Total Reflux Research Articles

Effect of the angle of rotation of structured packing layers on separation efficiency in distillation column

It is well known that a good quality of liquid distribution over the surface of structured packings is crucial for high performance of large diameter columns. The angle of rotation of the packing layers and their number are among the main parameters characterizing the distribution of liquid in a structured packing over the column cross-section and height. This paper presents investigation results on the influence of the rotation angle of structured packing layers on separation efficiency, pressure drop, distribution of local composition of mixture and local liquid flow rate under the packing. The experiments were carried out in distillation column with the internal diameter of 0.9 m on a structured packing with a specific area of 500 m2/m3, and the corrugation angle of packing equal to 45°. The mixture of refrigerants R114 and R21 at the pressure of 3 bar and total reflux was used as the working fluid. The column was packed with 11 packing layers with rotation angles of 20, 45, 70, and 90 degrees. According to experimental results, a decrease in the angle of packing layer rotation from 90 to 20 degrees leads to a decrease in separation efficiency, while the HETP value increases by 10–12%.

Hydration of cyclohexene to cyclohexanol in a hybrid reactive distillation with a side decanter

Nowadays, more than 1 Mt of cyclohexanol is produced each year by the direct hydration of cyclohexene according to the patented Asahi process proposed in 1990. The Asahi process involves a reactor and a separation system to recover the reactants back to the reactor and collect the pure product. The non-reacted water is recovered in a decanter and the non-reacted cyclohexene in a distillation column. Nowadays, many processes have been successfully intensified, combining several unit operations into a single unit providing savings in units, piping and often also in energy due to the synergies generated. Examples of these synergies are: the continuous removal of products push forward the reaction to total conversion overcoming the chemical equilibrium limitations; the catalyst placed in the rectifying section of the column becomes protected from heavy compounds that could poison or deactivate the catalyst; the enthalpy of reaction is directly used in the separation; the boiling point of the mixture avoids hot spots that could damage the catalyst, etc. Although its advantages, it is not widely used in the industry and further study on intensification providing further successful examples are required.The present study shows by rigorous simulation with Aspen Plus V9.0 that the Asahi process is a good candidate to be intensified in a single unit. The rigorous simulation results show that cyclohexanol is collected with a molar fraction purity of 0.9999 at the bottoms of a hybrid reactive distillation column with 11 equilibrium stages operated at total reflux, i.e. total conversion of reactants. The water is fed at the top to stage 1 and the cyclohexene on stage 3, both in equimolar flow rate. The catalyst is only placed in these three stages at the column top. A side stream from stage 6 is fed to a side decanter, where the aqueous phase is recycled to the column top (stage 1) and the organic phase to the next bottom stage, i.e. stage 7. As in the Asahi process, a great excess of water is present to push the reaction equilibrium forward. Hence, the molar ratio of water recycled vs feed to the system is of 125. The reboiler duty is 197 kJ/mol of cyclohexene, and the condenser duty is 564 kJ/mol cyclohexene due to the exothermic reaction. Therefore, a novel intensified process scheme for cyclohexene hydration is proposed.

365 The Prevalence and Clinical Significance of Esophageal Motility Disorders in Patients Presenting With Laryngopharyngeal Reflux (LPR) Symptoms

INTRODUCTION: Esophageal motor dysfunction may underlie impaired bolus and refluxate clearance in laryngopharyngeal reflux (LPR). However, the prevalence of co-existing esophageal dysmotility and correlation with reflux parameters and symptoms in LPR is unknown. METHODS: We conducted a retrospective study of consecutive patients with suspected LPR referred for high-resolution manometry (HRM) and combined hypopharyngeal-esophageal multichannel intraluminal impedance and pH testing (HEMII-pH) at a tertiary center in 3/2018-5/2019. Validated symptom surveys were prospectively collected at the time of testing, including Reflux Symptom Index (RSI), Gastroesophageal Reflux Disease Questionnaire (GERD-Q), and 12-item short-form health survey (SF-12). HRM findings were categorized using the Chicago Classification v3.0. Statistical analyses were performed using ANOVA or Fisher’s exact test. RESULTS: 113 patients (64% female, mean age 54.9 years) were included, with 52 (46%) having abnormal findings on HRM. The most common diagnosis was ineffective esophageal motility (IEM) [n = 37 (32.7%)]. 19 (16.8%) patients were found to have either a disorder of esophagogastric junction (EGJ) outflow or a major disorder of peristalsis, of which EGJ outflow obstruction (EGJOO) was the most prevalent diagnosis [n = 11 (9.7%)] (Table 1). With the exception of increased distal acid exposure time (AET) among patients with hypercontractile motility disorders (9% vs 2% in patients with normal HRM, P = 0.03), there were no differences in pharyngeal bolus reflux events, total bolus reflux events on impedance, and AET across HRM findings. Reporting throat symptoms as a primary complaint on presentation was associated with greater odds of having abnormal HRM compared to esophageal symptoms alone (OR 5.5, P = 0.005) (Figure 1). However, the presence and specific type of motility disorder were not associated with symptom severity as measured on RSI, GERD-Q, or health-related quality of life on the SF-12. CONCLUSION: Esophageal motility disorders are prevalent among patients with suspected LPR symptoms, including up to one of six with either a disorder of EGJ outflow or major disorder of peristalsis. Patients with these conditions are more likely to report throat symptoms as a primary complaint. However, there was no correlation between HRM findings and symptom severity. The role of esophageal motor dysfunction in patients with LPR symptoms remains to be further defined.

364 Shorter Esophageal Length Is Associated With Increased Proximal Reflux and Symptom Severity in Patients Presenting With Laryngopharyngeal Reflux (LPR) Symptoms

INTRODUCTION: Laryngopharyngeal reflux (LPR) is a heterogeneous condition with various underlying pathologies. The effect of esophageal anatomy on LPR is unclear. Shorter distance between lower esophageal sphincter (LES) and upper esophageal sphincter (UES) may allow refluxate to more easily reach the pharynx. We aimed to examine the effect of esophageal length on reflux parameters and symptoms. METHODS: 115 consecutive patients (64% female, mean age 53.9 yrs) with suspected LPR referred for high-resolution manometry (HRM) and combined hypopharyngeal-esophageal multichannel intraluminal impedance-pH testing (HEMII-pH) at a tertiary center in 3/2018-5/2019 were enrolled. Validated symptom surveys were prospectively collected at time of testing, including Reflux Symptom Index (RSI) and 12-item short-form health survey (SF-12) for health-related quality of life (HRQOL). Esophageal length was measured from the distal margin of UES to the proximal margin of LES on HRM. Univariate analyses were performed with Pearson correlation or Student’s t-test. Generalized linear regression was used for multivariate analysis. RESULTS: Mean esophageal length on HRM was 20.4 cm (SD = 2.2). Esophageal length was significantly shorter among patients with a hiatal hernia ≥2 cm (19.2 cm vs 20.6 cm, P = 0.01), but did not correlate with any primary motility disorder per Chicago classification v3.0. Shorter esophageal length was significantly associated with higher acid exposure time and proximal reflux events on impedance, with a trend toward more total reflux events (Table 1). Esophageal length was also shorter among patients with pharyngeal reflux events on HEMII-pH compared to those without (20.0 cm vs 20.9 cm, P = 0.04). Even after controlling for hiatal hernia size, esophageal length remained independently predictive of reflux severity and pharyngeal reflux events. There was a correlation between shorter esophageal length and more severe symptoms on the heartburn/chest pain/indigestion subscore of RSI, but not total RSI or throat symptom subscores (Table 2). Shorter esophageal length was associated with lower physical health scores on SF-12 for HRQOL (Figure 1). CONCLUSION: Shorter esophageal length is independently associated with increased reflux severity, proximal reflux, and pharyngeal reflux, even after controlling for hiatal hernia size. It also correlates with more severe typical reflux symptoms and physical HRQOL. Decreased esophageal length may play a role in the pathophysiology of reflux in patients with LPR symptoms.

Gastroesophageal reflux in cystic fibrosis across the age spectrum.

Scientific advances have improved longevity in cystic fibrosis (CF) patients and many of these patients can expect to experience age-related gastrointestinal co-morbidities. We aimed to assess the extent to which age might impact gastroesophageal reflux (GER) in patients with CF. Our esophageal pH-multichannel intraluminal impedance monitoring database was searched for tracings belonging to CF patients ≥2 years old without prior fundoplication and not taking anti-reflux medications immediately prior (within 7 days) and during the study. Tracings were retrospectively analyzed; Impedance and pH variables were evaluated with respect to age and pulmonary function. Twenty-eight patients were enrolled; 16 children (3.1-17.7 years) and 12 adults (18.2-48.9 years). Among pH probe parameters, correlation analysis showed DeMeester score (P=0.011) and number of acid reflux events lasting >5 minutes (P=0.047) to be significantly correlated with age. Age was not significantly correlated with any of the impedance parameters. Age was negatively correlated with baseline impedance (BI) in the distal esophagus (r=-0.424, P=0.023) and BI was negatively correlated with several pH parameters, including reflux index (r=-0.553, P=0.002), number of total acid reflux events (r=-0.576, P=0.001), number of acid reflux events lasting >5 minutes (r=-0.534, P=0.003), and DeMeester score (r=-0.510, P=0.006). Pulmonary function (percent predicted forced expiratory volume in one minute; ppFEV1) was negatively correlated with age (r=-0.494, P=0.0007). The interaction of age and ppFEV1 and any of the reflux parameters, however, was not significant (P>0.05); the strongest evidence for an interaction was found for the number of acid reflux events reaching the proximal esophagus, but this interaction still did not reach statistical significance (P=0.070). In a small cohort, we found evidence that age may be associated with increased acid exposure and that both age and increased acid exposure are associated with reduced BI in the distal esophagus. The negative relationship between pulmonary function and age in our cohort is not related to GER. This pilot study supports the need for esophageal assessment and treatment of GER as standard components of clinical care for an aging CF population.

Strong Intra-Esophageal Reflux May Contribute to the Development of Barrett’s Adenocarcinoma and Affect the Localization

Background: There has been no study that has directly measured the esophageal reflux factors in Barrett’s adenocarcinoma (BA) using 24-h multichannel intraluminal impedance-pH monitoring (24-h MII-pH). We aimed to clarify the esophageal reflux factors in Barrett’s esophagus (BE) and BA and the factors that determine the location of BA with 24-h MII-pH. Methods: We performed 24-h MII-pH in 26 patients with superficial BA treated endoscopically (BA group) and 13 patients with BE (BE group) and examined the esophageal reflux factors (esophageal acid exposure time [AET], bolus exposure (acid, weakly acid, and alkaline), and number of reflux episodes. In the BA group, there were 16 cases in which the lesions were localized in an area in contact with the esophagogastric junction (EGJ; EGJ group), and 10 cases in which the lesions were proximal to the BE and separated from the EGJ (non-EGJ group). Results: Total reflux in the bolus exposure in the BA group showed higher values compared to that in the BE group. The total of acid and weakly acid reflux of bolus exposure was significantly higher in the BA group than that in the BE group. The BA group also had greater numbers of total reflux episodes than the BE group. As for the cancer locations in BE, the cases in which the lesions were located proximally and separated from the EGJ had more AET and total reflux and acid reflux indicated by bolus exposure compared to the lesions adjacent to the EGJ. Conclusions: Stronger gastro-esophageal reflux appeared to be an important factor in the development of adenocarcinoma from BE. In addition, the cancer location in BE may be related to the intensity of esophageal reflux.

The outcome of fundoplication in patients with GERD based on abnormal impedance testing.

The role of impedance testing in selecting patients for antireflux surgery is poorly understood. The aim of this study was to compare the outcomes of patients that underwent antireflux surgery for GERD based on an abnormal pH/abnormal impedance test versus a normal pH/abnormal impedance test. Records of patients who had an abnormal off-medication impedance test (≥ 48 total reflux events) who underwent antireflux surgery were reviewed and divided into two groups: normal [pH-] or abnormal [pH+] esophageal acid exposure (DeMeester score > 14.7). Symptom resolution was compared: scale 1 (no resolution) to 5 (complete resolution). Eighty-two patients met criteria: 44 [pH+] and 38 [pH-]. There were no differences in the demographics or indications for surgery. The frequencies of heartburn and regurgitation symptoms were significantly reduced by fundoplication in both groups. Complete resolution of heartburn was more common in the [pH+] group (90%) compared to the [pH-] group (67%) [p = 0.02]. Resolution of regurgitation was similar in both groups (90% in the [pH+] group vs 79% in the [pH-] group, p = 0.20). The mean dysphagia frequency score decreased for the [pH+] group, but increased in the [pH-] group. New-onset dysphagia was more common in [pH-] patients (23%) compared to [pH+] patients (5%), (p = 0.02). Continued use of PPI medications was significantly more likely in [pH-] group (42%) compared to the [pH+] group (21%). There was no difference in surgical satisfaction rates between groups. Patients with abnormal impedance and increased esophageal acid exposure had significantly better symptom resolution, less dysphagia, and less frequent PPI use with antireflux surgery versus those with normal pH. These findings urge caution in the use of abnormal impedance values with normal esophageal acid exposure for the selection of patients for an antireflux operation.

A rate-based dynamic model of multicomponent distillation column for 18O isotope separation

The rate-based model of multicomponent distillation was developed in order to study dynamic behavior of a distillation column used for 18O isotope separation under total reflux condition. The present research describes water distillation as a multicomponent reactive distillation process using a mechanistic method in which reaction and isotope exchanges between the components can be predicted based on the molecular thermodynamics and principles of probability. The non-equilibrium formulation was applied based on the mass transfer of nine components in the phases interface resulting via Maxwell-Stefan equations. The separation factors of these components for equilibrium calculations were estimated by empirical correlation as a function of temperature. The distillation column was equipped with the Sulzer-CY packing and initially was fed through enriched water of 18O that was obtained from cascade of industrial columns. The dynamic equations of the model were solved by the Euler method. The model validation was carried out using comparing the model results with the experimental data obtained from a column of semi-industrial distillation. The results of the non-equilibrium model showed that despite the complexity to solve the rate-based model equations, it had a valid prediction in 18O isotope separation process.

The Production of the Isotope 15N by Isotopic Exchange in Nitrox System at Pressure

The operation of 15N production plant at pressure of 0.7 +/- 0.05 bar in stable conditions at total reflux and in production is demonstrated. The 10M HNO3 flows used in the primary column were 6.6 L/h and 6.0 L/h, 47, respectively 33% higher than that of atmospheric pressure (4.5 L/h) and corresponding flow rates of the same column were 3.12 mL/cm2. min, respectively 2.83 mL/cm2.min for operation at pressure, compared to 2.12 mL/cm2�.min at atmospheric pressure. The 10M HNO3 flows used in the final column were 324 mL/h and 264 mL/h, 62, respectively 32 % higher than that of the atmospheric pressure (200 mL/h) and flow rates of that column were: 3.05 mL/cm2.min, respectively 2.49 mL/cm2.min, compared to 1.86 mL/cm2�.min for atmospheric pressure operation. The HETP values are lower for both separation columns operated at pressure and higher 10M HNO3 flow rates, that being an argument in the favour of operation the 15N production plant by isotopic exchange in Nitrox system at pressure. The nitrogen enriched in 15N losses in the waste sulphuric acid, evacuated at the bottom of product refluxer stage II, were : 5.18 -10.58 ppm of feeding with 10M HNO3 of the plant. Any losses of nitrogen enriched in 15N represent an additional uncontrolled production, which diminishes the production of 15N plant. In the case of operation at pressure the flows of H15NO3 extracted as plant product are higher than those corresponding to atmospheric pressure because the nitric acid solution is chemically equilibrated with nitrogen oxides at the operation pressure and temperature. At a pressure of 1 atm. in the 15N production plant the nitrogen content of nitric acid solution would be 10.919M instead of 10M.

DOZ047.122: Inadequate response of atretic esophagus during acidic gastroesophageal reflux

Abstract Patients with atretic esophagus (OA) are candidates to severe gastroesophageal reflux. In a previous study, we observed that in OA operated children the complete transmission of contractions during the whole day and during acid reflux periods is poor compared to controls (C). Investigate the motor response of OA during periods of meal (M) and periods of acid reflux (GOR) in OA patients. Methods Prolonged monitoring of esophageal motor function recorded with three sensors: P1 above and P2, P3 below the suture, combined with pH-metry between P2 and P3. Number/min and amplitude of contractions and transmissions between P1-2-3 or P2-3 are compared during total time, meal and reflux periods and between OA with or without GOR. Population 13 operated patients (OA) mean age 7.75 years and 10 controls (C). Results Contractions/min in OA at P1 M = 1.4 SD 1.2 versus GOR = 0.8 SD 1.1: P < 0.05 at P2 M = 2.0 SD 1.4 versus GOR = 1.4 SD1.4: P < 0.05 at P3 M = 2.2 SD 1.3 versus GOR = 1.5 SD1.4: P < 0.05 Complete transmission (P1-2-3) in OA during M compared with total time (T) is increased (29 vs. 32%: P < 0.5), but not during GOR (29 vs. 28%: NS). No difference in distal transmission (P2-3) between C and OA during M (68.8 vs. 63.2) but difference during GOR (69.8 vs. 43 P < 0.01). Contractions/min are not different during M between 7/13 patients with normal (OAN) and 6/13 with abnormal (OAR) reflux index but differ during GOR: P2 OAN = 2.1 vs. P2 OAR = 0.6, P < 0.01; P3 OAN = 2.2 vs. OAR = 0.6, P < 0.05. Complete transmission (P1-2-3) in OAN is not different during M or GOR but different in OAR (M: 74.2 SD 33.5 vs. GOR 54.7 SD 30.5: P < 0.005); distal transmission (P2-3) is not different between OAN and OAR during M and RGO periods. Conclusion Esophageal motility remains impaired in the operated OA. GOR stimulations produce weaker responses than meals. In OAR alterations of response to GOR are more important in terms of decreased number of distal contractions and total transmission suggesting a motility disorder but also an altered sensitivity reducing primary peristaltic response to reflux.

Effect of citalopram on esophageal motility in healthy subjects-Implications for reflux episodes, dysphagia, and globus.

Drugs such as citalopram, "targeting" the serotonin pathway, can alter esophageal mechano-chemical sensitivity and gastrointestinal motility. The aim of this study was to clarify the effect of citalopram on esophageal motility and sphincter function, transient lower esophageal sphincter relaxations (TLESRs), and reflux events. Sixteen healthy volunteers (HV) receiving 20mg citalopram or placebo intravenously, in a randomized cross-over fashion, underwent two high-resolution impedance manometry studies involving liquid swallows and a high-fat, high-caloric meal. Manometric, reflux, and symptom-related parameters were studied. A lower distal contractile integral was recorded under citalopram, compared with placebo (P=0.026). Upper esophageal sphincter (UES) resting pressure was significantly higher after citalopram administration throughout the study (P<0.05, all periods). Similarly, the UES postswallow mean and maximum pressures were higher in the citalopram condition (P<0.0001, in both cases) and this was also the case for the 0.2s integrated relaxation pressure (P=0.04). Esophagogastric junction resting pressures in the citalopram visit were significantly higher during swallow protocol, preprandial period, and the first postprandial hour (P<0.05, in all cases). TLESRs and total reflux events were both reduced after citalopram infusion (P=0.01, in both cases). During treatment with citalopram, five participants complained about globus sensation (P=0.06). This citalopram-induced globus was associated with higher UES postswallow mean and maximum pressure values (P=0.01 and P=0.04, respectively). Administration of citalopram exerts a diversified response on esophageal motility and sphincter function, linked to clinically relevant phenomena: a reduction in postprandial TLESRs and the induction of drug-induced globus.

High-Resolution Manometry Diagnosis of Ineffective Esophageal Motility Is Associated with Higher Reflux Burden.

Ineffective esophageal motility (IEM) is the most commonly diagnosed abnormality on high-resolution manometry (HRM). However, the clinical significance of IEM and associated reflux burden remains unclear. Our primary aim was to compare reflux patterns between IEM versus normal motility on HRM. HRM and reflux studies in patients with IEM and normal motility were retrospectively reviewed. Esophageal pressure topography parameters, reflux variables, and patient-reported outcome questionnaires were explored. A total of 239 patients with IEM were explored. Of these, 146 underwent reflux monitoring. Additionally, 100 patients with normal HRM all of whom had undergone reflux monitoring were included. IEM patients were more likely to have an abnormal number of reflux events compared to normal (22.7% vs. 9.0%, p < 0.01). Including only off-proton pump inhibitor (PPI) testing, IEM patients had higher mean total acid exposure time (AET) and total reflux events compared to normal motility (p = 0.02). Within IEM patients, higher AET modestly correlated with increased percentage of impaired swallows. Increased reflux events modestly correlated with higher impaired swallows and decreased lower esophageal sphincter (LES) resting pressure. Reflux burden increased with higher esophagogastric junction (EGJ) subtype, driven mostly by subtype III, although there was no difference in the distribution of EGJ subtypes between the IEM and normal HRM cohorts. Patients with HRM diagnosis of IEM may be more prone to acid reflux while off-PPI and non-acid reflux while on-PPI. Reflux burden appears to be worse in IEM patients who have lower resting LES pressure, higher EGJ subtype, or higher percentage of impaired swallows.

Hydraulics and mass transfer performance of an advanced wire gauze structured packing under deep vacuum distillation conditions

Results are presented of total reflux experiments carried out at Fractionation Research Inc. with Montz-Pak A3-500M, an advanced corrugated sheet wire gauze packing, using Paraxylene/Orthoxylene system at 0.1 bara and for the first time at 0.02 bara. In both cases an expectedly good performance was achieved, ranging from eight stages at low- to five stages per meter bed height at upper limit of the operating vapour load. Interestingly, within preloading region the packing exhibited a better efficiency at 0.02 bara, however this was at the expense of somewhat increased pressure drop, and, strikingly, no gain on capacity side. Delft model proved capable of capturing observed trends, but exhibits a pronounced discrepancy with respect to measured efficiency and pressure drop at 0.02 bara, and suggests a higher flooding limit than observed.

Can Impedance-pH Testing on Medications Reliably Identify Patients with GERD as Defined by Pathologic Esophageal Acid Exposure off Medications?

IntroductionImpedance-pH testing (MII-pH) while patients are on acid suppression medications is frequently used to evaluate persistent reflux symptoms. The aim of this study was to determine whether MII-pH on medications can reliably identify patients with gastroesophageal reflux disease (GERD) as defined by pathologic esophageal acid exposure off medications, and to determine if there is a threshold of total reflux episodes on medications where pH testing off medications may be unnecessary. MethodsA retrospective review identified all patients between 1/2010 and 4/2017 who underwent MII-pH testing on PPI medications and subsequently had pH testing off medications. GERD was defined on pH testing off medications by an abnormal DeMeester Score (DMS) and on MII-pH on medications by ≥ 48 total reflux episodes. Patients with an abnormal DMS by MII-pH on medications were excluded. ResultsThere were 71 patients, (22 males; 49 females), with a median age of 52 years. Based on ≥ 48 total reflux episodes by MII-pH testing on medications, 42 patients (59%) had GERD. When tested off medications, an abnormal DMS was present in 44 patients (62%). Among those with GERD based on impedance testing on medications, 31% did not have GERD based on pH testing off medications. Further, in the 29 patients with ≤ 48 total reflux episodes on MII-pH (normal test), 15 patients (52%) had pathologic acid exposure off medications. When there were > 73 reflux events with MII-pH on medications, all 15 patients in our series had pathologic acid exposure on pH testing off medications. ConclusionMII-pH testing on medications in patients with refractory GERD symptoms does not reliably correlate with a diagnosis of GERD as defined by pathologic esophageal acid exposure off medications. The commonly used abnormal MII-pH test value of ≥ 48 total reflux episodes is not validated and should not be used. However, in our series, patients with > 73 total reflux episodes had a high likelihood of having pathologic acid exposure off medications. Overall, the preferred strategy to evaluate patients with persistent GERD symptoms on acid suppression therapy should be pH testing off medications.

Economical retrofit of reactive distillation with a total reflux design or a total boil-up design

In many cases, the volatilities of the reactants and products are unfavorable for separation and purification; therefore, special designs for reactive distillation (RD) are required. In this study, RD configurations with total reflux and total boil-up designs are analyzed and evaluated under such scenarios to determine their applicability and disadvantages. Subsequently, simple and economical solutions were proposed to improve the performance of the existing RD using special designs for such cases, such as removing the product in the side stream: this enables more flexibility in design and allows more chances for improving reaction and separation efficiency. Response surface methodology handling both structural and operating variables simultaneously was used for optimizing the proposed configuration. An industrial case was simulated to demonstrate the proposed configuration. Furthermore, a novel dual-effect side stream RD was proposed to improve energy performance. As a result, the proposed retrofitted sequence could enhance energy efficiency up to 54% and reduce CO2 emissions of up to 52% compared to that for the existing sequence. This work also showed that this solution can bring an increase in capacity up to 15% with a small investment and short payback period.

Photocatalytic degradation of methylene blue with synthesized rGO/ZnO/Cu

In order to observe photocatalysts reactions, rGO/ZnO/Cu nano-structure was synthesized through total reflux combined hydrothermal method. The effects of adding rGO and Cu doping on ZnO lattice were assessed. FE-SEM, TEM, EDX analysis, and XRD tests were used to study the morphology and particle size of the catalyst. The XRD-SAXS verified the crystallinity of the catalysts. FTIR and Raman spectroscopy characterized the mineral oxide-GO bonds also DRS was applied to study the band gap. Photocatalytic degradation efficiency was investigated by methylene blue solution and 25 mg photocatalyst is the best dosage for degradation.

Comparison of various column packing materials efficiency for hydrocarbons and aqueous mixtures

The efficiency of industrial column packings is commonly tested by standard hydrocarbon mixtures. However, a reduced efficiency value is often observed, particularly during distillation of aqueous mixtures. In this paper, distillation experiments with various binary mixtures were carried out on different column packings to evaluate relative separation efficiencies of mixtures for each packing material. Each of the binary mixtures, which comprised heptane–methylcyclohexane, ethanol–water, morpholine–water, and acetic acid–water, was distilled under atmospheric pressure and total reflux ratio on column packings that were made of PTFE, ceramic, zirconium metal, and inox steel 316. According to the results, aqueous solutions of morpholine and acetic acid generally exhibited low relative separation efficiency (in comparison with standard mixture of heptane–methylcyclohexane), ranging between 40 % and 80 %. The highest relative efficiencies were observed with packings made of steel and ceramic. These observations will be useful for the future design of distillation columns, especially for aqueous solutions.

Predicting the Pressure Drop of Corrugated Sheet Structured Packings in Deep Vacuum Applications

Advanced corrugated sheet structured packings are considered a natural choice for&lt;br /&gt; deep vacuum distillation. In many of these applications that occur at absolute pressures&lt;br /&gt; below 0.01 bar at the top of the column, the low density gas/vapor driven by pressure&lt;br /&gt; ascends through an irrigated packed bed under laminar flow conditions. This implies that the packing geometry features aiming to reduce the form drag of advanced packing may not be as effective, if at all, as experienced in common applications where turbulent flow prevails. To consider this appropriately, a theoretically founded expression for laminar flow friction factor has been incorporated into Delft model (DM). With this extension, the predicted pressure drop within laminar flow region approaches closely that estimated using well-established empirical model available in software package SULCOL. In absence of adequate experimental evidence, extended DM was validated using newest data obtained at FRI with an advanced wire gauze structured packing in total reflux experiments carried out with paraxylene/orthoxylene system at 0.02 and 0.1 bar top pressure in a column with internal diameter of 1.22 m.

Erythromycin and Reflux Events in Premature Neonates: A Randomized Clinical Trial.

Gastroesophageal reflux disease (GERD) in premature neonates may manifest as apnea, bradycardia, growth failure, aspiration, or feeding intolerance. Erythromycin ethylsuccinate (EES), is often used as a pro-kinetic in the management of GERD, despite lack of evidence or safety from randomized controlled trials. We sought to study the efficacy of enteral EES at a dose of 50 mg · kg · day in decreasing the frequency of gastroesophageal reflux events as determined by pH-multichannel intraluminal impedance (pH-MII) monitoring. In a randomized, double-blind, placebo-controlled trial, eligible premature neonates with clinical signs of GERD underwent 24-hour pH-MII monitoring. If >5 reflux events were identified on pH-MII, then subjects were randomized to receive either EES or placebo. Repeat 24-hour pH-MII was performed on day 7 of study treatment and compared to initial pH-MII. Forty-three premature neonates were enrolled. Of those, 31 neonates were randomized, 15 to EES and 16 to placebo with a median (IQR) pretreatment total reflux events per 24 hours of 23 (16-40) and 29 (12-40), respectively. Day 7 total events per 24 hours decreased by 4 events in the EES group to 19 (15-33) and by 10 events in the placebo group to 19 (11-26) (P = 0.09). There were no differences in pretreatment and day 7 acidic and nonacidic reflux, proximal reflux, total or percent reflux time, median or longest bolus clearance time, or nurse-reported apnea events between groups. Enteral EES did not decrease reflux events on 24-hour pH-MII at the dose studied. Therefore, it may be ineffective in the treatment of GERD in premature neonates.

Adding Acotiamide to Gastric Acid Inhibitors Is Effective for Treating Refractory Symptoms in Patients with Non-erosive Reflux Disease

BackgroundApproximately 30% of patients who are treated with proton pump inhibitors (PPIs) for gastroesophageal reflux disease (GERD) experience persistent symptoms. No prokinetic agent regiments are useful for symptom relief.AimsThis study was conducted to examine the effect of adding acotiamide to PPI or vonoprazan refractory GERD.MethodsThis was a randomized, prospective, double-blind, placebo-controlled trial. Seventy-one patients were enrolled. Patients underwent upper endoscopy before initial therapy [15 reflux esophagitis and 55 non-erosive reflux disease (NERD)]. Patients with persistent reflux symptoms were administered 300 mg/day acotiamide or placebo for 2 weeks. The primary endpoint was overall treatment effect (OTE), and gastrointestinal symptoms were evaluated. High-resolution manometry (HRM) and 24-h multiple intraluminal impedance-pH (MII-pH) monitoring were conducted before and after treatment when possible.ResultsSeventy patients were randomized (35 acotiamide and 35 placebo). Sixteen and 10 patients in the acotiamide and placebo groups, respectively, completed MII-pH and HRM. The OTE improvement rates were 28.6% and 14.3% in patients administered acotiamide and placebo, respectively (p = 0.145). In patients with NERD, however, the OTE improvement rate and responder rate for regurgitation in the acotiamide group was significantly higher than those in the placebo group (29.6 vs. 7.1%; p = 0.030, 37.0 vs. 10.7%; p = 0.021, respectively). Acotiamide significantly reduced the total reflux episodes (p = 0.001), acid (p = 0.020), proximal reflux (p = 0.007), and liquid reflux (p = 0.013) episodes.ConclusionAdding acotiamide to gastric acid inhibitors can improve symptoms in patients with refractory NERD.