Removal of protein, histological dye and tetracycline from simulated bioindustrial wastewater with a dual pore size PPSU membrane

Wastewater from production of active pharmaceutical ingredients (APIs) often contains proteins, azo dyes or antibiotics, which cause severe water eutrophication and growth of drug-resistant bacteria. A series of polyphenylsulfone (PPSU) membranes was prepared to determine the relationships between pore structures and the abilities of different membranes to separate foulants, and the characteristics and performance of the ultrafiltration membranes were investigated. The structure of the skin layer and the cross-sectional texture were converted from dense and finger-like macrovoids to porous sponge shapes because of a delayed liquid-liquid (L-L) demixing time. Formation of novel PPSU membranes via noncovalent bonding interactions was evaluated, and this selectively affected the membrane surface pore structure, layer thickness, surface polarity and electronic repulsive force. All PPSU membranes demonstrated excellent rejection of organic foulants, including bovine serum albumin (BSA) (~100% rejection) and acid red 1 (AR1) (~90% rejection). Additionally, M5 provided an excellent tetracycline (TC) rejection efficiency of 89% in the 1^st cycle. Due to the small size of TC, pore size effects were displayed. Moreover, the pure water flux recovery rate (FRR) increased from 85% (M1, water/ethanol: 100/0) to 99.9% (M4, water/ethanol: 30/70) after BSA filtration because the weak nonsolvent decreased the roughness of the membrane surface, and the membrane made with added EtOH yielded excellent FRR values (99.9%) after AR1 filtration. Therefore, PPSU membranes successfully achieved over 90% rejection of organic foulants and excellent FRRs, indicating that they may be suitable for purifying wastewater from API plants that generate organic foulants with a wide range of sizes.

Highly Permeable Mixed Matrix Hollow Fiber Membrane as a Latent Route for Hydrogen Purification from Hydrocarbons/Carbon Dioxide

This work reported on the fabrication and investigation of a mixed matrix hollow fiber membrane (MMHFM) by incorporating commercially available alumina particles into a polyetherimide (PEI) polymer matrix. These MMHFMs were prepared by the dry-wet spinning technique. Accordingly, optimizing the spinning parameters, including the air gap distance and flow rate ratio, is key to determining the gas separation performance. However, there are few studies regarding the effect of the filler dimensions. Consequently, three sizes of alumina particles, 20 nm, 30 nm, and 1000 nm, were respectively added into the PEI phase to examine the influence of filler size on gas permeation property. Moreover, the permeation properties of lower hydrocarbons (i.e., ethane and propane) were also measured to evaluate potential for emerging applications. The results indicated the as-synthesized membrane exhibited a remarkable hydrogen permeance of 1065.24 GPU, and relatively high separation factors of 4.53, 5.77, and 5.39 for H₂/CO₂, H₂/C₂H₆, and H₂/C₃H₈, respectively. This resulted from good compatibility between the larger fillers and the PEI polymer, as well as a reduction in the finger-like voids. Overall, the MMHFM in this work was deemed to be a promising candidate to separate hydrogen from gas streams, based on the comparison of the separation performance against other reported studies.

Fabrication of waterproof gas separation membrane from plastic waste for CO2 separation

In this study, waste polystyrene (wPS) plastic was used to prepare gas-separation membranes with hot-pressing technology to reduce the accumulation of plastic waste. Polystyrene is a commonly used polymer for the production of plastic products, and it is also used in the synthesis of membranes for gas separation. Compared to the traditional synthesis process, hot-pressing is environmentally friendly because it does not require organic solvents. The mobility of the polymer chain and the integrity and free volume of the membrane are affected by the temperature, pressure, duration, and annealing environment of the hot-pressing process, thereby altering the performance of the membrane. Additionally, when the wPS contained polybutadiene, the gas separation membranes showed a selectivity of 17.14 for CO₂/N₂. The membranes also exhibited ideal waterproof performance when the membranes were operated under water pressures of 1-5 bar. Therefore, membranes derived from wPS through hot pressing are waterproof and can be used for gas separation. Furthermore, they are expected to maintain their separation performance in complex environments.

Insights into the Role of Polymer Conformation on the Cutoff Size of Carbon Molecular Sieving Membranes for Hydrogen Separation and Its Novel Pore Size Detection Technology

In this study, three polymer precursor conformations, dilute, semi-dilute, and concentrated, were used to fabricate carbon molecular sieving (CMS) membranes via a fixed carbonization protocol. The effects of the precursor conformation on the microstructure of the resultant CMS membranes were characterized by Raman analysis. Their ability to separate light gases, such as H₂/CH₄ and H₂/N₂, was assessed with a single-gas system. Additionally, a novel method was proposed to detect the cutoff size of the CMS membranes created in this study. The method combined high-resolution transmission electron microscopy (HR-TEM) and a focused ion beam (FIB) system. Finally, due to the semi-dilute solution's denser polymer chains and lack of severe polymer entanglement, highly graphited CMS membranes with excellent gas separation performance were successfully synthesized using a semi-dilute polyetherimide dope solution. Interlayer distances in the carbon matrix were visualized and measured using our novel probing tool (HR-TEM and FIB) and software. The CMS membrane fabricated with a semi-dilute dope exhibited the best gas separation performance of the tested membranes. It had the most ordered carbon sheet orientation and exhibited a superior selectivity of H₂/CH₄ = 293 with a hydrogen permeability of 1138.7 Barrer, far surpassing the reported permselectivity of other membranes. We believe that the high H₂/CH₄ selectivity presented here is unprecedented for CMS membranes reported in the literature.

The Viable Fabrication of Gas Separation Membrane Used by Reclaimed Rubber from Waste Tires

Improper disposal and storage of waste tires poses a serious threat to the environment and human health. In light of the drawbacks of the current disposal methods for waste tires, the transformation of waste material into valuable membranes has received significant attention from industries and the academic field. This study proposes an efficient and sustainable method to utilize reclaimed rubber from waste tires after devulcanization, as a precursor for thermally rearranged (TR) membranes. The reclaimed rubber collected from local markets was characterized by thermogravimetric analyzer (TGA) and Fourier transfer infrared spectroscopy (FT-IR) analysis. The results revealed that the useable rubber in the as-received sample amounted to 57% and was classified as styrene–butadiene rubber, a type of synthetic rubber. Moreover, the gas separation measurements showed that the C7-P2.8-T250 membrane with the highest H₂/CO₂ selectivity of 4.0 and sufficient hydrogen permeance of 1124.61 GPU exhibited the Knudsen diffusion mechanism and crossed the Robeson trade-off limit. These findings demonstrate that reclaimed rubber is an appealing, cost effective, and sustainable alternative, as a precursor for TR membranes, for application in gas separation. The present approach is useful in the selection of a suitable reclaimed rubber precursor and related membrane preparation parameters, leading to the advancement in the recycling value of waste tires.

Tailored Pt/TiO₂ Photocatalyst with Controllable Phase Prepared via a Modified Sol-Gel Process for Dye Degradation

Pt/TiO2 photocatalysts with controllable phase were successfully prepared by controlling the hydrolysis pH values during the sol-gel process followed by Pt photodeposition. The effect of different phases of TiO2 coated with Pt on the catalytic properties and the photocatalytic activities were also investigated. The characterization results of the synthesis of TiO2 under neutral/alkaline and acidic conditions during the hydrolysis step revealed the facile formation of the anatase phase and the brookite/rutile phase, respectively. Pt/TiO2 photocatalysts prepared at hydrolysis pH values of 2, 7, and 10 had different TiO2 phase compositions, but the main crystalline sizes of the photocatalysts were all close to 6 nm. The Pt/TiO2 particles prepared at various hydrolysis pH values were all spheroidal. The PL results indicated that the anatase/rutile junction of a Pt/TiO2 sample had a lower recombination rate than did the anatase phase of Pt/TiO2 owing to the longer recombination pathway. However, the anatase phase of Pt/TiO2 exhibited better degradation ability than the anatase/rutile junction of Pt/TiO2, and the degradation rate decreased with a decrease in the anatase composition of TiO2, indicating that anatase composition in the Pt/TiO2 system played an important role of enhancing the photocatalytic degradation of Acid Red 1 dye.

Effect of the preparation method on activity of Cu-ZSM-5 nanocatalyst for the selective reduction of NO by NH3

The selective catalytic reduction of NO with ammonia (NH₃-SCR) was studied over Cu-ZSM-5 nanocatalysts which were prepared by several methods, including conventional ion-exchange (IE), conventional impregnation (IM), ultrasound-enhanced impregnation (UIM), and conventional deposition-precipitation (DP) using NaOH and homogeneous deposition-precipitation (HDP) using urea. The nanocatalysts were subsequently characterized by Fourier transform infrared spectroscopy, temperature-programmed reduction with hydrogen (H₂-TPR), ammonia temperature-programmed desorption (NH₃-TPD), X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscope, and Brunauer-Emmett-Teller. The catalytic activity of the Cu-ZSM-5 nanocatalysts for NO removal decreased in the following order: Cu-ZSM-5 (HDP) > Cu-ZSM-5 (UIM) > Cu-ZSM-5 (IM) > Cu-ZSM-5 (IE) > Cu-ZSM-5 (DP). The effect of various preparation methods for Cu-ZSM-5 on the activity of NO conversion was compared and catalytic experiments revealed a strong correlation between the acid sites' strength and easily reducible isolated Cu²⁺ with NO conversion. Catalyst (HDP) (which showed excellent deNO activity) mainly contains easy reducibility of isolated Cu²⁺ ions, more strong acid sites, and higher specific surface area when compared with other catalysts.

Modeling preparation condition and composition-activity relationship of perovskite-type LaxSr1-xFeyCo1-yO3 nano catalyst

In this paper, an artificial neural network (ANN) is first applied to perovskite catalyst design. A series of perovskite-type oxides with the LaxSr1-xFeyCo1-yO3 general formula were prepared with a sol-gel autocombustion method under different preparation conditions. A three-layer perceptron neural network was used for modeling and optimization of the catalytic combustion of toluene. A high R2 value was obtained for training and test sets of data: 0.99 and 0.976, respectively. Due to the presence of full active catalysts, there was no necessity to use an optimizer algorithm. The optimum catalysts were La0.9Sr0.1Fe0.5Co0.5O3 (Tc=700 and 800 °C and [citric acid/nitrate]=0.750), La0.9Sr0.1Fe0.82Co0.18O3 (Tc=700 °C, [citric acid/nitrate]=0.750), and La0.8Sr0.2Fe0.66Co0.34O3 (Tc=650 °C, [citric acid/nitrate]=0.525) exhibiting 100% conversion for toluene. More evaluation of the obtained model revealed the relative importance and criticality of preparation parameters of optimum catalysts. The structure, morphology, reducibility, and specific surface area of catalysts were investigated with XRD, SEM, TPR, and BET, respectively.

Presacral teratocarcinoma presenting as anal fistula and rectal adenocarcinoma: a unique case presentation and literature review

Somatic malignancy arising from presacral or retroperitoneal primary teratoma is extremely rare. We report the case of a 37-year-old male patient with adenocarcinoma of respiratory type arising from primary presacral teratoma, but which first presented as anal fistula and rectal adenocarcinoma. The two tumors show the same morphology and immunophenotype (CK7–CK20+CDx2+). Malignant adenocarcinoma transformations from the normal respiratory epithelium are also found. To the best of our knowledge, this is the second case of respiratory type adenocarcinoma arising from primary presacral mature cystic teratoma.

Synthesis of granular activated carbon/zero valent iron composites for simultaneous adsorption/dechlorination of trichloroethylene

The coupling adsorption and degradation of trichloroethylene (TCE) through dechlorination using synthetic granular activated carbon and zerovalent iron (GAC-ZVI) composites was studied. The GAC-ZVI composites were prepared from aqueous Fe(2+) solutions by impregnation with and without the use of a PEG dispersant and then heated at 105°C or 700°C under a stream of N(2). Pseudo-first-order rate constant data on the removal of TCE demonstrates that the adsorption kinetics of GAC is similar to those of GAC-ZVI composites. However, the usage of GAC-ZVI composites liberated a greater amount of Cl than when ZVI was used alone. The highest degree of reductive dechlorination of TCE was achieved using a GAC-ZVI700P composite (synthesized using PEG under 700°C). A modified Langmuir-Hinshelwood rate law was employed to depict the behavior of Cl liberation. As a result, a zero-order Cl liberation reaction was observed and the desorption limited TCE degradation rate constant decreased as the composite dosage was increased. The GAC-ZVI composites can be employed as a reactive GAC that is not subject to the limitations of using GAC and ZVI separately.

Characteristics of two types of stabilized nano zero-valent iron and transport in porous media

Nano-scale zero-valent iron (NZVI) has been shown to be suitable for remediating contaminated aquifers. However, they usually aggregate rapidly and result in a very limited migration distance that inhibits their usefulness. This study employed poly acrylic acid (PAA) and carboxymethyl cellulose (CMC) to synthesize two types of stabilized styles of NZVI with finer sizes (namely PNZVI and CNZVI). The mobility of stabilized NZVI was also demonstrated on the basis of transport in porous media. The results show that the PNZVI has a uniform particle size of 12 nm. However, tens of CNZVI particles with diameters of 1-3 nm were packed into secondary particles. Both the PNZVI and the CNZVI exhibited amorphous structures, and the stabilizer was bound to particle surfaces in the form of bidentate bridging via the carboxylic group, which could provide both electrostatic and steric repulsion to prevent particle aggregation. This study also proposes presumed stabilized configurations of PNZVI and CNZVI to reasonably illustrate their different dispersed suspension types. On the basis of the breakthrough curves and mass recovery, this study observed that the mobility of PNZVI in classic Ca(2+) concentration of groundwater was superior to CNZVI. Nonetheless, the mobility of CNZVI would be decreased less significantly than PNZVI when encountering high Ca(2+) concentrations (40 mM). Presumably, increasing the pore flow velocity would enhance the mobility of stabilized NZVI. Overall, the results of this study indicate that PNZVI has the potential to become an effective reactive material for in situ groundwater remediation.

Evaluating the potential of CNT-supported Co catalyst used for gas pollution removal in the incineration flue gas

This study investigated the use of Cu/Al(2)O(3), Co/Al(2)O(3), Fe/Al(2)O(3), and Ni/Al(2)O(3) catalysts for the growth of carbon nanotubes (CNTs). These CNTs were used as support for Co catalyst preparation and Co/CNT catalysts were applied to a catalytic reaction to remove BTEX, PAHs, SO(2), NO, and CO simultaneously in a pilot-scale incineration system. The analyzed results of EDS and XRD showed low metal content and good dispersion characteristics of the Al(2)O(3)-supported catalysts by excess-solution impregnation. FESEM analyzed results showed that the CNTs that were synthesized from Co, Fe, and Ni catalysts had a diameter of 20nm, whereas those synthesized from Cu/Al(2)O(3) had a diameter of 50nm. Pilot-scale test results demonstrated that the Co/CNT catalyst effectively removed air pollutants in the catalytic reaction and that there was no obvious deactivation by Pb, water vapor, and coke deposited in the process. The thermal stabilization at 250 degrees C and hydrophobicity properties of CNTs enhanced the application of CNT catalysts in flue gas.

The prospect and development of incinerators for municipal solid waste treatment and characteristics of their pollutants in Taiwan

Taiwan is a small, densely populated island with unique experiences in the construction and operation of incinerators. In such a small area, Taiwan has built 22 incinerators over a short span of time, combusting large amount of municipal solid waste as much as 23,250 tons per day. This study focuses on the history of construction and development of incinerators in Taiwan as well as the characteristics of pollutants, such as heavy metals (Pb, Cd, and Hg), acid gases (NO _x , SO _x , CO, and HCl), and dioxins emitted from the incinerators. Furthermore, the study also covers the generation and composition of municipal solid waste (MSW), and the production of energy in Taiwan. According to Taiwan's data on pollutant emissions, the emission level of pollutants is under control and meets the stringent regulations of Taiwan Environmental Protection Administration (TEPA). Researches have shown that using air pollution control devices (APCDs) in the operation of incinerators provides effective measures for air pollutant control in Taiwan. The main advantage of using incinerators is the generation of electricity (waste-to-energy) during the incineration of municipal solid waste, producing energy that can be consumed by the general public and the industry. Taiwan's extensive experience in incinerator construction and operation may serve as an example for developing countries in devising waste treatment technology, energy recovery, and the control of contagious viral diseases.

Characterizing PAH emission concentrations in ambient air during a large-scale joss paper open-burning event

Large-scale open burning of joss paper is an important ritual practice for deity worshipping during Buddhist and Taoist festivals. Since Buddhism and Taoism are two of the most popular religions in Chinese societies and some Asian countries, the impact of joss paper burning on the air quality needs further investigation. This study explores the concentrations of polycyclic aromatic hydrocarbons (PAHs) in ambient air during one of the most important festivals, in which large-scale burning of joss paper occurs in temples and in people's houses. The PAH concentrations were measured simultaneously at a temple site and a background site during both the festival and non-festive (ordinary) periods. Each ambient sample was extracted by the Soxhlet analytical method (for both particle-bound and gas-phase) and analyzed with gas chromatography. Experimental results indicate that the total PAH concentration during the festival period is approximately 4.2 times higher than that during the ordinary period (5384 ng m(-3) vs. 1275 ng m(-3)). This study also employed statistical methods including diagnostic ratios and principal component analysis (PCA) to identify the possible PAH emission sources. Joss paper burning and vehicular emissions are identified as the principal sources of airborne PAHs during the large-scale open-burning event. The results of this work provide useful information for public awareness concerning PAH emission from the open burning of joss paper.

Quadruple rescue therapy for Helicobacter pylori infection after two treatment failures

BACKGROUND

A standard third-line therapy for Helicobacter pylori infection is lacking, and antimicrobial sensitivity data for patients who failed eradication therapy are often unavailable in clinical practice. We therefore designed the prospective study to assess the efficacy of levofloxacin, amoxicillin, bismuth and rabeprazole quadruple therapy as a third-line treatment for H. pylori infection.

PATIENTS AND METHODS

From September 2005 to August 2007, 37 consecutive H. pylori-infected patients who had failed standard first-line and second-line treatments underwent a 10-day quadruple therapy comprising rabeprazole (20 mg b.i.d.), bismuth subcitrate (300 mg q.d.s.), amoxicillin (500 mg q.d.s.) and levofloxacin (500 mg o.d.). Follow-up endoscopy with rapid urease test, histological examination and culture was performed at 6 weeks after the end of treatment to evaluate the response to therapy.

RESULTS

Helicobacter pylori was successfully eradicated in 31 out of 37 patients (84% by both intention-to-treat analysis and per-protocol analysis). All patients complied with the eradication therapies, and only seven patients (19%) complained of mild-to-moderate adverse events. Amoxicillin- and levofloxacin-resistant strains were observed in 17% and 22% of the patients, respectively. There were no significant differences between H. pylori eradication rates and antibiotic resistances.

CONCLUSIONS

The 10-day levofloxacin- and amoxicillin-based quadruple therapy is well tolerated and achieves a high eradication rate as a third-line empirical treatment for H. pylori infection.

Quadruple rescue therapy for Helicobacter pylori infection after two treatment failures

BACKGROUND

A standard third-line therapy for Helicobacter pylori infection is lacking, and antimicrobial sensitivity data for patients who failed eradication therapy are often unavailable in clinical practice. We therefore designed the prospective study to assess the efficacy of levofloxacin, amoxicillin, bismuth and rabeprazole quadruple therapy as a third-line treatment for H. pylori infection.

PATIENTS AND METHODS

From September 2005 to August 2007, 37 consecutive H. pylori-infected patients who had failed standard first-line and second-line treatments underwent a 10-day quadruple therapy comprising rabeprazole (20 mg b.i.d.), bismuth subcitrate (300 mg q.d.s.), amoxicillin (500 mg q.d.s.) and levofloxacin (500 mg o.d.). Follow-up endoscopy with rapid urease test, histological examination and culture was performed at 6 weeks after the end of treatment to evaluate the response to therapy.

RESULTS

Helicobacter pylori was successfully eradicated in 31 out of 37 patients (84% by both intention-to-treat analysis and per-protocol analysis). All patients complied with the eradication therapies, and only seven patients (19%) complained of mild-to-moderate adverse events. Amoxicillin- and levofloxacin-resistant strains were observed in 17% and 22% of the patients, respectively. There were no significant differences between H. pylori eradication rates and antibiotic resistances.

CONCLUSIONS

The 10-day levofloxacin- and amoxicillin-based quadruple therapy is well tolerated and achieves a high eradication rate as a third-line empirical treatment for H. pylori infection.

High-dose versus low-dose esomeprazole-based triple therapy for Helicobacter pylori infection

BACKGROUND

This prospective, randomized, controlled study was conducted to compare the efficacies of high-dose and low-dose esomeprazole-based triple therapies for Helicobacter pylori eradication in Taiwan.

MATERIALS AND METHODS

From January 2004 to June 2006, 240 H. pylori-infected patients were randomly assigned to undergo high-dose (40 mg b.d.) or low-dose (40 mg o.d.) esomeprazole combined with clarithromycin (500 mg b.d.) and amoxicillin (1 g b.d.) for one week. Follow-up endoscopy was performed at eight weeks after the end of treatment to evaluate the response to therapy.

RESULTS

Intention-to-treat analysis demonstrated no differences between eradication rates of high-dose and low-dose groups (92% vs. 90%, respectively, P > 0.05). Per-protocol analysis yielded comparable results (95% vs. 93%). Both groups exhibited similar frequencies of adverse events (13% vs. 11%) and drug compliance (96% vs. 93%). Multivariate analysis indicated that only good compliance (odds ratio: 10.3, 95% CI, 3.0-35.7) was an independent predictor of treatment success.

CONCLUSIONS

This work demonstrates that low-dose esomeprazole-based triple therapy yields a similar eradication rate as high-dose esomeprazole-based therapy in Taiwan. Since the cost of the low-dose regime is lower than that of the high-dose regime, low-dose esomeprazole-based triple therapy can reasonably be recommended for the first-line eradication of H. pylori for Taiwanese and probably most Asians.

Randomized comparison of two rescue therapies for Helicobacter pylori infection

BACKGROUND

Bismuth salts are not available worldwide. It remains unknown whether clarithromycin can replace bismuth salts as an adjuvant agent in the rescue regimens for Helicobacter pylori infection. We therefore designed the prospective study to compare the efficacies of two rescue therapies for H. pylori infection after standard triple therapies.

PATIENTS AND METHODS

Ninety-three patients who failed H. pylori eradication using proton pump inhibitor plus clarithromycin and amoxicillin were randomly assigned to undergo rescue therapy with esomeprazole, clarithromycin, tetracycline and metronidazole (ECTM group, n = 46) or esomeprazole, bismuth subcitrate, tetracycline and metronidazole (EBTM group, n = 47). Follow-up endoscopy was performed at 8 weeks after the end of treatment to assess the treatment response.

RESULTS

Intention-to-treat analysis demonstrated both groups had similar eradication rates (ECTM 74% vs. EBTM 77%; P = 0.76) and drug compliance (ECTM 94% vs. EBTM 96%; P = 0.68). However, the frequency of adverse events in the ECTM group was higher than that in EBTM group (ECTM 57% vs. EBTM 36%, P = 0.05). In the EBTM group, eradication rate of metronidazole-resistant strains was lower than that of metronidazole-susceptible strains (67%[8/12] vs. 100%[9/9], P = 0.05). However, eradication rates were similar between metronidazole-susceptible and metronidazole-resistant strains in ECTM group (69%[9/13] vs. 70%[7/10], P = 1.00).

CONCLUSIONS

The new ECTM second-line therapy can achieve similar eradication rate as standard EBTM therapy. It may be very useful in countries where bismuth salts are not available.

Effects of acid treatments of activated carbon on its physiochemical structure as a support for copper oxide in DeSO(2) reaction catalysts

To enhance the dispersion of active sites, modification of the AC supports with different acid solution might result in various surface oxygen groups which act as anchoring sites for metallic precursor to stay and improve the reactivity between AC supports and copper precursor. In the present work, the AC support is tailored with HCl and HNO(3), respectively. The pore structure, surface oxygen groups of the AC support and catalysts as well as catalyst dispersion before and after acid treatments are systematically studied by BET, pH(slurry), TPD, and XRPD analyses. It is found that the order of activity in DeSO(2) reaction is as follows: Cu/AC-HCl>Cu/AC>Cu/AC-HNO(3). The same sequence is also observed for the pore structure of AC supports, the catalyst dispersion, but not for the amounts of CO(2) evolving during TPD experiments of supports. The key role of acid treatment on carbon surface chemistry and pore structure, which are closely related to catalyst dispersion and adsorption capacity, is examined to rationalize these findings. Furthermore, under the NO/NH(3)=1 the NO could be selective catalytic reduction with NH(3) in the presence of O(2), which catalyzed by fresh and spent AC-supported catalyst.

Experimental testing of spray dryer for control of incineration emissions

The research investigated the absorption/adsorption efficiency of sulfur dioxide (SO2), heavy metals, and polycyclic aromatic hydrocarbons (PAHs) with different Ca-based sorbents in a spray dryer during incineration process. For further improving the adsorption capacity of Ca-based sorbents, different spraying pressure and additives were carried out in this study. Experimental results showed that CaO could be used as an alternative sorbent in the spray dryer at an optimal initial particle size distribution of spraying droplet. In the spray dryer, Ca-based sorbents provided a lot of sites for heavy metals and PAHs condensing and calcium and alkalinity to react with metals to form merged species. As a result, heavy metals and PAHs could be removed from the flue gas simultaneously by condensation and adsorption. The additions of additives NaHCO3, SiO2, and KMnO4 were also found to be effective in improving the removal efficiency of these air pollutants.

Endoscopic 13C-urea breath test for the diagnosis of Helicobacter pylori infection

BACKGROUND

Endoscopic 13C-urea breath test may avoid contamination of oral urease and rapidly discriminate Helicobacter pylori-positive and Helicobacter pylori-negative patients.

AIMS

To compare the accuracy of endoscopic 13C-urea breath test with conventional invasive methods in diagnosis of Helicobacter pylori infection.

PATIENTS

One hundred patients who attended for routine upper gastrointestinal endoscopy were included.

METHODS

13C-urea was applied to the stomach through the working channel of endoscope at the end of endoscopic examination. Breath samples were collected before endoscopy and 2, 4, 6, 8, 10 min after consumption of 100 or 50 mg 13C-urea. Helicobacter pylori infection was defined as those with positive culture or positive results of both histology and CLO test.

RESULTS

The accuracy of 100 mg endoscopic 13C-urea breath test was significantly higher than that of culture and CLO test (100% vs. 88% and 92%, p = 0.02 and 0.03, respectively). The accuracy of 50 mg endoscopic 13C-urea breath test was higher than that of histology and CLO test (98% vs. 90% and 96%, respectively), although the differences were not statistically significant.

CONCLUSIONS

Endoscopic 13C-urea breath test has a higher accuracy compared with biopsy-based modalities. It may be a good choice to diagnose Helicobacter pylori infection if endoscopy is indicated for a dyspeptic patient.

Pore structure effects on Ca-based sorbent sulfation capacity at medium temperatures: activated carbon as sorbent/catalyst support

The reaction between three different Ca-based sorbents and SO2 were studied in a medium temperature range (473-773 K). The largest SO2 capture was found with Ca(OH)2 at 773 K, 126.31 mg SO2 x g Ca(OH)2(-1), and the influence of SO2 concentration on the sorbent utilization was observed. Investigations of the internal porous structure of Ca-based sorbents showed that the initial reaction rate was controlled by the surface area, and once the sulfated products were produced, pore structure dominated. To increase the surface area of Ca-based sorbents available to interact with and retain SO2, one kind of CaO/ activated carbon (AC) sorbent/catalyst was prepared to study the effect of AC on the dispersion of Ca-based materials. The results indicated that the Ca-based material dispersed on high-surface-area AC had more capacities for SO2 than unsupported Ca-based sorbents. The initial reaction rates of the reaction between SO2 and Ca-based sorbents and the prepared CaO/AC sorbents/catalysts were measured. Results showed that the reaction rate apparently increased with the presence of AC. It was concluded that CaO/AC was the active material in the desulfurization reaction. AC acting as the support can play a role to supply O2 to increase the affinity to SO2. Moreover, when AC is acting as a support, the surface oxygen functional group formed on the surface of AC can serve as a new site for SO2 adsorption.

The utilization of catalyst sorbent in scrubbing acid gases from incineration flue gas

Catalyst sorbents based on alumina-supported CuO, CeO2, and CuO-CeO2 were applied to a dry scrubber to clean up the SO2/HCl/NO simultaneously from pilot-scale fluidized-bed incineration flue gas. In the presence of organic compounds, CO and the submicron particles SO2 and HCI removed by the fresh catalyst sorbents and NO reduced to N2 by NH3 under the catalysis of fresh and spent desulfurization/dechloridization (DeSO2/DeHCl) catalyst sorbents (copper compounds, Cu, CuO, and CuSO4) were evaluated in this paper. The fresh and spent catalyst sorbents were characterized by the Brunner-Emmett-Teller method (BET), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), inductively coupled plasma-mass spectrometry (ICP-MS), and the elemental analyzer (EA). The study showed that the performances of CuO, CeO2, and CuO-CeO2/gamma-Al2O3 were better than that of Ca(OH)2. The removal efficiency of SO2 and HCl was 80-95% in the dry scrubber system. Under NH3/NO = 1, NO could not be reduced to N2 because it was difficult to control the ratio of air/fuel in the flue gas. For estimating the feasibility of regenerating the spent catalyst sorbents, BET and EA analyses were used. They indicated that the pore structures were nearly maintained and a small amount of carbon accumulated on their surface.

The study of modified calcium hydroxides with surfactants for acid gas removal during incineration

The primary objective of the present work is to use additives to extend the sulfation reaction of the calcium hydroxide (Ca(OH)2) used to control SO2 emission from incineration processes. There are two reasons for adding surfactants (surface-active agent): (1) to provide an appropriate dispersion of the Ca(OH)2', thus preventing particle agglomeration due to humidity; (2) to alter the sulfation reaction environment by adsorbing heterogeneous materials on the surface of the Ca(OH)2 to extend the adsorption equilibrium. A dry scrubber integrated with a fabric filter was employed to study the effect of surfactants on the removal efficiency of acid gas in the flue gas with Ca(OH)2 as the sorbent. The operating parameters evaluated include: (1) the different surfactants (calcium lignosulfonate, sodium lignosulfonate, alkyl naphthalene sodium sulfonate and beta-naphthalene sodium sulfonate condensates) and (2) the composition of acid gas (i.e. sulfur dioxide (SO2), nitrogen oxide (NO) and hydrogen chloride (HCl)). The results show that modified Ca(OH)2 with surfactants could effectively decrease the emission of acid gas during incineration. Different additives had individual absorption efficiencies on different acid gases. On the whole, sodium lignosulfonate and beta-naphthalene sodium sulfonate condensates had better sorption capacity for SO2 and NO, but not for HCl. In addition, when SO2 coexisted with NO and HCl, the concentration of NO and HCl will result in decrease or increase of the removal efficiency of SO2.

Sequential changes of gastric hyperplastic polyps following endoscopic ligation

BACKGROUND

Endoscopic ligation has been extensively applied in the management of esophageal and gastric varices with or without bleeding. The varices are automatically eradicated through the use of ligation. However, whether avascular necrosis will occur in a gastrointestinal polyp when the base is ligated remains unclear. The aims of this pilot study were to investigate the sequential changes of gastric hyperplastic polyps following endoscopic detachable snare ligation and to determine the possibility of induction of avascular necrosis in these lesions following ligation.

METHODS

Eleven patients with eighteen gastric hyperplastic polyps were treated with endoscopic detachable-snare ligation. The polyps were observed for 5 minutes and biopsies were then conducted. At 14 days after endoscopic ligation, follow-up endoscopies were performed to assess the outcome of the strangulated polyps.

RESULTS

After being strangulated by the detachable snares, a majority of the polyps immediately congested (94%), and then developed cyanotic change (89%) approximately 4 minutes later. Pathological examination revealed severe venous congestion in the lamina propria of the strangulated polyps. On follow-up endoscopy 2 weeks later, all the snares had dropped off, and avascular necrosis occurred in sixteen polyps (89%). All of the polyps with avascular necrosis were detected to have developed cyanotic changes in initial endoscopy. No complications occurred during or following the ligation procedure.

CONCLUSIONS

Most gastric hyperplastic polyps develop avascular necrosis following ligation by detachable snare. Cyanotic change is an important predictor of the outcomes of the lesions following endoscopic ligation. The application of this ligation technique in treatment of bleeding or non-bleeding gastrointestinal polyps deserves further investigation.

Nephrogenic adenoma associated with cytomegalovirus infection of the ureter in a renal transplant patient: presentation as ureteral obstruction

Nephrogenic adenoma (NA), a rare benign lesion of the urinary tract, is widely accepted to be a metaplastic reaction due to urothelial injury. It mainly occurs in the urinary bladder and rarely in the ureter. Renal transplant recipients are prone to the development of NA. However in those patients, NA was diagnosed exclusively in the bladder. Herein, we present the--to our knowledge--first case of NA involving a transplanted ureter. A 42-year-old female kidney transplant recipient suffered hematuria, oliguria, and acute renal failure and presented with ureteral obstruction and hydronephrosis of the renal transplant. To our surprise, evidence of cytomegalovirus (CMV) infection of the NA was demonstrated using special immunohistochemical staining. The findings in this case raise the possibility that CMV infection, as an irritant of the ureteral epithelium, may be an etiological factor of NA.