New Inorganic–Organic Hybrid Materials and Their Oxides for Removal of Heavy Metal Ions: Response Surface Methodology Approach

In this paper, Cu(II), Fe(III), Pb(II), and Zn(II) heavy metal ions were removed from their aqueous solutions by using novel inorganic–organic hybrid materials, Al-GPTS-H and Al-GPTS-NaOSiMe₃-H (hybrid material-1 and 2, respectively), and their oxides (calcined-1 and 2) as adsorbents. These ions removal by adsorption was optimized by using response surface methodology (RSM). Central composite design (CCD) method was used in order to investigate the effects of initial pH, initial metal concentration of solutions and adsorbent quantity on the adsorption efficiency (R, %). As a result of the experiments under optimum conditions, the maximum % R values were obtained by hybrid material-1 for Fe(III) (99.89%) and by calcined material-1 for Pb(II) (97.14%), respectively. These quite high adsorption efficiency values have shown that these hybrid materials and their oxides are suitable to use for heavy metal ions removal from aqueous solutions.     

Bioavailability of wastewater-derived organic nitrogen to the alga Selenastrum Capricornutum

Recent attempts to control cultural eutrophication in nitrogen-limited systems have focused on the simultaneous control of all forms of nitrogen with the underlying assumption that inorganic and organic nitrogen are equally bioavailable. To assess the validity of this assumption, algal growth bioassays were conducted on denitrified wastewater effluent samples, in the presence and absence of bacteria isolated from an effluent-receiving surface water. Bioassay results indicated that wastewater-derived dissolved organic nitrogen (DON) is not bioavailable to the algae Selenastrum Capricornutum in the absence of bacteria. However, approximately half of the wastewater-derived organic nitrogen was available to the algae in the presence of bacteria during a 2-week incubation. These results suggest that while it is inappropriate to assume that wastewater-derived DON cannot cause cultural eutrophication, it will not cause as much eutrophication as inorganic nitrogen. Additional research is needed to develop methods of minimizing the discharge of bioavailable forms of wastewater-derived organic nitrogen by wastewater treatment plants.     

Fermentation and oxygen transfer characteristics in recombinant human growth hormone production by Pichia pastoris in sorbitol batch and methanol fed‐batch operation

BACKGROUND: The influence of methanol feed rate on recombinant human growth hormone (rhGH) production by Pichia pastoris hGH‐Mut⁺ in medium containing sorbitol was investigated at three different specific growth rates (µ), namely, 0.02 (MS‐0.02), 0.03 (MS‐0.03), and 0.04 (MS‐0.04). RESULTS: Increasing methanol feed rate above MS‐0.03 did not affect sorbitol consumption, showing that µ = 0.03 h^?1 is a threshold limiting value, above which sorbitol utilization became independent of methanol feed rate. Moreover, when sorbitol was consumed, no further cell growth was observed. Increase in methanol feed rate triggered cell synthesis and the highest cell concentration was obtained at MS‐0.04 as 48 g L^?1 (t = 18 h); whereas, the highest rhGH production, 270 mg L^?1, was obtained at MS‐0.03 as a consequence of lower extracellular protease production and higher AOX activity (41 U g^?1 CDW). Oxygen uptake rate increased with increasing µ, having the maximum value, 76.6 mmol m^?3 s^?1, at MS‐0.04. K_La had a tendency to increase with µ, having a maximum value of 0.15 s^?1 at MS‐0.04 (t = 15 h). CONCLUSION: By considering rhGH concentration and oxygen transfer characteristics, the bioprocess can be improved by a two‐stage feeding strategy, operating at MS‐0.04 at the beginning of fermentation, and thereafter shifting to MS‐0.03. Copyright © 2009 Society of Chemical Industry     

The effect of pumpkin fibre on quality and storage stability of reduced‐fat set‐type yogurt

In this study, the effect of pumpkin fibre (PF) on physicochemical, microbiological, rheological and microstructural characteristics of reduced‐fat yogurt samples was investigated during storage. PF was added at three different concentrations (0.5%, 1.0% and 1.5%) to standardised (1.55% fat ratio) cow's milk. Plain yogurt (PF‐free) was used for comparison. The addition of PF significantly affected total solid content, synaeresis, water‐holding capacity, apparent viscosity and colour parameters (L*, a*, b*) of yogurt samples for all sampling time. The addition of PF caused a reduction in L* values (from 94.89 to 88.67), but caused an increase in a* (from ?2.10 to +4.22) and b* (from 10.79 to 25.88) values. Yogurts with PF exhibited lower synaeresis and more viscous structure than PF‐free sample during storage. SEM images showed that distinctive microstructure profile was present between samples with or without PF. More filamentous structures and denser network were observed in the SEM images and these increased with increasing level of PF. Yogurt containing 1.0% PF showed a higher storage (G′) (3687.87 at 21 day) and loss (G″) (543.10 at 21 day) moduli in comparison with other samples. In conclusion, the results revealed that PF improved the physical quality and contributed textural properties of half‐fat yogurt.     

Thermal and mechanical properties of polypropylene nanocomposite materials reinforced with cellulose nano whiskers

We use polypropylene (PP, an apolar polymer) and cellulose nano whiskers (CNW, a polar material) to produce nano polymer composites with enhanced mechanical and thermal properties. To improve compatibility, maleic anhydride grafted PP has also been used as a coupling agent. To enhance the uniform distribution of CNW in the composite, the matrix polymer is dissolved in toluene, and sonification and magnetic stirring are applied. Good film transparency indicates uniform CNW dispersion, but CNW domains in the composite film observed under an scanning electron microscope may indicate slight agglomeration of CNW in the composite film. The tensile strength of the composite compared with neat PP improves by 70–80% with the addition of CNW. The crystallinity has also been improved by about 50% in the CNW reinforced samples. As the content of CNW increases, the composite exhibits higher thermal degradation temperature, higher hydrophilicity, and higher thermal conductivity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A study of the influences of transition metal (Mn,Ni) co-doping on the morphological,structural and optical properties of nanostructured CdO films

In this paper, a systematic investigations on the effects of transition metals such as Mn and Ni-dopant on physical properties of cadmium oxide (CdO) thin films coated on soda lime glass substrates by using SILAR method have been reported. The characterizations of un-doped, Mn-doped (Cd_0.99 Mn_0.01O) and Mn/Ni double doped CdO [(Cd_0.99?xMn_0.01Ni_xO)(0?≤?x?≤?0.001)] films were investigated by SEM, EDX, XRD and UV–Vis spectrophotometry to determine the morphological, structural and optical properties, respectively. SEM analysis showed that the surface morphologies of the CdO films were influenced by Mn doping and Mn/Ni co-doping. The EDX result verified the presence of expected elements Cd, O, Mn and Ni in the growing solution. The crystal phases of the samples and their crystallinity quality have been investigated by XRD measurements. The X-ray diffractograms show all the diffraction peaks are highly intense also they demonstrate the preferential orientations of (111) and (200) directions. Optical investigations revealed red shift with Mn doping and Mn/Ni co-doping in the absorbance spectrum.     

Occurrence of aflatoxins (B1, B2, G1, G2) in herbal tea consumed in Turkey

Aflatoxin contents in 12 types of herbal teas were determined by high performance liquid chromatography (HPLC) with fluorescence detector using immunoaffinity column clean-up. Forty eight samples were collected from four local herbal shops in Manisa, Turkey. Of the 48 samples analyzed, 43 were aflatoxin positive. The highest concentration of aflatoxin (34.18 µg/kg) was determined in a sample of camomile tea. The occurrence of AFB1, B2, G1 and G2 was found in samples at levels of 54, 29, 71 and 46 %, respectively. Aflatoxin B1, B2, G1 and G2 contamination levels varied from 0 to 14.2, 0 to 12.4, 0 to 13.5 and 0 to 28.7 µg/kg, respectively. Aflatoxin was not detected in five samples consisting of linseed, lime and fennel tea.     

Synthesis and characterization of thiophene functionalized polystyrene copolymers and their electrochemical properties

Thiophene functionalized polystyrene samples (TFPS) were synthesized by atom transfer radical polymerization (ATRP) of styrene, followed by Suzuki coupling with 3‐thiophene (Th) boronic acid. Conducting graft polymer of TFPS with thiophene was achieved at 1.5 V in tetrabutylammonium tetrafluoroborate/dichloromethane (TBAFB/DM) by electrochemical methods. Spectroelectrochemical analysis of the resulting copolymers [P(TFPS‐co‐Th)] reflected electronic transitions at 449, 721 and 880 nm, revealing π ? π* transition, polaron and bipolaron band formation, respectively. We also successfully established the utilization of dual type complementary colored polymer electrochromic devices using P(TFPS‐co‐Th)/poly(3,4‐ethylenedioxythiophene (PEDOT) in sandwich configuration. The switching ability, stability and optical memory of the electrochromic device were investigated by UV–visible spectrophotometry and cyclic voltammetry. Device switches between brown and blue color with a switching time of 1.3 s were prepared with optical contrast (%ΔT) of 25 %. Copyright © 2005 Society of Chemical Industry