Acid Red Research Articles

Synthesis, characterization of Gd-doped ZnO nanocrystals and their photocatalytic activity in the degradation of C.I. Acid Red 18

In this study, ZnO and Gd doped ZnO with various weight percentages (1, 2, 3, and 4 wt% Gd calcined at 450 °C and 2 wt% Gd doped ZnO calcined at 450, 550, 650, and 750 °C) have been prepared. XRD, TEM, DRS, PL measurements, EDX, and FTIR were used for the characterization of the as-prepared photocatalysts. The photocatalytic activity of the as-synthesized ZnO and Gd-doped ZnO products was assessed by AR18 as a model of textile contaminants degraded in water under UV radiation. The effect of operating parameters such as pH, contact time, the initial dye concentration, and the influence of different contents of gadolinium doping and analysis were estimated. We use some active species such as ethanol, K2Cr2O7, KI, and Oxalate to find the photocatalyst and the formation of the electron-hole mechanism of Gd-doped ZnO. After 40 min, the catalyst calcined at 450°C (at pH = 5.0, [AR18] = 1.0 × 10−5M)showed the highest efficiency (98.28 %). The amount of COD decrease after 40 min of irradiation is 98.6 %.

Synergism between polyethyleneimine, graphene oxide, and MgFeAl-layered triple hydroxide in removing acid red 1 dye and bisphenol A from contaminated water samples

Water pollution is rapidly growing, requiring the development of effective treatment processes. In this work, a novel adsorbent (composed of polyethyleneimine, graphene oxide, MgFeAl-layered triple hydroxide, abbreviated as PEI@GO/MgFeAl-LTH) was synthesized, characterized, and applied to remove two hazardous water pollutants (i.e., acid red 1 and bisphenol A). The adsorption performance of the synthesized PEI@GO/MgFeAl-LTH nanocomposite was benchmarked to its parental materials (i.e., GO, PEI@GO, MgFeAl-LTH, and GO/MgFeAl-LTH). The results demonstrated that the adsorption capacity of bisphenol A (BPA) and acid red 1 (AR1) onto the nanocomposite are 352.0 and 155.5 mg/g, respectively, which are higher than their adsorption on GO, PEI@GO, MgFeAl-LTH, and GO/MgFeAl-LTH. The obtained adsorption isotherms and kinetics data were fitted using different models, which showed that Redlich-Peterson isotherm and Avrami kinetics models provide excellent fits for the obtained experimental data; the other models provided mixed results. The zeta potential measurements and the study of the pH effect suggest that the adsorption of BPA and AR1 onto the PEI@GO/MgFeAl-LTH nanocomposite is governed by more than a single mechanism. Furthermore, thermodynamics analysis demonstrated that the adsorption of AR1 and BPA is an exothermic (the respective ∆H values are −27.59 and −11.21 kJ/mol), spontaneous, and physical in nature. With respect to the reusability of this nanocomposite, the results revealed that it is highly stable and easily regenerable using a cheap solvent (i.e., 0.2 M NaOH). Accordingly, this study demonstrates the efficacy and superiority of the synthesized PEI@GO/MgFeAl-LTH nanocomposite in efficiently capturing toxic organic pollutants from aqueous environments.

Evaluation of the Dye Extraction Using Designed Hydrogels for Further Applications towards Water Treatment.

In this work, novel chitosan-silica hydrogels were synthesized and investigated by various complementary techniques. The hydrogels were obtained via the immobilization of chitosan (Ch) on the surface of mesoporous cellular foams (MCFs). The latter silica materials were obtained by a sol-gel process, varying the composition of the reaction mixture (copolymer Pluronic 9400 or Pluronic 10500) and the ageing temperature conditions (80 °C or 100 °C). The role of the silica phase in the hydrogels was the formation of a scaffold for the biopolymeric chitosan component and providing chemical, mechanical, and thermal stability. In turn, the chitosan phase enabled the binding of anionic pollutions from aqueous solutions based on electrostatic interaction mechanisms and hydrogen bonds. To provide information on structural, morphological, and surface properties of the chitosan-silica hydrogels, analyses such as the low-temperature adsorption/desorption of nitrogen, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy (FTIR) were performed. Moreover, the verification of the utility of the chitosan-silica hydrogels as adsorbents for water and wastewater treatment was carried out based on kinetic and equilibrium studies of the Acid Red 88 (AR88) adsorption. Adsorption data were analyzed by applying various equations and discussed in terms of the adsorption on heterogeneous solid-surfaces theory. The adsorption mechanism for the AR88 dye-chitosan-silica hydrogel systems was proposed.

Industrial Solid Waste-Based Layered Double Hydroxide Composite with Enhanced Adsorption Affinity to Congo Red, Acid Red, and Reactive Red

Industrial Solid Waste-Based Layered Double Hydroxide Composite with Enhanced Adsorption Affinity to Congo Red, Acid Red, and Reactive Red

Isotherms, kinetics and thermodynamics of industrial dye acid red 27 adsorption on Sugarcane Bagasse Ash.

In this study, sugarcane bagasse ash (SCBA), obtained as residue from the sugar mill, was used as an adsorbent for Acid Red 27 (AR27) removal from aqueous solutions. The ash characterization data showed 23.63% of organic compounds and silica (α-SiO2) as the most expressive inorganic compound (confirmed by X-ray diffractogram), the BET surface area had a value of 62.79 m2.g-1 and the pHpzc was 8.45. Regarding the adsorptive tests, the optimal initial pH to the dye removal was 2.0. The adsorption equilibrium reached in about 4h contact time and optimum SCBA dosage was found to be 4g.L-1. The pseudo-second order model best represented the adsorption kinetics. The Freundlich equation presented the best fit to the equilibrium data for the removal of AR27 by ash, with maximum adsorption capacity of 15mg.g-1 at pH 2.0. Thermodynamic study indicate that AR27 adsorption on SCBA occurs through a physisorption mechanism, with ΔHºads < 15kJ.mol-1. The ΔHºads evaluated by Vant' Hoff equation was explained as a combination of water desorption enthalpy, ΔHºW and isosteric like enthalpy, ΔHºD for the dye adsorption in liquid environment. The ΔHºD = 9.2kJ.mol-1 was calculated from Clausius-Clapeyron approach. The effects of coexisting anions on the adsorption and regeneration and reuse of the adsorbent were also investigated. This study suggests that SCBA, which was used without any pretreatment, has the potential to be applied as a low-cost adsorbent to mitigate effluents contamination with AR27 dye at low concentrations.

Chitosan and Ferrite Nanoparticles Modified Zeolite (ZSM-5) as Adsorbent for the Removal of Acid Red Dye from Water

The present study involved the synthesis and characterization of nanocomposites (NCs) consisting of MgFe2O4-chitosan-ZSM-5 zeolite (MgF-Cs-Ze), NiFe2O4-chitosan-ZSM-5 zeolite (NiF-Cs-Ze), and MgFe2O4@ NiFe2O4-chitosan-ZSM-5 zeolite (MgF@NiF-Cs-Ze). These NCs were investigated for their potential application as effective adsorbents in various environmental contexts. In order to investigate the composition and physical properties of the NCs, XRD, FT-IR, SEM-EDX, and TEM techniques were utilized. The present study is aimed at evaluating acid red (AR) dye adsorption behavior from aqueous solutions onto MgF-CS-Ze and NiF-CS-Ze NCs under different experimental circumstances. The study revealed that the NCs MgF-CS-Ze and NiF-CS-Ze exhibited maximum capacity for adsorption of 55.55 mg g-1 and 41.66 mg g-1, respectively, in that regard when tested with AR dye. These findings underscore the significant adsorption capabilities of these NCs. Examining the adsorption kinetics revealed that AR dye adsorption process followed the pseudo-second-order kinetic model. Resulting from thermodynamic studies, it was discovered that the adsorption of AR dye onto MgF-CS-Ze and NiF-CS-Ze NC process was an exothermic and spontaneous.

Methylene blue and acid red adsorption on biochar made from modified sugarcane bagasse: A dynamic, equilibrium, and thermodynamic investigation

This study synthesized biochar adsorbents from chemically activated sugarcane bagasse using ZnCl2 at pyrolysis temperatures of 400, 500, and 600°C. The modified bagasse biochar was used to remove methylene blue (MB) and acid red (AR) dyes. The surface characteristics of the modified bagasse biochars were analyzed using Scanning Electron Microscope (SEM), Fourier Transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. Batch adsorption experiments were conducted to assess the impact of various parameters on adsorption performance. Among the different bagasse biochar samples, Zn-BC-600 exhibited superior adsorption capacities for MB and AR with values of 182.225 and 43.324 mg/g, respectively. The adsorption efficiency was significantly influenced by pH, with optimal conditions at pH = 6.0 for MB and pH = 2.0 and 10.0 for AR. The adsorption process for MB and AR on Zn-BCs followed a pseudo-second-order kinetic model, indicating chemisorption as the primary mechanism. Adsorption isotherm studies revealed that Zn-BCs conform to the Freundlich model, proposing a multilayer adsorption due to the heterogeneity of the biochar surface. Regeneration experiments indicated that Zn-BCs could be reused for multiple adsorption cycles. In conclusion, the modified bagasse biochar showed strong adsorption affinity for both MB and AR, particularly for MB, making it a promising adsorbent for treating printing and dyeing wastewater.

Adsorption of acid red 18 from aqueous solutions by GO-COFe2O4: Adsorption kinetic and isotherms, adsorption mechanism and adsorbent regeneration

In the present study, graphene oxide-cobalt ferrite (GO-CoFe2O4) was synthesized by sol-gel method as an adsorbent in the removal of acid red 18 (AR18) dye. The characteristics of the magnetic adsorbent were analyzed through SEM, TEM, XRD, FTIR, N2 adsorption-desorption, and VSM. The findings of the diagnostic analysis showed a surface area of 58.92 m2/g, a pore size of 2 nm, and a magnetic property of 3.82 emu/g for the GO-CoFe2O4 composite. The effect of the operational parameters determined the maximum removal efficiency (100%) at pH of 5, adsorbent dosage of 1 g/L, and AR18 concentration of 25 mg/L. The effect of anions on the removal rate of AR18 by GO-CoFe2O4 composite was evaluated, and the results were its negative effect in reducing the efficiency in the order of NaCl < NaNO3 < Na2SO4 < Na2CO3. Thermodynamic parameters including ΔG°, ΔH°, and ΔS° explained that the adsorption of AR18 on the synthesized composite is favorable, spontaneous, and endothermic. The experimental data was studied by four kinetic equations including pseudo-first-order, pseudo-second-order, Elovich and intraparticle-diffusion and the results based on R2 and qe were consistent with pseudo-second-order kinetics. Eleven isotherm models were selected for adsorption equilibrium data, and the data were fitted with all isotherm models with R2 > 0.95. The results of adsorbent regeneration by peroxymonosulfate (PMS) activation showed that with increasing treatment time and PMS amount (up to 10 mM), the regeneration efficiency increases significantly up to 73.72%.

A sensitive lateral flow test strip sensor for visual detection of acid red 18 in food using bicentric-emission carbon dots.

Hazardous synthetic colorants have found widespread use in food production, and excessive consumption of these pigments can pose potential risks to human health. In this study, we propose an ultrasensitive fluorescence method for the analysis of Acid Red 18 (AR18) in food products. The method is based on the nitrogen-doped carbon dots (N-CDs) derived from tris and resorcinol through a hydrothermal way. The as-synthesized N-CDs exhibit two emission centers at 425 nm and 541 nm, corresponding to the excitation wavelengths of 377 nm and 465 nm, respectively. Upon the addition of AR18, the fluorescence intensity at 541 nm significantly decreases with a simultaneous, though less pronounced, reduction in the intensity at 425 nm, which is attributed to the localization of fluorescence resonance energy transfer (L-FRET). Specifically, a novel ratiometric fluorescent probe was constructed based on the extracted data from the 3D fluorescence excitation-emission matrix. This probe demonstrates a wide linear range from 0.0539 to 30 μM and a low limit of detection (LOD) of 53.9 nM. For practical applications, a portable fluorescent sensor based on a lateral flow test strip (LFTS) was designed for real-time monitoring of AR18. Color channel values were determined using a smartphone application, resulting in a satisfactory LOD of 75.3 nM. Furthermore, the suitability of the proposed ratiometric fluorescent probe was validated through the detection of AR18 in real food samples, consistently achieving recovery rates in the range of 99.7-101.4%. This research not only expands the scope of CDs in sensing fields, but also provides an effective strategy for the development of an excellent platform for real-time AR18 detection, contributing to public food safety.

Biosynthesis and Stabilization of Nanosilver Using Houttuynia Extract for Degradation of Azo Acid and Mordant Dyes

Silver nanoparticles (AgNPs) are promising candidates for environmental remediation due to their exceptional catalytic properties. However, their tendency to aggregate during formation undermines their stability, posing challenges for large-scale production. This study presents a one-step biosynthesis method of AgNPs using Houttuynia plant (Houttugniae herba) extract, where the plant biomolecules act as both reducer and stabilizer. The bioreduction kinetics were meticulously optimized using the one-factor-at-a-time (OFAT) approach, establishing the ideal synthesis conditions as follows: 1.0 mM AgNO3, 0.1 ml Houttuynia plant extract, heated at 80 °C for 45 minutes, with the medium at pH 9. Morphological characterization revealed the formation of spherical, well separated, and highly crystalline (d-spacing = 0.237 nm) AgNPs with an average particle size of 7.756 ± 2.372 nm. The synthesized AgNPs exhibited remarkable catalytic activity in reducing azo dyes, achieving degradation rates of approximately 98% for both acid red 1 (AR1) and mordant blue 9 (MB9) within 4 and 20 minutes, respectively. This eco-friendly and cost-effective method can be an excellent alternative for treating industrial effluents.

Hybrid calcium magnesium ferrite: A multifaceted nanomaterial for energy, sensing, and environmental applications

The current work employs the urea aided conventional sol–gel procedure to synthesize hybrid calcium magnesium ferrite (CMF – CaO/MgFe2O4) nanomaterial. To verify the existence of synthesized nanomaterials, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and UV diffuse reflectance spectroscopy (UV-DRS) are employed. The observed crystalline size of the nanomaterials is 44.14 nm. The estimated band gap is 2.36 eV, which is validated using UV-DRS equipment. The investigation's findings are supported by actual applications in electrochemical studies and photocatalytic degradation of synthesized hybrid CMF. It was also investigated how to modify the working electrode's surface to detect heavy metals, drugs, and biomolecules like uric acid, paracetamol, creatinine, cadmium and mercury. Electrochemical research was done to determine the ideal properties of CMF as an electrode material for use in batteries, supercapacitors, and sensors applications. Furthermore, synthesized hybrid CMF exhibits excellent photocatalytic activity, employed as a catalyst to decolorize acid red 88(AR-88) dyes at room temperature under visible light illumination, with a 120-minute photocatalytic activity with the degradation efficiencyof 60.40 %.

Organically modified montmorillonite as an environmental adsorbent of pollutants: Formaldehyde from urea-formaldehyde resin and Acid Red 183 dye from the aqueous solution

In this research, a composite based on montmorillonite (K10) modified with HDTMABr was used. The characterization of the pure K10, NaMMT and OMMT was performed using XRD, FTIR-ATR, SEM, TG, DTG, and DTA. Ion exchange capacity (CEC) and specific surface area (SSA) were also determined. The sulfite method was used to determine free and liberated formaldehyde (FA) from synthesized urea-formaldehyde/montmorillonite (UF/MMT) composites. This research aims to demonstrate the bifunctionality of OMMT and that it can be used both for the capture of FA from the synthesized cross-linked UF resin and for the adsorption of the anionic dye Acid Red 183 (AR183) from aquatic medium. SEM analysis showed that there are changes in the morphology of the OMMT and the formation of a hollow network, which affects the absorption capacity of the clay. The calculated values of free and liberated FA in the UF/OMMT composites are drastically reduced and amount to 0.12% and 0.96%, respectively, compared to the composites with K10 (0.6% and 2.04%, respectively). Also, very promising results were obtained of the adsorption of AR183 dyes from the aquatic medium using OMMT. The results show that OMMT (0.5 g OMMT/50 cm3 aqueous dye solution, c=20 mgdm−3) managed to remove 85.95% of AR183 dye (pH dye=7). The adsorption mechanism of AR183 on OMMT follows the Freundlich isotherm and proceeds according to the pseudo-first-order kinetic model. Overall, the findings of this work indicate that the use of the obtained OMMT has great potential in removing pollutants from two totally different systems.

Decolourization and degradation of azo-dyes by the NaClO/NiOOH catalytic oxidation system

ABSTRACT Azo dyes are highly toxic and difficult to degrade. Decolourization of acid red 18 (AR18) and reactive yellow 4 (RY4) dye wastewater by the NaClO/NiO x (OH) y catalytic system was studied. The influence of reaction conditions was investigated. Their degradation mechanism was discussed by free radical scavenging experiment, and the degradation pathways were proposed. The continuous flow experiment was conducted. The results showed that the catalytic oxidation has a good decolourization effect on AR18, but it is not ideal for RY4. The continuous flow experiment of 3000 min showed that the decolourization effect was stable. The concentration of Ni2+ in the effluent from the reactor was always up to the standard, and the catalyst was not deactivated. The decolourization mechanism of the two dyes is different: AR18 is mainly decolourized by atomic oxygen/singlet oxygen, while RY4 is mainly decolourized by NaClO. The catalysts were characterized by XPS and XRD. The surface contains the largest proportion of chemisorbed oxygen. With the extension of the catalyst service time, chemisorbed oxygen decreased slightly and was converted into atomic oxygen/singlet oxygen, which was consumed in the decolourization process. Compared with the used catalysts, the β-NiOOH crystallinity of the fresh catalyst is better. The quantitative structure–property relationship analysis based on the decolourization data shows that there is a good linear correlation between the decolourization rate of azo dyes and their molecular structure descriptors. The inorganic–organic properties balance (IOB) value was determined as the main molecular descriptor that affected the decolourization of dyes.

A comparative study of green and chemical approaches for photocatalytic activity of novel hybrid bismuth magnesium ferrites (BiMgFe2O4) nanoparticles for Acid Red-88 dye degradation

Uncontrolled release of several dangerous pollutants had negatively impacted the environment causing water pollution and retarded plant growth. Recently, nanoferrites utilized as photocatalyst to eliminate water pollutants. The benefitsofhybrid photocatalyst have significantly improved separating and charge transfer capabilities. In the present investigation novel bismuth magnesium ferrites (BMF - BiMgFe2O4) are synthesized via conventional solution combustion method using green and chemical approach. The particles are confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM),Energy disperse X-ray diffraction analysis (EDX), UV-DRS (UV diffuse reflectance spectroscopy). The observed crystalline size for the nanoparticles synthesized by green and chemical approach is 25.15 nm and 18.55 nm respectively. Analyzed band gap observed is 2.89 eV and 1.98 eV for green and chemical approach that are confirmed by employing UV-DRS technique. The outcomes obtained from studies are verified with capable applications in photocatalytic degradation. The application of BiMgFe2O4 as catalyst for decolourisation of acid red 88 (AR-88) dyes under visible irradiation at room temperature exhibits superior photocatalytic activity for BiMgFe2O4 is 74.22 % and 85.27 % using green and chemical approach for 120 min respectively. It's significant that the environmental impact of the whole procedure has been assessed with regard to the development of green gramplants utilizing the treated wastewater exhibiting effective plant growth. The overall feasibility of the research presented here provides the opportunity to apply chemically synthesized BMF acts as superior photocatalyst for pollutants from particles in practical applications related to wastewater treatment and other applications in daily life. Using degradedwater yields productive plant growth.

Modeling of the adsorption of acidic dyes by chitosan using both kinetic and thermodynamic comparisons

Two chitosans from two different sources crab shell chitosan (CC) and deep-pink shrimp chitosan (CP) were used in a batch system to test the adsorption of two acidic dyes, Acid Red 183 (AR183) and Acid Red 114 (AR114), and the results were compared with those of acid-washed powdered activated carbon (PAC). The effects of temperature, contact time, and starting dye concentration on the removal of AR114 and AR183 dye were investigated in a series of batch adsorption studies. The two chitosans had the highest dye absorption capacity for each AR dye-adsorbent system at 45 °C. The capacity of each adsorbent to adsorb increased when the initial dye concentration was increased up to 500 mg L−1. Chitosan CP was the most efficient of the three adsorbents, with maximum AR114 and AR183 absorption of 440 and 447 mg g−1, respectively, at 45 °C. At all concentrations and temperatures examined, the pseudo-second-order kinetic model accurately represented the adsorption kinetics, and the rate constants of second-order adsorption (k2) at these temperatures were calculated, respectively. The thermodynamic study revealed that the adsorption of dyes on chitosans was feasible, spontaneous, and endothermic process, and the adsorption of the dyes on each adsorbent may be chemical in nature. Results indicated that the synthesized chitosans were shown to be a promising adsorbent for the removal of dyes from aqueous solutions.

Synthesis of SmMnO3/Sm2O3 nanocomposites as efficient photocatalysts for organic dye degradation by sol gel pechini method

In this research, we present SmMnO3/Sm2O3 nanocomposites as a novel ferromagnetic photocatalyst, synthesized through a straightforward sol-gel Pechini method utilizing citric acid and oxalic acid as fuels. Achieving the desired morphology involved varying the fuel type and calcination temperature. Comprehensive physicochemical characterizations were conducted using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller BET. With a band gap of 2.1 eV in the visible range, the SmMnO3/Sm2O3 nanocomposites exhibit promising optical properties. The photocatalytic prowess of these nanocomposites was systematically assessed against Malachite Green and Acid Red, with optimization of key parameters such as light source, pollutant concentration, and catalyst dosage. Notably, the peak photocatalytic activity was observed for Malachite Green, achieving an impressive 96% degradation under visible light within 120 min. The elucidation of the photocatalytic mechanism employed scavengers, revealing the pivotal role of OH• in the photodegradation process. Recycling experiments demonstrated consistent and acceptable results over five cycles, affirming the recyclability and durability of the SmMnO3/Sm2O3 nanocomposites. This study introduces a novel ferromagnetic photocatalyst with notable photocatalytic efficiency, emphasizing its potential applications in environmental remediation. The novelty of this work lies in the introduction of a new nanocomposite for photocatalysis in visible light, achieving high efficiency within a short time frame of 120 min.

Visible-light photocatalytic degradation of two textile dyes by recyclable ZnO-Perlite: kinetic models and cost analysis

ABSTRACT Zinc oxide (ZnO), as an n-type semiconductor photocatalyst, is often selected due to its excellent photocatalytic performance and is supported on commercial expanded perlite (EP) to enhance interfacial charge separation efficiency under visible LED light. The structure and photocatalytic properties of the synthesised photocatalyst via the co-precipitation route were studied through XRD, FT-IR, SEM, EDX and pHpzc analyses. The photocatalytic response was evaluated by studying the degradation of two toxic and refractory azo dyes, reactive black 5 (RB5) and acid red 14 (AR14). Azo dyes (20 mg L−1) were completely degraded in the studied system, which occurred at pH 7 and 3, with catalyst amounts of 2 and 1 g L−1, and in the presence of H2O2 at 2 and 10 mM under LED light (15 W) within 2 h for RB5 and AR14, respectively. The degradation of RB5 and AR14 followed first-order kinetics with Kobs values of 0.0218 and 0.0169 min−1 and R2 values of 0.9271 and 0.8325, respectively. The assessment of energy consumption (EEO) and total operation cost (OC) confirmed that the supported ZnO offered the lowest power and cost requirements to transform selected pollutants into the acquired effluent, with values of 20.65 and 25.13 kWh m−3 and 3.11 and 3.205 USD kg−1 for RB5 and AR14, respectively, compared to using only VIS/ZnO, VIS/EP and VIS. Furthermore, the catalyst exhibited stability without the need for any additional chemicals for up to 10 h (5 reuse cycles). Additionally, the presence of major anions (sulphate, chloride and alkalinity) reduced the degradation efficiency in a real water matrix (1.74 and 1.47 times for RB5 and AR14, respectively) compared to that in distilled water.

A new methodology for the prediction of optimal conditions for dyes' electrochemical removal; Application of copula function, machine learning, deep learning, and multi-objective optimization

In the present study, a new methodology has been introduced for predicting the simultaneous removal optimal conditions of Acid red 33 (AR33), Reactive orange 7 (RO7), Acid yellow 3 (AY3), and Malachite green (MG) dyes. Since industrial wastewater contains a variety of dyes, simultaneous prediction of their removal efficiency is a practical issue. The goal of this research was to address challenges associated with modeling this type of removal process. In the first part of this methodology, the c-vine copula function was used to generate synthetic data since the use of most modeling methods requires a large number of data, and studying different experimental conditions is time- and cost-consuming. Besides, Artificial neural network, Adaptive neuro-fuzzy inference system, Least-square support vector machine, and Long-short term memory algorithms were applied for modeling the dyes' removal efficiency using experimental and synthetic data. Utilizing synthetic data significantly improved the accuracy of modeling. For the purpose of finding the optimal amount of dyes' removal efficiency simultaneously, the removal efficiency of each dye is defined as an objective function. This leads to a problem requiring multi-objective optimization. Hence, the Multi-Objective Adaptive Guided Differential Evolution was employed for multi-objective optimization of dyes' removal efficiency. The optimization process was carried out based on the four objective functions including AR33, RO7, AY3, and MG dyes' removal efficiency. The results indicated a direct relationship between dyes' removal efficiency on the Pareto front as well as a highly oscillating and nonlinear relationship with decision variables (pH, NaCl concentration, current, and Time) under optimal conditions. Finally, the average results of Technique for Order of Preference by Similarity to Ideal Solution and VIekriterijumsko KOmpromisno Rangiranje were utilized to select the best optimal conditions from the Pareto front. With pH, NaCl, Time, and current inputs at 6.60, 0.67 (g/L), 96.93 (min), 0.01 (A) (optimal conditions), the best removal efficiencies of 98.88, 37.02, 91.19, and 98.33 (%) were obtained for AR33, RO7, AY3, and MG dyes, respectively. The introduced method demonstrated excellent promise for predicting optimal conditions for dyes' removal efficiency as well as for making wastewater treatment systems easier to design.

Cd-CeO2@C: Synthesis via consumption of Cd2+ and organic pollutants and removal of organic pollutants

In this study, a Cd-CeO2@C photocatalyst was produced via the calcination of a precursor (Cd-Ce(OH)4@AR14) obtained by co-precipitation of Ce(NO3)3·6H2O, Cd(NO3)2·4H2O and acid red 14 (AR14). The structure, composition, morphology, and optical properties of the synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectrum (FT-IR), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopy (XPS) and Photoluminescence Spectroscopy (PL). The photocatalytic activity of the synthetized materials was evaluated by performing the degradation of AR14. The results showed that the band gap of CeO2 could be effectively reduced by Cd-doping, and that carbon bonds could decrease the recombination rate of photogenerated electrons and holes, resulting in enhancing the photocatalytic efficiency of the synthesized materials compared with that of pure CeO2. Hydroxyl groups play an important role in the photocatalysis because the adsorption of AR14 over Cd-CeO2@C is greatly affected by the content of hydroxyl groups. Moreover, effect of oxygen vacancies on the photocatalytic efficiency was investigated and the results showed that oxygen vacancies could improve the photocatalytic efficiency of the resulted samples.

New Methyl Methacrylate Derived Adsorbents - Synthesis, Characterization and Adsorptive Removal of Toxic Organic Compounds.

This study aimed to synthesize polymeric adsorbents by suspension polymerization using methyl methacrylate (MMA) with different crosslinking monomers. Divinylbenzene (DVB) and aliphatic monomers: ethylene glycol dimethacrylate (EGDMA) or N,N'-methylenebisacrylamide (NN) containing additional amide groups were used. The possibility of using the prepared copolymers (MMA-NN, MMA-EGDMA, MMA-DVB) as adsorbents for the removal of toxic compounds such as dyes (C.I. Acid Red 18 (AR18), C.I. Acid Green 16 (AG16), C.I. Acid Violet 1 (AV1), C.I. Basic Yellow 2 (BY2), C.I. Basic Blue 3 (BB3) and C.I. Basic Red 46 (BR46)) and phenol (PhOH) from dye baths and effluents was evaluated. Preferential adsorption of basic-type dyes compared to acid-type dyes or phenol was observed by the polymers. Adsorbent based on MMA-EGDMA exhibited the highest capacity for investigated dyes and phenol. The pseudo-second order kinetic model as well as the intraparticle diffusion model can find application in predicting sorption kinetics. Based on the equilibrium sorption data fitted to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich model, uptake of BB3, AV1 and PhOH is rather physisorption than chemisorption. The regeneration yield of MMA-EGDMA does not exceed 60 % using 1 M HCl, 1 M NaCl, and 1 M NaOH in 50 %v/v methanol.