Removal Of Reactive Black Research Articles

Interfacial Adsorption Interactions of Dyes and Chitosan/Activated Carbon@Curcumin Derivatives in Single-Component and Binary Solutions.

The remediation of wastewaters contaminated with dyes (discharged mainly from industry) is very important for preserving environmental quality and human health. In this study, a new composite chitosan (CS)-based adsorbent combined with activated carbon (AC) and curcumin (Cur) (abbreviated hereafter as CS/AC@Cur) in three different ratios (12.5%, 25%, and 50%) was synthesized for the removal of anionic [reactive black 5 (RB5)] and cationic [methylene blue (MB)] dyes in single-component or binary systems. The synthesized materials were completely characterized through Fourier transform infrared spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller analysis, and X-ray diffraction. Specifically, a decrease in the surface area of CS/AC@ was observed with the addition of curcumin, from 163 to 18 m2/g, for all CS/AC@Cur derivatives. In terms of the adsorption results, the optimal derivative for the removal of both RB5 and MB was found to be CS/AC@Cur50%, providing 93% removal at pH 2.0 ± 0.1 for RB5 and 54% removal at the optimum pH of 9.0 ± 0.1 due to electrostatic attractions. The Elovich and pseudo-second-order kinetic model, with a correlation coefficient R2 of >0.98, better tailored the results, indicating that adsorption was controlled by chemisorption. In addition, the Sips (Langmuir-Freundlich) isotherm model fitted better to the results, with calculated capacities of 338 and 307 mg/g for RB5 and MB, respectively. The thermodynamic analysis showed a spontaneous and endothermic procedure, with chemisorption as the main mechanism. Reuse experiments showed that the removal efficiency was retained at high levels, while stability studies revealed that the adsorbent retains its structural integrity, even at extreme pH values. Finally, the adsorption of RB5 and MB in a mixed solution was investigated, providing a competitive effect between the anionic and cationic dyes.

Efficient One-Pot Hydrothermal Synthesis of TiO2 Nanostructures for Reactive Black 5 Dye Removal: Experimental and Theoretical Insights

Water scarcity continues to be a major worldwide issue. Therefore, from a scientific perspective, it is crucial to develop a highly effective, affordable, environmentally friendly, and readily available metal-based adsorbent for wastewater treatment. This study focuses on synthesizing a mesoporous/nanosphere TiO2 using a free-template and eco-friendly method to effectively remove Reactive Black 5 (RB5) dye. The synthesis of TiO2 nanospheres was achieved through the use of titanium isopropoxide at 100 °C for 12 h in a one-pot hydrothermal process, successfully regulating their morphology and crystallite size. The TiO2 nanospheres were extensively characterized using multiple techniques, such as XRD, FE-SEM, zeta potential, FT-IR, HR-TEM, and BET surface area tools. Adsorption experiments revealed a notable capacity of 109 mg g−1 for RB5 dye, following pseudo-second-order kinetic behavior. The equilibrium data conformed well to the Langmuir isotherm model, indicating monolayer adsorption. Thermodynamic evaluations confirmed that the process was spontaneous, endothermic, and governed by physisorption. Calculations using density functional theory (DFT) provided additional support for the experimental findings, demonstrating strong binding interactions between the dye and the TiO2 (101) surface. The TiO2 nano-adsorbent showed excellent reusability and maintained high adsorption efficiency over multiple cycles, making it a promising candidate for wastewater treatment.

Macadamia nut residue-derived biochar: An eco-friendly solution for β-naphthol and Reactive Black-5 removal

The generation of liquid waste containing dyes and complex organic compounds is a problem in the textile industries. In this work, we evaluated the use of macadamia nut residue as a precursor of a biochar for the treatment of these effluents through the adsorption process. The macadamia nut endocarp undergoes a sequential treatment involving pyrolysis at 600 °C followed by physical activation with CO2 and H2O vapor at 700 °C. Characterization of the resulting macadamia nut residue-derived biochar (MB) is accomplished through various techniques, including X-ray diffractometry (XRD), thermogravimetric analysis (TGA), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), nitrogen physisorption analysis and the pH at the zero charge point (pHZCP). Performance studies reveal that pH exerts minimal influence on the adsorption phenomenon. The Elovich kinetic model effectively describes the adsorption kinetics for both β-naphthol and Reactive Black 5 (RB5), with adjusted coefficients of determination (R2adj) of 0.99 and 0.94, respectively. Further analysis using the intraparticle diffusion model demonstrates that β-naphthol adsorption kinetics involve multiple mechanisms, while RB5 adsorption is predominantly governed by intraparticle diffusion. Equilibrium adsorption data for both adsorbates fit well with the Sips isothermal model, yielding maximum adsorption capacities of qmax β-naphthol = 15.16 mg∙g−1 and qmax RB5 = 3.08 mg∙g−1 at 55 °C. The adsorption process for both compounds is spontaneous and endothermic, based on the enthalpy values, it can be inferred that the β-naphthol adsorption is governed by weak van der Waals forces, indicating physisorption. As for RB5, the enthalpy value suggests that the phenomenon occurs due to electrostatic interactions between the molecule and the surface groups with higher energy involved. This study highlights the potential of macadamia nut residue biomass as a precursor for biochar, demonstrating its favorable attributes for application as an effective adsorbent material in the removal of organic compounds such as β-naphthol and RB5 from wastewater streams within the textile industry.

Superior decomposition of xenobiotic RB5 dye using three-dimensional electrochemical treatment: Response surface methodology modelling, artificial intelligence, and machine learning-based optimisation approaches

The highly efficient electrochemical treatment technology for dye-polluted wastewater is one of hot research topics in industrial wastewater treatment. This study reported a three-dimensional electrochemical treatment process integrating graphite intercalation compound (GIC) adsorption, direct anodic oxidation, and ·OH oxidation for decolourising Reactive Black 5 (RB5) from aqueous solutions. The electrochemical process was optimised using the novel progressive central composite design–response surface methodology (CCD–NPRSM), hybrid artificial neural network–extreme gradient boosting (hybrid ANN–XGBoost), and classification and regression trees (CART). CCD–NPRSM and hybrid ANN–XGBoost were employed to minimise errors in evaluating the electrochemical process involving three manipulated operational parameters: current density, electrolysis (treatment) time, and initial dye concentration. The optimised decolourisation efficiencies were 99.30%, 96.63%, and 99.14% for CCD–NPRSM, hybrid ANN–XGBoost, and CART, respectively, compared to the 98.46% RB5 removal rate observed experimentally under optimum conditions: approximately 20 mA/cm2 of current density, 20 min of electrolysis time, and 65 mg/L of RB5. The optimised mineralisation efficiencies ranged between 89% and 92% for different models based on total organic carbon (TOC). Experimental studies confirmed that the predictive efficiency of optimised models ranked in the descending order of hybrid ANN–XGBoost, CCD–NPRSM, and CART. Model validation using analysis of variance (ANOVA) revealed that hybrid ANN–XGBoost had a mean squared error (MSE) and a coefficient of determination (R2) of approximately 0.014 and 0.998, respectively, for the RB5 removal efficiency, outperforming CCD–NPRSM with MSE and R2 of 0.518 and 0.998, respectively. Overall, the hybrid ANN–XGBoost approach is the most feasible technique for assessing the electrochemical treatment efficiency in RB5 dye wastewater decolourisation.

Accessible Eco-Friendly Method for Wastewater Removal of the Azo Dye Reactive Black 5 by Reusable Protonated Chitosan-Deep Eutectic Solvent Beads.

A novel approach to enhance the utilization of low-cost and sustainable chitosan for wastewater remediation is presented in this investigation. The study centers around the modification of chitosan beads using a deep eutectic solvent composed of choline chloride and urea at a molar ratio of 1:2, followed by treatment with sulfuric acid using an impregnation accessible methodology. The effectiveness of the modified chitosan beads as an adsorbent was evaluated by studying the removal of the azo dye Reactive Black 5 (RB5) from aqueous solutions. Remarkably, the modified chitosan beads demonstrated a substantial increase in adsorption efficiency, achieving excellent removal of RB5 within the concentration range of 25-250 mg/L, ultimately leading to complete elimination. Several key parameters influencing the adsorption process were investigated, including initial RB5 concentration, adsorbent dosage, contact time, temperature, and pH. Quantitative analysis revealed that the pseudo-second-order kinetic model provided the best fit for the experimental data at lower dye concentrations, while the intraparticle diffusion model showed superior performance at higher RB5 concentration ranges (150-250 mg/L). The experimental data were successfully explained by the Langmuir isotherm model, and the maximum adsorption capacities were found to be 116.78 mg/g at 298 K and 379.90 mg/g at 318 K. Desorption studies demonstrated that approximately 41.7% of the dye could be successfully desorbed in a single cycle. Moreover, the regenerated adsorbent exhibited highly efficient RB5 removal (80.0-87.6%) for at least five consecutive uses. The outstanding adsorption properties of the modified chitosan beads can be attributed to the increased porosity, surface area, and swelling behavior resulting from the acidic treatment in combination with the DES modification. These findings establish the modified chitosan beads as a stable, versatile, and reusable eco-friendly adsorbent with high potential for industrial implementation.

Removal of Reactive Black 5 by UV-C assisted peroxydisulfate process: Effect of parameters, kinetic study, and phytotoxicity assessment

ABSTRACT Photochemical removal of Reactive Black 5 (RB5) was investigated by the UV-C assisted peroxydisulfate (UV-C/PDS) process. Parameters affecting the removal of RB5 were examined. Activation of PDS by UV-C light significantly improved the removal efficiency compared to direct photolysis or PDS alone. The removal of RB5 by UV-C/PDS process fitted well with the pseudo first-order kinetic model under all tested conditions. Almost complete removal of RB5 was achieved at the end of 120 min within the pH range of 3–7, whereas 90.7 and 89.4% removal efficiency values were observed at pH = 9 and 11, respectively. An increase in PDS dosage in the range of 0.25–1 mM led to a rise in removal from 48.5 to 97.3% after 120 min, and a complete removal was observed with a dosage higher than 2 mM. Pseudo firstorder rate constant (kobs) increased linearly with PDS dosage from 0.0058 to 0.0518 min−1 in the 0.25 mM − 2.3 mM concentration range. The removal efficiency decreased with an increase in the initial concentration of RB5 from 20 to 50 mg L−1 and an exponential correlation was observed between kobs and initial concentration of RB5. Scavenging experiments conducted using t-butyl alcohol and ethyl alcohol implied that both sulphate and hydroxyl radicals were involved in the removal of RB5. Adding HCO3 − decreased the removal of RB5 within the range of 1–30 mM. The presence of CI− showed a negative impact on the removal at low concentrations (1–15 mM) and NO3 − slightly inhibited the removal of RB5. With corresponding stoichiometric PDS dosage, almost a complete mineralisation was achieved for RB5 solution and simulated dyebath effluent after 720 min of reaction time. EE/O values were determined to be 91.0, 76.8, and 41.1 kWh m−3 order−1 for UV-C/H2O2, UV-C/PMS, and UV-C/PDS processes, respectively. The phytotoxicity tests indicated that the intermediates could be more toxic than the parent compound.

Removal of Reactive Black 5 from simulated textile effluents by an electrocoagulation process: optimization by response surface methodology

Abstract The textile industry creates one-fifth of the world's industrial water pollution, thus, the electrocoagulation (EC) process was proposed and investigated as an alternative eco-friendly treatment for water reuse. This study aimed to assess the removal efficiency of the Reactive Black 5 (RB5) from synthetic textile effluent by EC. Key operating parameters on EC process efficiency were optimized using response surface methodology (RSM). The main independent variables studied were the current density, EC time, concentration, and pH while the RB5 dye removal was studied as the dependent variable. The range of the studied parameters affecting the EC process ranged from 10 to 60 mA/cm2, 5 to 30 min, 4 to 10 pH and 10 to 40 ppm for current density, EC time, pH, and RB5 concentration, respectively. The optimal operating parameters turned out to be 5.5 pH, 47.5 mA/cm2, 23.75 min, 17.5 ppm, and the predicted RB5 dye removal was 96.33%. The experimental dye removal with optimum operating conditions was in good agreement with the predicted removal efficiency. Therefore, the experiment results revealed the high potential of the EC process to effectively treat textile industry effluents and the RB5 dye removal was successfully optimized using Response Surface Methodology (RSM).

Impact of catalyst, chelating agent and light irradiation on electro-Fenton performance under not optimal conditions.

Electro-Fenton is a promising game-changer for distributed wastewater treatments for the removal of recalcitrant compounds that it is possible to find in industrial effluent and looking for a water reuse approach. This electrochemical advanced oxidation process (EAOPs) is able to provide fast removal of organic compounds, like dyes, due to the in-situ H2O2 production and its reaction with Fe2+ to form hydroxyl radicals. The literature clearly reports that this reaction reaches its optimum in acid conditions (pH = 3) and low catalyst concentrations [Fe2+<0.5 mM]. This paper wants to investigate the effects of the shifting from optimal conditions on the removal of reactive black 5 (RB5), treating solutions which contain a higher amount of catalyst and a less acid pH. Textile effluents usually contain also other metals able to act as catalyst for Fenton reaction, like copper. Here its activity has been investigated as well as the possible synergistic effect with Fe2+. The results confirm that copper can enhance RB5 removal, especially in those conditions critical for ferrous cation. In the second part, possible process modifications to overcome the issues introduced by unfavourable operating conditions (pH > 3 and Fe2+ > 0.5 mM) are considered, such as the usage of a chelating agent (EDTA) and the application of a light source. The results show the positive impact of these two system modifications highlighting the possibility to enlarge the application window of electro-Fenton systems.

Composite Activated Carbon Modified with AlCl3 for the Effective Removal of Reactive Black 5 Dye from Wastewaters

Many industries use huge amounts of synthetic dyes which may release into the wastewater in dyeing processes causing serious damage to aquatic life as they are recalcitrant, nonbiodegradable, stable to oxidizing agents, and toxic. Adsorption on activated carbon has been found to be a very efficient treatment method. In this work, a new adsorbent material composed of activated carbon and aluminum chloride (AC-Al) was prepared for the removal of a commercial anionic and anthraquinonic reactive dye, i.e., Reactive Black 5 (RB5) under various experimental conditions. Several parameters, such as the adsorbent’s dosage, initial RB5 concentration, pH, and contact time, were studied in order to determine the feasibility of AC-Al. According to the results, it was found that there was an increase in RB5 removal as the adsorbent’s dosage increased, especially, in pH 2 ± 0.1, where the removal rate increased, and reaching 100% by 1.0 g/L of AC-Al. Freundlich isotherm and pseudo-second-order kinetic models adequately fit the experimental data, indicating that favorable and heterogeneous adsorption occurred, closer to chemisorption. According to thermodynamics, it was found that the adsorption procedure was endothermic in nature (∆H0 = 62.621 kJ/mol) and spontaneous (∆G0 &lt; 0), and according to the positive value of ∆S0 0.0293 (kJ/mol∙K), there is an increase in random interaction between solid and liquid interfaces. Finally, the AC-Al adsorbent was successfully regenerated and reused for four cycles.

A facile and eco-friendly hydrothermal synthesis of magnetic graphite nanocomposite and its application in water purification

In this research, a magnetic graphite nanocomposite (MGN) was synthesized by an easy and efficient hydrothermal process from magnetite nanoparticles (NP-SYN) and graphite nanoplatelets (GR). MGN was characterized by X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), N2 adsorption and desorption analysis, X-ray photoelectron spectroscopy (XPS), and point of zero charge (pHpzc) analysis. The thickness for GR was found to be 34 nm, and crystallite sizes for NP-SYN and MGN were around 37 and 48 nm, respectively. MGN shows the presence of GR and iron oxides from the NP-SYN. The surface areas for GR, NP-SYN, and MGN were around 191, 18, and 121 m2 g−1, respectively. The pHpzc results for GR, NP-SYN, and MGN ranged from 6 to 7. The NP-SYN, GR, and MGN were used as adsorbents to remove reactive black 5 (RB5) dye from aqueous solution. This method’s batch removal process was designed based on a central composite rotational design (CCRD). The efficiency of RB5 uptake for all adsorbents was obtained from the quadratic model under optimum conditions of prominent parameters by desirability function (mass of adsorbent 6.6 mg, dye concentration 85.1 mg L−1, and agitation speed 902.7 rpm). Under these conditions, the adsorption capacity values were 10.16, 92.08, and 28.83 mg g−1 for NP-SYN, GR, and MGN, respectively, indicating that the adsorption power of the nanoparticle increased after incorporating GR, maintaining its magnetic properties. Therefore, the proposed adsorbents in this work have potential for removing RB5 dye from water solutions.

Sodium hydroxide pre-treated Aspergillus flavus biomass for the removal of reactive black 5 and its toxicity evaluation

The present study was focused on the removal of Reactive Black 5 (RB5) from aqueous solution using pre treated Aspergillus flavus as a biosorbent. Pre-treatment of fungal biomass with 0.1 M sodium hydroxide facilitated the removal of dye effectively when compared to untreated fungal biomass. Optimum biosorption conditions for RB5 removal was determined as a function of dye concentration (50–400 mg/L), biosorbent concentration (100–500 mg/L), incubation time (1–7hrs), pH (3–8) and temperature (20–50 °C). At the optimum conditions, the maximum removal efficiency of RB5 achieved by NaOH pretreated A. flavus was 91%. The dye removal was studied kinetically and it obeys the pseudo-second order model and the experimental equilibrium data well fitted the Langmuir isotherm indicating monolayer adsorption of dye molecules on the biosorbent. The thermodynamic parameters such as a change in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were calculated and negative values of ΔG suggested that the dye removal process was spontaneous at all temperatures. Furthermore, the values of ΔH revealed that the adsorption process was endothermic. Recovery of RB5 from the fungal biomass was effective using 0.1 M Na2CO3 as an eluent. The interaction of adsorbate with biosorbent was analyzed using UV–Vis and FT-IR spectroscopy, SEM and XRD analyses. Phytotoxicity and microbial toxicity studies revealed the non-toxic nature of the treated dye solution. Hence, the fungal biomass pretreated with NaOH was efficient in decolorizing RB5 as well as composite raw industrial effluent generated from dyeing industries.

Electrically supported mediator Co(II)-activated peroxydisulfate synergistic process for organic contaminants elimination

Among homogeneous catalysts, cobalt ions exhibit ultra-high persulfate activation performance. In this work, an electrically supported medium Co(II) activated peroxydisulfate synergistic process was established to eliminate organic contaminants in water. The synergistic catalytic effect was verified by comparing the oxidative degradation performance and reaction rate constant of different coupling systems. The decolorization ability of E-Co(II)-PDS on reactive black 5 (RB5) was explored, and the results showed that the removal rate of RB5 can reach 93.21% under the optimized conditions of current density of 5.71 mA/cm2, initial pH of 4, Co(II) concentration of 0.2 mM and PDS concentration of 5 mM. The effect of water matrix on the removal of RB5 was studied, and it was found that HCO3− and humic acid significantly inhibited the degradation of RB5, while Cl− and H2PO4− could effectively promote it at a certain concentration. Notably, the degradation of RB5 in E-Co(II)-PDS system achieved lower energy consumption, with an energy consumption per unit volume (EE/O) value of 0.4304 kWh·m−3. EPR test, quenching experiments and contribution rate analysis showed that the oxidation active species in E-Co(II)-PDS process were Co(III), sulfate radicals and hydroxyl radicals, and their oxidation contribution rates were 15.72%, 12.69% and 53.25%, respectively. Finally, the decomposition process of RB5 was proposed by the mass spectrometry results. The electric current promotes cobalt ion cycling and PDS activation through electron transfer, and induces Co(II) to promote the activation of PDS, which is the main mechanism of E-Co(II)-PDS system to achieve the robust degradation ability of RB5.

Removal of Reactive Black 5 Dye by Banana Peel Biochar and Evaluation of Its Phytotoxicity on Tomato

Removal of Reactive Black 5 (RB5) dye from an aqueous solution was studied by its adsorption on banana peel biochars (BPBs). The factors affecting RB5 dye adsorption such as pH, exposure time, RB5 dye concentration, adsorbent dose, particle size and temperature were investigated. Maximum 97% RB5 dye removal was obtained at pH 3 with 75 mg/L adsorbate concentration by banana peel biochars. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) were used to characterize the adsorbent material. The data of equilibrium were analyzed by Langmuir and Freundlich isotherm models. The experimental results were best reflected by Langmuir isotherm with maximum 7.58 mg/g adsorption capacity. Kinetic parameters were explored and pseudo-second order was found suitable which reflected that rate of adsorption was controlled by physisorption. Thermodynamic variables exhibited that the sorption process was feasible, spontaneous, and exothermic in nature. Banana peel biochar showed excellent regeneration efficiency up to five cycles of successive adsorption-desorption. Banana peel biochar maintained &gt;38% sorption potential of RB5 dye even after five cycles of adsorption-desorption. The phytotoxic study exhibited the benign nature of BPB-treated RB5 dye on tomato seeds.

Reactive Black 5 Removal with Ozone on Lab-scale and Modeling

ABSTRACT This study investigates modeling the ozone removal of the Reactive Black 5 (RB5) dye from an aqueous solution using a combination of nonlinear regression (NLR), multiple linear regression (MLR), and Intrinsically multiple linear regression (IMLR) models. Lack of use and evaluation of the IMLR method in estimating RB5 removal by ozonation attract attention. Experimental data were used in the R Core Team software for the development of the models and estimate of RB5 removal by ozone. The effects of variables such as pH, contact time, initial dye concentration, and applied ozone dosage on RB5 removal by ozone were investigated. Maximum 92% RB5 removal rate was obtained at pH 8, 60 min contact time, 100 mg/L initial RB5 concentration, and applied ozone dosage of 66 mgO3/L. Under these conditions, the amount of specific ozone consumption was 0.678 gO3/gRB5. In order to compare the models, coefficient of determination (R2) and mean square error (MSE) were utilized as reliability and precision criteria. The best R2 and MSE values for the IMLR model were calculated as 0.8940 and 0.098, respectively. To determine the appropriate model and coefficients, analysis of variance (ANOVA), and t-test were used, respectively. Whether the model is within the confidence interval was determined by the significance value (p) and the variation was <5% for the IMLR model. As a result, it was found that the best method for modeling RB5 removal from aqueous solution by ozone was the IMLR method. Detailed explanations on results were introduced in the study.

Reactive black 5 dyeing wastewater treatment by electrolysis-Ce (IV) electrochemical oxidation technology: Influencing factors, synergy and enhancement mechanisms

Reactive black 5 (RB5) dyeing wastewater poses a serious threat to the water environment safety and biological life health. It is of great significance to use an enhanced type of electrolysis-Ce(IV) electrochemical oxidation technology for the efficient treatment of RB5 dyeing wastewater. In this study, the effects of single-factor experimental conditions such as cerium (Ce) ion concentration, pH, current value, different catalytic systems on RB5 degradation effect in electrolysis-Ce(IV) system were investigated. The experimental results showed a significant synergistic and enhanced effect between the direct electrochemical oxidation process and Ce(IV) treatment alone, and their combination (electrolysis-Ce(IV)) could significantly enhance the RB5 treatment with a removal efficiency up to 91.6%. In addition, the background ions HCO3−, Cl−, PO43− and HA had an inhibitory effect on the electrolysis-Ce(IV) system, whereas Cl− had an enhanced effect. Meanwhile, reasonable energy consumption for the removal of RB5 was achieved in electrolysis-Ce(IV) with a maximum electrical energy per order (EE/O) value of 4.89 kWh·m−3. There are three possible reaction ways for RB5 degradation, and the generated organic intermediates with low molecular weight and biotoxicity, which facilitates further mineralization of the product and biodegradation. In the electrolysis-Ce(IV) system, the driving force for the oxidative removal of RB5 were direct electrochemical oxidation function, Ce(IV) ions and hydroxyl radicals, where direct electrochemical oxidation function and Ce(IV) ions were the key and dominant effect for RB5 removal. Compared with the direct electrochemical oxidation system alone, the Ce(IV) in the electrolysis-Ce(IV) system contributes much to enhancing and improving the RB5 degradation and is the key and core active degradation substance.

Peroxymonosulfate enhanced photocatalytic degradation of Reactive Black 5 by ZnO-GAC: Key influencing factors, stability and response surface approach

• ZnO-GAC was used in the photocatalysis of RB5 with the presence of PMS. • Cooperative effects of UV, ZnO surf e − and GAC mediated by PMS were observed. • The mineralization and degradation pathway of RB5 were investigated. • Effect of reaction parameters was evaluated by response surface methodology. Zinc oxide supported on granular activated carbon (ZnO-GAC) was synthesized for the photocatalysis of Reactive Black 5 (RB5) with the presence of peroxymonosulfate (PMS). RB5 removal was improved with increasing temperature and dosage of PMS or catalyst, but declined with increasing pH and RB5 concentration. The reaction followed first-order kinetic model and the activation energy was determined to be 16.15 kJ mol −1 . After 60 min treatment, 43.6% of TOC was removed and further extending the reaction time to 90 min resulted in 51.9% TOC removal. The evolution profile of ammonium and nitrate ions was monitored during the treatment, and the organic degradation products of RB5 oxidation were identified by LC-MS analysis with a plausible degradation pathway being proposed. Quenching experiments indicated that electron hole (h + ) and reactive radicals (e.g. HO • /SO 4 •− ) were mainly responsible for RB5 removal in the UV/ZnO-GAC/PMS system. The catalyst reuse experiment shows that ZnO-GAC had no obvious deactivation after four cycles, which implied the reusability and stability of the prepared catalyst. Response surface methodology (RSM) with Box-Behnken design (BBD) was used to evaluate the effect of operating conditions, including PMS concentration, reaction temperature and initial pH on the removal rate of RB5. The result of adequacy check indicated the proposed RSM model was reliable and accurate to analyze the operating parameters of the UV/ZnO-GAC/PMS system.

Evaluation of the sequential coupling of a bacterial treatment with a physicochemical process for the remediation of wastewater containing Cr and organic pollutants

A restoration strategy was developed for the treatment of two artificial liquid systems (Minimal Medium, MM, and Water Carbon Nitrogen, WCN) contaminated with Cr(VI), lindane (γ-HCH), phenanthrene (Phe), and reactive black 5 (RB5), through the use of an actinobacteria consortium, coupled with a physicochemical treatment using a column filled with nano-scale zero valent iron particles immobilized on dried Macrocystis pyrifera algae biomass. The Sequential Treatment A (STA: physicochemical followed by biological method) removed the three organic compounds with different effectiveness; however, it was very ineffective for Cr(VI) removal. The Sequential Treatment B (STB: biological followed by the physicochemical method) removed the four compounds with variable efficiencies. The removal of γ-HCH, Phe, and RB5 in both effluents did not present significant differences, regardless of the sequential treatment used. The highest removal of Cr(VI) and total Cr was observed in MM and WCN, respectively. Ecotoxicity tests (L. sativa) of the effluents treated with both methodological couplings demonstrated that the toxicity of WCN only decreased at the end of STA, while that of MM decreased at all stages of both sequential treatments. Therefore, MM would be more appropriate to perform both treatments.

Photodegradation of Reactive Black 5 and raw textile wastewater by heterogeneous photo-Fenton reaction using amino-Fe3O4-functionalized graphene oxide as nanocatalyst

Amino-Fe3O4-functionalized graphene oxide (AmGO) was synthesized and had its photocatalytic properties investigated in the degradation of Reactive Black 5 (RB5) dye and raw textile wastewater (RTW). Graphene oxide was synthesized via modified Hummers method and functionalized with diethylenetriamine and FeCl3 to obtain the AmGO. A 23 factorial design was carried out to optimize the best working conditions; the most statistically significant effect was the AmGO dosage, followed by the initial pH. Kinetics studies were performed and Chan & Chu model the most representative of the experimental data with R2 ≥ 0.95. Experiments of adsorption kinetics were carried out and evidenced that the adsorption of RB5 by AmGO was slower than photodegradation, in which the equilibrium state was reached after 300 min. Moreover, pseudo-second-order model showed the best fit with adsorptive capacity at equilibrium of 53.06 mg∙g−1. AmGO employment in the photodegradation of RB5 exhibited 75 % removal efficiency in less than 2h for the initial dye concentration of 100 mg∙L−1. AmGO also showed satisfactory recycling capacity, since it maintained RB5 removal up to 97 % after 6 cycles. RTW photodegradation experiments exhibited removal efficiencies of 53.25 % for apparent color, and 64.55 % for turbidity. Phytotoxicity assays using cucumber seeds showed low toxicity of the samples after photodegradation, which indicated that toxic compounds were fully mineralized.

Discolouration of contaminated water with textile dye through a combined coagulation/flocculation and membrane separation process with different natural coagulants extracted from Moringa oleifera Lam. seeds

AbstractThe removal of reactive black 5 (RB5) dye present in aqueous solution was studied by applying individual coagulation/flocculation (CF) and microfiltration (MF) processes as well as the combination of both processes (CF‐MF). In the CF process, three natural coagulants produced from Moringa oleifera Lam. seeds (MOS) were used: saline extract (ES) and the purified protein fractions of albumin (ALB) and globulin (GLO). In the MF process, a commercial polyethersulfone (PES) membrane was used. It was noticed that without the combination of both processes, the obtained RB5 removal was only 20.38% for ALB, 52.38% for GLO, and 12.50% for ES. However, when the CF process was combined with a microfiltration process, it was possible to achieve a higher textile dye removal, due to the formation of aggregates in the CF process larger than the pores of the microfiltration membrane. Especially with the ALB coagulant, the combined CF‐MF process achieved a removal greater than 95%. The results demonstrate the potential use of the purified proteins fractions of Moringa oleifera Lam. coagulant in combination with microfiltration process for water treatment.

Pineapple leaves based activated carbon for efficient removal of reactive black 5 in aqueous

Adsorption by activated carbon (AC) has been recognized and widely used in the dye wastewater treatment. Due to the effectiveness of AC, researchers have started to focus on developing AC from renewable sources, which is abundant and cheap. This research study the preparation of AC from pineapple leaves (PL) (termed as PLAC), a superior adsorbent for the removal of reactive black 5 (RB5). The PLAC has been synthesized via chemical activation where a chemical agent of sodium hydroxide (NaOH) was used for activation. A full factorial design was employed to investigate the significance of several parameters, such as impregnation ratio and reaction time between NaOH and PL, as well as carbonization effects of temperature and time on the removal of RB5. The results revealed that the adsorption of RB5 onto PLAC was highly dependent on the PLAC synthesis condition. The parameter of impregnation ratio has a significant influence on PLAC adsorption performance (with 98% contribution), as proven in ANOVA analysis. The desirability analysis indicated impregnated precursor with NaOH at 2.18 ratio for 2 h and carbonized at 464 °C for 60 min is the ideal preparation condition.