-carrageenan/potato starch bio-hydrogel is designed for the efficient removal of methylene blue (MB) dye from water. The incorporation of potato starch was successfully confirmed through XRD, FT-IR, and SEM analysis, while TGA highlighted the hydrogel's thermal stability. Batch adsorption experiments demonstrated excellent MB removal efficiency, with a maximum adsorption capacity of 116.1 mg/g under optimal conditions (initial dye concentration: 100 mg/L, contact time: 180 min, temperature: 20 °C, adsorbent dosage: 1.6 g/L, and pH: 11). FT-IR analysis indicated that electrostatic interactions and hydrogen bonding primarily govern the adsorption process. The adsorption followed pseudo-second-order kinetics and fitted well with the Langmuir isotherm model. Thermodynamic studies revealed that the adsorption was exothermic and spontaneous. A key feature of this bio hydrogel is its selective affinity for the cationic dye MB, in a mixture with Acid Orange (AO) and other cationic dyes (Rhodamine B (Rh B) and crystal violet (CV)). The adsorbent also demonstrated impressive reusability, maintaining 93 % of its efficiency after five cycles, highlighting its potential for sustainable and cost-effective water treatment.

UV-enhanced Fe2+/PDS system for degradation of acid orange 7: Kinetics, degradation mechanism and toxicity assessment

Based on the deficiency of the Fe2+ catalyzed persulfate (PDS) process, ultraviolet (UV) synergistic Fe2+ activated PDS system was introduced in this study for the degradation of acid orange 7 (AO7) dye. The effects of different initial pH, PDS dosage, Fe2+ dosage, and different UV intensities on the degradation rate of AO7 were investigated, and a kinetic model for the apparent reaction rate was determined. The results showed that the UV/ Fe2+/ PDS system was effective in degrading AO7 in a wide pH range. Under optimal conditions, 96 % removal of AO7 was achieved in 10 min. The effects of different inorganic anions on AO7 were discussed; Cl− had little effect on the degradation effect, and SO42−, NO3− and HCO3− inhibited the degradation of AO7 by the system to varying degrees. The presence of reactive radicals (SO4·− and·OH) in the reaction was determined by quenching experiments and EPR capture and their degradation contribution was further investigated. Nine intermediates of AO7 were detected by LC- MS/ MS, and the degradation pathway of AO7 was inferred by combining with UV– Vis spectra. Finally, the ecotoxicity and tritogenic effects of AO7 intermediates were assessed by Toxtree and T.E.S.T toxicity prediction models, which showed that the final degradation product toxicity was non-mutagenic, non-teratogenic, and devoid of hereditary and non-hereditary carcinogenicity.

Predicted kinetic behaviour of the oxidative degradation of organic pollutant using substituted MeCuFeO3 (Me = Ca, Sr, CaSr) perovskite catalysts

The substitution of different types of A-site metal cations within the perovskite structure leads to a change in the catalytic activity of the resultant catalyst, which subsequently affects the overall kinetic behaviour of the degradation of organic pollutants. Hence, understanding the kinetics behaviour of the substituted perovskite catalysis is crucial for determining the reaction rates of the degradation process. This study investigates the catalytic performance and kinetic analysis of substituted MeCuFeO3 (Me = Ca, Sr, CaSr) perovskite catalysts in the oxidation of organic pollutants, namely acid orange II (AOII) dye. The highest AOII degradation was achieved by CaCuFeO3 (97 %) followed by CaSrCuFeO3 (95 %) and SrCuFeO3 (91 %) within 60 min of reaction in the presence of oxidant (H2O2). Interestingly, the AOII oxidation by CaCuFeO3 followed a pseudo-second-order kinetic model while SrCuFeO3 and CaSrCuFeO3 were fitted to the BMG kinetic model. The reaction rate constant of CaCuFeO3 (k = 1.9 × 10−2 L.mg−1.min−1) was higher by a magnitude of two and three than that of CaSrCuFeO3 (k = 9.4 × 10−3 L.mg−1.min−1) and SrCuFeO3 (k = 6.3 × 10−3 L.mg−1.min−1), respectively. These results indicate that the partial substitution of Sr in the A-site of CaCuFeO3 leads to a slight deterioration in the overall catalytic performance of the oxidative degradation of AOII, which contributes to a change in the behaviour of the reaction kinetic models.

Photo-electrochemical study of TiO2/Co3O4 thin films in polluted electrolyte: A promising route for coupling hydrogen production with water remediation

The use of a photo-electrochemical cell (PEC) to produce hydrogen from wastewater is a promising innovation. In this context, this study investigates the impact of a pollutant on the photo-electrochemical properties of sol-gel synthesized TiO2 and TiO2–Co3O4 thin films for hydrogen production in a polluted electrolyte. Combining the photocatalytic properties of TiO2 with the electronic properties of Co3O4 offers an effective solution for achieving effective photo-electrochemical properties in polluted environments. Nevertheless, despite the lowest photocatalytic activity, the hybrid thin film TiO2–Co3O4 with the highest Ti/Co ratio (1:0.5) shows the most promising performance with simultaneous 11.4 μmol cm−2 h−1 H2 production and 12% acid orange 7 degradation after 3 h irradiation under xenon light without the use of any sacrificial agent. This indicates that the electronic conductivity provided by the presence of Co3O4 is a critical property for achieving optimal performance in PEC coupling for hydrogen production and wastewater treatment.

Selective oxidation of organic pollutants by unactivated and carbonate-activated peroxymonosulfate (PMS): Mechanism, kinetics, and transformation pathway

Although the activation mechanisms of peroxymonosulfate (PMS) by various homogeneous and heterogeneous catalysts have been reported, the chemistry of PMS in catalyst-free systems and its interaction with background oxygenated anions remains poorly understood. In this study, the unactivated PMS and carbonate-activated PMS (CO32–/PMS) systems for removal of various organic pollutant (including oxytetracycline (OTC), metronidazole (MNZ), methylene blue (MB), and acid orange G (OG)) were investigated. The results showed that 74.5 %, 90.21 %, 1.22 %, and 2.25 % of OTC, MB, OG, and MNZ were removed, respectively within 180 min in the unactivated PMS system due to the formation of ·OH and 1O2. 95.88 %, 100 %, 100 %, and 6.09 % of OTC, MB, OG, and MNZ were removed, respectively in the CO32–/PMS system, which is primary due to the generation of 1O2. The removal efficiencies of these four pollutants were significantly improved under alkaline conditions. In addition, the TOC removal rates were 21.88 % for MB and 26.53 % for OTC within 180 min in the CO32–/PMS system. The presence of Cl− and SO42− can greatly enhance the OTC removal efficiency both in the unactivated and CO32–/PMS systems. Through the high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, OTC degradation products in the unactivated PMS and CO32–/PMS systems were identified, revealing six different reaction mechanisms, including hydroxylation (+16 Da), decarbonylation (−28 Da), demethylation (−14 Da), secondary alcohol oxidation (−2 Da), deamination (−15 Da), and dehydration (−18 Da). This study provides insight into the reaction mechanism of catalyst-free PMS systems and may promote the application of unactivated PMS and CO32–/PMS systems for the remediation of organic contaminated water.

Bimetallic-organic framework (Fe, Cu)/carbon nanotubes encapsulated Ni nanoparticles as heterogeneous catalyst in Fenton-like process for degradation of acid orange 7 dye

Bimetallic-organic framework (Fe, Cu)/carbon nanotubes encapsulated Ni nanoparticles as heterogeneous catalyst in Fenton-like process for degradation of acid orange 7 dye

Visible Light-Assisted Periodate Activation Using Carbon Nitride for the Efficient Elimination of Acid Orange 7

The development of appropriate and effective periodate (PI) activation technology is currently a popular research area. This study presents a novel efficient photocatalytic activation approach of PI for pollutant degradation based on carbon nitride (g-C3N4) and visible light (Vis). The results show that the system can remove 92.3% of acid orange 7 (AO7) within 60 min under the g-C3N4/PI/Vis reaction system. The degradation rate constant (kobs) reached 4.08 × 10−2 min−1, which is 4.21, 5.16 times, and 51.3 times higher than that of the g-C3N4/Vis system (9.7 × 10−3 min−1), PI/Vis system (7.9 × 10−3 min−1) and the g-C3N4/PI system (7.96 × 10−4 min−1), respectively. Clearly, the addition of PI significantly enhances the degradation efficiency of AO7 in the system. Additionally, under the same reaction conditions, the presence of PI showed excellent oxidation capacity in the photoactivation process compared with other common oxidants, such as peroxymonosulfate, peroxydisulfate, and H2O2. Moreover, the g-C3N4/PI/Vis system showed excellent removal of AO7 across a wide range of pH levels and in the presence of various anions. Electron paramagnetic resonance (EPR) and quenching experiments suggested that the superoxide anions (•O2−) and singlet oxygen (1O2) dominated in the oxidation of pollutants in the g-C3N4/PI/Vis system. In addition, the catalyst showed relative stability during cyclic testing, although a slight reduction in degradation efficiency was observed. In brief, the g-C3N4/PI/Vis system is highly efficient and environmentally friendly, with significant application potential in wastewater treatment.

Streptomyces as a Novel Biotool for Azo Pigments Remediation in Contaminated Scenarios.

Azo pigments are widely used in the textile and leather industry, and they generate diverse contaminants (mainly in wastewater effluents) that affect biological systems, the rhizosphere community, and the natural activities of certain species. This review was performed according to the Systematic Reviews and Meta Analyses (PRISMA) methodology. In the last decade, the use of Streptomyces species as biological azo-degraders has increased, and these bacteria are mainly isolated from mangroves, dye-contaminated soil, and marine sediments. Azo pigments such as acid orange, indigo carmine, Congo red, and Evans blue are the most studied compounds for degradation, and Streptomyces produces extracellular enzymes such as peroxidase, laccase, and azo reductase. These enzymes cleave the molecule through asymmetric cleavage, followed by oxidative cleavage, desulfonation, deamination, and demethylation. Typically, some lignin-derived and phenolic compounds are used as mediators to improve enzyme activity. The degradation process generates diverse compounds, the majority of which are toxic to human cells and, in some cases, can improve the germination process in some horticulture plants. Future research should include analytical methods to detect all of the molecules that are generated in degradation processes to determine the involved reactions. Moreover, future studies should delve into consortium studies to improve degradation efficiency and observe the relationship between microorganisms to generate scale-up biotechnological applications in the wastewater treatment industry.

Pollutants Analysis and Life Cycle Assessment of a Photovoltaic Powered Textile Electro-Fenton Wastewater Treatment System.

Textile wastewater poses a substantial environmental challenge due to the persistence of organic dyes. This study introduces a novel approach using photovoltaic (PV) powered electro-Fenton (EF) technology for effective treatment of textile wastewater. Acid orange 7 (AO7), methylene blue (MB), and malachite green (MG) were selected as representative organic dyes to validate the method under varying experimental conditions. Analysis of variance (ANOVA) highlighted the significant influence of pollutant type, pH levels, and current density on the degradation efficiency of the system, with optimal conditions observed at pH = 3 and high current density. To underscore the environmental benefits, a comprehensive life cycle assessment (LCA) was conducted. The PV-powered EF system, when implemented in a textile mill, exhibited an energy payback time (EPBT) of 9.53 years, a greenhouse gas payback time (GPBT) of 4.45 years, and a life cycle cost (LCC) of 1.9 × 105 RMB. Comparative analysis with conventional Fenton and EF processes revealed substantial energy savings, with carbon emissions reduced by 95% and 78%, and energy consumption reduced by 87% and 52%, respectively.

Efficient adsorption of acid orange 7 from wastewater using novel bio-natural granular bentonite-sawdust-corncob (GBSC): Mixture optimization, adsorption kinetic and regeneration

The removal of dyes from industrial wastewater is one of the most environmental challenges that should be addressed through sustainable technologies. In this study, a novel green and cost-effective granular from bentonite and bio-wastes of sawdust and corncob (GBSC) was prepared for sustainable treatment of acid orange 7 (AO7) dye wastewater. The d-optimal mixture method was employed to determine the optimum combination of the GBSC in terms of dye adsorption and structure stability. Characterizations of the GBSC were investigated using SEM, XRD, FTIR and BET analyses and compared with bentonite powder (BP), modified bentonite powder (MBP), and granular modified bentonite (GMB). According to the results, a mixture of bentonite 60 wt%, sawdust 20 wt% and corncob 20 wt% at 550 °C yielded the optimal combination of the GBSC which resulted to the highest adsorption capacity 135.22 mg/g, the lowest mass loss 3.1% and maximum crushing strength 12.275 N. The kinetic and isotherm of the adsorption data were fitted well by the pseudo-second-order model and Langmuir isotherm. Our finding suggested a green circular economy model by utilizing agriculture wastes (sawdust and corncob) to synthesize GBSC for sustainable dye wastewater treatment, which offers a cost-effective adsorbent (0.907 $/g) with high regeneration (4 times reusability with 40.5% removal rate) to keep them in circulation for as long as possible.

Removal of Acid Orange 7 dye using Makgeolli lees with ultrasonic assistance

AbstractThis study investigated the efficient removal of Acid Orange 7 (AO7) dye in water by using Makgeolli lees, a popular by‐product obtained during the production of traditional Makgeolli beverages in Korea. By incorporating ultrasound, the effects of contact time, Makgeolli lees dosage, initial AO7 dye concentration, and initial pH of the dye solution were investigated and comprehensively compared with the same experiment using the stirring method. The results consistently showed ultrasound not only enhances the excellent adsorption ability of Makgeolli lees but also accelerates the process compared to the stirring method. The Langmuir isotherm model best described the adsorption process for both methods, suggesting monolayer adsorption on the surface of Makgeolli lees, with maximum capacities of 25.13 mg/g for ultrasound at 40 kHz and 20.41 mg/g for stirring methods. Furthermore, the study showed that optimal dye removal efficiency can be achieved with ultrasound conditions at 28 kHz frequency, 125 W/L power density, and 100% ultrasound intensity. This research promises that the integration of low‐cost biomass coupled with ultrasound could provide a potential solution for dye wastewater treatment.

Hybridized Co, Mn co-doped ZnO@graphite for photocatalytic degradation of orange G dye: Ecotoxicity and phytotoxicity evaluation

This study proposes a novel research investigation into the remediation of orange G dye (acid orange 10) contaminated solution using Co, Mn co-doped ZnO@graphite composite (MC-ZnO/G) material synthesized by a simple hydrothermal route. XRD, FT-IR, EDX, FE-SEM, TEM, BET analysis, UV-Vis DRS spectroscopy and XPS techniques were employed to analyse the physic-chemical characteristics of MC-ZnO/G nanocomposite. MC-ZnO/G shows a higher surface area of 27.4 m2/g than pristine ZnO (12.26 m2/g). Under optimal condition (concentration - 45 ppm, photocatalyst 20 mg and pH - 7), MC-ZnO/G photocatalyst attained a maximum degradation efficiency (MDE) of 97.8 % during 150 min of visible light exposure, whereas pristine ZnO shows a maximum degradation efficiency of 53.5 % only. Furthermore, MC-ZnO/G nanocomposite demonstrated strong stability and reusability, retaining 95.9 % of its stability even after 4 consecutive cycles. The radical studies have been carried out the scavengers, viz., IPA, BQN and EDTA. Under optimal levels, the elimination of OG dye is primarily due to the presence of •OH radicals. The treated effluent was evaluated for its effects on aquatic life, specifically Danio rerio (Zebra fish) by a survival rate of 2 days, and plants, namely Trigonella foenum-graecum (Fenugreek) by a survival rate of 7 days, in order to assess its toxicity.