Percentage Of Dye Removal Research Articles

A novelO‐carboxymethyl chitosan‐based hydrogel of an outstanding adsorption performance for removal of cationic Basic Red 12 dye from its aqueous solution

AbstractO‐Carboxymethyl chitosan (O‐CM‐chitosan) hydrogel, prepared in our previous study, was investigated in this work for the first time as adsorbent for Basic Red 12 (BR 12) dye. With rising temperature (from 25°C to 55°C) and decreasing solution pH (from 9 to 4), a lowering in both adsorption capacity (from 703.47 to 400.79 mg/g) and removal efficiency (from 70.34% to 40.08%) was observed. A significant increase in adsorption capacity (from 342.75 to 621.39 mg/g) was observed with increasing initial dye concentration (from 400 to 1000 mg/L), while a decrease in removal efficiency (from 85.69% to 62.14%) was noted. Pseudo‐second‐order model fitted well the adsorption. Isotherms of adsorption conform to Langmuir model with a maximum monolayer adsorption capacity of 625 mg/g. The value of∆H°(−23.99 kJ/mol) implied exothermic nature of adsorption process. Values of ΔG°indicated that the adsorption was spontaneous at low temperature and nonspontaneous at high temperature. The value of activation energy is equal to 13.071 kJ/mol. The dye removal percentage from the hydrogel was 88% at the first cycle. Thus,O‐CM‐chitosan hydrogel has promising and effective properties for removing BR 12 and similar dyes from aqueous media.

Effective removal of dyes along with binary mixture via optimized emulsion liquid membrane

This study aimed to evaluate the removal of harmful cationic dyes, namely brilliant green and safranin-O, from wastewater produced by industries like textile, pigment, and pharmaceutical, which pose a direct threat to human health and the environment. An emulsion liquid membrane (ELM) was employed to eliminate these dyes, and the efficiency of the membrane was measured by calculating the percentage of dye removal and the breaking rate. The study successfully optimized the ELM process to remove the dyes within an hour and demonstrated the membrane’s stability for more than 60 minutes. The results showed that the prepared ELM could remove 100% of the brilliant green dye and 99.6% of the safranin-O dye. A maximum breaking rate of 0.029% was obtained for brilliant green and 0.008% for safranin-O. Furthermore, the study resulted in the maximum removal of 99.36% and 99.15% for brilliant green and safranin-O dyes, respectively, in the binary system. When both dyes were present simultaneously, the maximum breakage observed was only 0.16%. The experimental results were analyzed using a UV–visible spectrophotometer and an optical microscope, and the optimization and analysis of the variance of means and signal-to-noise (S/N) ratio were carried out using the Taguchi L16 orthogonal array.

Introducing machine learning model to response surface methodology for biosorption of methylene blue dye using Triticum aestivum biomass

A major environmental problem on a global scale is the contamination of water by dyes, particularly from industrial effluents. Consequently, wastewater treatment from various industrial wastes is crucial to restoring environmental quality. Dye is an important class of organic pollutants that are considered harmful to both people and aquatic habitats. The textile industry has become more interested in agricultural-based adsorbents, particularly in adsorption. The biosorption of Methylene blue (MB) dye from aqueous solutions by the wheat straw (T. aestivum) biomass was evaluated in this study. The biosorption process parameters were optimized using the response surface methodology (RSM) approach with a face-centred central composite design (FCCCD). Using a 10 mg/L concentration MB dye, 1.5 mg of biomass, an initial pH of 6, and a contact time of 60 min at 25 °C, the maximum MB dye removal percentages (96%) were obtained. Artificial neural network (ANN) modelling techniques are also employed to stimulate and validate the process, and their efficacy and ability to predict the reaction (removal efficiency) were assessed. The existence of functional groups, which are important binding sites involved in the process of MB biosorption, was demonstrated using Fourier Transform Infrared Spectroscopy (FTIR) spectra. Moreover, a scan electron microscope (SEM) revealed that fresh, shiny particles had been absorbed on the surface of the T. aestivum following the biosorption procedure. The bio-removal of MB from wastewater effluents has been demonstrated to be possible using T. aestivum biomass as a biosorbent. It is also a promising biosorbent that is economical, environmentally friendly, biodegradable, and cost-effective.

Utilization of Cellulose Symbiotic Culture of Bacteria and Yeast (SCOBY) with Sweet Tea Media as Methylene Blue and Brilliant Green Biosorbent Material

The cellulose from Symbiotic Culture of Bacteria and Yeast (SCOBY) can be used as a biosorbent for dye adsorption, such as Methylene Blue and Brilliant Green. This study used sweet tea with a 6% of sugar concentration and 14 days of fermentation time to synthesize biosorbent material from SCOBY. The results from this synthesis are then characterized using FTIR, SEM, and BET. From the result of characterization, it was found that SCOBY has pores formed from cellulose. The results of the average pore size are 1.5976nm with a pore volume of 0.229cc/g, while the specific surface area is 143.244m2/g. The material that has been characterized is used to absorb the dye using Methylene Blue and Brilliant Green. The mass variation of absorbent is used in this study with variations of 0.5gr, 1gr, and 1.5gr and carried out to absorb the dye for three hours. The highest percentage of dye removal after three hours reached up to 100%, which proved that SCOBY is effective for dye removal.

Efficient fabrication of pH-modified graphene nano-adsorbent for effective determination and monitoring of multi-class pesticide residues in market-fresh vegetables by GC-MS

Toxic pesticide residues in edible vegetables cause major health risks for consumers, hence quantifying them is essential. However, simultaneous and trace level determination of xenobiotic residues of various classes in complex food matrices is still a challenging analytical task. In this experiment, reduced graphene oxide (RGO-B), a carbon nano-structure with stunning adsorbent properties and ultrahigh surface area (pore size ∼6 Å) was efficiently (≥96%) synthesized via pH-controlled reduction process and characterized by ultraviolet-visible (UV–VIS) spectrophotometer, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Fourier Transform Infrared (FTIR). Adsorption efficiency of different pH-regulated RGOs was studied in terms of dye (Malachite Green) removal percentage. Two-dimensional carbon (sp2) RGO was used as a dispersive solid-phase extraction adsorbent in a modified QuEChERS method in combination (4:1) with primary secondary amine (PSA) to extract 28 multi-class pesticides (OC, OP, SP) from chilli, cabbage, tomato, and cucumber. The experimental results established the best extraction ability and adsorption capacity of RGO over traditional and high-cost adsorbents. Moreover, the introduction of graphene has helped improve the percent recovery (75.36–118.32%) with acceptable (<12.8%) relative standard deviation (RSD) at limits of quantification (LOQs) (S/N = 10:1) levels of 0.01–0.1 mgL−1. Gas chromatography-mass spectrometry (GC-MS)-based multi-pesticide analytical method was successfully validated as per SANTE/12682/2019 guidelines for monitoring 144 market-fresh vegetables in West Bengal, India. The analysis results indicated that eight (8) samples (5.55%) were contaminated with toxicants 5–10 times higher than the European Union Maximum Residue Limits (EU-MRLs). Matrix removal abilities and cost analysis proved that graphene has significant prospects as an expectant non-conventional adsorbent for low-cost (53.3% cheaper) pesticide residue analysis.

Optimization, kinetics and thermodynamics for the removal of crystal violet dye using synthesized FeNPs from Carica papaya leaves extract

Human eyes have long been captivated by color. The addition of color to textiles is what gives them their appealing appearance. Dyes are crucial to the textile industry because they not only give textiles, paper, and leather color, but they are also extremely harmful when untreated dye industry waste water is thrown into nearby water bodies. Methods of color removal become quite important in this situation. The ferrous nanoparticles recently developed from Carica papaya leaves have significant adsorptive capabilities. The current research focuses on employing ferrous nanoparticles made from Carica papaya leaves to remove the crystal violet pigment from fabrics. By using SEM and FTIR analysis, nanoparticle characterization is carried out. While keeping other parameters constant, the effects of changing the contact time, adsorbent dosage, PH of the aqueous dye solution, initial dye concentration, and temperature are examined. Adsorption isotherm experiments are conducted using the Freundlich, and Langmuir models. It is shown that the Freundlich isotherm is best suited for this analysis, with a maximum capacity of 120 mg/g and an adsorption coefficient of kf = 51.40 and R2 = 0.992. Plotting pH against dye removal percentage revealed that considerable adsorption occurred at a pH value of 7. It gives good agreement with pseudo second-order kinetics for cystal violet removal. Thermodynamic parameters, including changes in free energy, enthalpy, and entropy were studied.

Synthesis of bagasse nanocellulose-filled composite polyurethane xerogel for the efficient adsorption of Rhodamine-B dye from aqueous solution: investigation of adsorption parameters.

In this study, polyurethane (PU)-based xerogels were synthesized by using the biobased polyol derived from chaulmoogra seed oil. These polyol was used for the preparation of PU xerogels using methylene diphenyl diisocyanate hard segment and polyethylene glycol (PEG6000) as soft segment with 1,4-diazabicyclo[2, 2, 2]octane as catalyst. Tetrahydrofuran, acetonitrile and dimethyl sulfoxide were used as the solvents. Nanocellulose (5wt %) prepared from bagasse were added as filler, and the obtained composite xerogels were evaluated for chemical stability. The prepared samples were also characterized by using SEM and FTIR. Waste sugarcane bagasse nanocellulose proved as a cheap reinforcer in the xerogel synthesis and for the adsorption of Rhodamine-B dye from the aqueous solution. The factors that affect the adsorption process have been studied including the quantity of the adsorbent (0.02-0.06g), pH (6-12), temperature (30-50) and time (30-90). Central composite design for four variables and three levels with response surface methodology has been used to get second-order polynomial equation for the percentage dye removal. RSM was confirmed by the measurement of analysis of variance. Increase in the pH and quantity of the adsorbent was found to increase the sorption capacities of the xerogel (NC-PUXe) towards rhodamine B, maximum adsorption.

Removal of organic and inorganic effluents from wastewater by using degradation and adsorption properties of transition metal-doped nickel ferrite.

Removal of water pollutants (methylene blue dye and heavy metals) was achieved by zinc/manganese-doped nickel ferrites (Ni1 - xMxFe2O4, where x = 0.00, 0.025, 0.10). Degradation of dye was achieved under natural solar light illumination. Degradation studies of dye were conducted under different parameters such as contact time-80min, dye's concentration-5mg/L, pH-7, and dosage of ferrites-15mg. The adsorption of dye was studied using non-linear kinetics models (pseudo-first-order and pseudo-second-order) and isotherm models (Langmuir and Freundlich). The adsorption of dye followed pseudo-first-order kinetics (R2 = 0.99377) than second-order kinetics (R2 = 0.98063) and Langmuir isotherm model (R2 = 0.96095) than Freundlich model (R2 = 0.95962) with maximum adsorption efficiency of 29.62mg/g. Doping of nickel ferrites caused an increase in the removal percentage of methylene blue dye (80 to 90%) and inorganic effluents (75 to 95% for lead and 47 to 82% for cadmium). In addition to this, band gap energy (2.43 to 3.26eV) (UV-Vis spectroscopy), pore radius (65.2 to 74.8 A°), and specific surface area (16.45 to 27.95 m2/g) (BET analysis) were also increased. Generally, the results of the study revealed that synthesized nanoparticles can act as potential candidate for the removal of effluents from wastewater under optimum parameters along with recyclability, reusability, and separation under the influence of a magnetic field.

Isotherm and kinetic studies of acid yellow 11 dye adsorption from wastewater using Pisum Sativum peels microporous activated carbon

In this study, Pea Peels-Activated Carbon (PPAC), a novel biochar, was created from leftover pea peels (Pisum sativum) by wet impregnation with ZnCl2 and subsequent heating to 600, 700, and 800 °C in a CO2 atmosphere. Investigated how the newly acquired biochar affected the capacity to extract the AY11 dye from the aqueous solution. Through the use of FTIR, XRD, SEM, BJH, BET, DSC, EDX, and TGA studies, the prepared PPAC was identified. It was found that a pH of 2 is optimum for the AY11 dye elimination. The highest removal percentage of AY11 dye was 99.10% using a beginning AY11 dye concentration of 100 mg/L and a 1.0 g/L dose of PPAC. The highest adsorption capacity (Qm) of the PPAC was 515.46 mg/g. Freundlich (FIM), Halsey (HIM), Langmuir (LIM), Tempkin (TIM), and Gineralize (GIM) isotherm models were useful in examining the adsorption results. A variety of error functions, including the average percent errors (APE), root mean square errors (RMS), Marquardt's percent standard deviation (MPSD), hybrid error function (HYBRID), Chi-square error (X2) and a sum of absolute errors (EABS) equations, were also applied to test the isotherm models data. The PPAC experimental data were best suited by the HIM and FIM isotherm models. Elovich (EM), Pseudo-first-order (PFOM), Intraparticle diffusion (IPDM), Pseudo-second-order (PSOM), and Film diffusion (FDM) models were applied to study the kinetic adsorption results. The PSOM had a strong correlation coefficient (R2 > 0.99), and it was principally responsible for controlling the adsorption rate. Anions are typically absorbed during the adsorption mechanism of AY11 dye by PPAC owing to attractive electrostatic forces created with an increase in positively charged areas at acidic pH levels. The regenerated PPAC was used in six successive adsorption/desorption cycles. This study's outcomes show that PPAC successfully removes the AY11 dye from the aqueous solution; as a result, PPAC can be used repeatedly without experiencing considerable loss in effectiveness.

Photocatalytic activity of Zn-Cu-S alloy for the removal of dye pollutant: Synthesis, characterization, optimization and DFT insights

This study synthesized Zn-Cu-S alloy powder using mechanical alloying to eliminate EBT dye pollution. Multiple techniques were used to characterize the alloyed materials. The formation of intermetallic phase, Cu5Zn8, was realized, after 35 h milling process. After light irradiation, both the adsorption and photocatalytic activity of the alloyed material were observed. The EBT removal process was optimized by varying pH, lamp power, and alloy dosage (g/L) parameters. Response surface plots were employed to investigate the removal percentage of dye. Isotherm and kinetic models were utilized to investigate EBT uptake. The maximum adsorption capacity (qmL) of 222.8 mg/g was significantly higher than previously reported values. The maximum removal rate was determined to be approximately 87%. DFT calculations estimated the optimized geometry of the ground state of a semiconductor alloy by frontier molecular orbitals and explained the origin of the alloy photocatalyst's electronic transitions.

Adsorption Study of Methylene Blue from Aqueous Solutions onto Bituminous Coal Based Activated Carbon

Adsorption of methylene blue (MB) on activated carbon developed from bituminous coal (Barapukuria Coal) by physical activation has been investigated. The impacts of numerous variables, including absorbent concentration, contact time, initial dye concentration, and temperature, were explored. The equilibrium adsorption data analysis was performed using the Freundlich, Langmuir, and Temkin adsorption models. The Langmuir isotherm was considered to be the most appropriate. The Langmuir adsorption capacities (Qo) in 298, 303, 308, 313, 323, and 333K are 80.65, 84.75, 87.72, 90.09, 91.74, and 92.59 mg g-1, respectively. The dye removal percentages at 60 °C decline from 99.84% to 79.38% when dye concentrations are increased from 100 to 350 mgL-1. Increases in adsorbent concentration result in enhanced methylene blue adsorption because of increases in surface area and the number of active centers. From the thermodynamic studies, negative adsorption free energy (ΔG°) implies spontaneous adsorption, while positive enthalpy (ΔH°) reflects endothermic adsorption. Journal of Engineering Science 13(2), 2022, 91-100

Chitosan/tannic acid/ZnFe layered double hydroxides and mixed metal oxides nanocomposite for the adsorption of reactive dyes

The fabrication of the environmentally friendly nanocomposite beads containing chitosan (Chi), tannic acid (TA), layered double hydroxides (LDH), and mixed metal oxides (MMO) was carried out. The synthesized ZnFe LDH, ZnFe MMO, and fabricated beads (Chi/TA@LDH and Chi/TA@MMO) were characterized using FESEM, XRD, FTIR, BET, and TGA. The beads were applied for the simultaneous removal of three reactive dyes. The design of experiments was based on a full factorial design considering the effect of six independent variables (initial dye concentrations, adsorbent dosage, time, and adsorbent type) on the dye removal percentages (DR%) of each dye. Regression equations were extracted from the experimental results (R2 > 0.983) and high obtained F-values from analysis of variance (ANOVA) proved the significance of the models. The maximum adsorption capacity of the dyes onto, Chi/TA@LDH and Chi/TA@MMO beads were between 257 and 483 mg g−1. The spontaneity and exothermic nature of the adsorption processes were determined by thermodynamic studies (−8 < ΔH° (KJ mol−1) < −1, −22 < ΔG° (KJ mol−1) < −18). Reusability studies showed that the fabricated beads could be regenerated and applied several times.

Facile synthesis of biopolymer decorated magnetic coreshells for enhanced removal of xenobiotic azo dyes through experimental modelling.

Since contamination of xenobiotics in water bodies has become a global issue, their removal is gaining ample attention lately. In the present study, nZVI was synthesized using chitosan for removal of two such xenobitic dyes, Bromocresol green and (BCG) and Brilliant blue (BB), which have high prevalence in freshwater and wastewater matrices. nZVI functionalization prevents nanoparticle aggregation and oxidation, enhancing the removal of BCG and BB with an efficiency of 84.96% and 86.21%, respectively. XRD, FESEM, EDS, and FTIR have been employed to investigate the morphology, elemental composition, and functional groups of chitosan-modified nanoscale-zerovalent iron (CS@nZVI). RSM-CCD model was utilized to assess the combined effect of five independent variables and determine the best condition for maximum dye removal. The interactions between adsorbent dose (2-4 mg), pH (4-8), time (20-40 min), temperature (35-65 0C), and initial dye concentration (40-60 mg/L) was modeled to study the response, i.e., dye removal percentage. The reaction fitted well with Langmuir isotherm and pseudo-first-order kinetics, with a maximum qe value of 426.97 and 452.4mg/g for BCG and BB, respectively. Thermodynamic analysis revealed the adsorption was spontaneous, and endothermic in nature. Moreover, CS@nZVI could be used up to five cycles of dye removal with remarkable potential for real water samples.

Equilibrium Studies for Dye Adsorption onto Red Clay

In this study, it was aimed to remove malachite green, a cationic dye, from aqueous solutions by the adsorption method under various experimental conditions by using red clay. Red clay was used because it is abundant in nature and easily accessible in our region. In addition, it has been preferred as an adsorbent because it is used economically without any pre-treatment. The effects of initial malachite green concentration, temperature, adsorbent amount, and contact time on the adsorption process were evaluated. To examine the percent dye removal effect of the initial malachite green concentration, five different amounts of 25-150 ppm were examined. In order to examine the effect of the amount of red clay on the percentage of dye removal, five different amounts, in the range of 0.5-2 grams, were examined. In order to find the optimum time for the adsorption process, studies were carried out at four different values, 30-120 minutes. In the adsorption process of red clay and malachite green, experiments were carried out at three different degrees as 298, 313 and 333 K. After reaching equilibrium in the adsorption process, the data obtained were analyzed and studies were carried out by applying them to isotherm models. The results obtained from the adsorption process were compared with Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. It has been determined that the experimental studies are more compatible with the Dubinin-Radushkevich model. According to the results, it is incompatible with the Langmuir model. Accordingly, it can be said that the adsorption takes place in a multilayer and heterogeneous form.

Efficient Dye Removal from Real Textile Wastewater Using Orange Seed Powder as Suitable Bio-Adsorbent and Membrane Technology

Textile wastewater is widely produced and its discharge without treatment contributes to environmental pollution. The adsorption process is a suitable and eco-friendly process due to its low initial cost, no formation of degradation products, operation simplicity, insensitivity to toxic compounds, and the possibility of removal from greatly diluted solutions. Orange seed (OS) powder, from which lipids were removed by hexane extraction, was evaluated as a bio-adsorbent to remove dyes from real textile wastewater. In the screening step, pH was a more significant variable (p-value &lt; 0.05) than bio-adsorbent dosage, temperature, stirring speed, and process time. Moreover, under optimized conditions (pH = 2.6, 0.58 g/L from OS powder and 26 °C), more than 95% of the dye was removed from real textile wastewater. Additionally, the dye removal percentage was reduced by only 4% when the volume of textile wastewater was increased from 0.05 L to 10 L. Then, 96% turbidity was removed using a 3 µm tubular ceramic membrane at a pH of 11. Furthermore, the permeate flux through the membrane was kept constant for longer than was observed at low pH (&lt;11). Therefore, the proposed process is an interesting option, due to the fact that orange seeds are currently not valorized and, combined with the membrane process, this could prove a suitable option for the treatment of real textile wastewater.

Predicting the degradation of reactive red-147 dye in textile wastewater using response surface methodology technique

The human health, aquatic life and environment are greatly affected by the existence of industrial waste in water especially the textile dye. Advanced oxidation processes (AOPs) are considered more effective in removing the toxic pollutants from the waste water in comparison with traditional biological, physical and chemical processes. The later have the limitations of high energy requirement, cost and production of secondary pollutants during the treatment process. AOPs received significant attentions to eliminate the recalcitrant dyes from the aqueous environment owing to the production of highly reactive hydroxyl radicals produced via light irradiation. This study focused on using the response surface methodology (RSM) to evaluate its prediction and optimizing capability in the deployment of AOPs in removing obstinate pollutants from industrial waste water. The data were obtained from the existing literature related to the decomposition of textile dye [reactive red (RR-147)] under UV illumination in the presence of hydrogen peroxide (H2O2) and the photocatalyst, i.e., titanium dioxide (TiO2). The influence of different process parameters like dye concentration, pH of the solution, H2O2 contents, UV illumination time and photocatalyst were studied on dye removal percentage. The input parameters for efficient removal process were optimized using developed RSM models. Four different scenarios were created to see the effect of selected parameters while keeping the remaining process parameters maintained at fixed values. The predicted results depicted that the dye removal percentage was mainly affected by the tested variables, as well as their synergistic effects which was observed compliant with the experimental results. Performance analysis of the developed RSM models showed a high coefficient of determination value significantly higher than R2 = 0.99), thus guaranteed a satisfactory prediction equations of the second-order regression models. The observed results showed that for 50 ppm dye concentration, H2O2 0.9 ml, pH 3.4, TiO2 0.6 g and UV irradiation time 60 min, the maximum breakdown of 92% was observed. The degradation of the RR-147 dye is tested to be more effectively accomplished by the UV/H2O2/TiO2 system.

Simultaneous bioremediation of Disperse orange-2RL Azo dye and fatty acids production by Scenedesmus obliquus cultured under mixotrophic and heterotrophic conditions

Several types of green photosynthetic microalgae can grow through the process of heterotrophic growth in the dark with the help of a carbon source instead of the usual light energy. Heterotrophic growth overcomes important limitations in the production of valuable products from microalgae, such as the reliance on light, which complicates the process, raises costs, and lowers the yield of potentially useful products. The present study was conducted to explore the potential growth of green microalga Scenedesmus obliquus under mixotrophic and heterotrophic conditions utilizing Disperse orange 2RL Azo dye as a carbon source to produce a high lipid content and the maximum dye removal percentage. After 7 days of algal growth with dye under mixotrophic and heterotrophic conditions with varying pH levels (5, 7, 9, and 11), KNO3 concentrations (1, 1.5, 2, and 3 g/L), and dye concentrations (20, 40, and 60 ppm); dye removal percentage, algal dry weight, and lipid content were determined. The results showed that the highest decolorization of Disperse orange 2RL Azo dye (98.14%) was attained by S. obliquus in heterotrophic medium supplemented with glucose at the optimal pH 11 when the nitrogen concentration was 1 g/L and the dye concentration was 20 ppm. FT-IR spectroscopy of the dye revealed differences in peaks position and intensity before and after algal treatment. S. obliquus has a high concentration of oleic acid, which is enhanced when it is grown with Disperse orange 2RL Azo dye, making it ideal for production of high-quality biodiesel. In general, and in the vast majority of instances, heterotrophic cultivation is substantially less expensive, easier to set up, and requires less maintenance than mixotrophic cultivation. Heterotrophic cultivation allows for large-scale applications such as separate or mixed wastewater treatment along with biofuel production.

Visible light-driven photocatalytic degradation of Rhodamine B dye onto TiO2/rGO nanocomposites

In the current study, a series of reduced graphene oxide coated titanium dioxide nanocomposites (TiO 2 /rGO) were fabricated via a simple hydrothermal synthetic route using graphite flakes and titanium (IV) oxysulfate - sulfuric acid hydrate as precursors for rGO and TiO 2 synthesis, respectively. The TiO 2 /rGO nanocomposites were fabricated with various weight ratios of rGO (5, 10, and 15%) and their photocatalytic activity against Rhodamine B (RhB) dye removal was investigated. The composition, optical activity, morphology, and porosity of the obtained nanomaterials were determined using different techniques, including X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), UV-Vis diffuse reflectance spectroscopy (DRS) and Raman spectroscopy. Hence the XRD results showed that the TiO 2 /rGO nanocomposites were successfully fabricated. The TEM images exhibited the efficient distribution of TiO 2 NPs on the rGO nanosheets. The significant structural changes in TiO 2 /rGO nanocomposites were reflected in the Raman spectra, indicating nanocomposite hybridization. The optical bandgap of the as-synthesized nanomaterials was slightly shifted from 3.14 eV (bare TiO 2 ) to 2.75 eV (TiO 2 /rGO 15%). Based on the photocatalytic degradation results, the best removal percentage of RhB dye was approached by TiO 2 /rGO (5%) at optimum conditions ([RhB]= 15 ppm, pH 9, catalyst dose= 1.2 g/L, and irradiation time= 120 min). The highly efficient TiO 2 /rGO (5%) nanocomposite showed enhanced photocatalytic behavior for the degradation of RhB dye, with a maximum removal percentage of (∼94.55%). Various reactive oxygen species (ROS) scavengers were employed to study the mechanism of photocatalytic degradation of RhB dye. The TiO 2 /rGO (5%) nanocomposite showed good cycling stability for five cycles. • The TiO 2 /rGO nanocomposites were fabricated with various weight ratios of rGO (5, 10, and 15%) • The morphological images exhibited the efficient distribution of TiO 2 NPs on the rGO nanosheets. • The UV-Vis spectra showed that the bandgap values of the nanocomposites decreased with increasing the concentration of the reduced graphene oxide. • The highly efficient TiO 2 /rGO (5%) nanocomposite showed enhanced photocatalytic behavior for the degradation of RhB dye, with a maximum removal percentage of (∼94.55%).

Application of RSM for Bioremoval of Methylene Blue Dye from Industrial Wastewater onto Sustainable Walnut Shell (Juglans regia) Biomass

Dyes are a significant group of organic contaminants known to negatively affect both humans and aquatic environments. In the textile industry, interest in agricultural-based adsorbents has increased, particularly around adsorption. In this study, methylene blue was eliminated from an aqueous solution using a walnut (Juglans regia) shell. These materials are widely available and inexpensive, and its cost can be a major factor in wastewater treatment batch experiments. Response surface methodology (RSM) is based on a face-centred central composite design, used to identify the independent variable. With the use of RSM, the biomass of J. regia shells was assessed for its capacity to absorb dyes from aqueous solutions, including methylene blue. Maximum methylene blue dye removal percentages (97.70%) were obtained with a 30 mg/L concentration of methylene blue dye, 1.5 gm of biomass, an initial pH of 6, and a contact duration of 60 min at 25 °C. Additionally, particles were absorbed onto the J. regia shell’s surface throughout the biosorption process, according to scan electron microscopy. Functional groups were discovered in the Fourier Transform Infrared Spectroscopy spectra, which are crucial for binding during the biosorption of methylene blue. It has been demonstrated that J. regia shell biomass performs well as a biosorbent in the removal of methylene blue from wastewater effluents. It is also a promising, biodegradable, environmentally friendly, economical, and cost-effective biosorbent.

RAW OYSTER SHELL SORBENT FOR REMOVAL OF CONGO RED DYE

Raw oyster shell was successfully prepared as an adsorbent for removing Congo Red (C.R.) dye in an aqueous solution using an adsorption technique. The various parameters influencing this adsorption process, such as adsorbent size, adsorbent dosage, initial dye concentration, contact time, pH, agitation speed and agitation time, were studied. The maximum percentage of dye removal of 96.3% was obtained at the optimised conditions of 75 μm of adsorbent size, 1.0 g of adsorbent dosage, 30 mg/L of initial dye concentration, pH 3, 110 rpm of agitation speed and 75 min of agitation time. The experimental data were analysed using two adsorption models, the Langmuir isotherm model and the Freundlich isotherm model. The adsorption data obtained well fitted for the Langmuir isotherm model indicate a monolayer adsorption reaction involved during the adsorption process. The result shows that raw oyster shells could be employed as a suitable alternative adsorbent to remove Congo red dye in an aqueous solution.Keywords: raw oyster shell, adsorption, congo red