RESUMO
In the present work, catalytic wet air oxidation (WAO) technique was applied to biomethanated spent wash from a local sugar factory. This wash water exhibited high biological oxygen demand (BOD5â¯=â¯8100â¯mg/L) and chemical oxygen demand (CODâ¯=â¯40,000â¯mg/L). The objectives of oxidative pre-treatment were two-fold, viz. efficient treatment of wash water and enhanced biogas recovery. For the catalytic oxidation process, two iron-based heterogeneous catalysts were employed, viz. Fe2O3 and Fe/C. To synthesize the Fe/C catalyst, activated carbon (AC) support was modified either by thermal treatment or chemical treatment with nitric acid; accordingly, the catalyst was named as Fe/AC-T or Fe/AC-N. In a batch slurry reactor, catalyst performance was investigated at Tâ¯=â¯175⯰C, [Formula: see text] â¯=â¯0.69â¯MPa and ωâ¯=â¯33â¯mg/L (here, T, [Formula: see text] and ω denote temperature, oxygen partial pressure and catalyst loading) for 1â¯h. Based on the conversions of COD and total organic carbon (TOC) and the improvement in biodegradability index (BI), it was found that the activity of the catalysts reduced in the order: Fe/AC-Nâ¯>â¯Fe/AC-Tâ¯>â¯Fe2O3. The results were more encouraging (COD conversionâ¯=â¯87%, color reductionâ¯=â¯88% and BI valueâ¯=â¯0.71) when carbon adsorption (5% w/v) followed WAO over Fe/AC-N. Clearly, our novel hybrid process for pre-treatment, viz. wet oxidation-carbon adsorption showed potential. Post biomethanation, around 1.2 Nm3 biogas (CH4 72%) was formed per cubic meter of the wastewater; without pre-treatment by catalytic WAO and carbon adsorption, the yield of biogas (CH4 11%) was just 1 Nm3 for every cubic meter of wastewater. After a last aerobic treatment step, 97% COD was removed and BI value was 0.84. Finally, a kinetic model was proposed to describe kinetics of COD reduction. In this way, a promising method was suggested for treating a complex wastewater.
Assuntos
Biocombustíveis , Ferro , Eliminação de Resíduos Líquidos , Ar , Biodegradação Ambiental , Catálise , Resíduos Industriais , Oxirredução , Águas ResiduáriasRESUMO
Wet air oxidation (WAO) is a candidate technique for the effective treatment of spent caustic wastewater. In this work, cresols were chosen as model compounds to represent cresylic spent caustic wash. Graphene oxide (GO) is a promising catalyst as well as support for the wet oxidation process, due to its unique structure and properties. For the first time, GO and ruthenium supported on graphene oxide (Ru/GO) were employed for WAO of cresylic isomers. The aforesaid materials were synthesized by modified Hummer's method and characterized using scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. The performance of the investigated materials for WAO of cresols was studied in a slurry reactor. The best reaction conditions for GO were 175⯰C and 0.69â¯MPa O2 pressure. Total organic carbon (TOC) degradation achieved at these conditions was 54.9, 48.9 and 61.2% for o-cresol, m-cresol and p-cresol, respectively. The amount of TOC degradation obtained by using Ru/GO at the same reaction conditions was 66.4, 53.4 and 73.9% for o-cresol, m-cresol and p-cresol, respectively. It was found that the order of reactivity for cresols was p-cresolâ¯>â¯o-cresolâ¯>â¯m-cresol. Finally, kinetics of TOC destruction during CWAO of p-cresol over GO was described using a two-step power law model.
Assuntos
Grafite/química , Rutênio/classificação , Poluentes Químicos da Água/química , Catálise , Cáusticos , Oxirredução , Óxidos , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory, non-communicable, and relapsing skin disease that affects all age groups. There is a dearth of literature that reports the disease burden, and epidemiology and highlights unmet needs in the diagnosis and management of AD in India. METHODS: A total of ten specialists including dermatologists, pediatric dermatologists, and pediatricians with more than ten years of experience and practicing in different parts of India served as the expert panel during the virtual meet conducted on January 24, 2021. A questionnaire comprising 32 questions on different aspects of AD management was categorized among different sections: burden of disease (five questions), age of onset and prevalence (five questions), etiology and pathogenesis (six questions), diagnosis and severity of the disease (seven questions), and treatment (nine questions). Consensus was defined when agreement was provided by ≥90% of the experts. RESULTS: Considering the profound impact AD has on the quality of life (QoL) of patients, the expert panel recommended patient counseling while moderate to severe cases of AD need a prompt referral to a specialist. The panel did not recommend any specific diagnostic and severity criteria as a standard due to the inherent limitations associated with every criterion. The role of environment and changing lifestyle in addition to genetic and familial risk factors for AD was also considered. The panel unanimously recommended to conduct a countrywide, multicenter survey/study to estimate the true prevalence of AD in India. Further, the experts recommended to follow proper treatment protocols and to perform longitudinal monitoring for understanding corticosteroid treatment associated side effects. CONCLUSION: This guidance focuses on identifying the unmet gaps and provides practical recommendations for improving QoL, diagnosis, prognosis, and overall management of patients with AD in India.
RESUMO
Glucosamine, the amino sugar made from glucose, is a safe and natural reagent for post-combustion carbon dioxide capture. Its most plentiful derivative, N-acetylglucosamine (or NAG), was studied in this work with respect to its reaction kinetics in aqueous solutions. A stirred cell reactor with a flat gas-liquid interface was used, and it was found that CO2 reacts with NAG via a pathway similar to that with alkanolamines. In the 20-100 mM range of NAG concentration, the second-order rate constant at T = 308 K was 125 kmol m-3 s-1. For the 303-313 K range, the activation energy was 42 kJ mol-1. In a study on vapor-liquid equilibrium, it was found that the loading capacity of NAG (100 mM) at 303 K was 0.6 mol CO2/mol NAG, while the equilibrium partial pressure of CO2 was 0.8 kPa. Three rate promoters were tested, and piperazine showed better efficacy than monoethanolamine and 2-amino-2-methyl-1-propanol in aqueous NAG solutions. This work is expected to stimulate further interest in this new, green CO2 capturing solvent.
RESUMO
N,N-Diethylethanolamine (DEEA) is a very promising absorbent for CO(2) removal from gaseous streams, as it can be prepared from renewable resources. Aqueous mixtures of DEEA and piperazine (PZ) are attractive for the enhancement of CO(2) capture, due to the high CO(2) loading capacity of DEEA and high reactivity of PZ. In the present work, for the first time, the equilibrium and kinetic characteristics of the CO(2) reaction with such mixtures were considered. Kinetic data were obtained experimentally, by using a stirred cell reactor. These data were interpreted using a homogeneous activation mechanism, by which the investigated reaction was considered as a reaction between CO(2) and DEEA in parallel with the reaction of CO(2) with PZ. It is found that, in the studied range of temperatures, 298-308 K, and overall amine concentrations, 2.1-2.5 kmol/m(3), this reaction system belongs to the fast pseudo-first-order reaction regime systems. The second-order rate constant for the CO0 reaction with PZ was determined from the absorption rate measurements in the activated DEEA solutions, and its value at 303 K was found to be 24,450 m(3)/(kmol s).
Assuntos
Dióxido de Carbono/química , Etanolaminas/química , Piperazinas/química , Poluentes Químicos da Água/química , Absorção , Dióxido de Carbono/análise , Recuperação e Remediação Ambiental/métodos , Etanolaminas/análise , Cinética , Piperazina , Piperazinas/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análiseRESUMO
Migraine patients who do not respond to conventional therapy, develop unacceptable side-effects, or are reluctant to take medicines resort to complementary and alternative medicines (CAM). Globally, patients have been seeking various non-conventional modes of therapy for the management of their headaches. An Ayurvedic Treatment Protocol (AyTP) comprising five Ayurvedic medicines, namely Narikel Lavan, Sootshekhar Rasa, Sitopaladi Churna, Rason Vati and Godanti Mishran along with regulated diet and lifestyle modifications such as minimum 8 h sleep, 30-60 min morning or evening walk and abstention from smoking/drinking, was tried for migraine treatment. The duration of the therapy was 90 days. Out of 406 migraine patients who were offered this AyTP, 204 patients completed 90 days of treatment. Complete disappearance of headache and associated symptoms at completion of AyTP was observed in 72 (35.2%); mild episode of headache without need of any conventional medicines in 72 (35.2%); low intensity of pain along with conventional medicines in 50 (24.5%); no improvement in seven (3.4%) and worst pain was noted in three (1.4%) patients, respectively. In 144 (70.5%) of patients marked reduction of migraine frequency and pain intensity observed may be because of the AyTP. Though the uncontrolled open-label design of this study does not allow us to draw a definite conclusion, from this observational study we can make a preliminary assessment regarding the effectiveness of this ayurvedic treatment protocol.