Hexadecylpyridinium Chloride Monohydrate Research Articles

Organo magadiites for diclofenac adsorption: influence of the surfactant chain.

The presence of drugs in aquatic environments has been considered a global challenge and several remediation technologies have been proposed, including adsorption. In this study, new diclofenac adsorbents were obtained from the reaction of sodium magadiite (Na-Mag) with surfactants dodecylpyridinium chloride hydrate (C12pyCl) and hexadecylpyridinium chloride monohydrate (C16pyCl)), 1-hexadecyltrimethylammonium bromide (C16Br), and dodecyltrimethylammonium bromide (C12Br). The synthesis was carried out in the microwave at 50°C for 5min using surfactant amounts of 100% and 200% in relation to the cation exchange capacity of Na-Mag. The elemental analysis indicated that surfactants with a longer organic chain were more incorporated into Na-Mag, whose values were 1.42 and 1.32mmolg-1 for C16pyMag200% and C16Mag200%, respectively. X-ray diffraction results suggested formation of intercalated products with basal space in the range of 2.81-4.00nm. Diclofenac was quickly adsorbed on all organophilic magadiites, at an equilibrium time of 1min. Drug capacity adsorption was influenced by the arrangement and packing density of organic cations, the basal distance, and the organic contents of the samples at high drug concentrations. Alkylpyridinium magadiites exhibited maximum adsorption capacities higher than alkylammonium magadiites, of 96.4, 100.7, 131.7, and 166.1mgg-1 for C12pyMag100%, C12pyMag200%, C16pyMag100%, and C16pyMag200%, respectively, at pH 6.0 and 30°C. Diclofenac removal by samples was not affected by the presence of ibuprofen, which was also removed from binary system by organophilic magadiites reaching removal of 76.5% and 86.9% by C16pyMag100% and C16pyMag200%, respectively. Regeneration studies demonstrated a drug removal percentage of 83-92% for C16pyMag and C16Mag after three cycles of adsorption.

Examination of eutectic phase change materials composed of diols and ionic liquids

This paper presents solid–liquid phase equilibrium studies of binary systems composed of pyridinium chloride monohydrates: hexadecylpyridinium chloride monohydrate, [PyC16][Cl] or dodecylpyridinium chloride monohydrate, [PyC12][Cl] with diols: 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol and 1,12-dodecanediol. These systems were selected to obtain eutectic mixtures with a high melting enthalpy and lower volatility (thus flammability) than pure diols. Ten eutectic Phase Change Materials (ePCMs) with melting points ranging from 265 K to 333 K (-8 °C to 60 °C) and enthalpies of melting from 125.9 to 212.8 J·g−1 were obtained. Experimental data were then correlated with the Non-Random Two-Liquid (NRTL) equation, and mixtures of eutectic composition were subjected to physicochemical characterisation. Using DSC, the latent heats of pure components and eutectic mixtures were determined, as well as the viscosity and the thermal conductivity of ePCMs was measured as a function of temperature. The final objective of the study was to increase the thermal conductivity of ePCMs by adding carbon nanotubes or expanded graphite, and to characterise the performance of such composite systems. The stability of nanofluids containing no less than 1 wt% SWCNTs and from about 10 wt% EG was confirmed under both isothermal and energy storage operating conditions, i.e. during a series of at least 1000 phase transformations. The addition of an inexpensive EG at 10 wt% increases the thermal conductivity by up to 200 % and reduces the probability of ePCM leakage as the material retains its shape even after melting.

A self-assembly hydrophobic oCDs/Ag nanoparticles SERS sensor for ultrasensitive melamine detection in milk

A simple, ultra-sensitive, and super-stable hydrophobic SERS platform for detection of melamine in milk is developed. The hydrophobic SERS platform was constructed via directly growing hydrophobic carbon/silver nanoparticles on glass by in-situ one-step carbonization using hexadecylpyridinium chloride monohydrate as stabilizer and reducing agent. The performances of SERS platform are systematically studied by using Rhodamine 6G (R6G) as a model, which achieves detection level of 10−13 M and enhancement factor of 3.4 × 1010 for R6G detection with good uniformity and reproducibility, as well as 110 days stability in air. The FDTD simulation was used to confirm SERS enhancement mechanism. More importantly, SERS platform delivers good linear property in the range from 0.01 to 100 ppm, and low limit detection of 9 ppb for melamine detection in milk through direct drop on the platform. The SERS platform could have great applications in food safety, environmental monitoring, biomedicine and other fields.

Enhanced removal of radioactive iodine anions from wastewater using modified bentonite: Experimental and theoretical study

Efficient and cost-effective removal of radioactive iodine anions from contaminated water has become a crucial task and a great challenge for waste treatment and environmental remediation. Herein, we present hexadecylpyridinium chloride monohydrate modified bentonite (HDPy-bent) for the efficient and selective removal of iodine anions (I− and IO3−) from contaminated water. Batch experiments showed that HDPy-bent could remove more than 95% of I− and IO3− within 10 min, and had maximum I− and IO3− adsorption capacities of 80.0 and 50.2 mg/g, respectively. Competitive experiments indicated that HDPy-bent exhibited excellent I− and IO3− selectivity in the excessive presence of common concomitant anions including PO43−, SO42−, HCO3−, NO3−, Cl− (maximum mole ratio of anions vs iodine anions was ∼50,000). An anion exchange mechanism was proposed for the selective adsorption of iodine anions. Optimal adsorption structure of HDPy+/I− (IO3−) at atomic level and driving forces of the I− (IO3−) adsorption were calculated by density functional theory (DFT) simulations. Moreover, the good durability and reusability of the HDPy-bent has been demonstrated with 5 adsorption-desorption cycles. Dynamic column experiment also demonstrated that HDPy-bent exhibited excellent removal and fractional recovery capabilities towards I− and IO3− from simulated groundwater and environmental water samples. In conclusion, this work presents a promising adsorbent material for the decontamination of radioactive iodine anions from wastewater on a large scale.

The inhibition performance of heterocyclic compounds on Q235 steel in methanol/formic acid medium: Experimental and theory

The present paper discusses the adsorption and inhibitory effect of nitrogen-containing compound, 1-dodecyl-3-methyimidazolium chloride (DMIC), dodecylpyridinium chloride (DPC) and hexadecylpyridinium chloride monohydrate (HDPC) on Q235 steel corrosion in a new system（10 mol·L−1 methanol/0.1 mol·L−1 formic acid medium. The experimental study was carried out using a series of techniques such as weight loss, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). contact angle test, Raman spectra, X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM) served to identify microscopic variation on Fe surface. Adsorption isotherm model controlling the adsorption process are calculated and discussed. Moreover, the relationships between molecular structure and corrosion inhibition performance of three inhibitors were verified by quantum chemical calculation and molecular dynamics simulation. The results obtained from the electrochemical methods showed that DMIC, DPC and HDPC imparted high resistance and behaved as mixed-type corrosion inhibitors dominated with anode. inhibition efficiency (η%) increased with the increase of inhibitors concentration to attained 88.81%, 92.69%, 93.67% at 0.06 mol·L−1, respectively. Surface studies confirmed the existence of an adsorption film on the metal surface. The obtained results demonstrated that the adsorption process on the metal surface followed the Langmuir adsorption model. Quantum chemical calculations and molecular dynamics simulation (MD) testified the effect of the chemical structure of three inhibitors on its inhibition efficiency, which had a good agreement with the experimental data.

Technetium-99 decontamination from radioactive wastewater by modified bentonite: batch, column experiment and mechanism investigation

Technetium-99 (99Tc), as one of the important high-yield fission products, poses a significant threat to the environment and human health due to its radiotoxicity, long half-life, high solubility and mobility in the environment. Thus, removal of 99TcO4− from radioactive wastewater is considerably imminent for waste disposal and environment conservation. In this work, Hexadecylpyridinium Chloride Monohydrate modified bentonite (HDPy-bent) was synthesised and used as an adsorbent to remove 99TcO4−. The adsorption behaviours of ReO4− as an analogue for TcO4− were investigated as functions of contact time, solution pH, initial concentration, and competing anions using batch techniques. It is demonstrated that the HDPy-bent showed an excellent adsorption ability for ReO4− at the pH range of 2–11, fast adsorption kinetic (reaching equilibrium within 3 min at room temperature), and maintains desirable ReO4− adsorption in the presence of concomitant anions at an excessive concentration of 500 times (Cl−, HCO3−, NO3−, CO32−, SO42− and PO43−). As for adsorption mechanism, we propose the anion exchange process at low concentration of Re(VII) and precipitation reaction at high concentration, while the driving force of the high ReO4− adsorption ability is the interaction between ReO4− anion and pyridinium ring of HDPy+, which is confirmed by density functional theory (DFT) simulations. Additionally, DFT studies also shed light on the adsorption structure of HDPy+/ReO4− and the origin of adsorption selectivity. Moreover, four adsorption-desorption cycles suggest that the HDPy-bent has good durability and reusability. Furthermore, ReO4− can be removed completely and recovered fractionally by using the chromatography column packed with HDPy-bent from simulated groundwater samples. The work presented herein demonstrates a low-cost adsorbent which can efficiently remove 99Tc from contaminated water.

Oxidized Black Phosphorus Nanosheets as an Inorganic Antiresorptive Agent

Black phosphorus (BP) is a newly discovered two-dimensional material that has promising applications from bioelectronics to biomedicine. However, facile oxidation of BP leads to changes in surface ...

Square wave voltammetry at carbon paste electrode modified with surfactant for alpha tocopheryl acetate determination in cosmetics

The aim of this study was describe electrochemical properties of a carbon paste electrode (CPE) bulk modified with 30% (w/w) surfactant sodium dodecyl sulphate (CPE/SDS) and demonstrates its application in the determination of α‑tocopheryl acetate (α‑TAc), known as vitamin E acetate, in selected cosmetic products, especially body creams. In addition to anionic SDS, cationic hexadecylpyridinium chloride monohydrate (CPC) was also tested as possible modifier. It was found that selection of surfactant type and its content significantly affect an electrical conductivity and mechanical stability of these heterogeneous electroanalytical sensors in pure organic solvents. Under this study, it was found that CPC is a totally inappropriate mediator due to very high backgroundcurrent. Together with other lipophilic vitamins characterized by antioxidant activity (dominantly retionoids), this completely synthetic substance is widely used as significant cosmetic additive due its preservative properties. Monitoring of its content in cosmetic products is usually performed by high‑performance liquid chromatography (HPLC) with UV detection. This standard analytical protocol is always burdened with the complex and time‑consuming preparation of the sample before analysis. For that reason, robust and simple electroanalytical method based on anodic oxidation of the α‑TAc at CPE/SDS by square wave voltammetry (SWV) performed in pure organic electrolyte (99.8% acetonitrile containing 0.1 mol·L‑1 LiClO4) was developed. Moreover, simple dissolution of sample in supporting electrolyte using ultrasonic bath and subsequent filtering through a stacked filter included all the necessary procedures for sample preparation. The linear range from 0.1 to 1.2 mmol·L‑1and limit of detection 37 µmol·L‑1 were found at pulse amplitude 10 mV and frequency 10 Hz as optimum. In analysis of selected cosmetics, the developed electroanalytical method was not validated using comparison with standard HPLC. At least, the recovery was verified by analysis of model sample and value 95.8% was calculated.

A New Sensor for Determination of Anionic Surfactants in Detergent Products with Carbon Nanotubes as Solid Contact

AbstractA new solid‐state sensor for potentiometric determination of surfactants with a layer of multi‐walled carbon nanotubes was prepared. As a sensing material, 1,3‐didecyl‐2‐methylimidazolium–tetraphenylborate ion‐pair was used. The investigated sensor showed a Nernstian response for both dodecylbenzenesulphonate (DBS, 57.6 mV/decade of activity between 5 × 10−7 to 1 × 10−3 M) and sodium lauryl sulfate (LS, 58.4 mV/decade of activity between 2 × 10−7 to 2 × 10−3 M). It responded in 8–10 s for each ten‐fold concentration change in the range of 1 × 10−6 to 3 × 10−3 M. The detection limits for DS and DBS were 2 × 10−7 and 3 × 10−7 M, respectively. The sensor revealed a stable response (signal drift 2.6 mV/h) and exhibited satisfactory selectivity performances for LS over most of the anions generally used in surfactant‐based commercial detergents. The main application of this sensor was the end‐point determination in potentiometric titrations of anionic surfactants. The (diisobutyl phenoxy ethoxy ethyl)dimethyl benzyl ammonium chloride (Hyamine), cetyltrimethylammonium bromide, hexadecylpyridinium chloride monohydrate (HDPC) and 1,3‐didecyl‐2‐methylimidazolium chloride were tested as potential cationic titrants, and all exhibited analytically usable titration curves with well‐defined equivalence points. The standard solution of HDPC was used as a cationic titrant by all potentiometric titrations. The operational life‐time of the sensor described was prolonged to more than 3 months.

One-pot solvothermal synthesis of PdCu nanocrystals with enhanced electrocatalytic activity toward glycerol oxidation and hydrogen evolution

The catalytic capability of bimetallic nanocatalysts is closely correlated with their size, shape, and crystal structures. Herein, a facile one-pot solvothermal strategy is designed to fabricate uniform spherical PdCu nanocrystals (NCs) assembled by many smaller grains. Oeylamine (OAm) is acted as the reaction solvent and reductant. KBr and hexadecylpyridinium chloride monohydrate (HDPC) are used as the capping agent and surfactant to avoid the aggregation, respectively. The architectures possess larger electrochemically active surface area (ECSA) of 13.6 m2 g−1 than commercial Pd black (4.4 m2 g−1), showing the improved catalytic ability for glycerol oxidation reaction (GOR) in alkaline electrolyte in contrast with Pd black. Besides, the obtained catalyst exhibits more positive onset potential (−56 mV) and Tafel slope (51 mV decade−1) toward hydrogen evolution reaction (HER) in acidic media relative to commercial Pd/C, albeit with their performance bellow commercial Pt/C catalyst.

Adsorption potential of 2,4-dichlorophenol onto cationic surfactant-modified phoenix tree leaf in batch mode

It is essential and important to remove chlorophenols from solution. The natural phoenix tree leaf (NTL) was modified by a cationic surfactant, hexadecylpyridinium chloride monohydrate (CPC), and applied as an adsorbent (modified phoenix trees’ leaf (MTL)) to enhance the capability to remove 2,4-dichlorophenol in aqueous solutions. Analysis of elemental composition, SEM and FTIR indicated that CPC was adsorbed on the surface of NTL. 2,4-dichlorophenol (2,4-DCP) was selected as adsorbate and the adsorption experiments were carried out in batch mode. Effects of physical–chemical parameters such as solution pH, coexisted salt, and contact temperature were investigated. The optimum pH was 6.3 and the effect of salt concentration is not significant. The adsorption quantity was up to 188.8 mg g−1 at experimental condition. The equilibrium adsorption data were fitted adequately to Freundlich and Henry isotherms, and the corresponding constants were calculated for these models. In addition, the adsorption kinetic data were analyzed using the pseudo-first-order and pseudo-second-order kinetic equations. The results showed that the pseudo-second-order model was better to fit the experimental data, which indicated that the adsorption of 2,4-DCP was controlled predominantly by a chemical adsorption process. Thermodynamic study suggested that the adsorption of 2,4-DCP on CPC–MTL was an endothermic process. Furthermore, the adsorbed 2,4-DCP was desorbed effectively up to 83% and the exhausted adsorbent could be regenerated and reused, making the adsorption process more feasible and economical. The results indicated that MTL can be used as an efficient adsorbent for the removal of 2,4-DCP from aqueous solutions.

Construction of Dandelion-like Clusters by PtPd Nanoseeds for Elevating Ethanol Eletrocatalytic Oxidation

We successfully synthesized a dandelion-like PtPd heterogeneous structure via a facile one-pot hydrothermal route by reducing Na2PdCl4 and H2PtCl6 with ascorbic acid in the presence of hexadecylpyridinium chloride monohydrate. Hexadecylpyridinium chloride monohydrate acted as the shape-directing agent, which is critical to the reproducible formation of dandelion-like PtPd nanoclusters (DPtPdNC). The prepared DPtPdNC with an average diameter of 40nm composed of dozens of branched arm assembled by Pt and Pd heterogeneous nanoseeds. DPtPdNC had a strong electron-electron interaction. What's more, there were numerous nanoscale steps, kinks and edges in DPtPdNC open channel structure. As a result, an optimized DPtPdNC made by fine-tuning ratio of the Pt (7%) and Pd (93%) showed hugely active surface sites and a superior electrocatalytic performance for ethanol oxidation was well as a long durability.

One-pot synthesis of platinum3cobalt nanoflowers with enhanced oxygen reduction and methanol oxidation

Herein, a simple one-pot approach is developed for preparation of Pt3Co nanoflowers by co-reduction of Pt (II) acetylacetonate (Pt(acac)2) and Co (III) acetylacetonate (Co(acac)3) in oleylamine, without any seed or template. It is found that hexadecylpyridinium chloride monohydrate (HDPC) is served as both the stabilizing and structuring-directing agent that plays an important role in the formation of well-dispersed flower-like Pt3Co nanoparticles. The as-prepared Pt3Co nanoflowers show the enhanced catalytic performance for oxygen reduction reaction (ORR) in comparison with solid Pt3Co nanoparticles and commercial Pt black catalysts, dominated by a four-electron pathway based on the Koutecky–Levich equation. Meanwhile, Pt3Co nanoflowers exhibit the improved catalytic activity and long-term stability towards methanol oxidation reaction (MOR), using solid Pt3Co nanoparticles and commercial Pt black catalysts as references. The improved catalytic features of Pt3Co nanoflowers are mainly attributed to the porous three-dimensionally interconnected structures, enlarged specific surface area, ligand effect and bifunctional mechanism between Pt and Co. The as-developed method provides a promising pathway for preparation of highly efficient electrocatalysts for ORR and MOR.

Adsorption of anionic dyes in aqueous solution using chemically modified barley straw

An agricultural waste derived adsorbent was prepared by chemically modified barley straw with NaOH and a cationic surfactant hexadecylpyridinium chloride monohydrate (CPC). The prepared adsorbent, BMBS, was used for removal of anionic dyes; Acid Blue (AB40) and Reactive Blue 4 (RB4) from aqueous solution in a batch adsorption system. The adsorbent was characterized by FT-IR and elemental composition. The stability of CPC adsorbed on straw surface was also evaluated by exposing to aqueous solution. In adsorption tests, influence of operation parameters such as contact time, initial concentration and pH of solution on AB40 and RB4 uptake were investigated and discussed. The CPC was observed strongly attached to straw surface and removal percentage of AB40 and RB4 was increased with increasing in contact time. The adsorption of dyes on modified straw surface was favorable at high acidic condition and desorption was found relatively low upon exposing to the desorption agent (i.e water). Dynamic experiment revealed that the kinetic data fitted well to the pseudo-second-order model for both of the dyes. The isotherm study also indicated that RB4 and AB40 adsorption suited well with the Langmuir model, The maximum adsorption capacity determined from the Langmuir isotherm at 25 degrees C was 51.95 mg g(-1) and 31.5 for AB40 and RB4, respectively.

Adsorptive separation of emulsified oil in wastewater using biosorbents

ABSTRACTAn agricultural waste, barley straw, was chemically modified using a cationic surfactant hexadecylpyridinium chloride monohydrate (CPC) to obtain a biosorbent for removal of emulsified mineral oil from aqueous solution. The physical and chemical properties of the raw and surfactant‐modified barley straw (SMBS) were characterized by N2 adsorption, bulk density, Fourier transforms infrared spectra and the composition of cellulose, hemicellulose and lignin. The adsorption tests were performed using a standard mineral oily wastewater in a batch adsorption system. The effects of contact time and pH of solution on the emulsified oil uptake were investigated and discussed. It was found that the removal efficiency of emulsified oil increased with the increase in contact time. Biosorption was found to be less favorable at high acidic condition and a maximum removal was obtained at about neutrality. The isotherm study indicated that emulsified oil adsorption on SMBS was fitted well with the Langmuir model rather than the Freundlich model. The maximum adsorption capacity determined from the Langmuir isotherm was 518.6 mg g−1 at 25 °C. The kinetic study revealed that equilibrium time was achieved in less than 40 min and the kinetic data were fitted well to the pseudo‐first‐order model. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Preparation of bioadsorbents for effective adsorption of a reactive dye in aqueous solution

AbstractThe surface of barley straw, an agricultural waste, was modified chemically using a cationic surfactant hexadecylpyridinium chloride monohydrate (CPC) and used as an adsorbent for removal of Reactive Blue 4 (RB4) from aqueous solution. The raw and surfactant‐modified barley straws (SMBS) were characterized by Fourier transform infrared and elemental analysis. The stability of CPC adsorbed on straw surface was evaluated by exposing to water and organic solvents. The adsorption was performed on removing RB4 from wastewater in a batch adsorption system. The effects of contact time, initial concentration of dye and pH of solution on RB4 uptake were investigated and discussed. It was found that the removal percentage of RB4 increased with the increase in contact time. Adsorption was favorable at acidic condition and the maximum removal of 100% was obtained at pH 3. Dye‐loaded SMBS was stable and percentage of desorption was less than 7% in water. The kinetic studies revealed that the kinetic data fitted well to the pseudo‐second‐order model. The isotherm study also indicated that RB4 adsorption on SMBS matched well with the Langmuir model other than the Freundlich model. The maximum adsorption capacity determined from the Langmuir isotherm was 29.2 mg g−1 at 25 °C. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Removal of emulsified oil from oily wastewater using agricultural waste barley straw

An agricultural byproduct, barley straw, was chemically modified by a cationic surfactant, hexadecylpyridinium chloride monohydrate (CPC) and employed as an adsorbent to remove emulsified canola oil from aqueous solution. The textural and surface properties of the surfactant modified barley straw (SMBS) were characterized by N 2 adsorption, FT-IR, SEM, surface acidic/basic groups and surfactant desorption. The low desorption of CPC from SMBS demonstrated a strong bonding of the CPC to straw surface. Several factors such as adsorption temperature, solution pH, loading of adsorbent, and particle size on oil adsorption were investigated. It was found that addition of CPC created a non-polar layer on barley straw surface thus endowing SMBS with much better adsorption capacity for oil removal from water. The adsorption was found less favorable at high acidic condition and the maximum adsorption capacity was observed at about neutrality. Larger particle size would result in lower adsorption while adsorption temperature would not affect oil adsorption significantly. The kinetic study revealed that equilibrium time was short and the isotherm study indicated that the oil adsorption was fitted well by the Langmuir model. The adsorption capacity determined from the Langmuir isotherm was 576.0 ± 0.3 mg g −1 at 25 °C.

Removal of emulsified food and mineral oils from wastewater using surfactant modified barley straw

Barley straw, an agricultural waste, was chemically modified and evaluated for the removal of emulsified oils from aqueous solution. The chemical modification was performed using NaOH and a cationic surfactant, hexadecylpyridinium chloride monohydrate (CPC). The surface textural and chemical properties of the surfactant modified barley straw (BMBS) were characterized by N 2 adsorption, FT-IR, SEM and water soluble mineral content. The adsorption tests were carried out in batch adsorption system for removal of standard mineral oil (SMO) and canola oil (CO) from water. For both emulsified oils in wastewater, adsorption was found to be strongly related with solution pH. The isotherm study indicated that emulsified oil adsorption on BMBS could be fitted well with the Langmuir model other than Freundlich model. The maximum adsorption capacity for CO and SMO at 25 °C determined from the Langmuir isotherm is 613.3 and 584.2 mg g −1, respectively. Desorption tests in water solution show that oil is strongly bonded with adsorbent and desorption is only about 1–2% in 24 h.

Brain Heart Infusion Broth May Not Be a Required Component for the Decontamination Process for the Isolation of Mycobacterium Avium Subspecies Paratuberculosis from Fecal Samples using ESP® Broth Cultures

Based on the authors' laboratory experience indicating that increased bacterial contamination in Mycobacterium avium ssp. paratuberculosis (MAP) cultures may be because of the addition of brain heart infusion broth (BHI) during the decontamination process, this study was designed to examine whether BHI is a required component for the isolation of MAP from ESP(R) broth cultures. Twenty-six National Veterinary Services Laboratory (NVSL) proficiency test samples supplied for the year 2005 were used for the comparison. Two paired sets of samples were processed in the experiment. In one set, the hexadecylpyridinium chloride monohydrate (HPC) and antibiotic brew were prepared in half strength BHI and for the other set, HPC and antibiotic brew were prepared in sterile distilled water. Culture of the 26 samples using the BHI/HPC decontamination method identified 13 (50%) positives, whereas culture using the water/HPC decontamination method identified 14 (54%) positives. The proportions of samples with a positive result did not differ significantly between the 2 decontamination methods. Although in most cases it took longer to identify a positive result by the BHI method, the difference between methods with respect to the number of days to a positive culture result was not statistically significant. Retrospective data collected from the Animal Disease Diagnostic Laboratory, Ohio also suggest that inclusion of BHI in the decontamination protocol may not have any effect on MAP recovery or contamination rate. Elimination of BHI from broth cultures may increase the sensitivity of MAP isolation, and reduce the cost of testing.

양(+) 이온성 및 음(-) 이온성 계면활성제 첨가가 반추위 혼합 미생물에 의한 In vitro 건물소화율 및 미생물 성장에 미치는 영향

반추동물의 생산효율을 향상시킬 목적으로 반추위 환경을 조절하려는 노력들이 수십년간 지속되어 오면서 그동안 주로 사료급여 및 사양관리 시스템 개발(NRC, 2001)이 근간을 이루어 왔으나, 최근에는 유전공학, 효소공학, 생물공학, 미생물공학, 천연물화학 등의 발전으로 식물추출물, 항생제, 미생물제제, 계면활성제 등 다양한 분야에서 연구가 진행되고 있다 (Yang과 Russell, 1993; 이 등, 1997; Lee 등, 2003; Lee와 Ha, 2003; Busquet 등, 2006). 그 중, 계면활성제인 surfactant는 미생물 세포막 표면에 부착하여 미생물에 대한 산소공급을 차단함으로써 호기성 미생물 성장을 감소시키며 (Hulme와 Stranks, 1970), 세포내, 외의 효소를 유리시켜 효소기능 및 분비를 촉진 하는 것 (Reese와 Maguire, 1969; Munn 등, 1983; Yazdi 등, 1990)으로 알려져 있다. 이러한 surfactant의 작용원리를 이용하여 반추위내 혐기성 발효를 촉진시키기 위한 제제로서 그 가능성이 높이 평가되어 왔는데, 지금까지 반추위 발효 조절 기능이 밝혀진 계면활성제는 비이온성으로서 반추동물의 소화율과 생산성에 기여할 수 있는 제제로서 인정받고 있다. 계면활성제를 이용한 일련의 시험 중, 앞서 수행한 비이온성 계면활성제와 양쪽 이온성(+/－) 계면활성제를 이용한 시험에서 비이온성 계면활성제는 in vitro 반추위 발효양상에 매우 긍정적인 결과를 얻었으나 양쪽 이온성(+/－) 계면활성제는 반추위 미생물에 오히려 독성으로서 작용하는 결과를 얻었다(De Oude, 1992). 또한 양(+)이온성과 음(－)이온성 계면활성제에 대한 국내의 연구가 전무한 사항이라 참고 자료를 찾을 수가 없었다. 따라서 본 시험은 일반적으로 많이 사용하는 양(+)이온 또는 음(－)이온성을 띄는 계면활성제를 선발하여 반추위 발효 성상 및 미생물 합성에 어떠한 영향을 미치는지를 규명해 보고자 실시하였다. In order to investigate the effects of supplemental ionic surfactants in in vitro ruminal fermentation, N-Lauroylsarcosine sodium salt(N-LSS) and sodium dodecyl sulfate(SDS) for negative(－) ionic surfactant, and hexadecylpyridinium chloride monohydrate(HPCM) and hexadecyltrimethyl ammonium bromide(HTAB) for positive (+) ionic surfactant were supplemented by 0.05% and 0.1% into the Dehority’s artificial medium containing rice straw(1mm) as a substrate. In vitro DM digestibility, the growth of rumen mixed microbes, pH, cumulative gas production and SEM(Scanning Electron Microscopy) observation of microbial attachment on rice straw particle were investigated through the experiment composing 9 treatments (two supplemental levels of two positive ionic(+) surfactant, two supplemental levels of two negative(－) ionic surfactant) including the control. The sample collection was at 6, 12, 24, 48 and 72 h post fermentation with 3 replications per treatments. DM digestibility in treatments supplemented (+) or (－) surfactants almost stopped afterward 12 h fermentation, in vitro DM digestibility at 72 h post fermentation in the ionic surfactants was at half level of that of the control(P<0.05). Accumulative gas production in in vitro was less(P<0.05) with addition of ionic surfactants compared to the control. The amount of rumen mixed microbes recovered from in vitro incubation fluid pleateaued at 12 h post fermentation for the positive (+) ionic surfactants, but steadily increased as fermentation time elapsed for the control. Rumen microbial growth rate was significantly(P<0.05) low in the negative(－) ionic surfactant compared to the control. pH of the incubation fluid was ranged from 6.02 to 7.20, and was the highest in the negative(－) ionic surfactants, and was the lowest in the control(P<0.05). In SEM observation, rumen microbial population attached on rice straw particle was less with addition of ionic surfactants than the control. In conclusion we could not found any positive effects of negative- and positive- charged surfactants on rumunal fermentation characteristics and rumen microbial growth rates.