Dye Adsorption Process Research Articles

Super functional anionic hydrolysis lignin for capturing dyes

Hydrolysis lignin is a major product of the enzymatic fractionation of lignocellulosic biomass and its functionalization plays a crucial role in valorizing this material. In this work, functional hydrolysis lignin-derived polymer (hydrolysis lignin-acrylic acid polymer, AA-HL) was generated to act as an adsorbent and coagulant for eliminating ethyl violet (EV) dye from solutions. AA-HL was partially soluble in water. The soluble fraction of the lignin polymer in the coagulation studies led to the complete dye removal from the solutions at a 6 mg/g dosage following the charge neutralization mechanism. The performance of insoluble AA-HL as an adsorbent was also investigated using a Quartz crystal microbalance with dissipation (QCM-D), and the results indicated the great adsorption of the dye to the insoluble AA-HL. The high stability of AA-HL adsorbent was also confirmed in the dye adsorption process at 40 ᵒC. Furthermore, the dye adsorption on AA-HL was promoted by increasing the ionic strength of the solution to 500 mM NaCl, suggesting the existence of the strong hydrophobic interaction between the dye moiety and AA-HL. The results suggested that soluble and insoluble super functional lignin derivatives can be produced from hydrolysis lignin with a strong affinity toward dyes.

Utilization of cationic polymer-modified fly ash for dye wastewater treatment

Reuse of modified fly ash for treatment of dye wastewaters is a promising new technology with the potential to mitigate two waste streams currently having negative effects on the environment. In the present study, cationic fly ash adsorbent was prepared by immobilizing with poly-epichlorohydrin-dimethylamine for treating reactive dye wastewaters. Characterization analyses confirmed that poly-epichlorohydrin-dimethylamine had been immobilized onto fly ash, and this immobilization could change the Zeta potential of fly ash from negative to positive throughout the range of pH from 3 to 11, but could not alter its crystal structure. Static adsorption analyses demonstrated that dye adsorption process was spontaneous and endothermic, and the experimental data were better in accord with pseudo-second-order kinetic model. Column experiments showed that cationic fly ash displayed a dramatically high dye adsorption capacity, which was over 1.5 times more than that of commercial activated carbon. Reusability study confirmed that synthesized cationic fly ash can be used repeatedly in column. Especially, in order to avoid secondary pollution, the generated disabled cationic fly ash adsorbent can be reused to produce polymer concretes as a functional filler. The present work can provide new insight into the utilization of modified fly ash for treating wastewaters.

Telechelic PEG‐polymers end‐capped with chromophores: Using as cationic reactive dyes and salt‐free dyeing properties on cotton fabrics

AbstractIn this article, telechelic polymers containing polyethylene glycol (PEG) moieties as space groups were combined with chromophores to synthesize cationic reactive dyes (BCD‐R, BCD‐Y, and BCD‐B). The salt‐free dyeing performance of these telechelic polymeric cationic reactive dyes on cotton fabrics was evaluated. The exhaustion and fixation of the dyes in salt‐free dyeing was above 89.33 and 77.22%, respectively. The color fastness of dry rubbing for the three dyes reached grade 4–5, and their color fastness to light reached grade 5–6. Their washing fastness also reached grade 4–5, except for that of BCD‐Y (grade 3–4). The results showed that the dyes possessed good leveling and build‐up properties and substantivity to cellulose fiber. The zeta potential (ξ‐potential) of dyed fabric was estimated, and it was found that the ξ‐potential of the fabrics increased after dying with telechelic polymeric cationic reactive dyes, and the more dye that was used, the greater ξ‐potential increase. The exhaustion curves of dyes were also determined, and they were much different from those of anionic reactive dyes. The adsorption kinetics and isotherms of BCD‐R were investigated. It was found that the pseudo‐second‐order kinetic model gave the best fit of the experimental data at all three tested dyeing temperatures (25, 45, and 65°C) with R2 values over 0.998. Both the Langmuir and Freundlich models could be used to describe the adsorption of BCD‐R onto cellulose fibers and the Langmuir model fit the experimental data better than the Freundlich model. The thermodynamic parameters (ΔG, ΔS, ΔH, and activation energy) of the dye adsorption process were researched further. The results indicated that the adsorption of BCD‐R onto cotton fibers was spontaneous and exothermic and that after adsorption onto the cotton fibers, the degree of freedom of the dye decreased.

Simultaneous Determination and Optimization of Titan Yellow and Reactive Blue 4 Dyes Removal Using Chitosan@hydroxyapatite Nanocomposites

Chitosan (CS) and hydroxyapatite (HA) nanocomposites have been prepared and used for the simultaneous removal of Titan Yellow (TY) and Reactive Blue 4 (RB 4) dyes from aqueous solutions in single and binary batch systems. Chitosan@hydroxyapatite nanocomposites (NCs) were characterized by diverse techniques such as EDX, FTIR, TGA, and FESEM. Derivative spectrophotometry (DS) was developed to the determination of TY and RB 4 in two-compound mixtures employing the ‘zero-crossing’ technique. The influence of operational variables (such as sorbent mass, contact time, pH, and initial concentration of dyes) on the dyes adsorption is evaluated. A response surface methodology based on a Hybrid central composite design is used to optimize the removal of dyes by CS@HA NCs through a batch adsorption process. In optimum conditions (pH = 4, sorbent dosage = 0.03 g TY (initial TY concentration) = 1100 mg L−1 and RB 4 (initial RB 4 concentration) = 950 mg L−1), the maximum uptake capacities of dyes were obtained 170.7 and 118.4 mg g−1 for TY and RB 4 dyes, respectively. The Langmuir isotherm model was convenient for elucidating the dye adsorption process in both single and binary solutions. The adsorption kinetics of both TY and RB 4 dyes were in best correlation with pseudo 2nd order model. The thermodynamic calculations elaborated that the adsorption of TY and RB 4 dyes was endothermic and spontaneous.

Kinetic and Thermal Studies of Adsorption of Allura Red Dye by Surface Functionalized Magnetite Nanoparticles

In the present study, chitosan functionalized magnetite nanoparticles (CS@MNPs) were synthesized by a simple and economical coprecipitation technique for efficient magnetic removal of allura red dye (ARD) by adsorption technique from the aqueous solution. Size and surface properties of the bare and surface functionalized MNPs were determined with the help of XRD and TEM technique. Surface functionalization of the bare MNPs was confirmed with the help of FT-IR spectroscopy and TGA techniques. Magnetic properties of the synthesized bare and functionalized MNPs were determined by VSM technique. The effect of various parameters including adsorbent dosages, contact time, temperature on adsorption capacity of the CS@MNPs for allura red dye were investigated with the help of UV-vis spectrophotometer. The pseudo second order kinetics and Langmuir adsorption isotherm model were found to fitted well with the adsorption process of dye onto the chitosan functionalized magnetite nanoparticles (CS@MNPs).

Adsorption of methyl red dye from aqueous solution onto eggshell waste material: Kinetics, isotherms and thermodynamic studies

In the last years, numerous studies were carried out to examine the utilization of low cost adsorbent as an alternative technique for the adsorption of dye. Hence, the main objective of this study is to evaluate the potentiality of eggshell powder (ESP) as an effective adsorbent for the adsorption of methyl red (MR) dye. The prepared adsorbent was characterized by Fourier-transform infrared spectroscopy (FTIR) and Thermo-gravimetric analysis (TGA). The effects of solution pH (2–10), adsorbent dosage (2–10 ​g/300 ​mL), contact time (0–180 ​min), initial dye concentration (20–100 ​mg/L) and temperature (25–55 ​°C) on the decolorization efficiency of MR were studied. The adsorption studies showed that ERP removed almost 82% of MR at the optimized conditions i.e. solution pH of 2, adsorbent dosages of 8 ​g/300 ​mL, initial dye concentration of 20 ​mg/L, contact time of 180 ​min and temperature of 25 ​°C. The pseudo-first order and second order kinetics models were employed to describe the kinetics data. Kinetic data were found to best fit pseudo second order kinetic model than pseudo first order kinetic. The adsorption isotherm study showed that adsorption experimental data were fitted well by Langmuir isotherm model as compared to Freundlich model. The maximum monolayer dye adsorption capacity (qmax) at pH of 2 and temperature of 25 ​°C was found to be 1.66 ​mg/g. Thermodynamic study showed that the adsorption process of MR dye onto ESP was endothermic in nature.

Adsorption removal of Congo red onto L-cysteine/rGO/PANI nanocomposite: equilibrium, kinetics and thermodynamic studies

In this paper, adsorption of Congo red (CR) onto L-cysteine decorated with reduced graphene oxide/polyaniline composite at room temperature was investigated. The morphology and structure properties of as-prepared nanocomposite were verified by UV–visible spectroscopy (UV–visible), powder X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), and Brunauer Emmett Teller (BET) studies. Effect ofabsorbent dosage, contact time, initial dye concentration and temperature were studied and optimal conditions for the adsorption process of Congo red dye were found. The obtained results indicated that isotherms data fitted well to Langmuir model. While kinetics data fitted well to the pseudo-second-order kinetic equation and the adsorption process was generally governed via intra-particle diffusion. Thermodynamic data showed that adsorption process of CR was endothermic and spontaneous in nature. At optimal conditions, the maximum adsorption capacity of CR was calculated and found to be 56.57 mg/g, which shows that L-cysteine functionalized reduced graphene oxide/polyaniline based nanocomposite can be efficiently used for wastewater management.

Polyaniline coated tungsten trioxide as an effective adsorbent for the removal of orange G dye from aqueous media.

In this work, the core–shell PANI@WO3 composite was obtained from the reaction of aniline monomer polymerization with WO3 particles; sodium persulfate was used as an oxidant. Various analytical techniques such as scanning electron microscopy (SEM-EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS) were used to characterize the as-prepared PANI@WO3 adsorbent, which well confirmed that the WO3 particles were coated by polyaniline polymer. The PANI@WO3 composite was tested as an adsorbent to remove reactive orange G (OG) for the first time. pH, adsorbent dose, contact time, initial dye concentration, and temperature were systematically investigated in order to study their effect on the adsorption process. The experimental findings showed that the PANI@WO3 composite has considerable potential to remove an aqueous OG dye. Langmuir and Freundlich's models were used to analyze the equilibrium isotherms of OG dye adsorption on the PANI@WO3 composite. As a result, the best correlation of the experimental data was provided by the Langmuir model, and the maximum capacity of adsorption was 226.50 mg g−1. From a thermodynamic point of view, the OG dye adsorption process occurred spontaneously and endothermically. Importantly, PANI@WO3 still exhibited an excellent adsorption capability after four regeneration cycles, indicating the potential reusability of the PANI@WO3 composite. These results indicate that the as prepared PANI@WO3 composite could be employed as an efficient adsorbent and was much better than the parent material adsorption of OG dye.

Applicability of gypsum in selective removal of anionic dye molecules from aqueous medium

This article describes how selectively anionic organic molecules could be removed from aqueous medium using naturally available gypsum (GS) adsorbent. Gypsum (CaSO4.2H2O) shows strong interactions with anionic dye molecules while it dos not show any affinity towards cationic dye molecules. We have shown the removal efficiency of gypsum taking chlorazole yellow (anionic dye) and methylene blue (cationic dye) as examples of adsorbates. The GS has been to be even more effective than activated carbon in attaining chlorazole yellow (CY) removal. Three well-known kinetic equations e.g. pseudo-first-order, pseudo-second order and intraparticle diffusion were exploited to interpret the experimental data. Results show best fitting with second order kinetic process with excellent regression coefficient (r2 = 0.99) for the adsorption process. The equilibrium data were analyzed exploiting some adsorption isotherm models. It was apparent that the Freundlich isotherm model superbly fitted for CY dye adsorption process. And the maximum adsorption capacity, Qm, was obtained as 12.85 mg g−1 at room temperature. The negative values of Gibb’s free energy change (ΔGo) suggests that the CY dye molecule adsorption process is spontaneous in nature. Moreover, negative enthalpy change (ΔHo) indicates the exothermic nature of the adsorption process. The outcome could be exploited where anionic organic molecules are required to be separated, selectively.

ЗАСТОСУВАННЯ КИСЛОТНО АКТИВОВАНОГО ЦЕОЛІТУ В ТЕХНОЛОГІЇ ОЧИЩЕННЯ СТІЧНИХ ВОД ВІД БАРВНИКІВ

The work aims to study the process of activation of natural zeolite by inorganic acids, in particular, HNO3and H3PO4to verify their effectiveness when extracting dyes from aqueous media in batch mode.It is proposed to use the method of purification with sorbents modified with mineral acids nitric, hydrochloric, and ortho-phosphate to increase the absorption capacity concerning water-soluble dyes. The analysis of the process of purification and neutralization of dyes in water systems with the help of zeolite of the Sokernyanskoye deposit was carried out experimentally. Chemical activation, which was carried out by the impregnation method, was used to improve the sorption properties. Samples of chemically activated zeolite were obtained. Due toacid activation, Al, K, Na, Ca, Mg, Fe ions are released, which release micro-and mesopores in the sorbent, which increases its porosity and improves sorption properties. The composition of activated natural mineral zeolite with HNO3, HCl, H3PO4acids were characterized. The chemical composition of activated zeolite was determined by X-ray fluorescence.The efficiency of acid-activated zeolite for the extraction of dyes from wastewater was tested. The dependences of the dye extraction process from model solutions using ordinary and acid-activated zeolite have been established. The dye content in the treated wastewater was determined by the photometric method. The kinetic regularities of the dye adsorption process during contact of natural and activated zeolite samples in the time interval every 6 h for 24 h have been established. It was found that the concentration of pollutants varies and depends on the type of acid and has a decisive influence on the obtained chemical properties of the modified samples.It is recommended to use zeolite activated with hydrochloric acid asa natural adsorbent at a dose of 4 g/dm3with a contact time of 24 hours. According to these technological parameters, the dye content in water decreases from 117 mg/dm3to 41 mg/dm3.The obtained results allow to significantly expand the knowledge about the areas of application of natural sorbents in various technological processes.

Acid red G dye removal from aqueous solutions by porous ceramsite produced from solid wastes: Batch and fixed-bed studies

AbstractA novel porous ceramsite was made of municipal sludge, coal fly ash, and river sediment by sintering process, and the performance of batch and fixed-bed column systems containing this material in the removal of acid red G (ARG) dye from aqueous solutions was assessed in this study. The results of orthogonal test showed that sintering temperature was the most important determinant in the preparation of porous ceramsite, and it possesses developed pore structure and high specific surface area. Batch experiment results indicated that the adsorption process of ARG dye toward porous ceramsite was a spontaneous exothermic reaction, which could be better described with Freundlich–Langmuir isotherm model (R2 > 0.992) and basically followed the pseudo-first-order kinetic equation (R2 > 0.993). Column experiment results showed that when the porous ceramsite was used as packing material, its adsorption capacity was roughly improved by 3.5 times compared with that in batch system, and the breakthrough behavior was simulated well with Yoon–Nelson model, with R2 > 0.954. This study suggested that the novelty man-made porous ceramsite obtained from solid wastes might be processed as a certain cost-effective treatment material fit for the dye removal in aqueous solutions.

Synthesis of chitosan hydrogel polymer for removal of radioactive organic research waste prior to treatment

ABSTRACT Chitosan hydrogel polymer (CHGP) has been exploited as the second most abundant natural material in the environment for preparing a new adsorbent with a low cost, higher removal capacity of dyes, good stability overworking pH range and environmentally safe for treating aqueous solutions of organic pollutants Arsenazo-III (Ar-III) and Alizarin Red S (ARS). The characteristics of the prepared polymer were revealed through infrared analysis (FTIR) as well as a scanning electron microscope (SEM). Various factors affecting the treatment process were studied through batch experiments. These factors are the agitation time, pH, different polymer weights, and the initial concentrations of Ar-III and ARS dyes in the solution plus temperature. The Freundlich and Langmuir isothermal models were applied and the equilibrium data showed that they fit well with the Langmuir model for both the reagents removal processes. Based on this model, the maximum capacity values were estimated at 99.9 and 62.5 mg/g for Ar-III and ARS at ambient temperature, respectively. In terms of kinetics, we find that the adsorption process of both dyes onto the prepared CHGP polymer corresponds to the pseudo-first-order mechanism. Also, a suggested reaction mechanism was established based on the electrostatic, hydrogen bonding, and mainly pH. Through practical experience the optimum conditions for efficient removal of both Ar-III and ARS reagents (dyes) from contaminated radioactive solutions by using CHGP are the initial dye concentration 100 mg L-1, pH = 6, shaking time 120 min. and the polymer dose 0.01 g at ambient temperature. Finally, the results showed that the prepared polymer (CHGP) could be promisingly applied in removing both Ar-III and ARS dyes from radioactive waste solutions.

Experimental and theoretical study of dyes adsorption process on chitosan-based cryogel

In this research, the adsorption of three synthetic dyes dissolved in an aqueous solution on chitosan cryogel beads (Q-C-EGDE) was compared. The effect of the pH of the solution on the adsorption capacity of each dyes was analyzed. Furthermore, the kinetics and adsorption isotherms were compared, at temperatures of 283.15 K, 303.15 K and 323.15 K, and the kinetic and adsorption equilibrium data were fitted to three mathematical models, respectively. The biosorbent was characterized by scanning electron microscopy (SEM), the nitrogen physisorption BET method and Fourier transform infrared spectroscopy (FTIR). The characterization results show that the cryogel is composed of low-surface, macroporous, porous grooved walls. The functional groups that took part in the adsorption were mainly amino groups (NH3+). When comparing the adsorption capacities, it was found that the dyes adsorb in the following order Blue 1 > Red 2 > Yellow 5 reaching capacities from 1600 mg/L to 850 mg/L. The results of the adsorption and mathematical modelling suggest that the process is regulated mainly by physisorption and is largely limited by mass transfer mechanisms within the cryogel, where the electrostatic charges present affect adsorption. The latter was corroborated by the Monte Carlo simulation.

Adsorption of Orange II Onto Zn2Al–Layered Double Hydroxide Prepared From Zinc Ash

The dye industry is one of the largest water consuming industries, and at the same time generates large quantities of wastewaters. The resulting wastewaters require proper treatment before discharge, because the dye contents have a negative effect on the water body and organisms present in it. The most efficient treatment method for water containing dyes is represented by adsorption processes. The challenge with these adsorption processes is to develop new, efficient, viable, and economic adsorbent materials. Therefore, in the present paper, the performance of Zn2Al-layered double hydroxide, prepared from an industrial waste (zinc ash) as a zinc source, was investigated in the Orange II dye adsorption process. The Zn2Al-layered double hydroxide prepared from secondary sources presents similar morphological and structural characteristics as those prepared from analytical grade reagents. The influence of initial dye concentration, adsorption time, solid:liquid ratio, pH, and temperature was evaluated in order to confirm the benefit of this waste valorization. A comparison with the reference Zn2Al-layered double hydroxide prepared from analytical grade reagents was performed and the results show that due to the small presence of impurities, the material prepared from zinc ash shows better adsorption capacities (qmax,exp = 42.5 mg/g at 293 K) than the material prepared from reagents (qmax,exp = 36.9 mg/g at 293 K), justifying the utilization of secondary sources for layered double hydroxides preparation. The proposed treatment process presents advantages from both economic and environmental protection point of view.

Study of adsorption of anionic dyes over biofabricated crystalline α-MnO2 nanoparticles.

The leaf extract of Ficus retusa plant was used for fabrication of α-MnO2 nanoparticles (NPs). The extract was utilized as a reducing agent for green synthesis of nanomaterial. The synthesis of nanocrystals was confirmed using different analytical techniques such as field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) spectroscopy and thermogravimetric analysis (TGA). The synthesis of NPs was studied over a wide range of temperatures from 80 to 800°C. It was found that perfectly crystalline α-MnO2 NPs were successfully synthesized at 800°C. The synthesized NPs were applied as an adsorbent for adsorption of azo dyes such as methyl red (MR) and methyl orange (MO) which are released as wastes from industries into water bodies and pollute the water. The removal efficiency was analysed and optimized depending on various parameters like pH, concentration of NPs, and contact time. The experimental data was explained by three isotherm models, viz. Langmuir, Freundlich and Temkin isotherms. Kinetic and thermodynamic studies of adsorption were also carried out, which depicted that the adsorption process of both dyes was exothermic in nature and followed pseudo-second-order kinetics. The results confirmed that NPs are easily fabricated through a green route and prove to be an excellent adsorbent for the removal of MO and MR dyes from their aqueous solutions. The maximum adsorption capacity of NPs synthesized was found to be 116.1mgg-1 and 74.02mgg-1 for MO and MR dyes, respectively. Graphical abstract.

Design and Synthesis of Novel NIR Dyes with Phosphonic Acid Derivative Anchoring Groups Aiming Towards Stable Dye-Sensitized Solar Cells

Introduction: The solar energy is a promising solution to the sustainable energy supply and the relevant environmental concerns. Production of the traditional solar cells is expensive and this poses difficulty for the mass-level implementation of this kind of solar cells. So, there has been a lot of effort and interest to propose cost-effective and efficient solar cells, where dye-sensitized solar cells (DSSCs) are one of the potential candidates. DSSCs have emerged due to their good photo conversion efficiency (PCE) beyond 12 % in spite of photon harvesting window mainly in the visible region (400-700 nm). Dyes are the “Heart” of the solar cells and anchoring group present in it not only controls the overall PCE but also stability of photo anode, which ultimately controls the stability of DSSCs. Amongst various anchoring groups, phosphonic acid has been widely reported to give improved stability to the DSSCs as compared to their most commonly used carboxylic acid anchoring group counterparts. Owing to huge possibilities of molecular structures, quantum chemical (QC) calculations have emerged as one of the potential tools for the prediction of their energetics and spectral behavior. The goal of this research is to propose and develop of novel near infrared (NIR) dyes bearing phosphonic acid groups having the capability of improved stability as well as PCE focusing on Donor-Acceptor-Donor framework bearing squaraine dyes. Experimental: In this work, a series of unsymmetrical squaraine (SQ) dyes such as SQ-143, SQ-148, SQ-151, SQ-157, SQ-159 bearing different phosphonic acid anchoring groups with the molecular structure as shown in the Fig. 1 were logically designed and subjected to QC calculations using 6-311G/DFT/B3PW91 and PCM model using ethanol solvent to judge their suitability as sensitizer before the synthesis. Some of the suitable dyes having favorable energetics have been synthesized by multistep synthetic route. Structural characterization and confirmation have been done by 1H NMR and Fab Mass techniques followed by their Photophysical characterizations in 5 µM ethanolic solution for electronic absorption spectral behavior. Adsorption behavior of these dyes on the mesoporous TiO2 has been investigated by adsorbing the respective dyes from their 0.1 mM solution in ethanol. Photovoltaic characterization was also performed after fabricating DSSCs based on 10-12 µm thick mesoporous TiO2 with adsorbed dyes from their 0.2 mM solution as photo anode, catalytic amount of Pt coated conductive glass as counter electrode and I-/I3 - as redox electrolyte. Results and Discussion: After the successful synthesis and structural characterizations, SQ dyes under investigation were subjected to their photophysical characterizations. It can be clearly seen from the solution as well as solid-state absorption spectra shown in the Fig. 1 that due to extended p-conjugation in SQ-148 and SQ-157, exhibit bathochromically shifted absorption maxima as compared to their SQ-143 and SQ-151 dye counterparts. At the same time, in spite of having two free –OH groups in the dyes SQ-148 and SQ-143, former exhibited less extent of the dye aggregation. A swift dye adsorption in combination with reduced aggregated species are highly desired for commercial applications. Investigation pertaining to the dye adsorption behavior on the TiO2 reveals the trend of SQ-143>SQ-148>SQ-157>SQ-151 suggesting that less aggregation tends to the relatively higher rate of dye adsorption. This can be attributed to the swift diffusion of the dye molecules in the nanopores of the mesoporous TiO2 during the dye adsorption process. Stability of the adsorbed dyes on the mesoporous TiO2 is another important parameter responsible to impart the stability to the DSSCs. This was conducted by investigating the dye binding strength based on dye desorption studies. Apart from their synthesis and photophysical characterizations, dyes were also used as sensitizer to fabricate the DSSCs and implication of the nature anchoring groups on photon harvesting and overall PCE was also investigated. Results on the photovoltaic performance revealed that newly designed dye SQ-159 makes a good compromise imparting improved stability as well as PCE amongst the dyes under investigation. Acknowledgement: SSP would like to express sincere thanks to the Japan Society for Promotion of Science for the financial support by Grant-in-Aid for scientific research (C) [Grant No.-18K05300] to carry out the research Figure 1

Biosorption performance and cell surface properties of a fungal-based sorbent in azo dye removal coupled with textile wastewater

In this work, the biosorption ability of Sarocladium sp. dried biomass to remove Remazol Black dye has been studied. Optimum inoculum size and initial dye concentration were determined, and the salinity effect on the dye removal was evaluated. In the following, kinetic and isotherm of the adsorption were studied, and the adsorbent characteristics were determined using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, zeta potential, and Brunauer–Emmett–Teller analysis. Based on the results, maximum and minimum dye removal was determined at 1000 and 200 mg L−1 of Remazol Black dye as 54.39 and 24.02 mg g−1, respectively. Among the various azo dyes including Reactive yellow 145, Reactive blue 222, Reactive red 43, Direct blue 21, and Acid blue 161, dye removal capability of 87.96–97.43% was obtained. The solution salinity showed positive effect on the biosorption process. The biomass pretreatment with calcium nitrate enhanced the removal capacity by 70.48% and the maximum reduction in dye removal (− 61%) was obtained when the fungal biomass was treated by sodium hydroxide. Biosorption kinetic follows the first-pseudo-order model, and the obtained data best fits both Langmuir and Freundlich isotherm models. The maximum adsorption capacity of dried biomass for dye removal was 58.48 mg g−1. Based on FTIR, zeta potential value and pretreatment results, Yoshida H-binding, dipole–dipole H-binding, π–π and n–π interactions were probably involved in the dye adsorption process. The results showed that biomass has a high potential for different dyes adsorption from real textile wastewater. The present study declares the high potential of Sarocladium sp. dried biomass as an effective and inexpensive biosorbent which can be used for bio-treatment of effluents with multi-dyes.

Green Synthesis of Flowers-Like Nanostructured Calcium Silicates: Kinetics and Adsorption Isotherms of Malachite Green Dye Removal from Polluted Water

Microwaves assisted synthesis of flowers-like nanostructured calcium silicates from marble sawing powder and silica fume wastes has been successfully done in a very short reaction time, energy saving and cost effective approach. XRD analysis of the synthesized powder showed that wollastonite; CaSiO 3 is the predominant phase. Cotton-like structures which composed mainly of coalescenced tiny cubes in the range of less than 1000 nm in size have been obtained as observed from FESEM images. The maximum monolayer adsorption capacity, q max at 30 °C of Malachite green was found to be 17.12 mg/g. Different parameters affect the adsorption process as; pH, sorbent dose, dye concentration and temperature was experimented. The kinetics studies indicated that the adsorption kinetics of MG dye on calcium silicate followed the pseudo- first order reaction. The experimental results also showed that the Malachite green adsorption is fitted better to Freundlich isotherm model. The dye adsorption process was spontaneous, exothermic reaction as indicated from thermodynamic studies. Diffusion model reveal that intra-particle diffusion mechanism was not the sole rate-limiting step in this adsorption.

Influence of the alkyl chain length of surfactant on adsorption process: A case study

To investigate the effect of alkyl chain length of surfactant on the adsorption process behavior, the present study was applied the adsorption of anionic methyl orange (MO) dye using mineral pumice (NP) as natural adsorbent, and Dodecyltrimethylammonium bromide (DTAB), Tetradecyltrimethylammonium bromide (TTAB), and Cetyltrimethylammonium bromide (CTAB) modified pumice as namely DMP, TMP, and CMP, respectively. Due to the differences in the alkyl chain length of the surfactants, the effect of chain length on the MO dye adsorption process can be evaluated. For an understanding of the physical and chemical structure of adsorbents, XRF, SEM, BET, and FTIR analyses were performed. The effect of contact time, initial MO concentration, adsorbent dosage, and solution pH was studied. Langmuir, Freundlich, Jovanovic and Temkin isotherm models were used for fitting of the experimental data. Based on the results of the isotherm models and also calculating the errors of each model, the highest match was obtained with Langmuir isotherm, and the maximum adsorption capacities for NP, DMP, TMP, and CMP were 6.43, 18.13, 28.60, and 31.73 mg/g, respectively. Also, the results of kinetic studies showed that the data are in maximum agreement with the pseudo-second-order kinetic model. Therefore, it can be concluded that an extended surfactant chain increases the adsorption capacity, and it can be found that one of the effective factors in the adsorption processes is the hydrophobic interactions of the modifiers.

Preparation and Characterization of a three-component hydrogel composite and study of kinetic and thermodynamic applications of adsorption of some positive and negative dyes from their aqueous solutions

The composite hydrogels (AAC-co-AM)-g-MCC based on microcrystalline cellulose (MCC) and poly(acrylic acid-co-acrylamide) were synthesized by free radical polymerization in an aqueous suspension of (MCC) which use as initiator for the reaction, the structure and surfaces of hydrogels was characterized and analyzed with (FTIR), Xray diffraction spectroscopy (XRD), (FE-SEM) and thermogravimetric analysis (TGA).The adsorption mechanisms understand the dyes on surface of composite by thermodynamic Study of adsorption process Which include measuring the Enthalpy and Entropy and Gibbs energy, In addition, the dyes adsorption process accorded with pseudo-second-order rate equation, It also showed that adsorption isotherm of the composite Hydrogel is govern by Langmuir and Friendlish equations, The adsorption of dyes is a Physical adsorption, Based on structure analysis and adsorption kinetics of composite, the adsorption process was controlled by the ion-exchange mechanism.