Chemical equilibrium and kinetic study of the esterification of pure and deluted acrylic acid with 2 ethyl hexanol catalysed by amberlyst 15

In a typical acrylic manufacturing unit, waste water contains acrylic acid (AA) in a range of 4-15 wt% contributes to the high value of chemical oxygen demand. Due to the toxicity of AA to the aquatic organism, this wastewater should be treated before it is discharged. Recovery of AA from the waste water via esterification reaction in a reactive distillation column (RDC) could be a promising method to treat this waste water. Activity and kinetic studies using a batch system are important to examine the 'practicability of this method. In the present work, the activity and kinetic studies of the esterification of AA and 2-ethyl hexanol (2EH) were carried out in a batch system. Ion exchange resin, Amberlyst 15 was employed as a catalyst. The effect of various variables that affecting conversion and yield such as agitation speed, catalyst particle size, temperature, catalyst loading and initial reactant molar ratio were studied. The effect of the initial water content was studied using both the batch systems with total reflux (TR) and dean stark for continuously water removal (CWR). The increase of equilibrium conversion with the temperature indicated the endothermicity of the reaction. Temperature was the most significant variable that affected the conversion and yield. The highest conversion and yield were obtained at the temperature of 388 K, initial reactant molar ratio of AA to 2EH of 1:3 and catalyst loading of 10 wt%. The yield for the reactions of the AA solutions with different AA concentrations except the AA concentrations of 10-20 wt%, was enhanced significantly when the reactions were carried out using the CWR setup. Catalyst poisoning occurred during the reactions of the very dilute AA solutions (10-20%) due to the water inhibition and poly-acrylic acid deposition on the catalyst surface as validated by the catalyst characterisation studies. The pseudo-homogeneous (PH), Eley-Rideal (ER) and Langmuir-HinshelwoodHougen-Watson (LHHW) kinetic models were used to interpret the kinetic data. The best fit kinetic model for the main esterification reaction was shown by the non-ideal ER model while the side reaction, AA polymerisation was best interpreted by PH model. The kinetic data for the esterification of dilute AA was well described by the inclusion of the correction factor to the kinetic model of the esterification

Production of biogas from poultry manure

The objective of this research is to determine the extent of anaerobic biodegradation of raw manure, co-digested manure with bran, and co-digested manure with grass (as the substitute for rice straw) at 10% TS w/v each, and to establish methane yields from these treatments. The anaerobic digestion of high solids raw manure and also co-digested manure were conducted in a 4 L batch anaerobic tank which operated under mesophilic conditions at ambient temperature. The co-digestion with grass (as substitute for rice straw) and bran were carried out to determine whether any of these two materials inhibited or promote the greater production of biogas. This co-digestion of high solids raw manure were conducted with a ratio of total solid of chicken manure to co digested material of 90:10 for both co-digestion. The result shows that, the anaerobic digestion of 10% TS w/v of chicken manure (without co-digestion) have 3 major phases that is the phase 1 or the lagging phase, that was believed to be the hydrolysis phase of the manure, which occurred in about 14 days, phase 2, the exponential phase that was believed to be the methanogenesis phase of the manure, which occurred about 49 days later, and phase 3, the end phase, that was believed to shows the last phase that is usually inhibited by ammonia and VFA concentration . The result shows that the co digestion with bran is more feasible which produce high yield of methane and lowest yield of hydrogen sulphide in biogas produce. The recommendation have been made to optimize the methane production by two stages of anaerobic digestion and also by inoculate to start the proces

Kinetic and simulation studies of the esterification of acrylic acid with 2- ethyl hexanol in a batch and packed bed reactor

Wastewater containing acrylic acid (AA) imposes detrimental effect to the environment due to its high value of chemical oxygen demand. Recovery of AA from its dilute aqueous solution for heterogeneously catalysed esterification in a reactive distillation column (RDC) could be a promising approach. Typically, the feasibility study of these intensified processes was carried out in batch process to determine the reaction kinetics. It is insufficient to determine the other important fundamental data such as mass transfer and mixing which are also crucially required during the equipment design. This consideration is important to observe the probability of underperformance due to the problems such as incomplete catalyst wetting, severe mass-transfer resistances, or maldistribution. In the present study, the investigation on the suitable heterogeneous IER catalyst and appropriate operating window for the esterification reaction to recover AA from the wastewater was conducted. The fundamental data includes reaction kinetics, mass transfer and mixing for simulate, design, and construction of the intensified RDC and CR for the recovery of AA from the wastewater would also be obtained. The continuous flow tubular packed bed reactor (PBR), a system mimicking the reactive section in the intensified processes was used. The best sulfonic acid functional cation-exchange resin catalysts, SK104, SK1B, PK208, PK216, PK228, RCP145, and RCP160, were screened in a batch system. PK208 outperformed the other resins and it was used in subsequent studies. Eley-Rideal (ER) was the best kinetic model to correlate the production rate of 2EHA. Endothermicity of the AA esterification with 2EH was indicated by the increase of its equilibrium constant with temperature. The critical factor that contribute toward reaction performance include initial concentration of acrylic acid (AA), temperature, molar ratio of reactant (AA and 2EH), catalyst loading, and polymerisation inhibitor loading was studied using 2 factorial designs. Initial concentration of AA and temperature was found affected the esterification of AA with 2EH the most. Since the contribution of additional polymerisation inhibitor loading was not significant, this factor has been neglected to be studied in further experiment. The existing amount of the polymerisation inhibitor contained in raw AA is sufficient to avoid AA polymerisation. Residence time distribution (RTD) was studies to examine the mixing behavioural of system. Due to the severe channelling occurred, catalyst cage need to be install. An adsorption study using nonreactive binary mixtures was performed to observe the affinity of resin against each compound. The affinity of PK208 resin towards the chemical species involved in 2EHA synthesis in descending order is: water> AA> 2EH/2EHA. Catalytic performance of resin PK208 for the esterification between acrylic acid (AA) and 2-ethyl hexanol (2EH) was then evaluated in packed bed reactor (PBR) under various temperatures (55-90⁰C), catalyst loadings (1-15 g), molar ratios of AA to 2EH (1:1-1:5), and feed flow rates (1-5 ml/min). The best condition that gave highest yield, 66.44mol% was at 95 ⁰C, with catalyst loading of 5 g, molar ratio AA:2EH of 1:3, and feed flow of 1 ml/min. In contrast to the batch system, the effect of initial concentration of AA was found to be not significant anymore. The PBR simulation performed using plug flow reactor model showed that the predicted results deviated marginally from the experimental data, owing to the occurrence of dispersion in PBR as proven by the residence time distribution (RTD) study. The PBR experimental data well matched with the simulation results generated from the packed bed reactor model considering the axial dispersion in PBR. Thus, the identified operating window and fundamental data validated the potential of RDC in converting the AA in wastewater with the better efficiency

New Method For Acrylic Acid Recovery From Industrial Waste Water Via Esterification With 2-Ethyl Hexanol

Acrylic acid (AA) is an important component for the production of acrylate polymer. In a typical acrylic manufacturing unit, waste water contains AA in a range of 4–15wt.% contributes to the high values of chemical oxygen demand. Due to the toxicity of AA to the aquatic organism, this wastewater should be treated before it is discharged to the environment. The waste water could be evaporated before sending to the incineration which was neither economic feasible nor environmental friendly. Esterification of wastewater containing carboxylic acid with alcohol could be a promising method to recover the acid by converting it to ester while purifying the wastewater. In the present study, recovery of AA via esterification with 2-ethyl hexanol (2EH) was investigated. The model industrial wastewater with various concentration of AA (10–100% w/w) was reacted with 2EH to produce 2-ethyl hexyl acrylate (2EHA) in the setups with total reflux and continuouslywater removal. These Amberlyst-15 (ion exchange resin) catalyzed reactions were carried out under the mass transfer resistance free region. The performance of both systems was compared. The yield for the reactions of the AA solutions with the AA concentrations of 30–80% was enhanced significantly when the reactions were carried out using the second setup. The kinetic data of the esterification of dilute AA was well described by the Eley–Rideal (ER) kinetic model incorporated with a correction factor to consider the catalyst fouling effect and pseudo-homogeneous (PH) kineticmodel for the AA polymerization. The findings have shown the potential of recovering AA from the waste water stream via esterification. The concentrated AA solutions or larger amount of inhibitor should be adopted to prevent the catalyst fouling by the deposition of poly-acrylic acid on the catalyst surface

Kinetic Studies of the Esterification of Acrylic Acid with 2-Ethyl Hexanol Catalysed by Diaion Resins

Homogenous acid catalysts are often used in industries producing acrylate esters. The separation of these catalysts from the reaction medium is difficult, in addition to their toxicity and corrosiveness. The heterogeneously catalyzed esterification that uses the poly(styrene-divinylbenzene) sulfonated resin as catalyst can overcome the drawbacks of homogeneous catalysts. In the present work, the activity and kinetic studies of a batch-wise esterification of acrylic acid (AA) and 2-ethylhexanol (2EH) catalyzed by DIAION acidic ion exchange resins were carried out. DIAION resin PK208 out-performed the other resins due to its comparative ion exchange capacity and low percentage of cross-linkage that enhance the accessibility of the reactant. PK208 was used subsequently in the kinetic studies. The highest yield of 2-ethylhexyl acrylate (2EHA) achieved was 41% after 4 h reaction at an initial reactant molar ratio of AA to 2EH of 1 : 3, catalyst loading of 10 wt% and temperature of 388 K. Eley–Rideal (ER) was the best kinetic model to correlate the production rate of 2EHA. Endothermicity of the AA esterification with 2EH was indicated by the increase of its equilibrium constant with temperature

Association of Country Income Level With the Characteristics and Outcomes of Critically Ill Patients Hospitalized With Acute Kidney Injury and COVID-19

Introduction: Acute kidney injury (AKI) has been identified as one of the most common and significant problems in hospitalized patients with COVID-19. However, studies examining the relationship between COVID-19 and AKI in low- and low-middle income countries (LLMIC) are lacking. Given that AKI is known to carry a higher mortality rate in these countries, it is important to understand differences in this population. Methods: This prospective, observational study examines the AKI incidence and characteristics of 32,210 patients with COVID-19 from 49 countries across all income levels who were admitted to an intensive care unit during their hospital stay. Results: Among patients with COVID-19 admitted to the intensive care unit, AKI incidence was highest in patients in LLMIC, followed by patients in upper-middle income countries (UMIC) and high-income countries (HIC) (53%, 38%, and 30%, respectively), whereas dialysis rates were lowest among patients with AKI from LLMIC and highest among those from HIC (27% vs. 45%). Patients with AKI in LLMIC had the largest proportion of community-acquired AKI (CA-AKI) and highest rate of in-hospital death (79% vs. 54% in HIC and 66% in UMIC). The association between AKI, being from LLMIC and in-hospital death persisted even after adjusting for disease severity. Conclusions: AKI is a particularly devastating complication of COVID-19 among patients from poorer nations where the gaps in accessibility and quality of healthcare delivery have a major impact on patient outcomes

Characteristics and outcomes of COVID-19 patients admitted to hospital with and without respiratory symptoms

Background: COVID-19 is primarily known as a respiratory illness; however, many patients present to hospital without respiratory symptoms. The association between non-respiratory presentations of COVID-19 and outcomes remains unclear. We investigated risk factors and clinical outcomes in patients with no respiratory symptoms (NRS) and respiratory symptoms (RS) at hospital admission. Methods: This study describes clinical features, physiological parameters, and outcomes of hospitalised COVID-19 patients, stratified by the presence or absence of respiratory symptoms at hospital admission. RS patients had one or more of: cough, shortness of breath, sore throat, runny nose or wheezing; while NRS patients did not. Results: Of 178,640 patients in the study, 86.4 % presented with RS, while 13.6 % had NRS. NRS patients were older (median age: NRS: 74 vs RS: 65) and less likely to be admitted to the ICU (NRS: 36.7 % vs RS: 37.5 %). NRS patients had a higher crude in-hospital case-fatality ratio (NRS 41.1 % vs. RS 32.0 %), but a lower risk of death after adjusting for confounders (HR 0.88 [0.83-0.93]). Conclusion: Approximately one in seven COVID-19 patients presented at hospital admission without respiratory symptoms. These patients were older, had lower ICU admission rates, and had a lower risk of in-hospital mortality after adjusting for confounders

Thrombotic and hemorrhagic complications of COVID-19 in adults hospitalized in high-income countries compared with those in adults hospitalized in low- and middle-income countries in an international registry

Background: COVID-19 has been associated with a broad range of thromboembolic, ischemic, and hemorrhagic complications (coagulopathy complications). Most studies have focused on patients with severe disease from high-income countries (HICs). Objectives: The main aims were to compare the frequency of coagulopathy complications in developing countries (low- and middle-income countries [LMICs]) with those in HICs, delineate the frequency across a range of treatment levels, and determine associations with in-hospital mortality. Methods: Adult patients enrolled in an observational, multinational registry, the International Severe Acute Respiratory and Emerging Infections COVID-19 study, between January 1, 2020, and September 15, 2021, met inclusion criteria, including admission to a hospital for laboratory-confirmed, acute COVID-19 and data on complications and survival. The advanced-treatment cohort received care, such as admission to the intensive care unit, mechanical ventilation, or inotropes or vasopressors; the basic-treatment cohort did not receive any of these interventions. Results: The study population included 495,682 patients from 52 countries, with 63% from LMICs and 85% in the basic treatment cohort. The frequency of coagulopathy complications was higher in HICs (0.76%-3.4%) than in LMICs (0.09%-1.22%). Complications were more frequent in the advanced-treatment cohort than in the basic-treatment cohort. Coagulopathy complications were associated with increased in-hospital mortality (odds ratio, 1.58; 95% CI, 1.52-1.64). The increased mortality associated with these complications was higher in LMICs (58.5%) than in HICs (35.4%). After controlling for coagulopathy complications, treatment intensity, and multiple other factors, the mortality was higher among patients in LMICs than among patients in HICs (odds ratio, 1.45; 95% CI, 1.39-1.51). Conclusion: In a large, international registry of patients hospitalized for COVID-19, coagulopathy complications were more frequent in HICs than in LMICs (developing countries). Increased mortality associated with coagulopathy complications was of a greater magnitude among patients in LMICs. Additional research is needed regarding timely diagnosis of and intervention for coagulation derangements associated with COVID-19, particularly for limited-resource settings

Paediatric COVID-19 mortality: a database analysis of the impact of health resource disparity

Background The impact of the COVID-19 pandemic on paediatric populations varied between high-income countries (HICs) versus low-income to middle-income countries (LMICs). We sought to investigate differences in paediatric clinical outcomes and identify factors contributing to disparity between countries.Methods The International Severe Acute Respiratory and Emerging Infections Consortium (ISARIC) COVID-19 database was queried to include children under 19 years of age admitted to hospital from January 2020 to April 2021 with suspected or confirmed COVID-19 diagnosis. Univariate and multivariable analysis of contributing factors for mortality were assessed by country group (HICs vs LMICs) as defined by the World Bank criteria.Results A total of 12 860 children (3819 from 21 HICs and 9041 from 15 LMICs) participated in this study. Of these, 8961 were laboratory-confirmed and 3899 suspected COVID-19 cases. About 52% of LMICs children were black, and more than 40% were infants and adolescent. Overall in-hospital mortality rate (95% CI) was 3.3% [=(3.0% to 3.6%), higher in LMICs than HICs (4.0% (3.6% to 4.4%) and 1.7% (1.3% to 2.1%), respectively). There were significant differences between country income groups in intervention profile, with higher use of antibiotics, antivirals, corticosteroids, prone positioning, high flow nasal cannula, non-invasive and invasive mechanical ventilation in HICs. Out of the 439 mechanically ventilated children, mortality occurred in 106 (24.1%) subjects, which was higher in LMICs than HICs (89 (43.6%) vs 17 (7.2%) respectively). Pre-existing infectious comorbidities (tuberculosis and HIV) and some complications (bacterial pneumonia, acute respiratory distress syndrome and myocarditis) were significantly higher in LMICs compared with HICs. On multivariable analysis, LMIC as country income group was associated with increased risk of mortality (adjusted HR 4.73 (3.16 to 7.10)).Conclusion Mortality and morbidities were higher in LMICs than HICs, and it may be attributable to differences in patient demographics, complications and access to supportive and treatment modalities