Kinetics of RAFT homopolymerisation of vinylbenzyl chloride in the presence of xanthate or trithiocarbonate

The RAFT homopolymerisation of vinylbenzyl chloride (VBC, or chloromethyl styrene CMS) in bulk and in acetonitrile initiated by α,α′-azoisobutyronitrile (AIBN) in the presence of two chain transfer agents, O-ethyl-S-(1-methyloxycarbonyl)ethyl xanthate and dibenzyl trithiocarbonate, is presented. The reactions were monitored by ¹H nuclear magnetic resonance spectroscopy in the presence of 1,2-dichloroethane as the internal standard. Such a technique enabled one to assess the evolutions of log ([M]₀/[M]) and VBC conversion vs. time that were shown to be linear. Tobolsky’s law allowed one to determine the square of the propagation rate constant to the termination rate constant, $k_{\text{p}}^2/k_{\text{te}}$, of VBC, that worths about 3 × 10^?3 l mol^?1 s^?1 at 80 °C. On the one hand, the controlled character of the polymerisation involving dibenzyl trithiocarbonate was confirmed by size exclusion chromatography. On the other hand, the molar masses of poly(VBC) polymerised in the presence of the xanthate agent decreased with monomer conversion, as already stated with the macromolecular design via interchange of xanthates (MADIX) polymerisation of styrene.     

Enantioselective hydrolysis of styrene oxide with the epoxide hydrolase of Sphingomonas sp. HXN-200

The soluble bacterial epoxide hydrolase (EH) from Sphingomonas sp. HXN-200 catalyzed the enantioselective hydrolysis of racemic styrene oxide to give (S)-styrene oxide with an enantiomeric ratio (E) of 21–23 in aqueous buffer, better than any reported native EHs. The ring opening of the styrene oxide with this EH was only at the terminal position for the (S)-enantiomer and at the terminal and benzylic position in an 87:13 ratio for the (R)-enantiomer. Enzymatic hydrolysis of the styrene oxide in a two-liquid phase system significantly reduced autohydrolysis, thus improving the E to 26–29. Hydrolysis of 160 mM styrene oxide with cell-free extract (CFE) of Sphingomonas sp. HXN-200 (10 mg protein/mL) in aqueous buffer and n-hexane (1:1) for 30.7 h afforded 39.2% (62.7 mM) of (S)-styrene oxide in >99.9% ee. The lyophilized CFE was proven to be stable, while the rehydrated lyophilized CFE powder was successfully used for the hydrolysis of 320 mM styrene oxide in the two-liquid phase system, yielding 40.2% (128.6 mM) of (S)-styrene oxide in >99.9% ee after 13.8 h. No inhibitory effect of the diol product on the hydrolysis was observed when the diol concentration was lower than 476 mM, suggesting a straightforward process for the hydrolysis of up to 1 M styrene oxide.     

Reactivity of sugar cane bagasse as a natural solid phase extractor for selective removal of Fe(III) and heavy-metal ions from natural water samples

This work introduces the feasibility of using sugar cane bagasse (SCB) – a sugar cane industry waste – as a selective solid phase extractor for Fe(III). The order of metal uptake capacities in μmol g^?1 for the extraction of six tested metal ions from aqueous solution using static technique is Fe(III) > Cu(II) > Pb(II) > Zn(II) > Cd(II) > Co(II). Since SCB exhibits remarkable binding characteristics for Fe(III), special interest was devoted for optimizing its uptake and studying its selectivity properties under static and dynamic conditions. In this respect, batch experiments were carried out at the pH range 1.0–4.0, initial concentration of metal ion (10–100 μmol), weight of phase (25, 50, 75, 100, 125 and 150 mg) and shaking time (10, 30, 45, 60, 90, 120 and 150 min). FT-IR spectra of SCB before and after uptake of Fe(III) were recorded to explore the nature of the functional groups responsible for binding of Fe(III) onto the studied natural biosorbent. The equilibrium data were better fitted with Langmuir model (r² = 0.985) than Freundlich model (r² = 0.934). Moreover, Fe(III) sorption was fast and completed within 60 min. The adsorption kinetics data were best fitted with the pseudo-second-order type. As a view to find a suitable application of SCB based on its unique property as a benign sorbent, it was found that, Fe(III) spiked natural water samples such as doubly distilled water (DDW), drinking tap water (DTW), natural drinking water (NDW), ground water (GW) and Nile River water (NRW) was quantitatively recovered (>95.0%) using batch and column experiments, with no matrix interferences.     

Study on the performance of different types of three-dimensional chromatographic systems

The maximum achievable performance of possible types of three-dimensional chromatographic systems (LC × LC × LC) has been investigated. The Pareto-optimization approach was applied to establish a trade-off between three main objectives (total peak capacity, analysis time and dilution of the sample) and Pareto-front values were obtained. The performances of ^xLC × ^xLC × ^xLC (three-dimensional separation in space), ^tLC × ^tLC × ^tLC (three-dimensional separation in time) and the hybrid ^xLC × ^xLC × ^tLC system were compared mutually and with two-dimensional chromatographic systems. It was found that ^xLC × ^xLC × ^xLC performs best in terms of maximum achievable peak capacity in shortest analysis time. Based on current thin-layer-chromatography performance it should be possible to obtain a peak capacity of 50,000 within 20 min. If contemporary column-packing standards can be upheld the achievable limit is approximately 50% higher. However, in an ^xLC × ^xLC × ^xLC chromatographic system analytes remain in the separation domain after the analysis, which complicates the detection. Use of an ^xLC × ^xLC × ^tLC system with elution in the last dimension alleviates the detection problem. The maximum achievable peak capacity in the same analysis time is lower for ^xLC × ^xLC × ^tLC than for ^xLC × ^xLC × ^xLC. Using the same (reasonable) length of the separation domain (e.g. a cube 200 × 200 × 200 mm) for both systems, it is possible to achieve peak capacities of 78,000 for ^xLC × ^xLC × ^tLC operated in the gradient mode, which is twice higher than for an ^xLC × ^xLC × ^xLC system. A three-dimensional (three-column) time-based ^tLC × ^tLC × ^tLC system does not greatly improve the performance of ^tLC × ^tLC in terms of (maximum) peak capacity and (minimum) analysis time. Dilution factors in ^tLC × ^tLC × ^tLC are very high. Decreasing the dilution has a detrimental influence on the peak capacity. The trade-off between these objectives is of crucial importance. The influence of several parameters (length of the separation domain, particle size, etc.) on the performance of chromatographic systems was investigated, optimal ranges were found.     

Diels-Alder reaction with cyclopentadiene and electronic structures of (η5-cyclopentadienyl)M(CO)x(η1-N-maleimidato) (M = Fe,Mo, W,x = 2 or 3)

Diels-Alder reaction of (η⁵-cyclopentadienyl)M(CO)_x(η¹-N-maleimidato) complexes (M = Fe, Mo, W, x = 2 or 3) with cyclopentadiene has been studied. The observed order of reactivity was: N-ethylmaleimide > W complex > Mo complex > Fe complex. The X-ray structures of the adducts have been determined for M = W and Fe. DFT calculations on the starting complexes have been performed to explain the observed reactivity order.     

A green resolution–separation process for aliphatic secondary alcohols

In order to obtain both enantiomers of aliphatic secondary alcohols via a greener method, the four-step resolution–separation process involving lipase-catalyzed enantioselective esterification and hydrolysis as well as two separation procedures both via heterogeneous azeotropic distillation was developed. (S)-2-Pentanol (ee = 98.6%), (R)-2-pentanol (ee >99%), (S)-2-octanol (ee = 98.2%), and (R)-2-octanol (ee = 98.5%) were all produced in high purity (>98%) and high yield (>90%). In addition to the two model substrates, this method could also be applied to the resolution of other aliphatic secondary alcohols.     

Influence of the polymerisation time on the porous and chromatographic properties of monolithic poly(1,2-bis(p-vinylphenyl))ethane capillary columns

In order to elucidate the effect of the polymerisation time on the morphology of styrene based monolithic support materials, continuous poly(1,2-bis(p-vinylphenyl))ethane (BVPE) rods were synthesised in 1.0 ml glass vials by thermally initiated free radical polymerisations of BVPE in the presence of porogens (toluene, decanol) and a,a′-azoisobutyronitrile (AIBN) as initiator at 65 °C for different polymerisation times (60, 90, 150, 300 and 600 min). Porosity parameters like pore-size-distribution and total porosity were investigated by mercury intrusion porosimetry, while the specific surface area of the BVPE monolithic supports was determined by N₂-adsorption (BET) measurements. An untypical bimodal pore-size-distribution comprising a high fraction of both mesopores (2–50 nm) and macropores (mainly flow-channels in the micrometer range) was observed as a result of the stepwise decrease of the polymerisation time. In consequence of the significant changes of the pore-size-profile, shortening the polymerisation time also resulted in enhanced total porosity due to enlarged flow-channel diameters and increased surface area according to the presence of a considerable amount of mesopores. Results upon the porosity profile of the support are further confirmed by SEM images of monoliths polymerised for different time periods. Since mesoporosity and high surface area of the chromatographic support material play key roles in the interaction and thus retention of low-molecular-weight compounds, polymerisation time should also affect the chromatographic properties and applicability of these polymers. To study the influence of the polymerisation time towards the separation efficiency of small molecules on BVPE capillary columns (200 μm I.D., 8 cm), a mixture of homologous alkylbenzenes was chosen for column evaluation. In accordance with the observations of the porous properties of BVPE stationary phases, the rapid and high resolution separation of a range of low-molecular-weight compounds on monolithic BVPE supports were successfully realised. The methodical reduction of the polymerisation time has been demonstrated to be a simple and effective tool to tailor the porous properties of organic monoliths to provide novel polymer-based stationary phases with porous properties adequate for the rapid and high resolution chromatography of small organic molecules.     

Highly selective solid-phase extraction of trace Pd(II) by murexide functionalized halloysite nanotubes

The originality on the high efficiency of murexide modified halloysite nanotubes as a new adsorbent of solid phase extraction has been reported to preconcentrate and separate Pd(II) in solution samples. The new adsorbent was confirmed by Fourier transformed infrared spectra, X-ray diffraction, scanning electron microscope, transmission electron microscope and N₂ adsorption–desorption isotherms. Effective preconcentration conditions of analyte were examined using column procedures prior to detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of pH, the amount of adsorbent, the sample flow rate and volume, the elution condition and the interfering ions were optimized in detail. Under the optimized conditions, Pd(II) could be retained on the column at pH 1.0 and quantitatively eluted by 2.5 mL of 0.01 mol L^?1 HCl–3% thiourea solution at a flow rate of 2.0 mL min^?1. The analysis time was 5 min. An enrichment factor of 120 was accomplished. Common interfering ions did not interfere in both separation and determination. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 42.86 mg g^?1 for Pd(II).The detection limit (3σ) of the method was 0.29 ng mL^?1, and the relative standard deviation (RSD) was 3.1% (n = 11). The method was validated using certified reference material, and has been applied for the determination of trace Pd(II) in actual samples with satisfactory results.     

Thermodynamic and isotherm studies of the biosorption of Cu(II), Pb(II), and Zn(II) by leaves of saltbush (Atriplex canescens)

The Freundlich and Langmuir isotherms were used to describe the biosorption of Cu(II), Pb(II), and Zn(II) onto the saltbush leaves biomass at 297 K and pH 5.0. The correlation coefficients (R²) obtained from the Freundlich model were 0.9798, 0.9575, and 0.9963 for Cu, Pb, and Zn, respectively, while for the Langmuir model the R² values for the same metals were 0.0001, 0.1380, and 0.0088, respectively. This suggests that saltbush leaves biomass sorbed the three metals following the Freundlich model (R² > 0.9575). The K_F values obtained from the Freundlich model (175.5 · 10⁻², 10.5 · 10⁻², and 6.32 · 10⁻² mol · g⁻¹ for Pb, Zn, and Cu, respectively), suggest that the metal binding affinity was in the order Pb > Zn > Cu. The experimental values of the maximal adsorption capacities of saltbush leaves biomass were 0.13 · 10⁻², 0.05 · 10⁻², and 0.107 · 10⁻² mol · g⁻¹ for Pb, Zn, and Cu, respectively. The negative ΔG^∘ values for Pb and the positive values for Cu and Zn indicate that the Pb biosorption by saltbush biomass was a spontaneous process.     

Radiation-induced grafting of styrene into poly(vinylidene fluoride) film by simultaneous method with two different solvents

Radiation-induced grafting of styrene into poly(vinylidene fluoride) (PVDF) films with 0.125 mm thickness at doses of 1 and 2.5 kGy in the presence of a styrene/N,N-dimethylformamide (DMF) solution (1:1, v/v) and at doses of 20, 40 and 80 kGy in presence of a styrene/toluene solution (1:1, v/v) at dose rate of 5 kGy h^?1 was carried out by the simultaneous method under nitrogen atmosphere and room temperature, using gamma rays from a Co-60. The films were characterized before and after modification by calculated grafting yield (GY %), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). GY results shows that grafting increases with dose, and the grafting of styrene was confirm by FT-IR due to the new characteristic peaks and by the TG and DSC attributed to changes in thermal behavior of the grafted material. Results showed that the system allows the controlled grafting of styrene into PVDF using gamma rays at doses as low as 1 kGy in DMF.     

Evaluation of Schiff bases of 2,5-dimercapto-1,3,4-thiadiazole as photostabilizer for poly(methyl methacrylate)

The photostabilization of poly(methyl methacrylate) (PMMA) films by Schiff bases of 2,5-dimercapto-1,3,4-thiadiazole compounds was investigated. The PMMA films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the hydroxyl index with irradiation time. The changes in viscosity average molecular weight of PMMA with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (Φ_cs) of these complexes in PMMA films was evaluated and found to range between 4.19 × 10^?5 and 8.75 × 10^?5. Results obtained showed that the rate of photostabilization of PMMA in the presence of the additive followed the trend:[1] > [2] > [3] > [4] > [5].According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them, UV absorption, peroxide decomposer, and radical scavenger for photostabilizer mechanisms were suggested.     

Simultaneous determination of diastereoisomeric and enantiomeric impurities in SSS-octahydroindole-2-carboxylic acid by chiral high-performance liquid chromatography with pre-column derivatization

SSS-Octahydroindole-2-carboxylic acid (SSS-Oic) is a key intermediate used in the synthesis of some angiotensin-converting enzyme (ACE) inhibitors. The separation of diastereoisomers and enantiomers of Oic was performed using a pre-column derivatization chiral HPLC method. Phenyl isothiocyanate (PITC) was used as the derivatization reagent. Three PITC derivatives of Oic stereoisomers were separated on an Ultron ES-OVM chiral column (150 mm × 4.6 mm, 5 μm). Derivatization conditions such as reaction temperature, reaction time and derivatization reagent concentration were investigated. The chromatographic conditions for separation of the three PITC-Oic derivatives were optimized. The method was successfully applied in the diastereoisomeric and enantiomeric purity test of SSS-Oic.     

Competitive adsorption of toxic heavy metal contaminants by gum kondagogu (Cochlospermum gossypium): A natural hydrocolloid

Gum kondagogu (Cochlospermum gossypium), a naturally occurring tree biopolymer, is exploited as a biosorbent to remove metal ions from aqueous solutions. The removal efficiency of toxic metals by gum kondagogu was determined quantitatively in the order Cd²⁺ > Cu²⁺ > Fe²⁺ > Se²⁺ > Pb²⁺ > total Cr > Ni²⁺ > Zn²⁺ > Co²⁺ > As²⁺ at pH 5.0 ± 0.1 and temperature 25 ± 2 °C by inductively coupled plasma-mass spectrometry (ICP-MS). The biosorption (%) of various metal ions tested was found to be in the range of 97.3–16.7%, at pH 5.0. The morphological and mechanisms of interaction of toxic metal ions with gum kondagogu were assessed by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDXA) and X-ray diffraction (XRD) spectrum. The analysis indicated that biosorption process included morphological changes, precipitation, complexation and ion exchange mechanism for the removal of metal ions by the gum. XRD analysis indicated the amorphous nature of gum kondagogu, which facilitate metal biosorption. The metal ions adsorption leads to its deposition on the gum kondagogu matrix in a crystalline state.     

Selective Separation of Re(VII) and Tc(VII) by Xerogel Microcapsules Enclosing TOA Extractant

Special attention has been given to the separation and recovery of VII-group elements, Tc and Re, in relation to the partitioning of high-level liquid waste (HLLW) generated from the nuclear fuel reprocessing process. In this study, a tertiary amine (tri-n-octylamine, TOA), which is effective for the extraction of oxoanions, was encapsulated in Ca and H-types of alginate xerogel polymers (CaALG, HALG). The uptake behaviors of TcO4^-and ReO4⁻ (substitute of Tc) in the presence of HNO3 were examined by batch method using TOA-xerogel microcapsules (TOA-CaALG, TOA-HALG). The uptake of TcO4- in the presence of 0.1 M HNO3 was readily attained within 5 h, and a relatively large uptake(%) above 90% was obtained. The uptake(%) of Re(VII) for TOA-CaALG in the presence of 0.01∼0.1 M HNO3 was estimated to be about 90%, while gradually decreasing with HNO3 concentration, indicating that the extraction of HNO3 with TOA became dominant in this process: R3NH⁺NO3 (o) + ReO4 (aq) ↔ R3NH⁺ReO4 (o) + NO3 (aq). The order of the uptake(%) for different oxoanions in the presence of 0.01∼5 M HNO3 was Re(VII) > Zr(IV)> Se(VI) > Mo(VI) > Te(VI). The elution study of Tc(VII) revealed 95% and 99% of recovery with 5 M and 7 M HNO3, respectively. The chromatographic separation of Re(VII) from simulated HLLW (28 components of waste solution, SW-11E, JAEA) as well as from mixed solution was accomplished by the stepwise elution techniques using a column packed with TOA-MCs. The Re(VII) ions were effectively eluted with 5 M HNO3, and a relatively large recovery(%) of 98.60% was obtained. Other elements were eluted with H2O and 2 M HNO3. Thus the TOA-xerogel microcapsules are effective for the selective separation of Tc(VII) from HLLW.     

Enantiomeric separation of a melatonin agonist Ramelteon using amylose-based chiral stationary phase

A new simple isocratic chiral liquid chromatographic method was developed for the enantiomeric purity of Ramelteon[(S)-N-[2-(1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl) ethyl]-propionamide], a melatonin agonist in bulk drugs. The chromatographic separation was achieved on Chiralpak AD-H, 250 mm × 4.6 mm, 5 μm column using a mobile phase system consisting of n-hexane, ethanol and methanesulfonic acid in the ratio of 900:100:0.1 (v/v/v). The mobile phase was pumped on the column at the flow rate of 1 mL min^?1. Addition of methane sulfonic acid in the mobile phase enhanced chromatographic efficiency and resolution between the enantiomers. The resolution between the enantiomers was found to be more than four. The developed method was subsequently validated and proved to be accurate and precise. The experimentally established limit of detection and quantification of (R)-enantiomer were found to be 25.5 and 77.2 ng ml^?1, respectively, for 20 μl injection volumes. The percentage recovery of (R)-enantiomer was ranged from 98.5 to 101.9 in bulk drug samples of Ramelteon. The stability of Ramelteon sample in analytical solution was checked for about 48 h at room temperature and was found to be stable for about 48 h. The proposed method was found to be suitable and accurate for the quantitative determination of (R)-enantiomer in drug substance.     

High contrast ratio and fast switching polymeric electrochromic films based on water-dispersible polyaniline-poly(4-styrenesulfonate) nanoparticles

We prepared polyaniline-poly(4-styrenesulfonate) nanoparticles (PANI/PSS-NPs) by chemical oxidation polymerization in aqueous solution. We investigated the potential of the PANI/PSS-NPs to be used as an anode electrode for electrochromic devices and the effect of Li⁺ insertion (or deinsertion) kinetics and diffusion of Li⁺. A uniform electrochromic layer of PANI/PSS-NPs with a size of ca. 28 nm could be obtained by a solution process, specifically spin coating. The PANI/PSS-NPs film has a high Li⁺ diffusion coefficient (～7.7 × 10^?9 cm² s^?1) and low charge transfer resistance (～99 Ω), which result in its having a fast electrochromic response time (coloring time <1.7 s, bleaching time <2.4 s), and high coloration efficiency (>108 cm² C^?1).     

Multinuclear NMR and theoretical investigation on interactions between diperoxovanadate complex and 4-picoline-like ligands

To understand the 4-substituting group effects of organic ligands in pyridine ring on the reaction equilibrium, the interactions between a series of 4-picoline-like ligands and [OV(O₂)₂(D₂O)]^?/[OV(O₂)₂(HOD)]^? in solution were explored by the combined use of multinuclear (¹H, ¹³C, and ⁵¹V) magnetic resonance, DOSY, and variable-temperature NMR in 0.15 mol/L NaCl ionic medium for mimicking the physiological condition. Some direct NMR data are given for the first time. The reactivity among the 4-picoline-like ligands is 4-picoline > isonicotinate > isonicotinamide > ethyl isonicotinate. The competitive coordination results in the formation of a series of new six-coordinated peroxovanadate species [OV(O₂)₂L]^n? (L = 4-picoline-like ligands, n = 1 or 2). The results of density functional calculations provide a reasonable explanation on the relative reactivity of the 4-picoline-like ligands. Solvation effects play an important role in these reactions.     

Double-layer capacitance of waste coffee ground activated carbons in an organic electrolyte

Using ZnCl₂ activation we prepared a series of carbon electrodes from waste coffee grounds to study the effect of mesopores on double-layer capacitance in a tetraethyl ammonium tetrafluoroborate/acetonitrile electrolyte. The activated carbon with the largest mesopore volume achieved an energy density of 34 Wh kg^?1 at low current loads, and significantly retained an energy density of 16.5 Wh kg^?1 and specific capacitance of more than 100 F g^?1 at fast charge–discharge rates (20 A g^?1). The effect of mesopores on capacitance at fast charge–discharge rates is discussed.     

Dependence of enthalpic pairwise self-interactions on ionic strength: Some 2-deoxy and N-acetyl monosaccharides in aqueous NaCl solutions at T = 298.15 K

The dilution enthalpies of four derivatives of monosaccharides, namely 2-deoxy-d-glucose (2-DGlu), N-acetyl-d-glucosamine (GluNAc), 2-deoxy-d-galactose (2-DGal) and N-acetyl-d-galactosamine (GalNAc), in aqueous NaCl solutions of various molalities (b = 0–3.0 mol · kg⁻¹) have been determined respectively at T = 298.15 K by isothermal titration calorimetry (MicroCal ITC200). The corresponding values of enthalpic pairwise self-interaction coefficients (h₂) have been calculated according to the McMillan–Mayer theory. It was found that across the range studied of ionic strength (I) or molality (b = I), the h₂ coefficients are all positive, in the order h₂ (GluNAc) > h₂ (GalNAc) > h₂ (2-DGlu) > h₂ (2-DGal), and decrease gradually after increasing first up to a maximum at b ≈ 1.5 mol · kg⁻¹. The effects of ionic strength (I) on the trends of h₂ have been discussed from the point of view of complex (solute + solute) and (solute + solvent) interactions in solutions.     

Bengal gram seed husk as an adsorbent for the removal of dyes from aqueous solutions – Column studies

A continuous fixed bed (column) study was carried out by using seed husk of Bengal gram (Cicer arietinum) (SHBG) as a biosorbent for the removal of direct dye, Congo red (CR) from aqueous solutions. The effects of important factors, such as the value of initial pH, the flow rate, the influent concentration of CR, bed depth, particle size of SHBG, foreign ions and regeneration of CR were studied. The effect of similar type of direct dyes like direct turquoise blue 86 (DTB) and direct black 38 (DB) on the adsorption of CR in column containing SHBG is also studied by keeping other parameters constant. The studies confirmed that the breakthrough curves were dependent on flow rate, initial dye concentration, size of SHBG, initial pH of solution of CR and bed depth. The bed depth service time analysis (BDST) model was applied at different bed depths to predict the breakthrough curves. The model is found suitable for describing the biosorption process of the dynamic behaviour of the SHBG column and the data were in good agreement with BDST model. When the flow rate was 0.67 mL/min and the influent concentration of CR was mg L⁻¹, the column capacity was 6.572 mg g⁻¹. The removal capacity of SHBG was more in case of CR (6.572 mg g⁻¹) compared to other similar direct dyes of DTB (1.984 mg g⁻¹) and DB (1.612 mg g⁻¹). The removal of CR was enhanced in the presence of foreign ion potassium (8.308 mg g⁻¹) and decreased in the presence of calcium (5.58 mg g⁻¹). 120 ml of acetone is required for the completion of regeneration of the column and the total amount of CR recovered in this case. All the results suggested SHBG as a potential adsorbent for removal of CR from aqueous solution so that the rate of bio-sorption process is rapid.