Dye Adsorption Ability Research Articles

The removal of methylene blue and maxilon blue dyes using a polyvinyl alcohol/poly(acrylic acid-co-acrylamide) composite hydrogel from water

PurposeIn this study, polyvinyl alcohol (PVA)/poly[acrylic acid (AAc)-co-acrylamide (AM)] composite hydrogel was prepared by radical copolymerization in the presence of Fe3+ freezing-thawing method. The swelling behavior of the hydrogel was investigated. The novel synthesized hydrogel was used as an adsorbent for the removal of dyes from aqueous solutions. In this paper, methylene blue and maxilon blue 5G were selected as representative cationic dyes. In addition, adsorption isotherm models were used to describe the dye adsorption process.Design/methodology/approachThe prepared composite hydrogel was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy and UV–visible.FindingsThe prepared hydrogel exhibited excellent adsorption ability for both dyes. Various experimental conditions affecting the dye adsorption were explored to achieve maximum removal of both dyes. In addition, adsorption isotherm models were used to describe the dye adsorption process.Originality/valueTo the best of the author’s knowledge, synthesis of PVA/poly(AAc-co-AM) composite hydrogel in the presence of Fe3+ and investigation of the removal of methylene blue and maxilon blue 5G dyes is done for the first time successfully.

Synthesis, characterization and dye adsorption properties of a 3-fold interpenetrated cobalt(II)-metal organic framework based on (E)-5,5'-(but-2-ene-1,4-diylbis(oxy))diisophthalate and 1,4-bis(imidazole-1-yl)butane ligands

A new 3D cobalt(II)-metal organic framework, [Co 2 (μ 4 -L)(μ-bib) 2 ] n (1) was synthesized with solvothermal method by using (E)-5,5'-(but-2-ene-1,4-diylbis(oxy))diisophthalic acid (H 4 L) and 1,4-bis(1 H -imidazole-1-yl)butane (bib) in the presence of cobalt(II) ion. Compound 1 was characterized by elemental analysis, FTIR spectroscopy and single crystal X-ray diffraction (SCXRD) technique. SCXRD analysis result revealed that 1 displayed a 3-fold interpenetrated 3D framework with bbf topology. The dye adsorption ability of 1 towards methylene blue (MB) was assessed with diverse parameters (pH, the compound amount, temperature, contact time and initial MB concentration). Adsorption kinetics and isotherms fitted well with pseudo-second-order kinetic and Langmuir isotherm models. The highest adsorption capacity of compound 1 was 473.57 ​mg ​g −1 ​at pH ​= ​8.0, 20 ​°C. The adsorption ability could be due to the electrostatic interactions between cationic MB and negative charge density on 1 ​at pH ​= ​8.0. Overall, adsorption studies indicated that synthesized compound 1 may be an efficient alternative adsorbent for MB removal from aqueous solutions. A new 3D cobalt(II)-metal organic framework, [Co 2 (μ 4 -L)(μ-bib) 2 ] n (1) was synthesized and characterized. Compound 1 displayed 3-fold interpenetrated 3D+3D+3D→3D framework with bbf topology. Compound 1 displayed high cationic MB removal because compound 1 had the highest negative charge density at pH ​= ​8 and the highest adsorption value for MB was obtained as 473.57 ​mg ​g −1 ​at room temperature. • A Co(II)-metal organic framework was synthesized and characterized. • Compound 1 displayed 3-fold interpenetrated framework with bbf topology. • The adsorption ability of compound 1 towards MB was determined in the aqueous medium. • Compound 1 displayed high cationic MB removal. • The highest adsorption value for MB was obtained as 473.57 ​mg ​g −1 ​at room temperature.

A novel phosphazene-based amine-functionalized porous polymer with high adsorption ability for I2, dyes and heavy metal ions

A phosphazene-based amine-functionalized hybrid porous polymer (PHPP) with certain crystallinity has been successfully synthesized via Schiff base reaction between hexakis(4-formylphenoxy)cyclophosphazene and 4-(2-aminoethyl)diethylenetriamine. Although PHPP offered low porosity, it showed an excellent adsorption ability for volatile iodine, Hg2+, and Congo red (CR) due to the strong host-guest interaction.

Multi-functional composite membrane with strong photocatalysis to effectively separate emulsified-oil/dyes from complex oily sewage

Multi-functional filtration membranes, with effective purification capacity against diverse emulsified-oils, high adsorption ability for soluble organic dyes in aquatic system, good physical/chemical stability, and strong Photocatalysis induced anti oil/dye fouling functions, are highly desirable for the complex oily sewage purification, but still a challenge to be realized. Herein, a ternary beta-iron oxyhydroxide (β-FeOOH)/halloysite-nanotubes (HNTs)/polyvinylidene fluoride (PVDF) porous membrane has been designed to address this challenge. The resultant membrane exhibits effective separation efficiency towards various oil-water emulsions and high soluble pollutants adsorption by filtration during the rapid oily wastewater purification. Interestingly, it also displays high flux (~6500 L∙m −2 ∙h −1 ), good cycling stability (after 5 cycles the flux recovery rate is still closed to 100%), and strong chemical/physical stability. Given the robust photo-Fenton catalytic activity of β-FeOOH, the permeation flux and adsorption capacity of the fouled membrane could be quickly restored (recovery: higher than 99%) within 10 min under visible light irradiation. Our results open an alternative and effective route to solve the oil/dye fouling issue for complex wastewater remedy. • Highly flux and excellent efficiency for separating different oil/water emulsions. • Great adsorption capacity for soluble dyes in wastewater by simply filtering. • Strong physical and chemical stability. • Outstanding photocatalytic self-cleaning property and recyclability.

Formation of new crystalline qtz-[Zn(mIm)2] polymorph from amorphous ZIF-8.

The structure of a new ZIF-8 polymorph with quartz topology (qtz) is reported. This qtz-[Zn(mIm)2] phase was obtained by mechanically amorphising crystalline ZIF-8, before heating the resultant amorphous phase to between 282 and 316 °C. The high-temperature phase structure was obtained from powder X-ray diffraction, and its thermal behaviour, CO2 gas sorption properties and dye adsorption ability were investigated.

Orange dye Removal Efficiency by Few-layer Graphene: an Investigation by UV-Vis Spectroscopy-=SUP=-*-=/SUP=-

Nowadays, few-layer graphene (FLG) has been introduced as a new type of adsorbent. In this research, the orange dyes including, methyl orange (MO) as an industrial dye and the soft drink orange dye (orange Fanta soda) as a food dye, have been removed by FLG adsorbent. In all steps, UV-Vis spectroscopy as a valuable and fast method has been applied. The optical absorption coefficient has been decreased from 0.9 to less than 0.2 by FLG adsorbent for 50 ppm MO dye solution. Therefore, the MO solution with 50 ppm concentration converts to about 10 ppm output solution using 0.05 g of FLG adsorbent in a few minutes. It is about 80% adsorption dye removal efficiency. Also, MO dye removals have been performed in the range of 10 ppm to 500 ppm concentrations, but as the concentration of the solution increases, the dye adsorption ability of FLG decreases. The maximum efficient and optimum MO dye concentrations are about 100 ppm and 50 ppm, respectively, due to 0.05 g FLG adsorbent. It has been completely saturated at about 500 ppm concentration MO dye solution. Also, it has been observed that, for 50 ppm MO dye solution, increasing the amount of mass adsorbent from 0.05 g to 0.25 g can cause the output MO concentration to decrease from 10 ppm to 3 ppm. It has been revealed that about 94% of MO dye can remove by 0.25 g FLG adsorbent. The contact time due to 94% MO removal process is less than 5 minutes. Therefore, only by 0.25 g of FLG adsorbent we can purify wastewater containing 50 ppm MO dye to less than 3 ppm dye concentration, at less than a few minutes. Finally, the FLG glass tube filter can remove more than 90% food orange dye in less than 90 seconds for 50 ml of soft drink solution. Therefore, the FLG tube filtration process is so fast, easy, and high efficient. Keywords: adsorption, Few-Layer Graphene, methyl orange, UV-Vis spectroscopy, orange dye.

Orange dye removal efficiency by few-layer graphene: an investigation by UV-Vis spectroscopy

Nowadays, few-layer graphene (FLG) has been introduced as a new type of adsorbent. In this research the orange dyes including methyl orange (MO) as an industrial dye and the soft drink orange dye (orange Fanta soda) as a food dye have been removed by FLG adsorbent. In all steps UV-Vis spectroscopy as a valuable and fast method has been applied. The optical absorption coefficient has been decreased from 0.9 to less than 0.2 by FLG adsorbent for 50 ppm MO dye solution. Therefore, the MO solution with 50 ppm concentration converts to about 10 ppm output solution using 0.05 g of FLG adsorbent in a few minutes. It is about 80% adsorption dye removal efficiency. Also, MO dye removals have been performed in the range of 10 ppm to 500 ppm concentrations, but as the concentration of the solution increases, the dye adsorption ability of FLG decreases.The maximum efficient and optimum MO dye concentrations are about 100 ppm and 50 ppm, respectively, due to 0.05 g FLG adsorbent. It has been completely saturated at about 500 ppm concentration MO dye solution.Also, it has been observed that for 50 ppm MO dye solution increasing the amount of mass adsorbent from 0.05 g to 0.25 g can cause the output MO concentration to decrease from 10 ppm to 3 ppm. It has been revealed that about 94% of MO dye can remove by 0.25 g FLG adsorbent. The contact time due to 94% MO removal process is less than 5 minutes. Therefore, only by 0.25 g of FLG adsorbent we can purify wastewater containing 50 ppm MO dye to less than 3 ppm dye concentration, at less than a few minutes. Finally, the FLG glass tube filter can remove more than 90% food orange dye in less than 90 seconds for 50 ml of soft drink solution. Therefore, the FLG tube filtration process is so fast, easy, and high efficient. Key words: adsorption, few-layer graphene, methyl orange, UV-Vis spectroscopy, orange dye.

Dye and metal ion adsorption ability of Asian green mussel byssus thread complex; their microscopic and thermal property characterization

ABSTRACT Various physical, chemical, and biological factors act as pollutants and cause deleterious effects on the environment and living organisms. Several researchers are developing eco-friendly good adsorbent from agriculture waste materials for pollutant removal, especially aromatic dyes and heavy metal removal. We used the Asian green mussel byssus thread, a natural mariculture waste product for the removal of aromatic dyes (methylene blue and eosin Y) and heavy metals (zinc, copper, iron, mercury and lead). We documented the dynamicity of byssus thread dye and metal removal at different pH (pH 2–10) and different concentrations. The highest amount of metal removal was observed at pH 6.0, and the dye removal efficacy is related to the property of the dye (i.e. anionic or cationic dye). The byssus thread had a natural fluorescent property upon UV-excitation; however, microscopic examination revealed that metal and dye coordination significantly alter the byssus plaque region’s physical and chemical property rather than the thread regions. It was further confirmed by using DSC and TGA characterization of de-metaled and metal-treated byssus thread complex. We concluded that Perna viridis byssus thread could be used as a strong adsorbent for dye and metal removal from the water.

Ionic liquid grafted polyethersulfone nanofibrous membrane as recyclable adsorbent with simultaneous dye, heavy metal removal and antibacterial property

• PES-g-IL NFMs were fabricated by combining radiation grafting with electrospinning; • The NFMs exhibit multifunctional properties, including dye and heavy metal absorption and antibacterial properties; • The NFMs can be easily regenerated with high absorption and desorption efficiency. In view of the harmfulness of the pollutants in wastewater to both human being and environment, it is urgent to develop a multifunctional polymer adsorbent that can remove dyes, heavy metals and bacteria simultaneously. Herein, ionic liquid (IL) grafted Polyethersulfone (PES) (PES- g -IL) nanofibrous membranes (NFMs) were prepared by combining radiation induced grafting method and electrospinning strategy. The adsorption behavior, antibacterial property as well as reusability were examined for the obtained NFMs. It was found that the PES -g -IL NFMs exhibited excellent adsorption ability for heavy metal ions and dyes as well as good recyclability. The adsorption capacity for anionic dyes Congo Red (CR) and heavy metal ions (Cd(II)) reached 120.3 and 187.3 mg/g, respectively. The adsorption mechanism of CR was proved to be the electrostatic interaction between the NFMs and CR, while the adsorption of Cd(II) was driven by the complex between the nitrogen atoms on the imidazolium ring of the grafted ionic liquid and Cd(II). According to the adsorption kinetics, the adsorption of CR and Cd(II) was well fitted by the pseudo-second-order kinetic equation, indicating that the adsorption process was controlled by multiple steps. By calculating the thermodynamic parameters, it is indicated that the adsorption of CR and Cd(II) was a spontaneous physical adsorption process. In addition, PES- g -IL NFMs had excellent antibacterial ability. The killing rate of E. coli. was close to 99%. Given the above advantages, the PES- g -IL NFMs showed great potential in wastewater treatment.

Thermodynamic Study For Removing Of Crystal Violet Dye On Iraqi Porcelanite Rocks Powder

Natural Iraqi Porcelanite Rocks powder are better adsorbents due to better functionality, surface area, employed for the adsorption of crystal violet (cv) dye from aqueous media. Crystal violet is used as adye in cotton ;silk and printing ink, crystal violet (cv) dye is a water - soluble, toxic, recalcitrant organic dye that cause several health problems and environment pollution. This study involves the adsorption of crystal violet (cv) dye adsorbed from solution on the Iraqi Porcelanite Rocks powder surface was characterized by numerous techniques AFM. The Iraqi Porcelanite Rocks powder showed promising adsorption ability for Crystal violet dye. Batch experiments were designated to determine the effect of PH, dye concentration, adsorbent dose, temperature change and contact time in dye removal. Process variables were optimized and maximum dye adsorption of 31.38 mg/g was achieved at PH 8, 0.02 g adsorbent dose, 20 min. contact time, 25 for dye initial concentration of 30 mg/L. The isothermal data obtained using batch adsorption technique were fitted using Langmuir, Freundlich and Timken equation and it was found that the experimental data is well described by Freundlich isotherm model. Different thermodynamic parameters have shown natural Gibbs free energy (ΔG) of the system showed increasing spontaneity with temperature while positive entropy value (ΔS) implied random disorder of molecules featured at solution/solid interfase. Positive enthalpy value (ΔH) confirmed endotherimic nature of this adsorption process.

Intercalation of soft PPy polymeric nanoparticles in graphene oxide membrane for enhancing nanofiltration performances

• PPy particles make GOM with dye adsorption function for sub-nano dyes removement. • Intercalation of PPy improves the GOM’s stability extremely. • PPy nanoparticles modified GOM resulting in 14 times faster water flux. • PPy inhibits the swelling feature of GOM and exhibits improved separation ability. Graphene oxide-based membrane (GOM) has been massively studied in the dye/water separation field, predominately relying on their 1 nm-sized interlayer distance spacing (D-spacing). However, the inefficient removal of sub-nanosized dye molecules and swelling-induced weak long-term stability are currently two key challenges faced by GOM. In this work, we intercalate the soft polymeric polypyrrole (PPy) nanoparticles into GOM to address such gaps. The strong dye adsorption ability of PPy results in the increase of the sub-nanosized MB molecule rejection rate from 60% for GOM to 97% for GO-PPy membrane (GPM) after the initial filtration treatment. Simultaneously, the nanochannels of GPM are partially expanded, leading to an approximately a ~14 times water permeability (21.14 L m -2 h −1 bar −1 ) improvement over GOM (1.56 L m -2 h −1 bar −1 ). More importantly, the strong hydrogen-bond, electrostatic, and π-π interactions between GO and PPy improve the membrane mechanical stability and further reduce the D-spacing, while the enhanced separation ability of nano-sized dye molecules is also exhibited evidenced by the > 99% rejection rates of CV, EBT, CR, and TB. We consider that our strategy could promote the design and development of the high-performance GOM for nanofiltration applications.

Mussel-inspired photothermal synergetic system for clean water production using full-spectrum solar energy

A simple manufacturing strategy of photothermal synergetic system for seawater desalination and sewage purification. • • A multi-scale rough structure was prepared by wet chemical etching and mussel chemistry inspiration. • • A low-cost and easy-to-manufacture photothermal synergetic system. • • Full-spectrum solar absorption and highly-efficient solar evaporation. • • The solar-driven purification of various sewage and the photocatalytic degradation of organic pollutants are realized. Facing the long-term shortage of global water resources, the use of solar energy for desalination and wastewater treatment has always been the focus of human exploration. Here, inspired by mussel-chemistry, we designed a functional photothermal-photocatalysis system based on Cu foam with abundant marigold-like CuO nanoflowers and Prussian blue (PB) nanoparticles. This superhydrophilic composite material (CuO@PDA/PB) has superior full-spectrum solar energy absorption (300–2500 nm), which achieved interfacial heating under solar radiation to generate stable water vapor. Besides, superhydrophobic CuO@PDA/PB with self-floating properties and Janus CuO@PDA/PB with asymmetric wettability and anti-turnover ability were prepared to systematically compare the effects of wettability on solar energy utilization. We conclude that the hydrophilicity of the sample and the strong capillary pumping effect are more conducive to water transmission, and the superhydrophilic CuO@PDA/PB has a higher evaporation rate (1.39 kg m –2 h −1 ) and efficiency (87.10%) than other samples under 1.0 sun. Importantly, the superhydrophilic CuO@PDA/PB with excellent salt-tolerance and antifouling property can also be used for the purification of the saline solution, oily wastewater and dyeing effluents via the solar-driven water evaporation. Moreover, CuO@PDA/PB possessed superior adsorption and photocatalytic degradation ability for the organic dyes in dyeing wastewater. Therefore, this solar-driven superwetting functional material provides an expandable and cost-effective platform for seawater desalination and sewage purification.

Exfoliation of 2D materials by saponin in water: Aerogel adsorption / photodegradation organic dye

The biggest challenge for the paint industry is to clean the contaminated waste dye solution before it released into the water or to reuse it to create new paint and to protect the water from environmental pollution. Here in this work, exfoliating layered transition metal dichalcogenide materials prepare to the exfoliated 2D materials thin sheets in water with the assistance of natural saponin. Then, the three-dimensional (3D) MoS2-aerogel composite was synthesized by using greenway exfoliated two-dimensional (2D) MoS2 thin sheets to form MoS2-aerogel composite. The prepared 3D MoS2-aerogel composite demonstrates excellent 94% methylene blue (MB) dye adsorption ability over 5min. Moreover, the adsorbed MB of the MoS2-aerogel shows ∼80% dye degradation activity in the presence of visible light. Therefore, these synthesized 3D MoS2-aerogel composite could be an excellent candidate for photocatalytic applications in the future.

Adsorptive removal of acridine orange dye by green tea/copper-activated carbon nanoparticles (Gt/Cu-AC np)

Abstract Textile production is the rapidly growing industry in present days with dying as one of the most prominent operations involved. Dumping untreated wastewater from dye houses contaminate the local water bodies. Thus, dye removal is of great importance and recent applications using Green tea/Copper-Activated Carbon nano materials showed high dye adsorption ability. This work deals with the removal of acridine orange dye by using depleted green tea leaves and activated carbon, both in the form of nano sized particles combinedly as Green tea/Copper-Activated Carbon nanoparticles (Gt/Cu-AC np). These particles are characterized using SEM, XRD and FTIR analysis. The Experimental study for Adsorption of Acridine Orange Dye is carried out in batch process and concentration measurement is done by indirect measurement mode using UV Spectrophotometer at a wavelength of 400 nm range. Various parameters such as agitation time, agitation speed, Dosage of adsorbent (Gt/Cu-AC np), Initial concentration, and pH of acridine orange dye solution vs %Removal of acridine orange dye in solution is studied using plots, while maintaining other parameters constant when dealing with one. Using these plots different parameters are optimised to obtain 98% dye removal. Kinetics for acridine orange dye removal is studied and it is observed that the data best fits into pseudo second order kinetics. Adsorption Isotherm studies are carried out using Langmuir, Freundlich, and Temkin Adsorption isotherms, and it is observed that the experimental data follows a more likely Freundlich Adsorption Isotherm model with maximum adsorption capacity of 95.43 mg of Acridine orange adsorbed per gram of Green tea/Copper-Activated Carbon nanoparticles. (Gt/Cu-AC np).

Facile bile salt-induced synthesis of porous MnO2 nanoflowers: applications in dye removal and oxidation

MnO2 is an important functional oxide with wide applications such as in the oxidation of benzylic and allylic alcohols, as an electrode material for supercapacitors, in dyes removal etc. Herein, we demonstrate a simple, bile-salt induced synthesis of porous MnO2 at neutral pH from potassium permanganate. By tuning the reaction conditions we obtained porous δ-MnO2 with high surface area which adsorbed cationic organic dyes with high efficiency. Because of its high reactivity, we also observed higher yields in standard oxidation reactions as compared to commercial MnO2. The outstanding dye adsorption and oxidation abilities coupled with the simple method of preparation can make this material useful for practical applications such as for wastewater treatment.

In-situ hard template synthesis of mesoporous carbon/graphite carbon nitride (C/CN-T-x) composites with high photocatalytic activities under visible light irridation

Carbon/graphite carbon nitride (C/CN-T-x) hybrid composites with high photocatalytic activities under visible light irradiation were synthesized by an in-situ hard template method using the partially formaldehyde-modified dicyandiamide (PFMD) and tetraethyl orthosilicate (TEOS) as the precursors and template, respectively. The structures of the as-prepared composites were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), elemental analysis, nitrogen adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The composite prepared under the optimal conditions exhibits the large surface area of 174 m 2 ･g −1 and high photocatalytic activity for the degradation of methylene blue (MB) under visible light irradiation. The significant improvement in photocatalytic activity of the composite, as compared with the pure graphite carbon nitride (CN), is attributed to the large surface area, strong dye adsorption ability and enhanced separation efficiency of photogenerated electron-hole pairs. • Carbon and carbon nitride composites were prepared using partially formaldehyde-modified dicyandiamide (PFMD) and tetraethyl orthosilicate (TEOS) as the precursors and template, respectively. • The carbon content could be easily controlled by adjusting the mass ratio of PFMD to TEOS. • The composites presented larger surface area, and improved photocatalytic activity. • The reasonable photocatalytic mechanism were investigated.

Synthesis of Tri-S-Triazine Based g-C3N4 Photocatalyst for Cationic Rhodamine B Degradation under Visible Light

In this research, graphitic carbon nitride (g-C3N4) photocatalysts were synthesized through a simple calcination process at various temperatures, which were 400, 500, 550, and 600 °C, by using low-cost urea as a precursor. The obtained g-C3N4 samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area and porosity analyses, and ultraviolet–visible-near-infrared (UV–VIS-NIR) spectroscopy. The correlations between the calcination temperature, properties, and photocatalytic activity of prepared products were investigated. The results demonstrated that the g-C3N4 photocatalysts can be successfully synthesized at temperatures of 500–600 °C with a controlled heating rate of 5 °C/min. In contrast, the intermediate product was observed in sample calcined at 400 °C. It was demonstrated that calcination at higher temperatures possibly increased the active sites and enhanced both of the photocatalytic activity and dye adsorption ability. Herein, the dye degradation efficiency (DE%) under visible light irradiation within 10 min were presented as 2.52, 16.01, 62.37, and 92.64% which were well developed as a function of calcination temperature from 400 °C, 500 °C, 550 °C, to 600 °C, respectively. Furthermore, the dye degradation rate could possibly induce decomposition pathway of rhodamine B. The photocatalytic efficiency was maintained after four times of reuse. It can be concluded that the thermal process plays an important role in controlling the properties and photocatalytic performance of g-C3N4.

The Influence of Soaking Time on Photocatalytic Performance of g-C<sub>3</sub>N<sub>4</sub> under Visible Light Irradiation

In this research, visible-light responsive g-C3N4, photocatalyst was achieved through the simple calcination of urea at 600 °C by using the muffle furnace. The effects of calcination soaking time on preparation of high performance g-C3N4 were studied at 1, 2, 3, and 4 h. The g-C3N4 prepared at various soaking times were characterized by the X-ray diffraction (XRD) for crystallographic information and the Fourier-transform infrared spectroscopy (FTIR) for chemical composition analysis. Further, in the case of morphology and surface area of prepared photocatalysts, the Transmission Electron Microscope (TEM) and Brunauer, Emmett and Teller (BET) were applied. The results demonstrated that g-C3N4 with tri-s-triazine based units could be synthesized by calcination of urea at 600 °C and soaking for 1-4 h, as evidently confirmed by XRD and FTIR. For photocatalytic performance in rhodamine B dye degradation under visible light irradiation of achieved g-C3N4 tended to increase as soaking time increased. Moreover, the dye adsorption ability of prepared photocatalysts was obviously developed upon increase of soaking times. Herein, the highest photocatalytic performance was obtained from sample which was soaked at 4 h.

A facile approach to synthesis of cobalt ferrite nanoparticles with a uniform ultrathin layer of silicon carbide for organic dye removal

Abstract Dispersions of surface capped ferrite nanoparticles have many practical applications in heat transfer, optics, memory devices, sensors and biomedicine. However, capping of ferrite nanoparticles with a stable ultrathin layer of organic or inorganic materials, without compromising magnetic properties, still remains a challenge. Here, we demonstrate, for the first time, a facile and rapid approach to cap cobalt ferrite nanoparticles with a uniform ultrathin layer of silicon carbide (~1.4 nm) by using an organosilica coating agent, dichlorodimethylsilane (DCDMSi), through sonochemical approach. The ultrasonic cavitation process is exploited for aiding the rapid and effective capping of SiC over CoFe2O4 through self-restrained condensation of silanol moieties. The synthesized silicon carbide coated CoFe2O4 nanoparticles (CFSi) and uncoated CoFe2O4 (CFUC) are characterized using Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analyzer with simultaneous differential scanning calorimetry (TGA-DSC), Vibrating sample magnetometer (VSM), X-ray diffractometer (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX) and dynamic light scattering (DLS). The organic dye adsorption ability of capped particles was investigated using dyes with different functional moieties. The plausible mechanism of SiC capping, adsorption mechanism and the mode of interaction of different functional moieties are also elicited. The unique benefits of this approach include non-requirement of metal catalysts, hazardous chemicals, high temperature or pressure, long reaction time and exogenous initiators. Unlike the conventional approaches, this technique facilitates synthesis of fine magnetic nanoparticles with a uniform and robust ultrathin layer of silicon carbide. The results suggest that straight through channel dye removal by continuous feed through packed beds of CFSi particles under a magnetic field is possible without the need of centrifugation, precipitation, filtration, washing and ultrasonication.

Acid-treated clay materials (Southwestern Tunisia) for removing sodium leuco-vat dye : Characterization, adsorption study and activation mechanism

Abstract Clay deposits of El Haria formation (Jebel Stah of the Gafsa basin, Southwestern Tunisia) was treated with sulfuric acid to improve its surface properties and dye adsorption ability. Acid treatment was carried out at 60 °C, by varying time of treatment from 0 to 6 h. The influence of activation was investigated using X-ray Diffraction (XRD), chemical analysis, Fourier Transform Infra-Red (FTIR) spectroscopy, specific surface area (SSA), and cation exchange capacity (CEC). The raw clay contained a major phase of smectite and kaolinite, in addition to quartz, feldspars, calcite and dolomite as impurities. Acid treatment led to the dissolution of cations, such as Al3+, Mg2+ and Fe3+ from the octahedral sheets and thus increased surface acidity, specific surface area and porosity of the material. The surface area could be greatly changed as a function of time of treatment, and it increased from 450 to 590 m2 g−1. The adsorption ability of acid activated clay was investigated using sodium leuco-vat dye as a typical pollutant. The effects of contact time, pH and temperature were studied in batch mode. The adsorption equilibrium was analyzed by Freundlich and Langmuir models. The results revealed that Langmuir isotherm provided a better fit to the experimental data. The modified clay showed a higher removal efficiency for dye (88%) than raw material, with a maximum adsorption capacity of 15.45 mg L−1. Thermodynamic parameters suggested endothermic and physical nature.