A trickling fibrous-bed bioreactor for biofiltration of benzene in air

A novel trickling fibrous-bed bioreactor was developed for biofiltration to remove pollutants present in contaminated air. Air containing benzene as the sole carbon source was effectively treated with a coculture of Pseudomonas putida and Pseudomonas fluorescens immobilized in the trickling biofilter, which was wetted with a liquid medium containing only inorganic mineral salts. When the inlet benzene concentration (C_gi) was 0·37 g m⁻³, the benzene removal efficiency in the biofilter was greater than 90% at an empty bed retention time (EBRT) of 8 min or a superficial air flow rate of 1·8 m³ m⁻² h⁻¹. In general, the removal efficiency decreased but the elimination capacity of the biofilter increased with increasing the inlet benzene concentration and the air (feed) flow rate. It was also found that the removal efficiency decreased but the elimination capacity increased with an increase in the loading capacity, which is equal to the inlet concentration divided by EBRT. The maximum elimination capacity achieved in this study was ∽11·5 g m⁻³ h⁻¹ when the inlet benzene concentration was 1·7 g m⁻³ and the superficial air flow rate was 3·62 m³ m⁻² h⁻¹. A simple mathematical model based on the first-order reaction kinetics was developed to simulate the biofiltration performance. The apparent first order parameter K_l in this model was found to be linearly related to the inlet benzene concentration (K_l=4·64−1·38 C_gi). The model can be used to predict the benzene removal efficiency and elimination capacity of the biofilter for benzene loading capacity up to ∽30 g m⁻³ h⁻¹. Using this model, the maximum elimination capacity for the biofilter was estimated to be 12·3 g m⁻³ h⁻¹, and the critical loading capacity was found to be 14 g m⁻³ h⁻¹. The biofilter had a fast response to process condition changes and was stable for long-term operation; no degeneration or clogging of the biofilter was encountered during the 3-month period studied. The biofilter also had a relatively low pressure drop of 750 Pa m⁻¹ at a high superficial air flow rate of 7·21 m³ m⁻² h⁻¹, indicating a good potential for further scale up for industrial applications. © 1998 Society of Chemical Industry     

The treatment of waste-air containing mixed solvent using a biofilter: 1. Transient behavior of biofilter to treat waste-air containing ethanol

Transient behavior of a biofilter packed with mixed media (of granular activated carbon and compost) inoculated with a pure culture ofPseudomonas putida was observed at the height of each sampling port to treat wasteair containing ethanol. In addition, flooding effects of an excess supply of buffer solution was observed at each sampling port of the biofilter until it recovered the status prior to the flooding. Unlike previous investigations, various process conditions were applied to successive biofilter runs in order to monitor the corresponding unsteady behavior of the biofilter in this work. In early stage of biofilter run the removal efficiency of ethanol maintained almost 100%. However, it began to decrease when inlet load surpassed 100 g/m³/h consistent with maximum elimination capacity. At the end of biofilter-run removal efficiency was decreased and maintained at 40%. The results of this work were compared to those of such biofiltration studies as the work of Christen et al. from the point of view that pure cultures of microorganism were used in both works. Except for the period of flooding effect of the 2nd stage, the inlet load and removal efficiency continued at 105.5 g/m³/h and 95%, respectively, while they were 93.7 g/m³/h and 95%, respectively, according to the result of Christine et al. Removal efficiency remained at 90% for the beginning period of 3 days of the 3rd stage, and it gradually decreased to 60% for remaining 5 days of the stage with an inlet load of 158.26 g/m³/h, which may be interpreted as better than the result of Christine et al. Their result was that the removal efficiency on the inlet load of 154 g/m³/h of ethanol was continued to be 60% for 6 days of a separate biofilter run and decreased to 40% later. Thus, with similar inlet loads of ethanol, removal efficiency of this work was equivalent to or higher than that of Christine et al.     

Removal of hydrogen sulfide, benzene and toluene by a fluidized bed bioreactor

The dominant off gases from publicly owned treatment works include hydrogen sulfide, benzene, and toluene. In this research, hydrogen sulfide oxidized byBacillus cereus, and benzene with toluene were removed by VOC-degrading microbial consortium. The optimum operating condition of the fluidized bed bioreactor including both microorganisms was 30 ‡C, pH 6–8, and 150 cm of liquid bed height. The critical loading rate of hydrogen sulfide, benzene and toluene in the bioreactor was about 15 g/m³h, 10 g/m³h and 12 g/m³h, respectively. The fluidized bed bioreactor showed an excellent elimination capacity for 580 hours of continuous operation, and maintained stable removal efficiency at sudden inlet concentration changes.     

Biofiltration of toluene in the absence and the presence of ethyl acetate under continuous and intermittent loading

BACKGROUND: Two peat biofilters were used for the removal of toluene from air for one year. One biofilter was fed with pure toluene and the other received 1:1 (by weight) ethyl acetate:toluene mixture. RESULTS: The biofilters were operated under continuous loading: the toluene inlet load (IL) at which 80% removal occurred was 116 g m^?3 h^?1 at 57 s gas residence time. Maximum elimination capacity of 360 g m^?3 h^?1 was obtained at an IL of 745 g m^?3 h^?1. The elimination of toluene was inhibited by the presence of ethyl acetate. Intermittent loading, with pollutants supplied for 16 h/day, 5 days/week, did not significantly affect the removal efficiency (RE). Biomass was fully activated in 2 h after night closures, but 6 h were required to recover RE after weekend closures. Live cell density remained relatively constant over the operational period, while the dead cell fraction increased. Finally, a 15 day starvation period was applied and operation then re‐started. Performance was restored with similar re‐acclimatization period to that after weekend closures, and a reduction in dead cell fraction was observed. CONCLUSION: This study demonstrates the capacity of the system to handle intermittent loading conditions that are common in industrial practices, including long‐term starvation. Copyright © 2008 Society of Chemical Industry     

Synthesis of a new type poly(vinyl alcohol)/peat/bamboo charcoal/KNO3 composite bead used as biofilter material

A new type poly(vinyl alcohol) (PVA)/peat/bamboo charcoal (BC)/KNO₃ composite bead was prepared, which has a diameter of 2.4–6.0 mm and a density of 1.133 g/cm³ and is a porous spherical particle. The biochemical kinetic behaviors of n‐butyl acetate in PVA/peat/BC/KNO₃ spherical composite bead biofilter (BC biofilter) and PVA/peat/granular activated carbon (GAC)/KNO₃ spherical composite bead biofilter (GAC biofilter) were investigated. The values of half‐saturation constant K_s for BC biofilter and GAC biofilter were 27.89 and 27.95 ppm, respectively. The values of maximum reaction rate V_m for BC biofilter and GAC biofilter were 13.49 and 13.65 ppm/s, respectively. Zero‐order kinetic with the diffusion limitation was regarded as the most adequate biochemical reaction model for the two biofilters. The microbial growth rate and biochemical reaction rate for two biofilters were inhibited at higher inlet concentration, and the degree of inhibitive effect was more pronounced in the inlet concentration range of 100–800 ppm. The biochemical kinetic behaviors of the two biofilters were similar. The maximum elimination capacity of BC biofilter and GAC biofilter were 111.65 and 122.67 g C/h m³ bed volume, respectively. The PVA/peat/BC/KNO₃ composite bead was suitable as a biofilter material. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Bioremediation of contaminated air using an external-loop airlift bioreactor

Biological air treatment methods are gaining popularity in the chemical industries due to their low cost and ability to convert many hazardous volatile organic compounds (VOCs) into harmless byproducts. An external loop, airlift bioreactor (ELAB) is used to separately bioremediate two prototype, water-soluble VOC compounds: p-cresol and ethanol. In both cases, the effluent air was cleansed and bioremediated to below detectable limits (beyond 99.7% removal) due to the efficient scrubbing action of the ELAB. The bioreactor continued to provide this removal efficiency up to maximum air p-cresol concentration of 0.6 g/m³ and ethanol concentration of 110 g/m³ and at bioreactor loading rates up to 8 g/m³ h for p-cresol and 220 g/m³ h for ethanol. A dynamic and quasi-steady state, biokinetic model is shown to predict the transient bioremediation process very well using batch growth biokinetic parameters.     

Adsorption of Ni2+ from aqueous solutions by novel polyethyleneimine‐attached poly(p‐chloromethylstyrene) beads

In this study Ni²⁺ adsorption properties of polyethyleneimine (PEI)‐attached poly(p‐chloromethylstyrene) (PCMS) beads were investigated. Spherical beads with an average size of 186 μm were obtained by the suspension polymerization of p‐chloromethylstyrene conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, PCMS beads had a specific surface area of 14.1 m²/g. PEI chains could be covalently attached onto the PCMS beads with equilibrium binding capacities up to 208 mg PEI/g beads, via a direct chemical reaction between the amine and chloro‐methyl groups. After PEI adsorption with 10% (w/w) initial PEI concentration, free amino content of PEI‐attached PCMS beads was determined as 0.91 mEq/g. PEI‐attached PCMS beads were utilized as adsorbents in the adsorption/desorption of Ni²⁺ ions from synthetic solutions. The adsorption process was fast; 90% of adsorption occurred within 90 min, and equilibrium was reached at around 2 h. Adsorption capacity was obtained to be 78.2 mg/g at a pH of about 6.0. The chelating beads can be easily regenerated by 0.1 M HNO₃ with higher effectiveness. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2467–2473, 2002     

Removal of dibenzothiophenes in kerosene by adsorption on rice husk activated carbon

The capacity of rice husk activated carbon (RHAC) to adsorb refractory sulfur compounds of dibenzothiophenes (DBTs) from commercial kerosene was evaluated in terms of their textural and chemical characteristics. Rice husk activated at 850 °C for 1 h showed an acceptable adsorption capacity for DBTs, despite a much lower specific surface area (473 m²/g) and total pore volume (0.267 cm³/g), when compared to micro-porous activated carbon fiber with a large specific surface area (2336 m²/g) and total pore volume (1.052 cm³/g). The volumes of ultramicropores acting as DBTs adsorption sites, and of mesopores leading DBTs into the ultramicropores were closely related to the DBTs adsorption capacity of the RHACs.     

Removal of heavy‐metal ions by magnetic beads containing triazole chelating groups

The aim of this study was to prepare magnetic beads that could be used for the removal of heavy‐metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate–1‐vinyl‐1,2,4‐triazole) [m‐poly(EGDMA–VTAZ)] beads were produced by suspension polymerization in the presence of a magnetite Fe₃O₄ nanopowder. The specific surface area of the m‐poly(EGDMA–VTAZ) beads was 74.8 m²/g with a diameter range of 150–200 μm, and the swelling ratio was 84%. The average Fe₃O₄ content of the resulting m‐poly(EGDMA–VTAZ) beads was 14.8%. The maximum binding capacities of the m‐poly(EGDMA–VTAZ) beads from aquous solution were 284.3 mg/g for Hg²⁺, 193.8 mg/g for Pb²⁺, 151.5 mg/g for Cu²⁺, 128.1 mg/g for Cd²⁺, and 99.4 mg/g for Zn²⁺. The affinity order on a mass basis was Hg²⁺ > Pb²⁺ > Cu²⁺ > Cd²⁺> Zn²⁺. The binding capacities from synthetic waste water were 178.1 mg/g for Hg²⁺, 132.4 mg/g for Pb²⁺, 83.5 mg/g for Cu²⁺, 54.1 mg/g for Cd²⁺, and 32.4 mg/g for Zn²⁺. The magnetic beads could be regenerated (up to ca. 97%) by a treatment with 0.1M HNO₃. These features make m‐poly(EGDMA–VTAZ) beads potential supports for heavy‐metal removal under a magnetic field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and sorption studies of microsphere copolymers containing β-cyclodextrin and poly(acrylic acid)

Microsphere polymeric materials containing β-cyclodextrin (β-CD) and poly(acrylic acid) (PAA) with tunable morphologies were prepared in order to improve their sorption characteristics in aqueous solution. The microsphere polymeric materials were prepared using a (water/oil) micro-emulsion-evaporation technique to condense β-cyclodextrin (β-CD) with PAA at various comonomer ratios and mixing speeds. The β-CD microsphere copolymers were characterized using FTIR, TGA, DSC, SEM, elemental (C and H) microanalyses, and solid state ¹³C-NMR spectroscopy. The sorption properties of the polymeric materials at 295 K in aqueous solution containing p-nitrophenol (PNP) were studied using a dye-based method with UV–Vis spectrophotometry at pH 4.6 and 10.3. The sorption isotherms of copolymer/PNP systems were evaluated with various isotherm models (e.g., Langmuir, BET, Freundlich, and Sips). The Sips isotherm showed the best overall agreement with the experimental results and the sorption parameters provided estimates of the sorbent surface area (12.0–331 m²/g) and the sorption capacity (Q_m = 0.359–2.20 mmol/g at pH = 4.6; Q_m = 0.070–0.191 mmol/g at pH = 10.3) for the microsphere copolymer/PNP systems in aqueous solution. The nitrogen adsorption properties of the microporous copolymers in the solid state were obtained at 77K with BET surface areas ranging from 0.275 to 4.47 m²/g. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Metal‐chelated polyamide hollow fibers for human serum albumin separation

We modified microporous polyamide hollow fibers by acid hydrolysis to amplify the reactive groups and subsequent binding of Cibacron Blue F3GA. Then, we loaded the Cibacron Blue F3GA‐attached hollow fibers with different metal ions (Cu²⁺, Ni²⁺, and Co²⁺) to form the metal chelates. We characterized the hollow fibers by scanning electron microscopy. The effect of pH and initial concentration of human serum albumin (HSA) on the adsorption of HSA to the metal‐chelated hollow fibers were examined in a batch system. Dye‐ and metal‐chelated hollow fibers had a higher HSA adsorption capacity and showed less nonspecific protein adsorption. The nonspecific adsorption of HSA onto the polyamide hollow fibers was 6.0 mg/g. Cibacron Blue F3GA immobilization onto the hollow fibers increased HSA adsorption up to 147 mg/g. Metal‐chelated hollow fibers showed further increases in the adsorption capacity. The maximum adsorption capacities of Co²⁺‐, Cu²⁺‐, and Ni²⁺‐chelated hollow fibers were 195, 226, and 289 mg/g, respectively. The recognition range of metal ions for HSA from human serum followed the order: Ni(II) > Cu(II) > Co(II). A higher HSA adsorption was observed from human serum (324 mg/g). A significant amount of the adsorbed HSA (up to 99%) was eluted for 1 h in the elution medium containing 1.0M sodium thiocyanide (NaSCN) at pH 8.0 and 25 mM ethylenediaminetetraacetic acid at pH 4.9. Repeated adsorption–desorption processes showed that these metal‐chelated polyamide hollow fibers were suitable for HSA adsorption. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3346–3354, 2002     

Biological treatment of a contaminated gaseous emission from a paint and varnish plant—from laboratory studies to pilot‐scale operation

A Vapour‐Phase Bioreactor (VPB), namely a biotrickling filter, was scaled‐up and operated in‐situ for the treatment of gaseous emissions from a paint and varnish industrial plant. A microbial culture able to degrade the target compounds was enriched and a laboratory‐scale VPB was established in order to evaluate the treatment's performance. The VPB presented removal efficiencies higher than 90% when exposed to Organic Loads (OL) of ca 50 g h^?1 m^?3 of reactor. The VPB was exposed to dynamic conditions often found in‐situ (eg night and weekend shutdown periods) and showed a fast capacity to recover, with and without mineral medium recirculation. After a prolonged interruption period (10 months), the VPB was not able to cope with OL of ca 25 g h^?1 m^?3 of reactor and re‐inoculation was required in order to recover the treatment performance. The VPB also showed limited treatment when exposed to higher OL (ca 500 g h^?1 m^?3 of reactor). The VPB was then scaled‐up and a 3 m³ VPB was operated in‐situ, showing removal efficiencies higher than 50% when exposed to an OL of c 5 g h^?1 m^?3 of reactor, thus complying with current legal demands. The addition of a maintenance feed was shown to be a useful tool for VPB pilot‐scale operation when shutdown periods occurred. A factorial design of experiments was carried out, which allowed reduction to one‐tenth of the initial supply of the main mineral medium constituents, namely phosphate buffer, ammonium and magnesium salts, and also elimination of the metal supplement. Overall, the VPBs were shown to be robust equipment, being able to respond actively to dynamic treatment scenarios, particularly night and weekend shutdown periods. Copyright © 2003 Society of Chemical Industry     

Integration of continuous biological and chemical (ozone) treatment of domestic wastewater: 1. Biodegradation and post‐ozonation

The continuous treatment of domestic wastewater by an activated sludge process and by an integrated biological–chemical (ozone) oxidation process were studied in this work. Chemical oxygen demand (COD), biochemical oxygen demand (BOD), absorbance at 254 nm (UV₂₅₄) and nitrogenous compound content were the parameters followed in order to evaluate the performance of the two processes. Experimental data showed that both UV₂₅₄ and COD reductions are improved in the combined biological–chemical oxidation procedure. Thus, reductions of 59.1% and 37.2% corresponding to COD and UV₂₅₄, respectively were observed after the biological process (hydraulic retention time = 5 h; mixed liquor volatile suspended solids concentration = 3142 g m⁻³) compared with 71.0% and 78.4% obtained when a post‐ozonation step ( D _O3 = 41.7 g m⁻³) was included. During conventional activated sludge treatment, appropriate nitrification levels are only achieved with high hydraulic retention time and/or biomass concentration. Ozonation after the secondary treatment, however, allows improved nitrogen content reduction with total nitrite elimination. Post‐ozonation also leads to a higher biodegradability of the treated wastewater. Thus, the ultimate BOD/COD ratio goes from 0.16 after biological oxidation to 0.34 after post‐ozonation with 41.7 g O₃ m⁻³. © 1999 Society of Chemical Industry     

Phosphorus sorption in relation to soil properties in some cultivated Swedish soils

Phosphorus (P) sorption properties are poorly documented for Swedish soils. In this study, P sorption capacity and its relation to soil properties were determined and evaluated in 10 representative Swedish topsoils depleted in available P. P sorption indices were estimated from sorption isotherms using Langmuir and Freundlich equations (X_m and a_F, respectively) and P buffering capacity (PBC). X_m ranged from 6.0 to 12.2 mmol kg^–1. All indices obtained from sorption isotherms were significantly correlated with each other (r=0.96^*** to r=0.99^***). Two single-point sorption indices (PSI₁ and PSI₂) were also determined, with additions of 19.4 and 50 mmol P kg^–1 soil, respectively. Both PSI indices were well correlated with X_m (r0.98^***), with PSI₁ giving the highest correlation. As isotherms for determining P sorption capacities involve laborious analytical operations, PSI₁ would be preferable for routine analyses. X_m was significantly correlated with Fe extracted by sodium pyrophosphate and ammonium oxalate, to Al extracted by ammonium oxalate and dithionite-citrate-bicarbonate and to organic c. X_m was also significantly correlated with the sum of Fe and Al extracted by ammonium oxalate. The best prediction of X_m through multiple regression was obtained when Fe extracted in ammonium oxalate and Al extracted in dithionite-citrate-bicarbonate were used. Based on the results obtained, both PSI₁ and oxalate-extractable Fe plus Al can be used for predicting P sorption capacity in Swedish soils.     

Treatment of mixed solvent vapors with hybrid system composed of biofilter and photo-catalytic reactor

The transient behavior of a hybrid system composed of biofilter and photo-catalytic reactor was observed at the height of each sampling port to treat waste-air containing ethanol. The biofilter packed with mixed media (of granular activated carbon and compost) was inoculated with a pure culture ofBurkholderia cepacia G4 andPseudomonas putida, while a photo-catalytic reactor was composed of 15W UV-A lamps and annular pyrex tubes packed with glass beads coated with sol type of TiO₂ before calcination. The maximum elimination capacities of toluene and ethanol turned out to be 130 g/m³/h and 230 g/m³/h, respectively, which were greater by 40 g/m³/h and 130 g/m³/h, respectively, than those from the experiments performed with a biofilter only. Thus, the maximum elimination capacities for toluene and ethanol increased by 44% and 130%, respectively, by use of a hybrid system. The photo-catalytic process contributed to the maximum elimination capacities of hybrid system on toluene and ethanol by 30.8% and 56.5%, respectively, which contributions for the elimination capacities on toluene and ethanol were allocated indirectly by 25.4% and 44.3% as well as directly by 5.4% and 12.2%, respectively. Direct contributions of photo-catalytic process were 17.5% and 21.5% to the increments of the elimination capacities on toluene and ethanol, respectively, while its indirect contributions were 82.5% and 78.5% to those on toluene and ethanol, respectively.     

Influence of surfactants on porous properties of carbon cryogels prepared by sol–gel polycondensation of resorcinol and formaldehyde

The role of surfactants on carbon cryogels is investigated by using three different surfactants, nonionic (SPAN80), cationic (trimethylstearylammonium chloride; C18) and nonionic polymeric fluorinated (FC4430) surfactants. By using different SPAN80 concentrations (10.0, 5.0, 2.5, 1.0 and 0.5 vol.%), double-structure carbon microspheres with S_BET (630–700 m²/g) and V_mes (0.51–0.93 cm³/g) are obtained. Mesoporous carbon cryogels with different S_BET and V_mes are prepared by using C18 with different volume ratios of cyclohexane to water in a C18/water/cyclohexane mixture. Carbon cryogels with S_BET (690–810 m²/g) and V_mes (0.83–1.74 cm³/g) are obtained when cyclohexane is contained in the mixture, on the contrary, when there is no cyclohexane in the mixture, a water-based carbon cryogel with low S_BET (480 m²/g) and V_mes (0.29 cm³/g) is obtained. Carbon cryogels prepared by using C18 have larger mesopore size and broader mesopore size distribution compared with carbon cryogels prepared by using other surfactants. Microcellular (sponge-like) carbon cryogels with mesoporous surface, S_BET (210–660 m²/g) and V_mes (0.37–0.92 cm³/g), are obtained by introducing FC4430 (two concentrations) to two starting RF solutions (C/W=6,45). Low FC4430 concentration leads to carbon cryogels with higher S_BET (610 and 660 m²/g) and narrower mesopore size distributions compared to the high concentration counterpart. Hence, it is found that different surfactant types have interesting effects on morphologies and porous properties of RF carbon cryogels.     

Study on a Novel Polymer-based Secondary Battery System

This study is intended to develop a polyindole-based polymer battery system which has a high electromotive force together with a high cycle property and is capable of fast charging and discharging. The battery includes poly(5-nitroindole) as the anode active material and polyaniline as the cathode active material. Sulfuric acid (40%) was used as the electrolytic solution with about 1.3-V electromotive force. The battery achieves about 79–65 mA h/g at charge and discharge current densities of 10–10³ A/m². As the theoretical capacity of poly(5-nitroindole) is 84 mA h/g, its capacity occurrence rate is 94% at a charge and discharge current density of 10 A/m² with a very high reaction rate. In addition, the discharge capacity at a charge and discharge current density of 10³ A/m² maintains 82% of the capacity relative to that at 10 A/m². This indicates that this battery has excellent fast charge and discharge properties. The cycle life of the battery, which is measured at a current density of 10³ A/m² with a discharge depth of 60% at 25°C, is about 32,000. This shows the battery system has an excellent cycle property. Moreover, the discarded battery will do little harm to the environment because it is free of heavy metals. In summary, this polyindole-based polymer battery system would be promising in future applications such as a hybrid electric vehicle with the development of the battery system.     

Synthesis and characterization of poly(HPMA)‐APMA‐DTPA‐99mTc for imaging‐guided drug delivery in hepatocellular carcinoma

To develop a theranostic agent for diagnostic imaging and treatment of  hepatocellular carcinoma (HCC), poly(HPMA)‐APMA‐DTPA‐^99mTc (HPMA: N‐(2‐hydroxypropyl methacrylamide; APMA: N‐(3‐aminopropyl)methacrylamide; DTPA: diethylenetriaminepentaacetic acid) and DTPA‐^99mTc were synthesized and characterized, and their HCC targeting was tested by in vitro cellular uptake and in vivo tumor imaging in this study. Radioactivity of HCC cells incubated with poly(HPMA)‐APMA‐DTPA‐^99mTc was significant higher (16.40%) than that of the cells incubated with DTPA‐^99mTc (2.98%). Scintigraphic images of HCC in mice obtained at 8 h after injection of poly(HPMA)‐APMA‐DTPA‐^99mTc showed increased radioactivity compared with that in mice injected with DTPA‐^99mTc. The results of postmortem tissue radioactivity assay demonstrated higher radioactivity of HCC tumor tissues (2.69 ± 0.15% ID/g) from the tumor‐bearing mice injected with poly(HPMA)‐APMA‐DTPA‐^99mTc compared with that of HCC tumor tissues in the tumor‐bearing mice injected with DTPA‐^99mTc (0.83 ± 0.03 %ID/g), (P <0.001). These results first directly confirm the significant passive hepatocellular tumor targeting of HPMA copolymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of precursors on the morphology and surface area of LaFeO3

Surface area and morphology of materials play an important role on their gas sensing performance because of the varying number and nature of adsorption sites. Current work reports a comparative study of LaFeO₃ synthesized by the facile hydrothermal method using two precursors; citric acid and KOH. The microstructure observed through FESEM and TEM showed different morphologies for the two precursors and calcination time (2?h & 6?h). Prior to calcination, higher surface area (50.54?m²/g) was obtained for LaFeO₃ prepared using KOH as compared to that for LaFeO₃ using citric acid (3.21?m²/g). Surface area increased from 3.21 to 7.06?m²/g for citric acid and decreased from 50.54 to 11.42?m²/g for KOH as calcination takes place for 6?h. Needle-shaped morphology of p-type LaFeO₃ with high surface area (50.54?m²/g) for KOH would provide large active sites which would enhance sensitivity towards gases. Hence, LaFeO₃ samples prepared using KOH with and without calcination are expected to give better performance for gas sensing than LaFeO₃ samples synthesized using citric acid.     

Effect of COD/NO3-N ratio on the performance of a hybrid UASB reactor treating phenolic wastewater

The effect of COD/O₃⁻-N ratio on the biodegradation of complex phenolic mixture was studied in bench scale hybrid upflow anaerobic sludge blanket (HUASB) reactors. HUASB reactor is a combination of a UASB unit at the lower part and an anaerobic fixed film at the upper end. The aim of this study was to evaluate the biodegradability of phenolic mixture (from synthetic coal wastewater) as the only carbon and energy source in continuous experiments using nitrate as the final electron acceptor. Synthetic coal wastewater contained phenol (490 mg/L); m-,o-,p-cresols (123.0 mg/L, 58.6 mg/L, 42 mg/L); 2,4-, 2,5-, 3,4- and 3,5 dimethyl phenols (6.3 mg/L, 6.3 mg/L, 4.4 mg/L and 21.3 mg/L) as major phenolic compounds representing the complex phenolic mixture. Nitrate nitrogen loading was increased from 0.11 g/m³/d to 0.5 g/m³/d in order to keep COD/NO₃⁻-N ratio as 20.1, 14.85, 9.9, 6.36 and 4.45. An input phenolics concentration of 752 mg/L and hydraulic retention time (HRT) of 24 h was maintained through out the study. Removal of phenolic mixture was found to increase with the lowering of COD/NO₃⁻-N ratio. Maximum phenolics removal of 98% was achieved at a COD/NO₃⁻-N ratio of 6.36. However, phenolics removal got adversely affected when COD/NO₃⁻-N ratio was reduced below 6.36. A nitrogen production efficiency of 78% was obtained according to nitrate consumption. Simultaneous denitrification and methanogenesis was observed in all the reactors throughout the study, demonstrating that denitrification is a feasible alternative for the treatment of coal wastewater. Granules degrading complex phenolic mixture were of diameter 1.6–2.25 mm.