Biosorption of Zn by dried biomass of Euglena gracilis from aqueous solutions

The effect of different concentrations of EDTA on instrumented root canal walls

The capability of cow hoof (CH) to remove Zn(II) from aqueous solution under the influence of sorbent size, solution pH, contact time, and sorbent dosage was investigated through batch studies. Equilibrium studies were conducted at three different temperatures (298, 308, and 318 K) by contacting different concentrations of Zn(II) solution with a known weight of cow hoof. The biosorption of Zn onto cow hoof was found to increase with increase in the mass of sorbent used while the biosorption efficiency was found to decrease with increase in sorbent particle size. The optimum conditions of pH 4 and contact time of 60 minutes were required for maximum removal of Zn(II) by cow hoof (mesh size 212 µm). The equilibrium data were modelled using Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. The data were best fitted by Langmuir model. The kinetic data were analysed using Lagergren kinetic equations and these were well fitted by the pseudo-second-order kinetic model. The thermodynamic parameters showed that the biosorption process was feasible, spontaneous, and endothermic.

Biosorption of Zn (II) by Pseudomonas aeruginosa isolated from a site contaminated with petroleum

Optimization of biosorption of Zn(II) ions from aqueous solutions with low-cost biomass Trametes versicolor and the evaluation of kinetic and thermodynamic parameters

The preparation, characterization, and environmental application of crosslinked chitosan-coated bentonite (CCB) beads for tartrazine adsorption have been investigated. CCB beads were characterized by using Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM), and Brunauer–Emmett–Teller (BET) surface area and Barrett–Joyner–Halenda (BJH) pore size distribution analyses were also determined. The values of pH of the aqueous slurry and pH of zero point charge (pHZPC) were almost equal. The adsorption at equilibrium of tartrazine was found to be a function of pH of the solution, stirring rate, contact time, and tartrazine concentration. The optimum conditions for tartrazine adsorption were pH 2.5, stirring rate of 400 rpm and contact time of 80 min. Pseudo-first-order and pseudo-second-order models were used to analyze the kinetics of adsorption with the latter found to agree well with the kinetics data, suggesting that the rate determining step may be chemisorption. The two most common isotherm models, Langmuir and Freundlich, were used to describe the adsorption equilibrium data. On the basis of Langmuir isotherm model, the maximum adsorption capacities were determined to be 250.0, 277.8, and 294.1 mg g−1 at 300, 310, and 320 K, respectively. Desorption studies were carried out at different concentrations of EDTA, H2SO4, and NaOH. All desorbing solutions showed poor recovery of tartrazine.

Potentially toxic trace elements, such as zinc, with high levels in water are very serious problems in many places around the world, sometimes in relation to natural sources and in other cases to anthropogenic ones. Adsorption process is among the most effective techniques for removing of many heavy metal ions from different types of water. In this study, an attempt has been made to investigate the efficiency of Calotropis procera roots (CP) in removing of Zn(II) from aqueous solution by using batch mode technique. During the removal process, the effects of solution pH, Zn concentrations and contact time on adsorption efficiency by CP roots were studied. Experimental equilibrium data were analyzed by the Langmuir and Freundlich isotherm models. The results showed that the best fit was achieved with the Langmuir isotherm equation with maximum adsorption capacity of 9.69 mg/g. The biosorption of Zn(II) was a fast process and followed the pseudo-second-order kinetic.

Removal of Zn +2 and Ni +2 by adsorption in a fixed bed of wheat straw

Biosorption of zinc from aqueous solution by cyanobacterium Fischerella ambigua ISC67: optimization, kinetic, isotherm and thermodynamic studies.

The aim of the study was to evaluate the effects of two different concentrations of EDTA at two different pH values for lmin & 10 min applications respectively on root dentin. 54 human maxillary incisors instrumented to size 60 to apical foramen were sectioned at the middle third (8mm sections) longitudinally into two equal mesial and distal halves. The sectioned specimens were irrigated for I and 10 min respectively using EDTA of concentrations 17% & 10% at 7.5 and 9 pH. The amount of demineralization and removal of smear layer was evaluated by phosphorus liberation, surface roughness studies and SEM analysis. Optimum results were obtained with EDTA at 10% concentration at 9 pH for 1 min.

The purpose of this study was to analyze the effect of the application of different concentrations of EDTA on the adhesion of fiber posts to root dentin using self-adhesive resin cements. After endodontic treatment, 78 single roots were randomly divided into six groups (n = 13) according to the combination of the following factors: surface dentin treatment - control (distilled water), 17% EDTA and 24% EDTA; and self-adhesive resin cement - RelyX U200 (RX); and Multilink Speed (ML). After fiber post cementation, six slices were obtained for each root. Ten roots of each group were used for bond strength (BS) and three for microhardness (MH) evaluations. Data obtained from BS and MH tests for each resin cement were subjected to two-way ANOVA (surface treatment vs. root region) and to a post-hoc Tukey's test (α = 0.05). The lowest BS value was observed in the 24% EDTA group for RX cement, whereas the highest values for ML cement were observed for the control group in the middle and apical regions. In the MH test, the lowest value for RX was observed for 24% EDTA in the cervical region, whereas and the highest value for the ML cement was observed in the control group. Regarding both self-adhesive resin cements tested, the application of 24% EDTA was not able to improve the adhesion of fiber posts to root canal.

Removal of heavy metal ions from aqueous solutions using various low-cost adsorbents

The removal of Malachite green (MG) from aqueous solutions by cross‐linked chitosan coated bentonite (CCB) beads was investigated and the CCB beads were characterized by Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X‐ray diffraction (XRD) analysis. Solubility and swelling tests were performed in order to determine the stability of the CCB beads in acidic solution, basic solution and distilled water. The amount of MG adsorbed was shown to be influenced by the initial pH of the solution, contact time and the initial MG concentration. A kinetic study indicated that a pseudo‐second‐order model agreed well with the experimental data. From the Langmuir isotherm model, the maximum adsorption capacity of MG was found to be 435.0 mg g–1. Desorption tests were carried out at different concentrations of EDTA, H2SO4 and NaOH. However, all desorbing solutions showed zero recovery of MG at all concentrations.

Biosorption of Zn2+ from aqueous solutions by biomass of Agaricus bisporus was investigated. The removal rates of Zn2+ by A. bisporus under different parameters (e.g., solution pH, bio-sorbent dosage and initial Zn2+ concentration) were studied. The inhibition of A. bisporus’s biosorption by anionic ligands EDTA (Ethylene Diamine Tetraacetic Acid), acetate and citrate) implied that EDTA and citrate might be used as eluting reagents. Regular and simultaneous solution pH change and light metal ions release after biosorption indicated that an ion exchange mechanism was involved. From FT-IR (Fourier Transform Infrared) spectroscopy, the main functional groups participated in biosorption were found. Biosorption of Zn2+ by A. bisporus could be well described by the Freundlich and Langmuir models. In conclusion, the biomass of A. bisporus showed high potential for the treatment of wastewater containing Zn2+.

Bismuth vanadate (BiVO4) powders were successfully synthesized in presence of EDTA via microwave irradiation and used as photocatalysts in the oxidation reaction of rhodamine B (rhB) under visible light. Different concentrations of EDTA (0.5 to 10%) to chelate Bi3+ ions were employed on the BiVO4 synthesis. Under the presence of EDTA, a monoclinic crystalline structure was obtained, whereas a mixture of monoclinic and tetragonal phases was observed in the absence of EDTA. In addition, the use of different EDTA concentrations promoted the formation the different shapes of particles. The BiVO4 sample synthesized with low concentration of EDTA (0.5%) exhibited about 85% of rhB decolorization in 300min at pH7.5. Therefore, this high efficiency can be attributed to a combination of intrinsic properties such as the morphology type and monoclinic structure of BiVO4 particles.

In the present investigation, the biosorption is carried out in a batch process to test the suitability of abundantly and freely available plant based material, Erythrina variegata orientalis (Indian coral tree) leaf powder, as an adsorbent for removal of Zn(II) from aqueous solution. The influence of various process parameters like agitation time, adsorbent size and dosage, pH of the aqueous solution and initial zinc concentration is studied. It is observed that there is a significant increase in percentage removal of Zn(II) as pH increases from 2 to 3 and attains maximum when pH is 7. The agitation time is to be 60 min. The Langmuir isotherm is more suited for biosorption followed by Freundlich isotherm. The biosorption of Zn(II) follows pseudo-second-order kinetics and is exothermic, irreversible and spontaneous. Key words: Biosorption, zinc, leaf powder, kinetics.