Acid Red Research Articles

Sol-gel synthesized flexible Na2Ti6O13–aluminium oxide fibres for photocatalytic degradation of Acid red 1

Sodium titanate (Na2Ti6O13; NTO) was loaded onto aluminium oxide fibres (AFs) using the sol–gel method to synthesize NTO/AF fibres. The surface roughness of NTO/AF-n fibres increased with increasing number of dip-coating cycles (n = 1–3). The Fourier transform infrared spectra and X-ray photoelectron spectroscopy spectra of NTO/AF-n demonstrated the loading of NTO onto AF. The bandgap energies of NTO/AF-1, NTO/AF-2, NTO/AF-3 and NTO were determined to be 3.08, 3.12, 3.38 and 3.45 eV, respectively. The production of hydroxyl radicals by fibres under irradiation decreased in the order of NTO, NTO/AF-1, NTO/AF-2 and NTO/AF-3. NTO/AF-n fibres were designed for convenient separation from water, with NTO/AF-1 exhibiting the highest activity among the NTO/AF-n samples. The photocatalytic degradation efficiencies of NTO/AF-1, NTO/AF-2 and NTO/AF-3 after 30 min of reaction were determined to be 61.4 %, 51.7 % and 44.3 %, respectively. Complete removal of Acid Red 1 from the solution was achieved through a photocatalytic reaction using NTO/AF-n. The activity of NTO/AF-n samples remained stable over five reaction cycles, indicating their application potential for large-scale water treatment.

Visible-light-assisted peroxymonosulfate activation using MIL-88A(Fe)/BiOI heterojunction composite to drive charge transport for eliminating acid red 18

A novel rod-shaped MIL-88A(Fe)/BiOI heterojunction composite is fabricated by an in-suit chemical deposition method for visible-light-assisted peroxymonosulfate activation to eliminate AR18 (acid red 18). A series of x%MIL-88A(Fe)/BiOI are obtained according to the mass ratio of MIL-88A(Fe) to BiOI. Among them, 30 %MIL-88A(Fe)/BiOI could remove 97.79 % AR18 within 40 minutes. The reaction parameters on this process are investigated, such as PMS concentration, catalyst dosage, initial pH and dye concentration. The optimal conditions are determined to be [catalyst]= 1 g·L−1, [PMS]=1 mM, pH=7.02. The scavenging experiments and EPR analysis manifest that 1O2 is the main active species for AR18 degradation. In accordance with the band structure, active species, XPS, PL, EIS and photocurrent response, the Z-scheme electron transfer path of the composite catalyst is proved under 500 W (λ > 420 nm) Xenon lamp irradiation. In the end, the stability and universality of the composite catalyst in practical application are evaluated by three cyclic tests and inorganic anion experiments. This work provides valuable guidance for synthesizing efficient and stable MOF based heterojunction photocatalysts.

Dynamic behavior of a fixed-bed adsorption column for acid red removal using natural Algerian cactos

In this work, the ability of Natural Algerian Cactus (NAC) to adsorb Acid Red (AR) from aqueous solution was investigated in a fixed-bed column. Scanning Electron Microscopy (SEM) was employed to examine the surface of the biosorbent, Fourier Transform Infrared Spectroscopy (FTIR) was utilized to analyze the chemical composition of NAC, and Brunauer-Emmett-Teller (BET) analysis was conducted to determine the surface area of NAC. We examined the effects of flow rate and influent concentration of AR on the efficiency of the fixed bed. Additionally, we analyzed the sorption of AR using the Thomas and Yoon-Nelson models at various dye concentrations and flow rates to predict breakthrough curves and determine the characteristic parameters of the fixed bed sorption column. The applied models were found to describe the NAC column biosorption process. The obtained results show that the natural Algerian cactus is an efficient Acid Red biosorbent from its aqueous solutions. A sorption capacity of 39.51 mg/g was recorded for the highest concentration (100 mg/l) at a flow rate of 0.8 mL/min while for the highest flow rate (2 mL/min), the sorption capacity attained 30.27 mg/g for a concentration of 50 mg/l. However, the longest breakthrough time was noted for the lowest concentration and flow rate respectively (tb=21h and te=38h for 50mg/l and 0.8 mL/min).

Exploring the diverse applications of sol–gel synthesized CaO:MgAl2O4 nanocomposite: morphological, photocatalytic, and electrochemical perspectives

A nanocomposite of CaO:MgAl2O4 was synthesized through a straightforward and cost-effective sol–gel method. The investigation of the novel CaO:MgAl2O4 nanocomposite encompassed an examination of its morphological and structural alterations, as well as an exploration of its photocatalytic activities and electrochemical characteristics. XRD analysis revealed a nanocomposite size of 24.15 nm. The band gap, determined through UV studies, was found to be 3.83 eV, and scanning electron microscopy (SEM) illustrated flake-like morphological changes in the CaO:MgAl2O4 samples. TEM, HRTEM, and SAED studies of a CaO:MgAl2O4 nanocomposite would reveal important details about its morphology, crystallography, and nanostructure. Photocatalytic activity was quantified by studying the degradation of Acid Red-88 (AR-88) dye in a deionized solution, achieving a 70% dye degradation under UV irradiation in 120 min. Plant growth examinations were carried out using dye degraded water to test its suitability for agriculture. The electrochemical energy storage and sensing applications of the prepared nanocomposite were examined using CaO:MgAl2O4 modified carbon paste electrode through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In conclusion, the synthesized CaO:MgAl2O4 nanocomposite demonstrated promising morphological and structural characteristics, efficient photocatalytic activity, and potential applications in electrochemical energy storage, highlighting its versatility for various technological and environmental applications.Graphical abstract

Investigate Performance of ATGF nanocomposite based on guar gum polymer for adsorption of Congo Red dye and alpha lipoic acid drug from wastewater: study kinetics and simulation

AbstractIn this study, the synthesized nanocomposite novel arginine/thiourea/guar gum/ferrite (ATGF) adsorbent was evaluated for the adsorption of alpha lipoic acid (ALA) and Congo Red (CR) from wastewater. The synthesized nanocomposite was examined by Brunauer–Emmett–Teller theory (BET), Termal gravimetric analysis (TGA), Fourier transform infrared spectrometer (FT‐IR), field emission scanning electron microscopy (FE‐SEM), X‐ray Diffraction (XRD), Vibrating sample magnetometer (VSM), and energy dispersive X‐ray (EDX). For the removal of ALA and CR from aqueous solution, the capacity of the nanocomposite was investigated by working on a series of experiments such as the effect of adsorbent dose, initial concentration, contact time, pH and temperature. The adsorption kinetics of these two pollutants were investigated using pseudo‐first‐order and pseudo‐second‐order velocity equations. The nanocomposite kinetics follow pseudo‐second‐order. Langmuir and Freundlich isotherms were investigated. The results show that the Langmuir isotherm model gives the maximum adsorption capacity of ALA as 96.93 mg g−1 and of CR as 229.34 mg g−1 on the nanocomposite. © 2024 Society of Chemical Industry.

Heterogeneous Photo-Fenton Degradation of Azo Dyes over a Magnetite-Based Catalyst: Kinetic and Thermodynamic Studies

Textile wastewater containing dyes poses significant environmental hazards. Advanced oxidative processes, especially the heterogeneous photo-Fenton process, are effective in degrading a wide range of contaminants due to high conversion rates and ease of catalyst recovery. This study evaluates the heterogeneous photodegradation of the azo dyes Acid Red 18 (AR18), Acid Red 66 (AR66), and Orange 2 (OR2) using magnetite as a catalyst. The magnetic catalyst was synthesized via a hydrothermal process at 150 °C. Experiments were conducted at room temperature, investigating the effect of catalyst dosage, pH, and initial concentrations of H2O2 and AR18 dye. Kinetic and thermodynamic studies were performed at 25, 40, and 60 °C for the three azo dyes (AR18, AR66, and OR2) and the effect of the dye structures on the degradation efficiency was investigated. At 25 °C for 0.33 mmolL−1 of dye at pH 3.0, using 1.4 gL−1 of the catalyst and 60 mgL−1 of H2O2 under UV radiation of 16.7 mWcm−2, the catalyst showed 62.3% degradation for AR18, 79.6% for AR66, and 83.8% for OR2 in 180 min of reaction. The oxidation of azo dyes under these conditions is spontaneous and endothermic. The pseudo-first-order kinetic constants indicated a strong temperature dependence with an order of reactivity of the type OR2 > AR66 > AR18, which is associated with the molecular size, steric hindrance, aromatic conjugation, electrostatic repulsion, and nature of the acid–base interactions on the catalytic surface.

Study on supercritical water regeneration of bio-based activated carbon saturated with acid red G

The dye and textile industry commonly employs activated carbon adsorption technology due to its cost-effectiveness and high efficiency. However, disposing of waste-activated carbon has a significant environmental and human health impact, and it’s a huge economic waste. This study investigates the kinetic and isothermal adsorption characteristics of Acid Red G dye adsorption by Powdered Activated Carbon derived from coconut shells. To effectively reuse activated carbon and maximise resource conservation, regeneration experiments were carried out using Supercritical Water at 24 MPa and 400 ℃ for 30 min. The experimental results demonstrated that, in comparison with thermal regeneration, supercritical water possesses the benefits of environmental protection, economic efficiency and extensive applicability. This is of considerable importance to the field of research concerning the regeneration of activated carbon.

Innovative fabrication of highly efficient CeO2 ceramic nanomaterials for enhanced photocatalytic degradation of toxic contaminants under sunlight

In this research, we report an innovative sonochemical technique for synthesizing cerium oxide (CeO2) nanoparticles utilizing glucose as a capping agent, significantly boosting their photocatalytic performance under visible light. Through meticulous optimization, our CeO2 nanoparticles demonstrated exceptional degradation efficiencies: 97.2 % for Acid Red 14, 99.1 % for Captopril, 98.7 % for Malachite Green, and 98.3 % for Amlodipine, substantially outstripping performance metrics of commercial TiO2 and untreated samples. Our kinetic analyses, based on the Langmuir-Hinshelwood model, indicated a superior rate constant of 0.0701 min⁻1 for Acid Red 14 degradation—reflecting a stark enhancement over other catalysts tested. Furthermore, mechanistic insights revealed that the significant improvement in photocatalytic activity was predominantly due to the generation of hydroxyl radicals and effective utilization of electron vacancies, with the role of these reactive species validated by detailed scavenger tests. This enhancement in photocatalytic efficiency is attributed to the sonochemical synthesis paired with glucose modification, which optimizes the nanoparticles' surface characteristics crucial for reactivity. Moreover, the nanoparticles showcased remarkable stability and reusability, maintaining an 87.8 % degradation rate after 11 cycles, evidencing minimal loss in activity and underscoring their potential for long-term applications in environmental remediation. This study not only paves the way for the practical application of CeO2 nanoparticles in pollutant degradation but also illustrates the broader applicability of sonochemically synthesized nanomaterials in sustainable environmental management, offering a promising solution to the challenge of complex organic pollutants in aquatic environments.

Efficient removal of organic pollutants on sponge-type inorganic adsorbent derived from spent cotton fiber/layered double hydroxides

For the whole life cycle of the textile industry, the disposal of printing and dyeing wastewater and the reuse of spent fibers were two of the main environmental problems. In this work, activated carbon fiber/layered double oxides (ACF/LDO) were prepared by the pyrolysis of spent cotton fiber/layered double hydroxides (LDH) composite. Compared to 2D structure LDH, 3D hierarchical ACF/LDO was formed by introducing activated carbon nanofibers as a skeleton. ACF/LDO had excellent adsorption properties for organic dye and the maximum adsorption capacity of acid red 27 (AR27) exceeded 800 mg/g. Due to the memory effect of LDH, the interconversion of ACF/LDO to ACF/LDH was observed during the adsorption and regeneration process. Meanwhile, the shrinkage and expansion of adsorbent occurred, which was similar to that of a sponge absorbing water. During the adsorption process, the average pore diameter of the adsorbent increased as ACF/LDO was converted to ACF/LDH, which increased the diffusion of organic dye inside the pores. On the contrary, the specific surface area and pore structure were restored during the regeneration process. Therefore, this composite displayed excellent adsorption capacity and repeatability, with no significant decrease was observed in adsorption capacity even after five consecutive cycles. The adsorption mechanism revealed that the removal of AR27 was dominated by electrostatic attraction and π-π interactions. The experiment provided a new strategy of treating wastewater with waste fiber.

Multifunctional applications of novel copper magnesium vanadate nanoparticles: Photocatalytic dye degradation and electrochemical properties

The multifunctional applications of nanomaterials in energy saving, electrochemical energy storage, and sensing devices are a current research trend. Novel Copper Magnesium Vanadate (CMV-CuMg2V2O8) nanoparticles have been synthesized by solution combustion method. The crystallite size calculated from XRD and TEM results was found to be 21 nm. The band gap estimated from UV–Vis DRS of CMV nanoparticles was found to be 3.82 eV. Its multifunctional applications were explored through for energy conversion, storage and sensing applications. Photocatalytic degradation of Acid Red-88 (AR-88) dye was conducted using CMV nanoparticles as photocatalyst under UV light. CMV nanoparticles modified carbon paste electrodes were prepared and its cyclic voltammetry (CV), Electrochemical impedence spectroscopy (EIS) and Galvanostatic charge–discharge (GCD) analysis were carried out using 1M KCl and NaOH electrolyte. With excellent specific capacitance of 266 Fg−1 in KCl electrolyte and 242 Fg−1 in NaOH electrolyte at 5 mV/s scan rate, CMV NPs was demonstrated to be a promising electrode material for supercapacitors. Electrochemical sensing analysis was carried out using the same electrode for the detection of paracetamol and ibuprofen within the range of 1–5 mM. The resulting copper magnesium vanadate nanoparticles have been verified as a possible electrode material for next-generation energy storage devices.

Preparation of silver-based metal-organic framework and chitosan hybrid material for removing drug and dye

Pharmaceuticals and personal care products and dyes have low biodegradability and high toxicity, seriously threaten the human health and ecological environment. Therefore, seeking effective removal methods has become the focus of research. In this study, silver-based metal-organic framework (Ag-MOF) and chitosan (CS) hybrid adsorbent (Ag-MOF-CS) was synthesized via solvothermal one-pot synthesis to remove diclofenac sodium (DCF) and acid Red 1 (AR1) from water for the first time. The morphology and structure of Ag-MOF-CS were confirmed by various characterizations. The effect on adsorption was investigated by changing the adsorbent dosage, pH and other conditions. The adsorption kinetics, adsorption isotherms and thermodynamics were analyzed. Ag-MOF-CS showed a high adsorption capacity. And the maximum adsorption capacity of Ag-MOF-CS for DCF and AR1 was 351.75 mg/g and 678.83 mg/g, respectively. The adsorbent bound to DCF and AR1 may via electrostatic forces, π-π interactions, hydrogen bonding. Even after four cycles of Ag-MOF-CS, the DCF removal can still be higher than 80 %. The eco-friendly Ag-MOF-CS demonstrated significant potential for utilization in treating wastewater.

Removal of acid red dye 1 from textile wastewater by heterogenous photocatalytic ozonation employing titanium dioxide and iron zeolite

Clean water is a necessity for all life to survive and flourish. However, natural waters are being continuously contaminated due to the release of waste streams in water. Hence, it is important to remove pollutants from wastewater to fulfill human needs. Conventional treatment methods are neither efficient nor economical for wastewaters that especially contain refractory toxic pollutants. This requires novel techniques like Advanced oxidation processes (AOPs), that may successfully degrade persistent micropollutants more efficiently. In this study, an azo dye Acid Red 1 was removed by three AOPs, namely Photocatalytic oxidation, Ozonation and Photocatalytic Ozonation, by employing heterogenous catalysts. TiO2 was used as photocatalyst, whereas Fe-Zeolite has been further added as Ozonation catalyst. The study revealed that photocatalysis degraded only 28% Acid red dye after 15 min, whereas for ozonation, the degradation percentage was 95% in same time. In combined photocatalytic ozonation process using TiO2, 95% degradation was achieved in just 9 min and treatment time further reduced to 5 min when Fe-zeolite was added. Optimization studies for initial concentration, UV intensity and catalyst loading were performed. Finally, rate constants and Electrical Energy per Order (EEO) values were determined for all AOPs, and mechanism was proposed.

Synthesis of iron loaded jackfruit peel biochar through microwave heating as a stable and active heterogenous Fenton catalyst for dye degradation

Iron-loaded biochar derived from jackfruit peels (Fe-JP) was synthesised by pyrolysis in a microwave furnace and iron was loaded onto the peels prior to pyrolysis, facilitated by sonication. The primary objective of the investigation was to examine the degradation process of methylene blue (MB) dye and Acid Red 1 (AR1) dye by the using Fe-JP biochar as a heterogeneous Fenton catalyst. The investigation encompassed an examination of the impact of different operating parameters, such as pH, catalyst dosage, and H2O2 concentration. The synthesised Fenton catalyst underwent characterization using Field Emission scanning electron microscopy (FESEM), Energy Dispersive X-ray (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques, Fourier transform infrared (FTIR) spectra analysis, Raman spectroscopy, Brunauer-Emmet-Teller (BET) analysis. At a pH of 3, using an initial MB dye concentration of 20 mg/L and initial AR1 dye concentration of 50 mg/L, an 8 mM H2O2 concentration, and a catalyst dose of 2 g/L, the maximum dye removal efficiency reached 96.5 % and 98 % respectively, while the total organic carbon (TOC) removal efficiency reached 68.5 % and 75 % respectively. The observed reaction time under the given experimental conditions was 120 min. The thermal stability of the biochar catalyst was found to be excellent based on the Thermogravimetric analysis (TGA) and Differential Scanning Calorimeter (DSC) studies. The catalysts that were developed demonstrated remarkable durability and negligible leaching of iron, hence enabling their repeated usage in subsequent cycles. The findings of the investigation suggest that the primary mechanism responsible for the degradation of the dye was the surface-based heterogeneous Fenton activity. Additionally, the effect of adsorption on the elimination of colour under varying pH conditions was examined, which had a very low influence in dye degradation (<30 %). The conducted scavenging investigations in the research have indicated the major involvement of hydroxyl radicals (OH) in the degradation process, followed by surface-bound hydroxyl radicals (OHsurface), superoxide radicals (O2−) and ultimately by singlet oxygen radicals (1O2). The study's economic analysis demonstrated that using microwave mode of heating for catalyst synthesis is both green and cost-effective. This observation suggests the possibility of practical implications in the domain of dye degradation.

Factorial design-aided derivatization-free fluorimetric ultrasensitive assay of vonoprazan with application in uniformity of dosage units and plasma samples analysis: Comprehensive and comparative greenness and whiteness assessment

This study presents a novel derivatization-free spectrofluorimetric method for the quantification of vonoprazan (VPZ) that is characterized by its high sensitivity, environmental friendliness, and cost-effectiveness. Notably, this method eliminates the requirement for pre-derivatization, extraction procedures, large amounts of organic solvents, and/or expensive instrumentation, which distinguishes it from previous approaches. The approach employed in this study relies on the formation of an association complex between VPZand the xanthene dye acid red 87 (AR87) under acidic conditions. The stability of the VPZ-AR87 complex was determined to be remarkably high, with a complex formation constant (Kf) value exceeding 2 x 106 M−1. The fluorimetric measurements rely on the quantitative and selective quenchingof the dye’s native fluorescence emission at 545 nm. The experimental parameters were optimized utilizing a quality-by-design 23 full factorial design. This strategy yielded a highly favorable linearity range of 10.0 to 400.0 ng/mL, with a correlation coefficient (r) of 0.9997. The presented methodology exhibited a high level of sensitivity, as evidenced by its ability to detect concentrations as low as 1.2 ng/mL. This sensitivity enabled its successful application for the estimation of VPZ in human plasma samples with high %recoveries (98.21–101.67) and low %RSD values (<1.52). Furthermore, content uniformity testing of low-dose VPZ tablets was performed according to United States Pharmacopeia guidelines. Greenness and whiteness metrics analysis showed a significant advantage of the proposed method over previously reported fluorimetric methods. Validation of the developed approach was carried out in accordance with ICHQ2 (R1) guidelines.

Can ozone mass transfer in water treatment be enhanced through independent pressurized ozonation?

The dissolved ozone equilibrium concentration is hard to improve by increasing the gas phase partial pressure due to the low initial pressure and difficulty in pressurization. In this study, a novel hydraulic pressurization technology was developed to reliably elevate the ozonation pressure and improve the solubility of ozone. It was located downstream of the ozone generator to avoid generator overpressure. Specifically, at the optimal pressure of 0.30 MPa with an initial ozone flow rate of 1–6 L min−1, the specific surface area of bubbles and turbulent dissipation rate in the ozonation reactor were up to 2.5- and 1.5-fold that of the atmospheric aeration. Meanwhile, the dissolved ozone equilibrium concentration, redox potential, and volumetric mass transfer coefficient were up to 2.4-, 1.6-, and 2.7-fold that of atmospheric aeration, respectively. The increase in bubble-specific surface area and turbulent dissipation rate, synergistically enhanced the mass transfer, contributing 83.2–94.4 % and 5.6–16.8 %, respectively. As the reactor pressure was increased from 0 to 0.30 MPa, the decolorization time of Acid Red 18 was shortened from 20 to 8 min, and the COD removal rate increased from 48.0 % to 85.0 %. This work provides an alternative approach coupled with a novel device that enhances the ozone mass transfer during water treatment.

Facile Construction Engineering of Pr6O11@C with Efficient Photocatalytic Activity.

In this study, facile construction engineering of Pr6O11@C with efficient photocatalytic activity was established. Taking advantage of the flocculation of Pr3+ in the base medium, acid red 14 (AR14) was flocculated together with Pr(OH)3 precipitate, in which Pr(OH)3 and AR14 mixed highly uniformly. Calcinated at high temperature in N2, a novel Pr6O11@C was successfully synthesized. The resulting materials were characterized by XRD, SEM, FT-IR, Raman, and XPS techniques. The results show that the cubic Pr6O11@C with Fm3m space group, similar to that of Pr6O11, was obtained. From the results of the photodegradation of AR14, it is found that the photocatalytic efficiency of Pr6O11@C is higher than that of pure Pr6O11 due to the formation of abundant carbon bonds and oxygen vacancies. Compared with pure Pr6O11 and other carbon-based composites, the acid resistance of Pr6O11@C is greatly improved due to the highly uniform dispersion of Pr6O11 and C, which lays a solid foundation for the practical application of Pr6O11@C. Moreover, the role of NH3·H2O and NaOH used as precipitants for the photocatalytic efficiency of Pr6O11 was investigated in detail.

Decolorization, degradation, and detoxification of textile dye and efficient hydrogen production by highly-stable MIL-177-LT@NiFe-LDH photoelectrocatalyst: Mechanism and economical studies

Combining organic compounds with inorganic layers leads to the development of innovative organic-inorganic hybrid materials with specific functional properties, opening up possibilities for advanced applications that go beyond current technological limits. In the present study, Ti-MOF (MIL-177-LT) was decorated with NiFe layered double hydroxide (NiFe-LDH) to fabricate a heteroatom electrocatalyst (MIL-177-LT@NiFe-LDH). The synthesized electrode included capable electron transportation, long-term stability, and high specific surface area. Photoelectrocatalytic degradation of the Azo dye (Acid Red 18) from water was studied with respect to the influence of pH, bias potential, temperature, and dye concentration. It was found that hydrogen evolution reaction (HER) has minimized overpotentials, i.e., 130 and 182 mV corresponding to the current densities of 400 and 1000 mA cm−2, respectively. High stability was also observed when a current density of 5000 mA cm−2 was applied to the modified electrode for 500 h. The layered architecture of the MIL-177-LT@NiFe-LDH composite provides high surface points for the degradation of dye molecules and water splitting for HER. The electrocatalyst showed great stability in the degradation process. The experiment was powered by solar cells, reducing the need for electricity and resulting in cost savings. Additionally, the treatment process was analyzed in terms of costs. Therefore, a promising approach is suggested in this study for developing high-performance organic-inorganic hybrid materials with exceptional electrochemical and photocatalytic properties.

2,3-pyridinedicarboxylic acid-modified MIL-88A(Fe) for enhanced peroxymonosulfate activation to degrade organic contaminants

Metal-organic framework (MOF)-based composites have shown a great application potential in photoassisted persulfate activation process and environmental remediation. Herein, 2,3-pyridinedicarboxylic acid (PDA) is firstly used to improve the catalytic activity of MIL-88A(Fe). The composite catalysts are effectively synthesized using a solvothermal method. At an 80.2 mg modification level of PDA, the catalyst [MIL-88A(Fe)-PDA-3] could achieve 98.20 % removal of AR18 (acid red 18) through the visible-light-assisted peroxymonosulfate (PMS) activation. It is 7.8-fold increase than pristine MIL-88A(Fe). The suitable conditions for AR18 elimination are 0.4 g/L MIL-88A(Fe)-PDA-3, 1.5 mM PMS and pH = 10. The interplay between influencing factors is explored by a response surface methodology. The quenching studies and EPR tests indicate the generation of active species such as ·OH, SO4·−, 1O2, O2·−, and FeIVO in the reaction system, with ·OH playing a significant role for AR18 degradation. A potential mechanism is proposed based on the above results. This study offers a fresh perspective for the development of efficient MOFs materials.

Activated carbon from hydrothermal carbonization of ice cream factory wastewater with H3PO4 activation. Synthesis, characterisation and adsorption properties

This work aims to treat ice cream wastewater (ICWW) by hydrothermal carbonization (HTC) and to produce activated carbon (AC). The HTC reduces COD, BOD5 and KTN by up to 80%, 55% and 93%, respectively. The obtained hydrochar was activated with H3PO4 at various impregnation ratios (1−4) and different temperatures (400−600 °C). The material with the best properties, named AC-2-500, was obtained at 500 °C with an acid impregnation rate of 2 and represents a spherical shape (specific surface area of 1432.44 m2 g−1, pore volume of 0.80 cm3g-1, and average pore diameter around 2.24 nm). The porous structure of AC-2-500 enabled to achieve high adsorption capacities of the order of 588.23 mg g−1 and 250 mg g−1 for rhodamine B (RhB) and acid red 97 (AR97), respectively. The adsorption equilibrium was reached in 30 min for RhB and 60 min for AR97. The linear forms of the Langmuir and Freundlich isotherms appear to produce reasonable models for the adsorption of dyes onto AC-2-500, with best results when applying Langmuir model. Both dyes adsorb spontaneously and endothermically, with an increase in the randomness at the solid/solution interface. Furthermore, the regeneration study revealed that during several adsorption-desorption cycles, AC-2-500 demonstrated a strong adsorption capability.

Zeolitic imidazolate framework-8/layered triple hydr(oxide) composite for boosting the adsorptive removal of acid red 1 dye from wastewater

Water pollution is one of the serious environmental problems the humanity currently faces. Adsorption is an attractive process for tackling water pollution. Accordingly, novel adsorbents were synthesized in this study through the coupling of zeolitic imidazolate framework-8 (ZIF-8) with MnCuAl layered triple hydroxide/oxide (MnCuAl-LTH/MnCuAl-LTO) via different approaches. The synthesized adsorbents were characterized using different techniques in order to reveal their textural properties, crystallinity, and functional groups before applying them to decontaminate wastewater samples contaminated with acid red 1 (AR1) azo dye. The BET results revealed that all the synthesized materials are highly porous with specific surface area ranging from about 35 to more than 1200 m2/g. Additionally, the XRD and FTIR results confirmed the formation of the targeted pristine and composite adsorbents. Preliminary adsorption studies showed that the ZIF-8@MnCuAl-LTH composite is the most effective material in removing AR1 from wastewater. Potential mechanism(s) for the superiority of ZIF-8@MnCuAl-LTH over other adsorbents (i.e., MnCuAl-LTH@ZIF-8, MnCuAl-LTO@ZIF-8, MnCuAl-LTH, MnCuAl-LTO, and ZIF-8) has been discussed. The results also demonstrated that the adsorption of AR1 onto ZIF-8@ MnCuAl-LTH is strongly pH-dependent. The adsorption isotherm results confirmed that the removal of AR1 is best fitted by the Redlich-Paterson isotherm with a high degree of compatibility with the Langmuir isotherm model. Similarly, the experimental data were well-fitted to the Avrami model, confirming the complex nature of AR1 adsorption onto ZIF-8@ MnCuAl-LTH. Additionally, the regenerability and stability of this adsorbent have been investigated, and the obtained results revealed that this adsorbent is stable and has a good reusability. Accordingly, the ease of fabrication, high adsorption capacity (qmax is about 1000 mg/g), and the good stability and reusability make ZIF-8@MnCuAl-LTH a very promising adsorbent for removing anionic azo dyes from wastewaters, demonstrating the significance of this study.