Solution Initial Dye Concentration Research Articles

Degradation of synthetic reactive Pyrazole-133 dye by using an advanced oxidation process assisted by gamma radiations

This study investigated the degradation of the reactive dye RP-133 in aqueous solution using various hydrogen peroxide concentrations and gamma radiation doses (1–20 kGy). The solution's initial dye concentration and pH were optimized for the most effective degradation efficiency. The dye was treated with H2O2 and gamma radiation separately. At an acidic pH, an absorbed dose of 20 kGy, and 0.9 mL of H2O2, a 95% decomposition rate was achieved. FTIR analysis revealed differences in the functional groups of treated and untreated dye. Intermediates formed during degradation were identified using GC-MS. Hemolytic and Ames tests assessed the cytotoxicity and mutagenicity of the dye. Gamma radiation treatment significantly reduced both mutagenicity and cytotoxicity. Cytotoxicity decreased from 15.1% to 7.6%, and mutagenicity of bacterial strains TA98 and TA100 was reduced by 81.3% and 82.3%, respectively. The formation of low-molecular-weight organic acids further oxidized to carbon dioxide and water, indicating the efficiency of the advanced oxidation process. Combining gamma radiation with H2O2 effectively degraded RP-133, reducing its cytotoxicity and mutagenicity.

Magnetic zinc oxide/silica microbeads for the photocatalytic degradation of azo dyes

Photocatalysis is a promising technique for the complete degradation of azo dyes that are present in wastewater. In this work, a new photocatalyst in the form of ZnO/Fe3O4/SiO2 hybrid microbeads was fabricated for the photocatalytic degradation of methylene blue. The microbeads were synthesised through self-assembly and subsequent agglomeration of nanoparticles within an aqueous phase of a water-in-oil emulsion template. Photocatalytic degradation experiments were conducted through exposure of a methylene blue solution to UV light. The hybrid microbeads performed better than ZnO powder at the same initial dye and ZnO concentration because of higher adsorption and degradation. The initial concentration of dye solution and catalyst dosage have a significant impact on the degradation. Higher degradation is seen with lower initial dye concentration and higher catalyst dosage. The presence of magnetic nanoparticles within the beads allows for their full recovery and reuse for degradation experiments. Complete degradation of dye was achieved using the new ZnO/Fe3O4/SiO2 microbeads.

Synthesis of oxidized carboxymethyl cellulose-chitosan and its composite films with SiC and SiC@SiO2 nanoparticles for methylene blue dye adsorption

The cationic methylene blue (MB) dye sequestration was studied by using oxidized carboxymethyl cellulose-chitosan (OCMC-CS) and its composite films with silicon carbide (OCMC-CS-SiC), and silica-coated SiC nanoparticles (OCMC-CS-SiC@SiO2). The resulting composite films were characterized through various analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS). The dye adsorption properties of the synthesized composite films were comprehensively investigated in batch experiments and the effect of parameters such as contact time, initial dye concentration, catalyst dosages, temperature, and pH were systematically evaluated. The results indicated that the film's adsorption efficiency was increased by increasing the contact time, catalyst amount, and temperature, and with a decreased initial concentration of dye solution. The adsorption efficiency was highest at neutral pH. The experimental results demonstrated that OCMC-CS films have high dye adsorption capabilities as compared to OCMC-CS-SiC, and OCMC-CS-SiC@SiO2. Additionally, the desorption investigation suggested that the adsorbents are successfully regenerated. Overall, this study contributes to the development of sustainable and effective adsorbent materials for dye removal applications. These films present a promising and environmentally friendly approach to mitigate dye pollution from aqueous systems.

Adsorption of Basic Yellow 28 and Basic Blue 3 Dyes from Aqueous Solution Using Silybum Marianum Stem as a Low-Cost Adsorbent.

In the present study, the ability of an adsorbent (SLM Stem) obtained from the stem of the Silybum Marianum plant to treat wastewater containing the cationic dyes basic blue 3 (BB3) and basic yellow 28 (BY28) from aqueous solutions was investigated using a batch method. Then, the SLM Stem (SLM Stem-Natural) adsorbent was carbonized at different temperatures (200-900 °C) and the removal capacity of the products obtained for both dyes was examined again. The investigation continued with the product carbonized at 800 °C (SLM Stem-800 °C), the adsorbent with the highest removal capacity. The dyestuff removal studies were continued with the SLM Stem-Natural and SLM Stem-800 °C adsorbents because they had the highest removal values. The surface properties of these two adsorbents were investigated using IR, SEM, and XRD measurements. It was determined that the SLM Stem-Natural has mainly non-porous material, and the SLM Stem-800 °C has a microporous structure. The optimal values for various parameters, including adsorbent amount, initial dye solution concentration, contact time, temperature, pH, and agitation speed, were investigated for BY28 dye and were 0.05 g, 15 mg/L, 30 min, 40 °C, pH 6 and 100 rpm when SLM Stem-Natural adsorbent was used and, 0.15 g, 30 mg/L, 30 min, 40 °C, pH 10, and 150 rpm when SLM Stem-800 °C adsorbent was used. For BB3 dye, optimal parameter values of 0.20 g, 10 mg/L, 30 min, 25 °C, pH 7, and 100 rpm were obtained when SLM Stem-Natural adsorbent was used and 0.15 g, 15 mg/L, 40 min, 40 °C, pH 10, and 100 rpm when SLM Stem-800 °C adsorbent was used. The Langmuir isotherm described the adsorption process best, with a value of r2 = 0.9987. When SLM Stem-800 °C adsorbent was used for BY28 dye at 25 °C, the highest qm value in the Langmuir isotherm was 271.73 mg/g. When the study was repeated with actual water samples under optimum conditions, the highest removal for the BY28 dye was 99.9% in tap water with the SLM Stem-800 °C adsorbent. Furthermore, the reuse study showed the adsorbent's efficiency even after three repetitions.

Removal of Brilliant Green Dye from Water Using Ficus benghalensis Tree Leaves as an Efficient Biosorbent.

The presence of dyes in water stream is a major environmental problem that affects aquatic and human life negatively. Therefore, it is essential to remove dye from wastewater before its discharge into the water bodies. In this study, Banyan (Ficus benghalensis, F. benghalensis) tree leaves, a low-cost biosorbent, were used to remove brilliant green (BG), a cationic dye, from an aqueous solution. Batch model experiments were carried out by varying operational parameters, such as initial concentration of dye solution, contact time, adsorbent dose, and pH of the solution, to obtain optimum conditions for removing BG dye. Under optimum conditions, maximum percent removal of 97.3% and adsorption capacity (Qe) value of 19.5 mg/g were achieved (at pH 8, adsorbent dose 0.05 g, dye concentration 50 ppm, and 60 min contact time). The Langmuir and Freundlich adsorption isotherms were applied to the experimental data. The linear fit value, R2 of Freundlich adsorption isotherm, was 0.93, indicating its best fit to our experimental data. A kinetic study was also carried out by implementing the pseudo-first-order and pseudo-second-order kinetic models. The adsorption of BG on the selected biosorbent follows pseudo-second-order kinetics (R2 = 0.99), indicating that transfer of internal and external mass co-occurs. This study surfaces the excellent adsorption capacity of Banyan tree leaves to remove cationic BG dye from aqueous solutions, including tap water, river water, and filtered river water. Therefore, the selected biosorbent is a cost-effective and easily accessible approach for removing toxic dyes from industrial effluents and wastewater.

Complexes of terpyridine scaffold as efficient photocatalysts for the degradation of methylene blue pollutant in wastewater effluents

In the present protocol, a series of varyingly substituted terpyridine-based ligands have been designed and synthesized. The synthesized ligands were coordinated with different transition metal cations. Their complexation with Fe(II), Co(II) and Zn(II) led to interesting coordination compounds which for the first time, were evaluated for their photocatalytic potential against the degradation of methylene blue. Almost all the tested complexes 1–9 exhibited fascinating photocatalytic properties. However, noteworthy, photocatalytic results revealed that zinc complexes 1 ([Zn (4′-(p-tolyl)-2,2′:6′,2″-terpyridine)(SO4)2−]), 4 ([Zn (N,N-Dimethyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)(SO4)2−]) & 7 ([Zn (N,N-Diphenyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)(SO4)2−]) have high potential against the degradation of methylene blue followed by iron complexes 3 ([Fe(4′-(p-tolyl)-2,2′:6′,2″-terpyridin)2](PF6)2), 6 ([Fe(4′-(N,N-Dimethyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)2]2PF6) &9 ([Fe(N,N-Diphenyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)2]2PF6) and then cobalt complexes 2 (Co(4′-(p-tolyl)-2,2′:6′,2″-terpyridin)2](PF6)2), 5 ([Co(4′-(N,N-Dimethyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)2]2PF6) &8 ([Co(N,N-Diphenyl-4-(2,2′:6′,2″-terpyridin-4′-yl)aniline)2]2PF6). Among all the complexes, maximum degradation efficiencies were observed for complex 1 (67.31 %) and complex 7 (65.91 %). The optimized photocatalytic conditions were found to be 10 mg/L of initial concentration of dye solution, 20 mg of catalyst dose, pH = 4 and irradiation time of 40 min. At optimized conditions complex 7 was found to be more efficient photocatalyst with rate constant value of 0.011 min−1 as compared to the rate constant value of 0.009 min−1 for complex 1. Both complexes followed the pseudo-first order kinetics model. The reusability test indicated only 8.62 % and 7.01 % loss of photocatalytic activity for complex 1 and complex 7, respectively, up to four cycles of photodegradation reflecting that these catalysts can be used again and again. This study suggested the remarkable potential of terpyridine metal complexes for the environmental remediation to remove harmful pollutants from aqueous bodies.

Synthesis of Starch-Grafted Polymethyl Methacrylate via Free Radical Polymerization Reaction and Its Application for the Uptake of Methylene Blue.

In this research, a new biodegradable and eco-friendly adsorbent, starch-grafted polymethyl methacrylate (St-g-PMMA) was synthesized. The St-g-PMMA was synthesized by a free radical polymerization reaction in which methyl methacrylate (MMA) was grafted onto a starch polymer chain. The reaction was performed in water in the presence of a potassium persulfate (KPS) initiator. The structure and different properties of the St-g-PMMA was explored by FT-IR, 1H NMR, TGA, SEM and XRD. After characterization, the St-g-PMMA was used for the removal of MB dye. Different adsorption parameters, such as effect of adsorbent dose, effect of pH, effect of initial concentration of dye solution, effect of contact time and comparative adsorption study were investigated. The St-g-PMMA showed a maximum removal percentage (R%) of 97% towards MB. The other parameters, such as the isothermal and kinetic models, were fitted to the experimental data. The results showed that the Langmuir adsorption and pseudo second order kinetic models were best fitted to experimental data with a regression coefficient of R2 = 0.93 and 0.99, respectively.

Adsorption of methylene blue dye from aqueous solutions onto natural clay: Equilibrium and kinetic studies

The objective of this work was the removal of the cationic dye (methylene blue (MB) chosen as a pollutant model) from an aqueous solution using a Moroccan clay sample from the region of raw Wazanne as a low-cost adsorbent. The effects of various parameters, such as adsorbent dose (0.05 to 5 g/L), dye concentration (100 to 1000 mg/L), contact time (10 to 120 min), temperature (20–60 °C), and solution pH (3–12), were investigated. The results showed that MB's adsorption on clay strongly depends on the solution's initial dye concentration, temperature, and pH. The kinetic adsorption results fitted well with a pseudo-second-order model with a correlation coefficient of R2 = 0.99. Langmuir and Freundlich isotherms were used to determine the adsorption mechanism. According to the results, the Langmuir model better describes the adsorption of MB with a maximum adsorption capacity of 456.62 mg/g. According to the thermodynamic parameters, Gibbs free energy ΔG°, enthalpy ΔH°, and entropy ΔS°, the adsorption process was feasible, spontaneous, and exothermic. Reusing the adsorbent is considered an important economic and environmental aspect of a sustainable development approach, given the regenerative capacity of the material. Various techniques for characterization of the adsorbent have been applied, including zero-point charge measurement (pH zpc), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses with an X-ray diffractometer.

Green mediated combustion synthesis of copper zinc oxide using Eryngium planum leaf extract as a natural green fuel: Excellent adsorption capacity towards Congo red dye

In the present study, meso/microporous CuO/ZnO nanostructures were synthesized via a green mediated solution combustion method by Eryngium planum leaf extract as natural fuel for the first time. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectrometer (FTIR), Thermogravimetric/differential thermal analysis (TGA/DTA), and N2 adsorption-desorption analyses were applied to characterize the as-prepared samples. The total pore volume and average pore diameter of the CuO/ZnO nanostructures were 0.06945 cm3/g and 4.76 nm, respectively. A batch adsorption test was conducted using the as-synthesized samples to evaluate their ability to remove congo red (CR) dye. In the following, the effective parameters in the adsorption of CR by CuO/ZnO nanostructures, including contact time, adsorbent dosage, pH of the solution, initial dye solution concentration, and temperature, were investigated in detail. Also, the kinetic, isotherm, and thermodynamic studies were evaluated. The results indicated that the intra-particle diffusion model (R2 = 0.9990) and pseudo-second-order model (R2 = 0.9998) are suitable models for describing the adsorption rate at the early (0–60 min) and later (60–240 min) times, respectively. According to the Langmuir isotherm model, the maximum adsorption capacity of CR by CuO/ZnO was found to be 357.14 mg/g. Moreover, the negative value for each of the parameters of ΔH° and ΔS° indicates that the adsorption at the solid/solution interface is exothermic and non-random during the process, respectively. Therefore, the proposed eco-friendly and inexpensive green synthesis method can be considered to develop new interesting materials to remove contamination from industrial wastewaters.

Removal of organic pollutant from wastewater using Nano Carbon synthesized from wood waste biomaterial as an adsorbent

With the help of eco-friendly waste materials like Manila tamarind tree bark and shells (Pithecellobium Dulce), the malachite green dye has been removed from wastewater in this investigation. The maximum adsorption of dye was achieved at pH 6.7 in the research work. The removal percentage of Malachite green dye was found to be dependent on the initial concentration of dye solution, and the maximum removal percentage was found to be 85% at 25 mg/L of Malachite green dye. The experimental methods were carried out using the batch adsorption technique. The pH parameter, temperature, adsorption dose, and contact time for the removal of Malachite green dye were studied. The Freundlich, Langmuir, and Temkin methods were used to calculate equilibrium adsorption data. The thermodynamic parameters such as a change in free energy (G0 ), enthalpy (H0 ), and entropy (S0 ) were determined. The negative values of G0 indicated that the process of dye removal was spontaneous at all values of temperature. Further, the values of H0 indicated the endothermic nature of the process of dye removal from the wastewater.

Carbon nanotubes loaded N,S-codoped TiO2: Heterojunction assembly for enhanced integrated adsorptive-photocatalytic performance

A visible-light active N,S-codoped TiO2 incorporated with carbon nanotubes (CNTs) was synthesized by a multicomponent heterojunction scheme. The synthesized photocatalysts was examined by several analysis techniques. The conventional TiO2, N-doped TiO2, TiO2/CNT and N,S-codoped TiO2 were also synthesized, characterized, and integrated adsorptive-photocatalytic degradation rates were subsequently compared and assessed, for comparative purposes as reference photocatalysts. The parametric study was also carried out to investigate the effect of various operational factors, such as solution pH, the photocatalyst loading and initial concentration of dye solution, on the adsorptive-photocatalytic performance. The best activity performance was attained with the N,S-TiO2/CNTs nanocomposite due to the synergistic effect of ternary components caused by the incorporation of dopants and CNTs in TiO2 lattice, providing a high number of adsorption sites and facilitating the effective separation of photogenerated charge carriers and minimal recombination rates. N,S-TiO2/CNTs exhibited around three times higher photocatalytic performance than that of the binary composites, i.e., N-TiO2, TiO2/CNTs, N,S-TiO2, and about four times higher than the conventional TiO2. Furthermore, the superior nanocomposites were also investigated for their recyclability for five consecutive cycles.

Banana stem based activated carbon as a low-cost adsorbent for methylene blue removal: Isotherm, kinetics, and reusability

A low-cost activated carbon from the banana stem (ACBS) was produced to contribute to environmental preservation in removing methylene blue from wastewater. It is originated from abundant agricultural waste and produced at moderate pyrolysis temperature and short pyrolisis time. In the ACBS production, the banana stem was impregnated with H3PO4 solution as the activating agent and followed by pyrolysis at 400 °C for a rapid time of 15 min. The treatment significantly improved the ACBS surface area to 837.453 m2/g. The influence of the ACBS dose and initial concentration of dye solution at various contact times were investigated in this study. The utilization of ACBS in low doses exhibited high removal efficiency of methylene blue (0.05 to 0.3 g/100 mL). It can remove methylene blue completely in 90 min of adsorption with an initial concentration of 50 g/mL. High removal efficiencies are still also demonstrated at higher initial concentrations with 99.762% removal for the initial concentration of 200 g/mL. Equilibrium adsorption data had the best agreement to the Freundlich isotherm model and pseudo-second-order kinetics model. It is predicted that ACBS has a maximum adsorption capacity of 101.01 mg/g. ACBS is an environmentally benign and favorable adsorbent in methylene blue removal and also effective for repeated usage up to 6 consecutive times with no desorption step.

Adsorption of Rhodamine 6G Dye on Binary System of Nanoarchitectonics Composite Magnetic Graphene Oxide Material.

Magnetic Graphene Oxide nanocomposite prepared by the co-precipitation method based on concept of nanoarchitectonics. In co-precipitation method, Graphene oxide converts into Magnetic graphene oxide nanocomposite with uniform deposition of Fe₃O₄ nano particles on the surface of Graphene oxide. Field Emission Scanning Electron Microscopy spectroscopy technique reveals the size (~2.5 nm) and uniformity of Fe₃O₄ nano particles on Graphene oxide surface. The other properties characterized by Scanning electron microscopy, Raman spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and vibrating-sample magnetometer. For Adsorption process, time, temperature, dose of adsorbent, initial concentration of dye solution and pH factors are optimize for Rhodamine 6G dye. Kinetic data expressed by Pseudo first order model and Pseudo second order model. Langmuir, Freundlich and Temkin isotherms used to evaluate the adsorption isotherm of Rhodamine 6G onto the surface of Magnetic graphene oxide nanocomposite and thermodynamic parameters tell us about the nature of reaction.

Removal of indigo carmine dye from aqueous solution by adsorption on biomass of Grevillea Robusta leaves

In the present paper revealed the procedure expulsion of the indigo carmine dye from fluid arrangement by utilizing acidified Grevillea Robusta leaves. Adsorption was done for evacuation of indigo carmine as an element of time contact, biosorbent dosage, initial concentration, pH and temperature. The Kinetics of adsorption process (pseudo-second order) is also applied to the equilibrium adsorption data Adsorption capacity of the biosorbent systematically studied by varying the initial concentration of dye solution 20 mg/L and at the optimised condition 8 g of biosorbent, 40 min contact time, at the temperature 313 °K and 6.0 pH.

Removal of Direct Red 81 from Aqueous Solution Using an Acidic Soil Containing Iron (Case Study of Lahijan Soil)

Direct Red 81, a dye widely used in textile industries, is frequently detected dye in water resources. High costs, the formation of hazardous byproducts, and high energy costs restrict the use of some removal methods. Therefore, the main objectives of this research are the feasibility of using soil containing iron as a low-cost adsorbent to remove (Direct Red 81) from the aqueous phase and determining the optimum conditions for maximum removal efficiency. The present study was conducted at a bench scale. The influence of different parameters including the number of adsorbents; initial concentration of dye solution and pH at different time intervals on dye removal efficiency were investigated. The maximum removal rate of dye (84%) occurred in pH=7 in the presence of 1 g soil with the initial dye concentration of 50 mg/L at 30 min reaction time. Moreover, due to the effect of acidic pH and the iron content of used soil, a significant increase was observed in the rate of Direct Red 81dye removal. In conclusion, using soil containing iron is an appropriate method for the removal of Direct Red 81 from aqueous solutions.

Oil palm frond for the adsorption of Janus Green dye

Abstract Nowadays, one of the major environmental issues is the discharge of industrial effluent containing dye residue which threaten human and environment. Seeking for an environmental friendly and low cost adsorbent which can remove dye effectively remain a challenge. In current study, oil palm frond was explored as adsorbent for removal of Janus Green B dye. The effect of initial dye solution concentration (50-250 mg/L), oil palm frond loading (1-7 g/L) and pH (2-8) on the Janus Green B dye adsorption capacity of the oil palm frond were investigated. The oil palm frond was characterized using different analytical techniques including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). The results showed that oil palm frond was able to remove Janus Green B dye with adsorption capacity as high as ∼67 mg/g at initial dye solution concentration of 150 mg/L, oil palm frond loading of 1 g/L and pH of 8.

Removal of malachite green from aqueous solution using activated carbon prepared from teak leaf litter

Teak leaf litter (TLL) was impregnated with phosphoric acid and activated at 400 °C for 1 h to produce teak leaf litter activated carbon (TLLAC). Equilibrium adsorption, kinetics and thermodynamics study was then used to assess the removal of malachite green (MG) from aqueous solution by the novel adsorbent. Temperature, pH and initial concentration of dye solution as well as dosage and contact time influenced the adsorption process. The optimum TLLAC dosage for adsorption of MG was 0.5 g/L. Removal of MG from aqueous solutions increased up to pH 10. The adsorption process was best described using Langmuir isotherm with 91.74 mg/g as the monolayer capacity of TLLAC. Pseudo-second order kinetic model best fit the adsorbent-dye interactions. The mechanism of uptake of MG by TLLAC was jointly influenced by both liquid film and intraparticle diffusion but neither was the rate controlling step. The exothermic process was spontaneous below 313 K. The value of ΔH° (-83.82 kJ/mol) implies possibility of influence of chemical adsorption in the system. The study revealed that TLLAC exhibited potentials to remove MG from aqueous solutions.

Synthesis of aminated calcium lignosulfonate and its adsorption properties for azo dyes

A low-cost adsorbent, aminated calcium lignosulfonate (ACLS) was prepared and successfully applied to the adsorption of Congo red and the Titan yellow dyes. The adsorbent was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), elemental mapping images (EMIs) and Brunauer–Emmett–Teller (BET) analysis. And the efficiency of ACLS for the removal of Congo red and the Titan yellow dyes was evaluated by several factors, such as temperature, pH, adsorbent dose, contact time and initial concentration of dyes solution. And the test ranges of temperature, pH, adsorbent dose, contact time and initial concentration of dye solution were 25–45°C, 2–12, 0.005–0.05g, 1–48h, 10–200mgL−1, respectively. The adsorption results demonstrated a good ability to remove dye with the removal rates of 97% and 91% for 30mgL−1 Congo red and 40mgL−1 Titan yellow, respectively. The adsorption kinetic and adsorption isotherms can be well described by the pseudo second order kinetic and the Langmuir isotherm model for the both dyes, respectively. Moreover, the maximum adsorption capacity of Congo red and Titan yellow reached 258.4mgg−1 and 190.1mgg−1 in the study of the Langmuir adsorption isotherm, respectively. Thermodynamic studies show that the adsorption of the two dyes is a spontaneous endothermic process. The results indicate that the ACLS has the potential to be used in the treatment of dye wastewater.

Preparation of Modified Reduced Graphene Oxide nanosheet with Cationic Surfactant and its Dye Adsorption Ability from Colored Wastewater

AbstractIn this paper, reduced graphene oxide (rGO) nanosheet from graphite was synthesized using the top‐down approach. The surface of rGO was modified by cetyltrimethylammonium bromide (CTAB) to prepare rGO/CTAB adsorbent for anionic dye removal. The prepared rGO/CTAB was characterized by XRD, FTIR, FE‐SEM and TGA. The operation parameters (surfactant concentration, adsorbent dosage, pH and initial concentration of dye solution) affecting the batch adsorption process to remove direct red 80 (DR80) and direct red 23 (DR23) were studied in detail. The dye adsorption capacity of rGO/CTAB was 213 and 79 mg/g for DR80 and DR23, respectively. In addition, dye removal followed the Langmuir isotherm with pseudo‐second order reaction kinetics.

Modification of the photocatalytic performance of various metal oxides by the addition of β-cyclodextrin under visible light irradiation

The photocatalytic decoloration of Neutral Red (NR) dye in aqueous solutions on various metal oxide (MO) photocatalysts (such CeO2, TiO2 and ZnO) has been investigated under visible light irradiation. The significance of addition of β-Cyclodextrin (β-CD) on the photocatalytic performance of the above catalysts has also been investigated. The interaction between semiconductors and β-CD were characterized in detail by FE-SEM, X-ray diffraction, and UV-vis Diffuse Reflectance spectral analyses. The analytical results indicated that the addition of β-CD shows no change in the lattice structure, crystalline features of semiconductors. The experiments were carried out to study the factors influencing the photocatalytic decoloration, such as the initial concentration of dye solution, catalyst concentration, illumination time and pH. The experimental results show that catalytic system bounded with β-CD exhibits superior photocatalytic activity than that of bare catalyst systems. The decoloration rate was pH dependent.