Cross-linked quaternary chitosan as an adsorbent for the removal of the reactive dye from aqueous solutions

Adsorption of reactive orange 16 by quaternary chitosan salt (QCS) was used as a model to demonstrate the removal of reactive dyes from textile effluents. The polymer was characterized by infrared (IR), energy dispersive X-ray spectrometry (EDXS) analyses and amount of quaternary ammonium groups. The adsorption experiments were conducted at different pH values and initial dye concentrations. Adsorption was shown to be independent of solution pH. Three kinetic adsorption models were tested: pseudo-first-order, pseudo-second-order and intraparticle diffusion. The experimental data best fitted the pseudo-second-order model, which provided a constant velocity, k₂, of 9.18 × 10⁻⁴ g mg⁻¹ min⁻¹ for a 500 mg L⁻¹ solution and a value of k₂, of 2.70 × 10⁻⁵ g mg⁻¹ min⁻¹ for a 1000 mg L⁻¹ solution. The adsorption rate was dependent on dye concentration at the surface of the adsorbent for each time period and on the amount of dye adsorbed. The Langmuir isotherm model provided the best fit to the equilibrium data in the concentration range investigated and from the isotherm linear equation, the maximum adsorption capacity determined was 1060 mg of reactive dye per gram of adsorbent, corresponding to 75% occupation of the adsorption sites. The results obtained demonstrate that the adsorbent material could be utilized to remove dyes from textile effluents independent of the pH of the aqueous medium.     

Adsorptive removal of reactive azo dye from an aqueous phase onto charfines and activated carbon

This contribution presents results pertaining to the adsorptive removal of reactive azo dye onto a low cost coal-based adsorbent (charfines) and its efficiency in dye colour sorption was compared with activated carbon (F400). Batch sorption studies were performed and the results revealed that charfines demonstrated an ability to adsorb the reactive azo dye. The sorption interaction of reactive dye on to charfines obeys the first order rate equation. The sorption data indicates that the adsorptive removal of the dye from aqueous solution is rather complex involving both boundary layer diffusion and intraparticle diffusion; however, intraparticle diffusion appears to be the rate limiting step. Isothermal data fit well with the rearranged Langmuir adsorption model. Desorption studies further indicated that the charfines facilitated chemisorption in the process of dye sorption while, activated carbon resulted in physisorption interaction. Dye sorption is found to be dependent on the aqueous phase pH and the dye uptake is greater at lower pH.     

Comparisons of adsorbent cost for the removal of zinc (II) from aqueous solution by carbon nanotubes and activated carbon

The reversibility of Zn2+ sorption onto single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs) and powdered activated carbon (PAC) was investigated to evaluate their repeated availability performance in water treatment. Under the same conditions, the Zn2+ sorption capacity of SWCNTs and MWCNTs was more than that of PAC and could be maintained after several cycles of water treatment and regeneration. A statistical analysis on the replacement cost of these adsorbents based on the best-fit regression of the measured equilibrium capacity of each water treatment cycle was also conducted. The results revealed that the SWCNTs and MWCNTs could be reused through a large number of water treatment cycles and thus appear cost-effective in spite of their high unit cost at the present time.     

Studies on the removal of Pb(II) from wastewater by activated carbon developed from Tamarind wood activated with sulphuric acid

The low-cost activated carbon were prepared from Tamarind wood material by chemical activation with sulphuric acid for the adsorption of Pb(II) from dilute aqueous solution. The activated carbon developed shows substantial capacity to adsorb Pb(II) from dilute aqueous solutions. The parameters studied include physical and chemical properties of adsorbent, pH, adsorbent dose, contact time and initial concentrations. The kinetic data were best fitted to the Lagergren pseudo-first-order and pseudo-second order models. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. The maximum removal of lead(II) was obtained 97.95% (experimental) and 134.22 mg/g (from Langmuir isotherm model) at initial concentration 40 mg/l, adsorbent dose 3g/l and pH 6.5. This high uptake showed Tamarind wood activated carbon as among the best adsorbents for Pb(II).     

Fabrication of superparamagnetic adsorbent based on layered double hydroxide as effective nanoadsorbent for removal of Sb (III) from water samples

In this study, the superparamagnetic adsorbent as Fe@Mg‐Al LDH was synthesised by different methods with two steps for the removal of heavy metal ions from water samples. An easy, practical, economical, and replicable method was introduced to remove water contaminants, including heavy ions from aquatic environments. Moreover, the structure of superparamagnetic adsorbent was investigated by various methods including Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and vibrating sample magnetometer. For better separation, ethylenediaminetetraacetic acid ligand was used, forming a complex with antimony ions to create suitable conditions for the removal of these ions. Cadmium and antimony ions were studied by floatation in aqueous environments with this superparamagnetic adsorbent owing to effective factors such as pH, amount of superparamagnetic adsorbent, contact time, sample temperature, volume, and ligand concentration. The model of Freundlich, Langmuir, and Temkin isotherms was studied to qualitatively evaluate the adsorption of antimony ions by the superparamagnetic adsorbent. The value of loaded antimony metal ions with Fe@Mg‐Al LDH was resulted at 160.15 mg/g. The standard deviation value in this procedure was found at 7.92%. The desorption volume of antimony metal ions by the adsorbent was found to be 25 ml. The thermodynamic parameters as well as the effect of interfering ions were investigated by graphite furnace atomic absorption spectrometry.     

In vivo study of anti‐epidermal growth factor receptor antibody‐based iron oxide nanoparticles (anti‐EGFR‐SPIONs) as a novel MR imaging contrast agent for lung cancer (LLC1) cells detection

Superparamagnetic iron oxide nanoparticles (SPIONs) conjugated with anti‐epidermal growth factor receptor monoclonal antibody (anti‐EGFR‐SPIONs) were characterised, and its cytotoxicity effects, ex vivo and in vivo studies on Lewis lung carcinoma (LLC1) cells in C57BL/6 mice were investigated. The broadband at 679.96 cm⁻¹ relates to Fe–O, which verified the formation of the anti‐EGFR‐Mab with SPIONs was obtained by the FTIR. The TEM images showed spherical shape 20 and 80 nm‐sized for nanoparticles and the anti‐EGFR‐SPIONs, respectively. Results of cell viability at 24 h after incubation with different concentrations of nanoprobe showed it has only a 20% reduction in cell viabilities. The synthesised nanoprobe administered by systemic injection into C57BL/6 mice showed good Fe tumour uptake and satisfied image signal intensity under ex vivo and in vivo conditions. A higher concentration of nanoprobe was achieved compared to non‐specific and control, indicating selective delivery of nanoprobe to the tumour. It is concluded that the anti‐EGFR‐SPIONs was found to be as an MR imaging contrast nanoagent for lung cancer (LLC1) cells detection.Inspec keywords: toxicology, biomedical MRI, lung, magnetic particles, biomedical materials, nanofabrication, nanomagnetics, transmission electron microscopy, nanomedicine, superparamagnetism, nanoparticles, iron compounds, proteins, cellular biophysics, molecular biophysics, cancer, tumours, Fourier transform infrared spectraOther keywords: MR imaging contrast agent, LLC1, superparamagnetic iron oxide nanoparticles, Lewis lung carcinoma cells, ex vivo conditions, cell viability, antiepidermal growth factor receptor antibody‐based iron oxide nanoparticles, antiEGFR‐SPION, lung cancer cell detection, antiepidermal growth factor receptor monoclonal antibody, cytotoxicity effects, C57BL‐6 mice, antiEGFR‐Mab, FTIR spectra, TEM, spherical shape, incubation, nanoprobe concentrations, systemic injection, Fe tumour uptake, image signal intensity, in vivo conditions, time 24.0 hour, Fe₃ O₄      

Integration of Cynodon dactylon and Muraya koenigii plant extracts in amino‐functionalised silica‐coated magnetic nanoparticle as an effective sorbent for the removal of chromium(VI) metal pollutants

Immobilised magnetic nanoparticles are extensively used owing to their superparamagnetic nature, surface interaction, and binding specificity with the appropriate portentous substances. The present research focuses on the development of a portentous, robust carrier, which integrates the silica‐coated amino‐functionalised magnetic nanoparticle (AF‐MnP) with the plant extracts of Cynodon dactylon (L1) and Muraya koenigii (L2) for the stable and enhanced removal of hazardous hexavalent chromium pollutant in the wastewater. Vibrating sample magnetometer (M _s – 45 emu/g) determines the superparamagnetic properties; Fourier‐transform infrared spectroscopy determines the presence of functional groups such as NH₂, Si–O–Si, C=C; high‐resolution transmission electron microscopy, field emission scanning electron microscope and energy‐dispersive X‐ray spectroscopy determine the size of the green adsorbents in the range of 20 nm and the presence of elements such as Fe, N, and Si determines the efficacy of the synthesised silica‐coated AF‐MnP. The AF‐MnP‐L1 shows the maximum adsorption capacity of 34.7 mg/g of sorbent calculated from the Langmuir isotherm model and the process follows pseudo‐second‐order kinetics. After treatment, the adsorbents can be easily separated from the solution in the presence of an external magnetic field and are reused for nine cycles after acid treatment with the minimal loss of adsorption efficiency.     

Graphene oxide-sulfated lanthanum oxy-carbonate nanocomposite as an adsorbent for the removal of malachite green from water samples with application of statistical optimization and machine learning computations

Sulfated lanthanum oxy-carbonate nanorods (S-La₂O₂(CO₃) NRs) was synthesized by the reverse micelle microemulsion method and then used to modify graphene oxide nanosheets to synthesize of graphene oxide-sulfated lanthanum oxy-carbonate (GO-S-La₂O₂(CO₃)) nanocomposite. By characterization of S-La₂O₂(CO₃) NRs and GO-S-La₂O₂(CO₃) nanocomposite by the Fourier Transform-Infrared (FT-IR) Spectrophotometry, Field Emission-Scanning Electron Microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), Transmission Electron Microscopy (TEM) and X-ray diffraction analysis (XRD), GO-S-La₂O₂(CO₃) was used for treatment of malachite green (MG). To find the optimum removal percentage (RP), influencing parameters were investigated by the response surface methodology based on central composite design (RSM-CCD). Adsorption mechanism was evaluated by Dubinin–Radushkevich (D-R), Langmuir, Temkin, Freundlich (two parameter equations) and Sips (Three parameter equations) isotherms and based on the results the adsorption of MG into the GO-S-La₂O₂(CO₃) nanocomposite obeyed by the Freundlich isotherm with the maximum adsorption capacity of 555.5 mg g^?1. Also, the results of kinetic analysis show that the adsorption of MG onto the GO-S-La₂O₂(CO₃) nanocomposite followed by the pseudo second order kinetic model. For estimation of adsorption behavior, different machine learning techniques are used and based on the results; ANFIS model has the confidential operation because of fuzzy procedure and flexibility of data mining in distributed adsorption data.     

Clarified sludge (basic oxygen furnace sludge) – an adsorbent for removal of Pb(II) from aqueous solutions – kinetics, thermodynamics and desorption studies

The basic oxygen furnace waste generated in steel plant has been used as a low cost adsorbent for the removal of Pb(II) from aqueous solution. The effect of pH, adsorbent dosage, initial metal ion concentration, contact time and temperature on adsorption process was studied in batch experiments. Results of the equilibrium experiments showed that the solution pH was the key factor affecting the adsorption characteristics. Optimum pH for the adsorption was found to be 5 with corresponding adsorbent dosage level of 5 g/L. The equilibrium was achieved within 1 h of contact time. Kinetics data were best described by pseudo second order model. The effective particle diffusion coefficient of Pb(II) is the order of 10⁻¹⁰ m²/s. The maximum uptake was 92.5 mg/g. The adsorption data can be well fitted by Freundlich isotherm. The result of the equilibrium studies showed that the solution pH was the key factor affecting the adsorption. External mass transfer analysis was also carried out for the adsorption process. The thermodynamic studies indicated that the adsorption is spontaneous and endothermic. The sorption energy (10.1745 kJ/mol) calculated from Dubinin–Radushkevich isotherm indicated that the adsorption process is chemical in nature. Desorption studies were carried out using dilute mineral acids to elucidate the mechanism of adsorption. Application studies were carried out considering the economic viewpoint of wastewater treatment plant operations.     

Preparation and surface properties of mesoporous silica particles modified with poly(N-vinyl-2-pyrrolidone) as a potential adsorbent for bilirubin removal

The surface of silica particles was modified with polyvinyl pyrrolidone (PVP) through sol–gel process. The different experimental techniques, i.e., thermogravimetric analysis (TGA and DTG), nitrogen adsorption, scanning electron microscopy (SEM), laser diffraction analysis (LDA), fourier transform spectroscopy (FTIR) are used to characterize the pure non-functionalized and functionalized silicas containing different amount of PVP. It was shown that PVP-modified silica samples have well developed porous structure; the values of specific surface area for PVP-modified silicas are in the range of 140–264 m² g⁻¹. While the non-functionalized silica shows the low surface area (S_BET = 40 m² g⁻¹). The BJH analysis showed that PVP can be used as an effective agent to increase an average pore size and total pore volume. The results indicate that PVP functionalized silicas show a potential as effective adsorbents for bilirubin removal compared to other available adsorbents.     

Synthesis and characterization of films based on cross linked blends of poly (vinylalcohol) and poly (vinylpyrrolidone) with glutaraldehyde for tissue engineering application

In these recent years, polymer blending is one of the significant interests by tissue engineering experts, since blending could produce biomaterials with enhanced physical and biological properties compare to the parent materials. In this context, present study aims at formation and characterization of polymeric blend of poly (vinylalcohol) and poly (vinylpyrrolidone) produced for tissue engineering application. Both polymers are blended at different concentrations to obtain films and nanofibers using solvent casting and electrospinning method respectively. The successful blending is confirmed by Fourier transform infrared spectroscopy, Field emission scanning electron microscope analysis and X‐ray diffraction. Later glutaraldehyde was added to chemically cross link the polymers and its effect was investigated on swelling and solubility properties of the blend. Experimental results reveal a relevant enhancement in the properties of poly (vinylalcohol) and poly (vinylpyrrolidone) blend when glutaraldehyde was added.     

Novel preparation and high electrical performance effect of Mn-doped ultra-high surface area activated carbon (USAC) as an additive for Ni hybrid capacitors

This paper reports the synthesis of various molar concentrations of manganese (Mn)-doped Ultra-High Surface area Activated Carbon (USAC) additives and their efficient use as cathode materials for supercapacitors. We synthesized the nanoparticles via a novel and facile dip-coating process and characterized them in detail by various analytical techniques. The SEM, EDAX, and XPS results showed that the Mn ions were successfully substituted on the USAC additives’ layered structure without any structural changes. The long cyclic stability of the as-prepared Mn-doped USAC additives was tested as a cathode material for supercapacitors at different current densities. The detailed experimental results showed that the Mn dopant content crucially determines the electrochemical performances of the USAC additives. Electrochemical measurements showed that the MnCEP-S600HTT with 0.10 mol% molar concentration of Mn dopant gives the best cycling performances. It delivers a discharge capacity of 262.9 mAh g^?1 after 100 cycles. Further increasing the current density to 1000 mA g^?1 allowed it to still maintain 253.6 mAh g^?1 after 200 cycles. We confirmed that the structure of Mn-doped USAC additives is an important pole to improve the structural stability and electrochemical properties.     

Synthesis and application of TiO<Subscript>2</Subscript>/SiO<Subscript>2</Subscript>/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles as novel adsorbent for removal of Cd(II), Hg(II) and Ni(II) ions from water samples

In the current study, SiO₂/Fe₃O₄ core–shell nanoparticles functionalized with TiO₂, using a simple method and application for removal of Cd(II), Hg(II) and Ni(II) ions from aqueous solution. The structure of the resulting product was confirmed by X-ray diffraction spectrometry, transmission electron microscopy (TEM), pH_pzc and Brunauer, Emmett and Teller methods. The average diameter of TiO₂/SiO₂/Fe₃O₄ nanoparticles according to TEM was obtained around 48 nm. In batch tests, the effects of pH, initial metal concentration, contact time and temperature were studied. Adsorption of metal ions was studied from both kinetics and equilibrium point of view. Maximum adsorption capacity of Cd(II), Hg(II) and Ni(II) on TiO₂/SiO₂/Fe₃O₄ nanoparticles was 670.9, 745.6 and 563.0 mg g^?1, respectively. Adsorption–desorption results showed that the reusability of nanoparticles was encouraging. This adsorbent was successfully applied to removal Cd(II), Hg(II) and Ni(II) ions in real samples including tap water, electronic wastewater and medical wastewater.     

Preparation of monodisperse cross-linked poly(glycidyl methacrylate)@Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@diazoresin magnetic microspheres with dye removal property

This article presented a versatile and robust adsorbent with both magnetic property and high adsorption capacity on the basis of poly(glycidyl methacrylate)@Fe₃O₄@diazoresin (PGMA@Fe₃O₄@DR) magnetic microspheres. The morphology, composition and magnetic properties of the magnetic microspheres were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, thermogravimetric analysis and the hysteresis loop measurements, respectively. The obtained microspheres were applied in the adsorption of dye in the wastewater. The effects of adsorption time, initial dye concentration, pH value and other conditions were explored. Results show that the magnetic microspheres were able to remove more than 98.5% of dyes in water under optimized conditions. The use of diazoresin not only protects the Fe₃O₄ particles from being corroded at different pH values, but also greatly improves the adsorption capacity.     

Simultaneous preconcentration and removal of iron, chromium, nickel with N,N'-etylenebis-(ethane sulfonamide) ligand on activated carbon in aqueous solution and determination by ICP-OES

In this study, Fe, Cr and Ni have been preconcentrated and removed by using N,N'-ethylenebis (ethane sulfonamide), (ESEN) ligand on activated carbon (AC) in aqueous solution. For this purpose, complexes between these metals and ligands have been investigated and used in preconcentration and removal studies. Factors which have affected adsorption of metals on activated carbon have been optimized. Adsorbed metals have been preconcentrated 10-fold and determined by ICP-OES. Interferences of Ca, Mg and K to this process have been investigated. The proposed method has been applied to the tap water and Ankara Creek water in order to Fe, Cr, and Ni remediation and preconcentration. Determination of metals by ICP-OES has been checked with standard reference material (NIST 1643e). The proposed method provides the recoveries of 87%, 108% and 106% for Fe, Cr and Ni, respectively, in preconcentration. It also provides the removal of Fe, Cr and Ni by 93%, 100% and 100% removal from waters, respectively.     

The structure of Ba3W2O9; an example of face-shared octahedra with tungsten (VI)

The structure of Ba₃W₂O₉ has been determined from powder x-ray diffraction data and found to be the same as in Cs₃Tl₂Cl₉. Two-thirds of the octahedral sites between hexagonal closest-packed BaO₃ layers (ABAB…) are filled by the tungsten atoms. The enneaoxo W₂O₉^6? group represents the first crystal chemistry example of tungsten (VI) in a face-sharing arrangement. Infrared and Raman data are consistent with overall 32 (D₃) site symmetry. Crystallographic and spectroscopic evidence supports a covalent bonding model with oxygen pπ → metal dπ stabilization of this tungsten (VI) phase.