Insight the mechanism of MgAl/layered double hydroxide supported on rubber seed shell biochar for Remazol Brilliant Violet 5R removal

The ever-increasing concentration of Remazol Brilliant Violet 5R discharged mainly from textile industry had cause serious environmental issues towards human and the surrounding ecosystem. Therefore, solving the issue related to dye contamination is seriously important. In this research study, MgAl/layered double hydroxide supported on rubber seed shell biochar (RSSB) had been prepared for Remazol Brilliant Violet 5R (RBV5R) dye adsorption. BET surface area and pore volume of RSSB were found to be 132.40 m²/g and 0.0732 cm³/g, respectively with presence of LDH metals on the RSSB surfaces. The batch adsorption studies showed that RBV5R uptake capacity was significantly enhanced (125.88 mg/g) compared to pristine RSSB (58.69 mg/g) at initial RBV5R concentration, contact time, adsorption temperature and pH of 300 mg/l, 1440 min, 60 °C and pH 2, respectively. The equilibrium and kinetic adsorption data were best fitted into the Freundlich and pseudo-first order model, respectively. The thermodynamic study confirmed the RBV5R adsorption was endothermic in nature and governed by physisorption process. All these findings signified that the MgAl/LDH-RSSB is a promising adsorbent for treating wastewater containing RBV5R dye.     

Adsorption treatment and recovery of the hazardous dye, Brilliant Blue FCF, over bottom ash and de-oiled soya

Two waste materials-bottom ash, a power plant waste, and de-oiled soya, an agricultural waste-are meticulously and successfully used as adsorbent for the removal and recovery of a hazardous triphenylmethane dye, Brilliant Blue FCF. Both the materials were characterized by chemical analysis, IR, DTA, SEM and XRD studies. Their physical characteristics like surface area, porosity, density and loss on ignition were also determined. The adsorption of the dye over both materials was achieved under different pH, adsorbate concentration, sieve size, adsorbent dosage, contact time and temperature, etc. conditions. For both the systems Langmuir and Freundlich adsorption isotherm models were applied and, based on these models, useful thermodynamic parameters were calculated. For both the adsorbents, the kinetic measurements indicate that the adsorption process follows first order kinetics and film diffusion and particle diffusion mechanisms are operative at lower and higher concentrations, respectively, in each case. By percolating the dye solution through fixed-bed columns the bulk removal of the Brilliant Blue FCF was carried out and necessary parameters were determined to find out the percentage saturation of both the columns. Recovery of Brilliant Blue FCF was made by eluting dilute NaOH of pH 11 through each column.     

Titania nanowires as substrates for sensing and photocatalysis of common textile industry effluents

Sensing and photocatalysis of textile industry effluents such as dyes using mesoporous anatase titania nanowires are discussed here. Spectroscopic investigations show that the titania nanowires preferentially sense cationic (e.g. Methylene Blue, Rhodamine B) over anionic (e.g. Orange G, Remazol Brilliant Blue R) dyes. The adsorbed dye concentration on titania nanowires increased with increase in nanowire dimensions and dye solution pH. Electrochemical sensing directly corroborated spectroscopic findings. Electrochemical detection sensitivity for Methylene Blue increased by more than two times in magnitude with tripling of nanowire average length. Photodegradation of Methylene Blue using titania nanowires is also more efficient than the commercial P25-TiO₂ nanopowders. Keeping illumination protocol and observation times constant, the Methylene Blue concentration in solution decreased by only 50% in case of P25-TiO₂ nanoparticles compared to a 100% decrease for titania nanowires. Photodegradation was also found to be function of exposure times and dye solution pH. Excellent sensing ability and photocatalytic activity of the titania nanowires is attributed to increased effective reaction area of the controlled nanostructured morphology.     

Removal of Reactofix Navy Blue 2 GFN from aqueous solutions using adsorption techniques

The wheat husk, an agricultural by-product, has been activated and used as an adsorbent for the adsorption of Reactofix Navy Blue 2 GFN from aqueous solution. In this work, adsorption of Reactofix Navy Blue 2 GFN on wheat husk and charcoal has been studied by using batch studies. The equilibrium adsorption level was determined to be a function of the solution pH, adsorbent dosage, dye concentration and contact time. The equilibrium adsorption capacities of wheat husk and charcoal for dye removal were obtained using Freundlich and Langmuir isotherms. Thermodynamic parameters such as the free energies, enthalpies and entropies of adsorption were also evaluated. Adsorption process is considered suitable for removing color, COD from waste water.     

Removal of Reactive Yellow 84 from aqueous solutions by adsorption onto hydroxyapatite

The adsorption of a reactive dye, Reactive Yellow 84, from aqueous solution onto synthesized hydroxyapatite was investigated. The experiments were carried out to investigate the factors that influence the dye uptake by the adsorbent, such as the contact time under agitation, absorbent dosage, initial dye concentration, temperature and pH of dye solution. The experimental results show that the amount of dye adsorbed increases with an increase in the amount of hydroxyapatite. The maximum adsorption occurred at the pH value of 5. The equilibrium uptake was increased with an increase in the initial dye concentration in solution. The experimental isotherm data were analyzed using Langmuir isotherm equation. The maximum monolayer adsorption capacity was 50.25 mg/g. The adsorption has a low temperature dependency and was endothermic in nature with an enthalpy of adsorption of 2.17 kJ mol⁻¹.     

Effective removal of anionic dyes from aqueous solutions by novel polyethylenimine-ozone oxidized hydrochar (PEI-OzHC) adsorbent

The adsorption behavior of the anionic dyes Remazol Brilliant Blue R (RBBR) and Reactive Black 5 (RB5) from aqueous solutions by polyethylenimine ozone oxidized hydrochar (PEI-OzHC) was investigated. The adsorption capacities of both dyes increased with functionalization of PEI in the hydrochar adsorbent. The results of surface characterization (FTIR, BET, TGA, elemental analysis, and SEM) showed that PEI modification greatly enhanced the adsorbent surface chemistry with a slight improvement of adsorbent textural properties. In addition, the adsorption kinetics data showed an excellent adsorption efficiency as reflected in the high removal percentages of the anionic dyes. The Isotherm results indicated that RBBR and RB5 dye adsorption occurred via monolayer adsorption, and chemisorption was the rate-controlling step. The PEI-OzHC adsorbent possesses higher maximum Langmuir adsorption capacity towards RBBR (218.3 mg/g) than RB5 (182.7 mg/g). This increase in adsorption capacity is attributed to the higher number of functional groups in RBBR that interact with the adsorbent. This study reveals the potential use of adsorbents derived from pine wood hydrochar in municipal as well as industrial wastewater treatment. Furthermore, surface chemistry modification is proven as an effective strategy to enhance the performance of biomass-derived adsorbents.     

Adsorption studies on the removal of Vertigo Blue 49 and Orange DNA13 from aqueous solutions using carbon slurry developed from a waste material

Waste material (carbon slurry), from fuel oil-based generators, was used as adsorbent for the removal of two reactive dyes from synthetic textile wastewater. The study describes the results of batch experiments on removal of Vertigo Blue 49 and Orange DNA13 from synthetic textile wastewater onto activated carbon slurry. The utility of waste material in adsorbing reactive dyes from aqueous solutions has been studied as a function of contact time, temperature, pH, and initial dye concentrations by batch experiments. pH 7.0 was found suitable for maximum removal of Vertigo Blue 49 and Orange DNA13. Dye adsorption capacities of carbon slurry for the Vertigo Blue 49 and the Orange DNA13 were 11.57 and 4.54 mg g(-1) adsorbent, respectively. The adsorption isotherms for both dyes were better described by the Langmuir isotherm. Thermodynamic treatment of adsorption data showed an exothermic nature of adsorption with both dyes. The dye uptake process was found to follow second-order kinetics.     

响应面优化微波辅助Fenton法降解活性艳蓝KN-R

以活性艳蓝KN-R为降解目标,通过单因素和响应面法优化了微波辅助Fenton法降解工艺.探讨了FeSO₄·7H₂O浓度、30%H₂O₂投加量、溶液酸度、微波功率、反应与静置时间等因素对脱色率的影响,并利用响应面法优化了脱色条件.结果表明,在FeSO₄·7H₂O物质的量浓度为0.10 mmol/L、30%H₂O₂加入量为1.74 mL/L、溶液pH值为3.8、微波功率为222 W、微波时间为6 min、静置时间为40 min时,活性艳蓝KN-R脱色率可达95.26%.     

Environment-friendly bio-materials based on cotton-carbon aerogel for strontium removal from aqueous solution

Cotton carbon aerogel was prepared and used as a new water-insoluble adsorbent to remove strontium from aqueous solution. A comprehensive study on adsorption of strontium by cotton carbon aerogel was conducted regarding the effects of initial pH, temperature, initial strontium concentration, and contact time. The adsorbent was characterized by SEM. The results of regression analysis indicated that the adsorption process largely depends on the pH and temperature. The optimum pH range for adsorption process is 5–7. The maximum removal efficiency of strontium from aqueous solution was 60.16%. Moreover, cotton carbon aerogel adsorbent has good reusability before the fifth reuse.     

Application of artificial neural networks for formulation and modeling of dye adsorption onto multiwalled carbon nanotubes

In this study, an artificial neural network (ANN) has been developed to predict the adsorption amount of dye (methylene blue) onto multiwalled carbon nanotubes. Batch experiments have been carried out to obtain experimental data. Important parameters in the adsorption system such as initial dye concentration, adsorbent dosage, temperature, pH and contact time have been used as the inputs of the network, while the output is the final concentration of dye in aqueous solution after adsorption. The neural network structure has been optimized by testing various training algorithms and different number of neurons in a hidden layer. An empirical equation for determination of final dye concentration in aqueous solutions after adsorption has been developed by using the weights of the optimized network. The results of the optimized ANN have been compared with conventional models in equilibrium and kinetic fields. According to error analysis and determination coefficient, the ANN was found to be the most appropriate model to describe this adsorption process. Sensitivity analysis showed that initial dye concentration, pH and contact time are the most effective parameters in this process. The influence percentages of these parameters on the output were 28, 24 and 24 %, respectively.     

Low-temperature synthesis of nanoparticle-assembled, transparent, and low-crystallized hydroxyapatite blocks

The mesoporous carbon CMK-3 adsorbent was prepared, characterized, and used for the removal of anionic methyl orange dye from aqueous solution. Adsorption experiments were carried out as batch studies at different contact time, pH, initial dye concentration, and salt concentration. The dye adsorption equilibrium was rapidly attained after 60 min of contact time. Removal of dye in acidic solutions was better than in basic solutions. The adsorption of dye increased with increasing initial dye concentration and salt concentration. The equilibrium data were analyzed by the Langmuir and Freundlich models, which revealed that Langmuir model was more suitable to describe the methyl orange adsorption than Freundlich model. Experimental data were analyzed using pseudo-first-order and pseudo-second-order kinetic models. It was found that kinetics followed a pseudo-second-order equation. Thermodynamic study showed that the adsorption was a spontaneous and exothermic process.     

Highly Efficient Methylene Blue Dye Removal by Nickel Molybdate Nanosorbent

Removing methylene blue (MB) dye from aqueous solutions was examined by the use of nickel molybdate (α-NiMoO₄) as an adsorbent produced by an uncomplicated, rapid, and cost-effective method. Different results were produced by varying different parameters such as the pH, the adsorbent dose, the temperature, the contact time, and the initial dye concentration. Adsorbent dose and pH had a major removal effect on MB. Interestingly, a lower amount of adsorbent dose caused greater MB removal. The amount of removal gained was efficient and reached a 99% level with an initial methylene blue solution concentration of ≤160 ppm at pH 11. The kinetic studies indicated that the pseudo-second-order kinetic model relates very well with that of the obtained experimental results. The thermodynamic studies showed that removing the MB dye was favorable, spontaneous, and endothermic. Impressively, the highest quantity of removal amount of MB dye was 16,863 mg/g, as shown by the Langmuir model. The thermal regeneration tests revealed that the efficiency of removing MB (11,608 mg/g) was retained following three continuous rounds of recycled adsorbents. Adsorption of MB onto α-NiMoO₄ nanoparticles and its regeneration were confirmed by Fourier transform infrared spectroscopy (FTIR) analysis and scanning electron microscopy (SEM) analysis. The results indicated that α-NiMoO₄ nanosorbent is an outstanding and strong candidate that can be used for removing the maximum capacity of MB dye in wastewater.     

Study of congo red adsorption on the polyaniline and polypyrrole

Polyaniline (PANI) and polypyrrole (PPY) were synthesized via in situ chemical oxidative polymerization and are used as adsorbents for removal of Congo Red (CR) dye from aqueous solution. The effects of various experimental parameters including pH of the solution, contact time, initial concentration, adsorbent dosage, and temperature on adsorption of CR by PANI and PPY were systematically investigated. The experimental results showed that the adsorption efficiency was increased with contact time and adsorbent dosage. The maximum removal efficiency was found after 45 minutes of solid/liquid contact with adsorbent doses of 0.4 and 1.73?g/L for PANI and PPY, respectively. The kinetic data were best fitted by the pseudo-second-order model. The adsorption equilibrium results were well fitted by the Langmuir isotherm model. These results suggest that the PANI and PPY can be used as alternative adsorbents for the treatment of wastewaters containing dyes.     

Adsorption study for removal of Congo red anionic dye using organo-attapulgite

The organo-attapulgite was prepared using hexadecyltrimethylammonium bromide (HTMAB) with equation equivalent ratio of HTMAB to CEC of attapulgite added and then used as adsorbent for the removal of Congo red (CR) anionic dye from aqueous solution. Adsorbent characterizations were investigated using infrared spectroscopy and X-ray diffraction. The effects of contact time, temperature, pH and initial dye concentration on organo-attapulgite adsorption for CR were investigated. The results show that the amount adsorbed of CR on the organo-attapulgite increase with increasing dye concentration, temperature, and by decreasing pH. The adsorption kinetics was studied with the pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and the rate constants were evaluated. It was found that the adsorption mechanisms in the dye/organo-attapulgite system follow pseudo-second-order kinetics with a significant contribution of film diffusion. Equilibrium data fitted perfectly with Langmuir isotherm model compared to Freundlich isotherm model, and the maximum adsorption capacity was 189.39 mg g⁻¹ for the adsorbent. Kinetic and desorption studies both suggest that chemisorption should be the major mode of CR removal by the organo-attapulgite. The results indicate that HTMAB-modified attapulgite could be employed as low-cost material for the removal of Congo red anionic dye from wastewater.     

Nanocomposite Silica Aerogel Activated Carbon: Preparation,Characterization and Application to Remove Lead(II) from Aqueous Solutions

Anovel nanocomposite adsorbent, Silica aerogel activated carbon (SA‐AC) has been prepared for the purpose of removing lead ions from aqueous solution in batch process. The nanocomposite was characterized by Fourier transform infrared spectra (FTIR) and scanning electron microscope (SEM). In the present investigation, Pb(II) adsorption experiments on nanocomposite were conducted on aqueous solution at different initial Pb(II) concentration, pH of the solution, adsorption temperature, adsorbent dosage and contact time. Optimum pH for the adsorption was found to be 6 with corresponding adsorbent dosage level of 0.5 g and 60 °C temperature. The equilibriumwas achieved within 30 min of contact time. It is remarkable that using the developed nanocomposite absorbent, more than 90% of Pb(II) can be removed under desirable experimental conditions. The efficiency of the ions adsorption was determined using atomic absorption spectroscopy. Langmuir and Freundlich isotherm models were applied to analyze the experimental data. The best interpretation for the experimental data was given by the Freundlich isotherm equation. Desorption experiments by elution of the adsorbent with nitric acid show that the nanocomposite could be reused without significant losses of its initial properties.     

Dye Pollutants removal from Waste water using Metal Oxide Nanoparticle embedded Activated Carbon: An Immobilization study

This study evaluated the feasibility of Rhodamine-B dye (Rh B) removal from aqueous solution, using Lead-Iron Oxide nanoparticles Loaded Activated Carbon (FePbO@AC). The parameters like pH, contact time, adsorbent/adsorbate dosage and temperature on adsorption was studied. Optimized conditions are pH of 7.0, 25?min contact time, 50?ppm of dye concentration and 200?mg of adsorbent concentration. The kinetics of adsorption was calculated using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The calculations revealed that the pseudo-second-order kinetic equation best-fit the adsorption data. The Langmuir isotherm model best fit the equilibrium data. The maximum sorption capacity (Q_max) for dye is 1000?mg Rh B/g FePbO@AC. Change in entropy (ΔS), Gibb’s free energy change (ΔG), and enthalpy (ΔH) were calculated for the adsorption of Rh B dye.     

Adsorption of Pb(II) and Ni(II) From Aqueous Solution by a High-Capacity Industrial Sewage Sludge-Based Adsorbent

In the present study, adsorption of Ni(II) and Pb(II) from aqueous solution was investigated using activated carbon synthesized with industrial wastewater sludge. The synthesized adsorbent was analyzed using nitrogen adsorption–desorption and Fourier transfer infrared (FTIR) techniques. Batch adsorption mode was used to evaluate the effect of solution pH, contact time, adsorbent dose, initial metal ion concentration, and temperature on the adsorption capacity of the synthesized adsorbent. The kinetic data were analyzed using different kinetic models. The pseudo-second-order equation gave the best fit to the experimental data for both metal ions. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherm models. The results showed that the data obtained for the Ni(II) and Pb(II) adsorption are in good agreement with the Langmuir model. The Langmuir mono-layer maximum adsorption capacities for Ni(II) and Pb(II) ions were estimated to be 74.06 and 88.76 mg g^?1 at 25°C, respectively. In addition, the thermodynamic studies proved that the adsorption process of both metals could be considered endothermic.     

Biosorption behaviors of uranium (VI) from aqueous solution by sunflower straw and insights of binding mechanism

Uranium (VI)-containing water has been recognized as a potential longer-term radiological health hazard. In this work, the sorptive potential of sunflower straw for U (VI) from aqueous solution was investigated in detail, including the effect of initial solution pH, adsorbent dosage, temperature, contact time and initial U (VI) concentration. A dose of 2.0 g L^?1 of sunflower straw in an initial U (VI) concentration of 20 mg L^?1 with an initial pH of 5.0 and a contact time of 10 h resulted in the maximum U (VI) uptake (about 6.96 mg g^?1) at 298 K. The isotherm adsorption data was modeled best by the nonlinear Langmuir–Freundlich equation. The equilibrium sorption capacity of sunflower straw was observed to be approximately seven times higher than that of coconut-shell activated carbon as 251.52 and 32.37 mg g^?1 under optimal conditions, respectively. The positive enthalpy and negative free energy suggested the endothermic and spontaneous nature of sorption, respectively. The kinetic data conformed successfully to the pseudo-second-order equation. Furthermore, energy dispersive X-ray, fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that U (VI) adsorption onto sunflower straw was predominantly controlled by ion exchange as well as complexation mechanism. The study revealed that sunflower straw could be exploited for uranium remediation of aqueous streams as a promising adsorbent.     

Effect of polyethyleneimine ion on the sorption of a reactive dye onto Leacril fabric: electrokinetic properties and surface free energy of the system

Data are presented on the kinetics, electrokinetics, and surface free energy in the process of adsorption of polyethyleneimine (PEI) as a pretreatment of Leacril, later dyed with the reactive dye Remazol Brilliant Blue R (RBBR). The electrokinetic potential of Leacril is negative, due probably to the presence of sulfonate and sulfate end-group onto Leacril fibers. The zeta potential of Leacril decreases in absolute value as a function of NaCl concentration in solution, probably because of compression of the electrical double layer. The zeta potential of Leacril as a function of the concentration of PEI in solution increases because of the adsorption of PEI ions through chemical reaction between the sulfonate end-groups of Leacril and the amine groups of PEI. The adsorption kinetics shows that an increase in the concentration of PEI, brings about an increase in the amount of RBBR adsorbed onto the fiber. This may be an indication of the chemical reaction between the reactive groups of the polyelectrolyte and dye molecules. The behavior of the surface free energy of the systems involved confirms these conclusions.