scholarly journals Insight into Equilibrium and Kinetics of the Binding of Cadmium Ions on Radiation-Modified Straw from Oryza sativa

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Sana Zulfiqar Ali ◽  
Makshoof Athar ◽  
Umar Farooq ◽  
Muhammad Salman
Keyword(s):  
Rice Straw ◽  
Adsorption Mechanism ◽  
Agricultural Waste ◽  
Uptake Capacity ◽  
Batch Mode ◽  
Toxic Heavy Metal ◽  
Equilibrium Study ◽  
Equilibrium And Kinetics ◽  
Kinetics Of ◽  
Insight Into

The present study reports the chemical modification of agricultural waste (rice straw) with urea using microwave radiation and the efficiency evaluation of this modified rice straw for the adsorption of a toxic heavy metal, cadmium. The elemental analysis of urea modified rice straw affirmed urea grafting on rice straw, and FTIR spectra of chemically benign modified adsorbent showed the presence of hydroxyl, carbonyl, and amino functional groups. Effects of process parameters (adsorbent dosage, contact time, agitation speed, pH, and temperature) were studied in batch mode. Parameters were optimized for the equilibrium study, and adsorption mechanism was elucidated using five mathematical models (Langmuir, Freundlich, Temkin, Harkin-Jura, and Dubinin-Radushkevich). Binding of Cd(II) ions on modified adsorbent followed Langmuir model, and the maximum uptake capacity was found to be 20.70 mg g−1. Kinetic modeling was done using six different kinetic models. The process was considered physisorption according to the obtained activation energy value. Thermodynamic parameters confirmed the process to be favorable and feasible. Exothermic nature of adsorption of Cd(II) ions on urea modified rice straw was confirmed by the negative value of ΔH°.

scholarly journals KINETIC, ISOTHERM AND EQUILIBRIUM STUDY OF ADSORPTION CAPACITY OF HYDROGEN SULFIDE-WASTEWATER SYSTEM USING MODIFIED EGGSHELLS

2017 ◽  
Vol 18 (1) ◽  
pp. 13-25 ◽  
Author(s):  
O A Habeeb ◽  
K Ramesh ◽  
Gomaa A. M. Ali ◽  
R M Yunus ◽  
O A Olalere
Keyword(s):  
Hydrogen Sulfide ◽  
Adsorption Capacity ◽  
Contact Time ◽  
Batch Mode ◽  
Initial Concentration ◽  
Equilibrium Study ◽  
Operating Variables ◽  
H2s Adsorption ◽  
Analytical Approaches ◽  
Kinetics Of

The studies of adsorption equilibrium isotherm and kinetics of hydrogen sulfide-water systems on calcite-based adsorbents prepared from eggshell are undertaken. The effects of operating variables such as contact time and initial concentration on the adsorption capacity of hydrogen sulfide are investigated. The modified eggshells are characterized by using different analytical approaches such as Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR). The batch mode adsorption process is performed at optimum removal conditions: dosage of 1 g/L, pH level of pH 6, agitation speed of 150 rpm and contact time of 14h for adsorbing hydrogen sulfide with an initial concentration of 100-500 mg/L. In the current study, the Langmuir, Freundlich, Temkin, and Dubinin models are used to predict the adsorption isotherms. Our equilibrium data for hydrogen sulfide adsorption agrees well with those of the Langmuir equation. The maximum monolayer adsorption capacity is 150.07 mg/g. Moreover, the kinetics of H2S adsorption by using the modified calcite of eggshell follows a pseudo-second-order model. From the current work, we have found that the calcite eggshell is a suitable adsorbent for H2S embeded inside the waste water. Most importantly, chicken eggshell is a waste and vastly available; hence, it could serve as a practical mean for H2S adsorption.

Adsorption Equilibrium and Kinetics of CO2 and H2O on Activated Carbon

2012 ◽  
Vol 27 (2) ◽  
pp. 139-145 ◽  
Author(s):  
Dong XU ◽  
Jun ZHANG ◽  
Gang LI ◽  
Penny XIAO ◽  
Paul WEBLEY ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Adsorption Equilibrium ◽  
Equilibrium And Kinetics ◽  
Adsorption Equilibrium And Kinetics ◽  
Kinetics Of

Submerged upflow biotower operation and computer simulation

1994 ◽  
Vol 30 (11) ◽  
pp. 143-146
Author(s):  
Ronald D. Neufeld ◽  
Christopher A. Badali ◽  
Dennis Powers ◽  
Christopher Carson
Keyword(s):  
Computer Simulation ◽  
Benzoic Acid ◽  
Computer Model ◽  
Rate Constants ◽  
Batch Mode ◽  
Operational Conditions ◽  
First Order ◽  
Low Concentrations ◽  
Biological Transformation ◽  
Kinetics Of

A two step operation is proposed for the biodegradation of low concentrations (< 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.

scholarly journals Rapid systemic surge of IL-33 after severe human trauma: a prospective observational study

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Olav Sundnes ◽  
William Ottestad ◽  
Camilla Schjalm ◽  
Peter Lundbäck ◽  
Lars la Cour Poulsen ◽  
...  
Keyword(s):  
High Resolution ◽  
Prospective Observational Study ◽  
Tissue Injury ◽  
Trauma Patients ◽  
Decoy Receptor ◽  
Interleukin 33 ◽  
Injured Patients ◽  
First Time ◽  
Kinetics Of ◽  
Insight Into

Abstract Background Alarmins are considered proximal mediators of the immune response after tissue injury. Understanding their biology could pave the way for development of new therapeutic targets and biomarkers in human disease, including multiple trauma. In this study we explored high-resolution concentration kinetics of the alarmin interleukin-33 (IL-33) early after human trauma. Methods Plasma samples were serially collected from 136 trauma patients immediately after hospital admission, 2, 4, 6, and 8 h thereafter, and every morning in the ICU. Levels of IL-33 and its decoy receptor sST2 were measured by immunoassays. Results We observed a rapid and transient surge of IL-33 in a subset of critically injured patients. These patients had more widespread tissue injuries and a greater degree of early coagulopathy. IL-33 half-life (t1/2) was 1.4 h (95% CI 1.2–1.6). sST2 displayed a distinctly different pattern with low initial levels but massive increase at later time points. Conclusions We describe for the first time early high-resolution IL-33 concentration kinetics in individual patients after trauma and correlate systemic IL-33 release to clinical data. These findings provide insight into a potentially important axis of danger signaling in humans.

scholarly journals Factors influencing the adsorption and photocatalysis of direct red 80 in the presence of a TiO2: Equilibrium and kinetics modeling

2021 ◽  
pp. 174751982198996
Author(s):  
Moussa Abbas
Keyword(s):  
Elimination Rate ◽  
Threshold Value ◽  
Heterogeneous Photocatalysis ◽  
Order Kinetic ◽  
Batch Mode ◽  
Adsorption Capacities ◽  
Initial Ph ◽  
Equilibrium And Kinetics ◽  
Order Kinetic Model ◽  
Charge Point

Among the different photocatalysts, TiO2 ( Eg = 3.1 eV, zero charge point (pHpzc = 6.3), and surface = 55 m2/g) is currently the most efficient and the most studied semiconductor due to its strong photocatalytic activity, non-toxicity, and chemical stability. The elimination of DR-80 on TiO2 is studied by adsorption in batch mode and by application of heterogeneous photocatalysis onto TiO2 under UV irradiation. The effects of contact time (0–60 min), initial pH (3–11), dose of the adsorbent (0.5–3 g L−1), and DR-80 concentration (40–60 mg L−1) on the adsorption of DR-80 by TiO2 are studied for optimization of these parameters. The kinetic parameters, rate constants, and equilibrium adsorption capacities are calculated and discussed for each applied theoretical model. The adsorption of DR-80 is well described by the pseudo-first-order kinetic model. The fitting of the adsorption isotherms shows that the models of Langmuir and Temkin offering a better fit and an adsorption 64.102 mg/g at 25 °C of DR-80 are eliminated. The results showed that the photocatalytic efficiency strongly depends on the pH while the initial rate of photodegradation is proportional to the catalyst dose, and becomes almost constant above a threshold value. It was found that the photodegradation is favored at low DR-80 concentrations in accordance with the Langmuir–Hinshelwood model with the constants Kad = 6.5274 L/mg and KL–H = 0.17818 mg L−1 min. However, the adsorption is improved for high DR-80 concentrations. It is found that the degradation depends on both the temperature and the pH with a high elimination rate at high temperature. The photocatalyst TiO2 has a better activity for the degradation of DR-80, compared to some commercial catalysts that have been described in the literature.

scholarly journals Silica Removal from a Paper Mill Effluent by Adsorption on Pseudoboehmite and γ-Al2O3

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2031
Author(s):  
Ruben Miranda ◽  
Isabel Latour ◽  
Angeles Blanco
Keyword(s):  
Paper Mill ◽  
Ph Adjustment ◽  
Paper Mill Effluent ◽  
Kinetics Studies ◽  
Silica Removal ◽  
Industrial Water Use ◽  
Optimum Ph ◽  
Initial Ph ◽  
Equilibrium And Kinetics ◽  
Kinetics Of

Effluent reuse is a common practice for sustainable industrial water use. Salt removal is usually carried out by a combination of membrane processes with a final reverse osmosis (RO). However, the presence of silica limits the RO efficiency due to its high scaling potential and the difficulty of cleaning the fouled membranes. Silica adsorption has many advantages compared to coagulation and precipitation at high pHs: pH adjustment is not necessary, the conductivity of treated waters is not increased, and there is no sludge generation. Therefore, this study investigates the feasibility of using pseudoboehmite and its calcination product (γ-Al2O3) for silica adsorption from a paper mill effluent. The effect of sorbent dosage, pH, and temperature, including both equilibrium and kinetics studies, were studied. γ-Al2O3 was clearly more efficient than pseudoboehmite, with optimal dosages around 2.5–5 g/L vs. 7.5–15 g/L. The optimum pH is around 8.5–10, which fits well with the initial pH of the effluent. The kinetics of silica adsorption is fast, especially at high dosages and temperatures: 80–90% of the removable silica is removed in 1 h. At these conditions, silica removal is around 75–85% (<50 mg/L SiO2 in the treated water).

Utilization of rice straw and tea composts for strawberry and tomato production

2020 ◽  
Vol 30 (4) ◽  
pp. 335-343
Author(s):  
R Ashrafi ◽  
RM Saiem ◽  
M Kamruzzaman ◽  
MSAA Mamun ◽  
HA Begum
Keyword(s):  
Rice Straw ◽  
Agricultural Waste ◽  
Total Sugar ◽  
Fruit Yield ◽  
Compost Tea ◽  
Tomato Production ◽  
Horticultural Crops ◽  
Beneficial Effects ◽  
Combined Application ◽  
Yield And Quality

The use of agricultural waste is of great interest to sustainable agriculture. An investigation was carried out to evaluate the effects of compost and compost tea made from agricultural waste rice straw on the yield and quality of two horticultural crops strawberry and tomato. In strawberry experiment, six treatments were considered which wereT1: 100% soil (as a control), T2: 80% soil + 20% compost, T3: 60% soil + 40% compost, T4: 40% soil + 60% compost, T5: 20% soil + 80% compost & T6: 100% compost. Results revealed that number of fruit, fruit yield and total sugar (%)was increased with the increasing level of compost up to 80% after that decreased at 100% compost. The treatment T5: 20% soil + 80% compost gave the best results among the treatments to grow strawberry with good yield (185.3 g/plant) and sweetness (total sugar 5.19%). On the other hand, six treatments i.e. T1: Control, T2: Compost (5 t/ha), T3: Compost tea (50% concentration), T4: Compost (5 t/ha) + Compost tea (50% concentration), T5: Compost tea (100% concentration) and T6: Compost (5t/ha) + Compost tea (100% concentration) were considered in tomato experiment. As a result, it was observed that combined application of compost (5 t/ha) along with compost tea (100% conc.) (T6) gave the highest yield of tomato than not only control (T1) but also single application of compost or compost tea (T2, T3, T4&T5). Level of compost tea concentration also showed significant effect on fruit yield of tomato. Comparing between treatment T4 and T6, fruit yield was found higher (1027.67 g/plant) in treatment T6: Compost (5t/ha) + Compost tea (100% conc.) than 961.3 g/plant in T4: Compost (5 t/ha) + Compost tea (50% conc.). So, it could be summarized that use of rice straw as compost and compost tea affects positively both in two experiments. The results of this study confirm the beneficial effects of compost to increase the yield and sweetness of strawberry and combination of compost and compost tea to increase the yield of tomato. Progressive Agriculture 30 (4): 335-343, 2019

scholarly journals Simulation of Folding Kinetics for Aligned RNAs

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 347
Author(s):  
Jiabin Huang ◽  
Björn Voß
Keyword(s):  
Evolutionary Conservation ◽  
Folding Kinetics ◽  
New Approach ◽  
Computational Approaches ◽  
Reasonable Time ◽  
Valuable Method ◽  
Kinetics Of ◽  
Insight Into ◽  
Folding Space ◽  
Standing Problem

Studying the folding kinetics of an RNA can provide insight into its function and is thus a valuable method for RNA analyses. Computational approaches to the simulation of folding kinetics suffer from the exponentially large folding space that needs to be evaluated. Here, we present a new approach that combines structure abstraction with evolutionary conservation to restrict the analysis to common parts of folding spaces of related RNAs. The resulting algorithm can recapitulate the folding kinetics known for single RNAs and is able to analyse even long RNAs in reasonable time. Our program RNAliHiKinetics is the first algorithm for the simulation of consensus folding kinetics and addresses a long-standing problem in a new and unique way.

Atomic-level insight into reasonable design of metal-based catalysts for hydrogen oxidation in alkaline electrolytes

2021 ◽  
Author(s):  
Lulu An ◽  
Xu Zhao ◽  
Tonghui Zhao ◽  
Deli Wang
Keyword(s):  
Fuel Cell ◽  
Anion Exchange ◽  
Hydrogen Oxidation ◽  
Anion Exchange Membrane ◽  
Atomic Level ◽  
Alkaline Electrolytes ◽  
Exchange Membrane ◽  
Kinetics Of ◽  
Insight Into ◽  
Hydrogen Utilization

Anion exchange membrane fuel cell (AEMFC) is becoming highly attractive for hydrogen utilization owing to the advantages of employing economic catalysts in alkaline electrolytes. Nevertheless, the kinetics of anodic hydrogen...

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