scholarly journals Cu(II) and As(V) Adsorption Kinetic Characteristic of the Multifunctional Amino Groups in Chitosan

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1194
Author(s):  
Byungryul An
Keyword(s):  
Kinetic Model ◽  
Kinetic Characteristic ◽  
Reaction Model ◽  
Mixed Solution ◽  
Amino Groups ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Film Diffusion ◽  
Single Solution ◽  
Total Capacity

Amino groups in the chitosan polymer play as a functional group for the removal of cations and anions depending on the degree of protonation, which is determined by the solution pH. A hydrogel beadlike porous adsorbent was used to investigate the functions and adsorption mechanism of the amino groups by removal of Cu(II) as a cation and As(V) as an anion for a single and mixed solution. The uptakes of Cu(II) and As(V) were 5.2 and 5.6 μmol/g for the single solution and 5.9 and 3.6 μmol/g for the mixed solution, respectively. The increased total capacity in the presence of both the cation and anion indicated that the amino group (NH2 or NH3+) species was directly associated for adsorption. The application of a pseudo second-order (PSO) kinetic model was more suitable and resulted in an accurate correlation coefficient (R2) compared with the pseudo first-order (PFO) kinetic model for all experimental conditions. Due to poor linearization of the PFO reaction model, we attempted to divide it into two sections to improve the accuracy. Regardless of the model equation, the order of the rate constant was in the order of As(V)-single > Cu(II)-single > As(V)-mixed > Cu(II)-mixed. Also, the corresponding single solution and As(V) showed a higher adsorption rate. According to intraparticle and film diffusion applications displaying two linear lines and none passing through zero, the rate controlling step in the chitosan hydrogel bead was determined by both intraparticle and film diffusion.

Phosphorus removal from aqueous solution using a novel granular material developed from building waste

2017 ◽  
Vol 75 (6) ◽  
pp. 1500-1511 ◽  
Author(s):  
Shengjiong Yang ◽  
Pengkang Jin ◽  
Xiaochang C. Wang ◽  
Qionghua Zhang ◽  
Xiaotian Chen
Keyword(s):  
Granular Material ◽  
Chemical Precipitation ◽  
Phosphate Removal ◽  
Precipitation Process ◽  
Order Kinetic ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Removal Capacity ◽  
Order Kinetic Model ◽  
Pseudo Second Order

In this study, a granular material (GM) developed from building waste was used for phosphate removal from phosphorus-containing wastewater. Batch experiments were executed to investigate the phosphate removal capacity of this material. The mechanism of removal proved to be a chemical precipitation process. The characteristics of the material and resulting precipitates, the kinetics of the precipitation and Ca2+ liberation processes, and the effects of dosage and pH were investigated. The phosphate precipitation and Ca2+ liberation processes were both well described by a pseudo-second-order kinetic model. A maximum precipitation capacity of 0.51 ± 0.06 mg g−1 and a liberation capacity of 6.79 ± 0.77 mg g−1 were measured under the experimental conditions. The processes reached equilibrium in 60 min. The initial solution pH strongly affected phosphate removal under extreme conditions (pH <4 and pH >10). The precipitates comprised hydroxyapatite and brushite. This novel GM can be considered a promising material for phosphate removal from wastewater.

scholarly journals Adsorption of pharmaceuticals from aqueous solutions using biochar derived from cotton gin waste and guayule bagasse

Biochar ◽  
2020 ◽  
Author(s):  
Marlene C. Ndoun ◽  
Herschel A. Elliott ◽  
Heather E. Preisendanz ◽  
Clinton F. Williams ◽  
Allan Knopf ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Functional Groups ◽  
Specific Surface Area ◽  
High Surface ◽  
Strong Interactions ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Cotton Gin Waste ◽  
Cotton Gin

Abstract Biochars produced from cotton gin waste (CG) and guayule bagasse (GB) were characterized and explored as potential adsorbents for the removal of pharmaceuticals (sulfapyridine-SPY, docusate-DCT and erythromycin-ETM) from aqueous solution. An increase in biochar pyrolysis temperature from 350 οC to 700 οC led to an increase in pH, specific surface area, and surface hydrophobicity. The electronegative surface of all tested biochars indicated that non-Coulombic mechanisms were involved in adsorption of the anionic or uncharged pharmaceuticals under experimental conditions. The adsorption capacities of Sulfapyridine (SPY), Docusate (DCT) and Erythromycin (ETM) on biochar were influenced by the contact time and solution pH, as well as biochar specific surface area and functional groups. Adsorption of these pharmaceutical compounds was dominated by a complex interplay of three mechanisms: hydrophobic partitioning, hydrogen bonding and π–π electron donor–acceptor (EDA) interactions. Despite weaker π–π EDA interactions, reduced hydrophobicity of SPY− and increased electrostatic repulsion between anionic SPY− and the electronegative CG biochar surface at higher pH, the adsorption of SPY unexpectedly increased from 40% to 70% with an increase in pH from 7 to 10. Under alkaline conditions, adsorption was dominated by the formation of strong negative charge-assisted H-bonding between the sulfonamide moiety of SPY and surface carboxylic groups. There seemed to be no appreciable and consistent differences in the extent of DCT and ETM adsorption as the pH changed. Results suggest the CG and GB biochars could act as effective adsorbents for the removal of pharmaceuticals from reclaimed water prior to irrigation. High surface area biochars with physico-chemical properties (e.g., presence of functional groups, high cation and anion exchange capacities) conducive to strong interactions with polar-nonpolar functionality of pharmaceuticals could be used to achieve significant contaminant removal from water. Graphic Abstract

Modelling casein aggregation and curd firming in goats' milk from backscatter of infrared light

2003 ◽  
Vol 70 (3) ◽  
pp. 335-348 ◽  
Author(s):  
Manuel Z Castillo ◽  
Fred A Payne ◽  
Clair L Hicks ◽  
José S Laencina ◽  
María-Belén M López
Keyword(s):  
Kinetic Model ◽  
Diffuse Reflectance ◽  
Block Design ◽  
Reaction Model ◽  
Order Reaction ◽  
Infrared Light ◽  
Wide Range ◽  
Data Points ◽  
Increasing Temperature ◽  
Reflectance Ratio

A kinetic model was proposed for describing the curd assembly of skimmed goats' milk during enzymic coagulation. The enzymic coagulation of milk was monitored using an optical sensor that measured diffuse reflectance (light backscatter) at 880 nm. The appearance of a shoulder, at low temperatures and protein concentrations, in the diffuse reflectance ratio profile after the inflection point of the curve (Tmax) appeared to separate the aggregation and curd firming steps. The diffuse reflectance ratio profile after Tmax was attributed to the overlapping of casein micelles aggregation and curd firming reactions. The developed kinetic model combined a second order reaction model to describe aggregation reactions and a first order reaction model to describe firming processes reactions. A completely randomised block design with three replications was used to determine the effect of protein concentration and temperature on kinetic constants. Milk was adjusted to three levels of protein (30, 50 and 70 g/kg), and coagulated at five temperatures (20, 25, 30, 35 and 40°C) to test a wide range of processing conditions. Data points from each profile after Tmax were fitted to the proposed model using non-linear regression. The average R2 and standard error of prediction (SEP) for 45 tests conducted were in the range of 0·9975±0·0027 and 0·0081±0·0037, respectively. A significant increase in characteristic times for aggregation (τ2) and curd firming processes (τ1) were found when temperature decreased or protein increased. Theoretical asymptotic value of reflectance ratio, R∞, increased with increasing level of protein and temperature (P<0·05). The parameter β1, which represented the fraction of diffuse reflectance ratio attributed to aggregation, decreased with increasing temperature and decreasing protein.

scholarly journals Removal of Cefdinir from Aqueous Solution Using Nanostructure Adsorbents of TiO2, SiO2 and TiO2/SiO2

2019 ◽  
Vol 33 (2) ◽  
pp. 235-248
Author(s):  
H. Banu Yener
Keyword(s):  
Rice Husk Ash ◽  
Control Mechanism ◽  
Reaction Model ◽  
Solution Temperature ◽  
Solution Ph ◽  
Freundlich Model ◽  
Adsorbent Surface ◽  
Adsorbate Concentration ◽  
Langmuir Isotherm Model ◽  
Spontaneous Occurrence

The adsorptive removal of cefdinir, an antibiotic, from aqueous solutions on TiO2, SiO2 and TiO2/SiO2 nanostructures was studied by batch experiments. The SiO2 particles were obtained from rice husk ash. Investigated were the effects of the solution pH, adsorbent dosage, initial adsorbate concentration, and solution temperature on both cefdinir uptake and removal. The studies suggest that the adsorption of cefdinir on the nanostructures was mainly due to the electrostatic interaction between the ionic adsorbate molecules and charged adsorbent surface sites. The adsorption isotherm data of TiO2 and SiO2 fit well to the Langmuir isotherm model and the Freundlich model for TiO2/SiO2. The thermodynamic studies indicated favorable and spontaneous occurrence of adsorption. The kinetic data of TiO2 fitted best with PSO reaction model equation, and was described well by Weber-Morris diffusion model with dominating control mechanism of intraparticle diffusion and limited contribution of internal film diffusion.

scholarly journals A Green and Efficient Method for the Preconcentration and Determination of Gallic Acid, Bergenin, Quercitrin, and Embelin from Ardisia japonica Using Nononic Surfactant Genapol X-080 as the Extraction Solvent

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ying Chen ◽  
Kunze Du ◽  
Jin Li ◽  
Yun Bai ◽  
Mingrui An ◽  
...  
Keyword(s):  
Gallic Acid ◽  
High Performance ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Micellar Extraction ◽  
Extraction Solvent ◽  
Ultrasonic Assisted ◽  
Preconcentration Factor ◽  
Interday Precision

A simple cloud point preconcentration method was developed and validated for the determination of gallic acid, bergenin, quercitrin, and embelin in Ardisia japonica by high-performance liquid chromatography (HPLC) using ultrasonic assisted micellar extraction. Nonionic surfactant Genapol X-080 was selected as the extraction solvent. The effects of various experimental conditions such as the type and concentration of surfactant and salt, temperature, and solution pH on the extraction of these components were studied to optimize the conditions of Ardisia japonica. The solution was incubated in a thermostatic water bath at 60°C for 10 min, and 35% NaH2PO4 (w/v) was added to the solution to promote the phase separation and increase the preconcentration factor. The intraday and interday precision (RSD) were both below 5.0% and the limits of detection (LOD) for the analytes were between 10 and 20 ng·mL−1. The proposed method provides a simple, efficient, and organic solvent-free method to analyze gallic acid, bergenin, quercitrin, and embelin for the quality control of Ardisia japonica.

scholarly journals Zinc Removal from Wastewater Using Hydrogel Modified Biochar

2014 ◽  
Vol 625 ◽  
pp. 842-846 ◽  
Author(s):  
Lamin Sanyang ◽  
Wan Azlina Wan Abdul Karim Ghani ◽  
Azni Idris ◽  
Ahmad Mansor
Keyword(s):  
Rice Husk ◽  
Kinetic Data ◽  
Ammonium Persulfate ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Modified Biochar ◽  
Zinc Removal ◽  
Swelling Capacity ◽  
Pseudo Second Order ◽  
Rice Husk Biochar

In this study, hydrogel-(rice husk) biochar composite (HBC-RH) was prepared using acrylamide (AAm) as monomer, with N.N’-methylenebisacrylamide (MBA) as crosslinker, ammonium persulfate (APS) as initiator and rice husk biochar (RHB). The synthesized hydrogel-(rice husk) biochar composite was characterized for swelling capacity andthen utilized for the removal of zinc from wastewater. The optimum batch experimental conditions for this study were determined by evaluating the effect of solution pH, adsorbent dosage, adsorbate initial concentration and contact time. Langmuir isotherm best fitted the HBC-RH sorption of Zinc whereas the kinetic data were best described by pseudo second-order. The maximum monolayer sorption capacity of HBC-RH for zinc was 35.75mg/g.

A Novel Method on Simultaneous Removal of SO2, NO and Hg0 from Simulated Flue Gas

2013 ◽  
Vol 316-317 ◽  
pp. 214-218 ◽  
Author(s):  
Yi Zhao ◽  
Fang Ming Xue ◽  
Yuan Shao
Keyword(s):  
Reaction Temperature ◽  
Flue Gas ◽  
Solution Concentration ◽  
Simultaneous Removal ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Wet Process ◽  
Temperature Solution ◽  
Novel Method ◽  
Removal Efficiencies

A novel wet process has been developed to simultaneously remove NO, SO2 and Hg0 from flue gas. According to the conditions of the bubbling reactor, diperiodatocuprate (Ⅲ) coordination ion solution was prepared with CuSO4•5H2O, KIO4, K2S2O8, and KOH, and the effects of the various influencing factors, such as diperiodatocuprate (Ⅲ) coordination ion solution concentration, reaction temperature, solution pH on removal efficiencies were investigated. The removal efficiencies of 98% for SO2, 90% for Hg0 and 56.8% for NO were obtained, respectively, under the optimal experimental conditions, in which diperiodatocuprate (Ⅲ) coordination ion solution concentration was 6 mmol /L, the reaction temperature was 323 K, and the solution pH was 9.0. That [Cu(OH)2(H3IO6)]- was the main existing form of the absorbent at the optimal experimental conditions was confirmed by calculating the concentration ratios of IO4- and its dissociation products / [IO4-]ex under different pH, and thereby simultaneous removal mechanism for SO2, NO and Hg0 was proposed.

Study on the Model of Limonite-TiO2 Combined Microspheres Photolysising Phenol in Source Water

2012 ◽  
Vol 518-523 ◽  
pp. 121-124
Author(s):  
Hong Xia Xia ◽  
Qi Hong Zhu
Keyword(s):  
Reaction Time ◽  
Light Intensity ◽  
Ph Value ◽  
Removal Rate ◽  
Source Water ◽  
Quadratic Regression ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Orthogonal Regression ◽  
Single Factor Experiment

This paper investigates the effect of Limonite/TiO2 combined microspheres dosage,solution pH, reaction time,light intensity on the removal rate of phenol in source water.Based on the single factor experiment, the experimental conditions are optimized by quadratic regression orthogonal rotation combination design.The quadratic orthogonal regression model of removal rate of phenol(y) to four factors of Limonite/TiO2 combined microspheres dosage(x1),pH(x2),reaction time (x3)and light intensity (x4) is established as Y=88.64+4.43X1+ 6.69X3+3.75X4-4.79X12-13.20X22-4.21X32-2.69X42+8.06X1X2-6.76X1X3-4.45X1X4.It can conclude from the model that when Limonite/TiO2 combined microspheres dosage is 1.5583g,solution pH value is 4.5095,reaction time is 102.12min,light intensity is 1710.8（x10 lux）,the yield(y) reaches the maximal(95.83%) and consistent with the confirmatory experiment result..

Kinetic Modelling of the Deposition of SiC from Methyltrichlorosilane

1991 ◽  
Vol 250 ◽  
Author(s):  
Stratis V. Sotirchos ◽  
George D. Papasouliotis
Keyword(s):  
Silicon Carbide ◽  
Kinetic Model ◽  
Gas Phase ◽  
Kinetic Modelling ◽  
Reaction Model ◽  
Heterogeneous Reactions ◽  
Reactor Model ◽  
Preliminary Results ◽  
Homogeneous Reactions

AbstractA kinetic model is presented for the deposition of silicon carbide through decomposition of methyltrichlorosilane (MTS). The developed model includes gas phase (homogeneous) reactions that lead to formation of deposition precursors and surface (heterogeneous) reactions that lead or can lead to deposition of silicon carbide, silicon, and carbon. The kinetic model is incorporated in a transport and reaction model for a tubular hot-wall reactor, and the overall reactor model is used to obtain some preliminary results on the effects of pressure and distance in the reactor on the rate of deposition and the composition of the deposit. The results show that the model can reproduce most of the experimental observations of the literature.

scholarly journals Synthesis of Nd-doped ZSM-5 and its application to treating slightly polluted water

2017 ◽  
Vol 8 (1) ◽  
pp. 86-93
Author(s):  
Mang Lu ◽  
Lin He ◽  
Yue Cheng
Keyword(s):  
Contact Time ◽  
Oxygen Demand ◽  
Raw Material ◽  
Molar Ratio ◽  
Polluted Water ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Factors Influencing ◽  
Orthogonal Experiments ◽  
Removal Efficiencies

Abstract In this study, ZSM-5 zeolite was synthesized using diatomaceous mud as the raw material, and then doped with different amounts of Nd2O3. The orthogonal experiments were performed to investigate the influence of Nd:Si molar ratio, zeolite dosage, contact time, solution pH and temperature on the removal of humic acid (HA). The removal of HA was comprehensively evaluated by chemical oxygen demand (COD), UV254 and UV410 of the solution. The results demonstrate that solution pH and zeolite dosage are the two most important factors influencing HA adsorption. The optimum experimental conditions were determined to be: 35 °C, Nd:Si molar ratio of 1:100, 2.0 g/L zeolite, pH 4 and 50 min contact time. Under these conditions, the removal efficiencies of UV254, UV410 and COD are 82.70%, 76.00% and 82.10%, respectively, corresponding to a comprehensive removal of 81.02%.

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