scholarly journals Column Adsorption Studies for the Removal of Cr(VI) Ions by Ethylamine Modified Chitosan Carbonized Rice Husk Composite Beads with Modelling and Optimization

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
S. Sugashini ◽  
K. M. Meera Sheriffa Begum

The objective of this present study is the optimization of process parameters in adsorption of Cr(VI) ions by ethylamine modified chitosan carbonized rice husk composite beads (EAM-CCRCBs) using response surface methodology (RSM) and continuous adsorption studies of Cr(VI) ions by ethylamine modified chitosan carbonized rice husk composite beads (EAM-CCRCBs). The effect of process variables such as initial metal ion concentration, adsorbent dosage and pH were optimized using RSM in order to ensure high adsorption capacity at low adsorbent dosage and high initial metal ion concentration of Cr(VI) in batch process. The optimum condition suggested by the model for the process variable such as adsorbent dosage, pH and initial metal ion concentration was 0.14 g, 300 mg/L and pH2 with maximum removal of 99.8% and adsorption capacity of 52.7 mg/g respectively. Continuous adsorption studies were conducted under optimized initial metal ion concentration and pH for the removal of Cr(VI) ions using EAM-CCRCBs. The breakthrough curve analysis was determined using the experimental data obtained from the continuous adsorption. Continuous adsorption modelling such as bed depth service model and Thomson model were established by fitting it with experimental data.

2020 ◽  
Vol 11 (4) ◽  
pp. 11891-11904

In the present study, batch mode adsorption was carried out to investigate the adsorption capacity of dried bael flowers (Aegle marmelos) for the adsorptive removal of Cu(II) ions from aqueous solutions by varying agitation time, initial metal concentration, the dose of adsorbent, temperature, and initial pH of the Cu(II) ion solution. The percentage removal of 98.7% was observed at 50 ppm initial metal ion concentration, 0.5 g/100.00 cm3 adsorbent dosage, within the contact time of 120 minutes at 30 ºC in the pH range of 4 – 7. The sorption processes of Cu(II) ions was best described by pseudo-second-order kinetics. Langmuir isotherm had a good fit with the experimental data with 0.97 of correlation coefficient (R2), and the maximum adsorption capacity obtained was 23.14 mg g-1 at 30 ºC. The results obtained from sorption thermodynamic studies suggested that the adsorption process is exothermic and spontaneous. SEM analysis showed tubular voids on the adsorbent. FTIR studies indicated the presence of functional groups like hydroxyl, –C-O, –C=O, and amide groups in the adsorbent, which can probably involve in metal ion adsorption. Therefore, dried bael flowers can be considered an effective low-cost adsorbent for treating Cu(II) ions.


2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Md. Nabul Sardar ◽  
Nazia Rahman ◽  
Shahnaz Sultana ◽  
Nirmal Chandra Dafader

Abstract This study focuses on the adsorption of hazardous Cr (III) and Cu (II) ions from aqueous solution by applying modified waste polypropylene (PP) fabric as an adsorbent. Pre-irradiation technique was performed for grafting of sodium styrene sulfonate (SSS) and acrylic acid (AAc) onto the PP fabric. The monomer containing 8% SSS and 16% AAc in water was used. Graft yield at 30 kGy radiation dose was 390% when 4% NaCl was added as additive. The prepared adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA) and dynamic mechanical analyzer (DMA). The influences of different parameters including pH, contact time, temperature and initial metal ion concentration were also investigated. The equilibrium adsorption data were better fitted to the Langmuir isotherm model with maximum monolayer adsorption capacity 384.62 mg/g for Cr (III) and 188.68 mg/g for Cu (II) ions. The kinetic data were better explained by pseudo first-order kinetic model having good matching between the experimental and theoretical adsorption capacity. The adsorption process was spontaneous, endothermic and thermodynamically feasible. Furthermore, investigation of desorption of metal ions and reuse of the adsorbent suggesting that the adsorbent is an efficient and alternative material in the removal of Cr (III) and Cu (II) from aqueous media.


2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Y. S. Mohammad ◽  
E. M. Shaibu-Imodagbe ◽  
S. B. Igboro ◽  
A. Giwa ◽  
C. A. Okuofu

Modeling of adsorption process establishes mathematical relationship between the interacting process variables and process optimization is important in determining the values of factors for which the response is at maximum. In this paper, response surface methodology was employed for the modeling and optimization of adsorption of phenol onto rice husk activated carbon. Among the action variables considered are activated carbon pretreatment temperature, adsorbent dosage, and initial concentration of phenol, while the response variables are removal efficiency and adsorption capacity. Regression analysis was used to analyze the models developed. The outcome of this research showed that 99.79% and 99.81% of the variations in removal efficiency and adsorption capacity, respectively, are attributed to the three process variables considered, that is, pretreatment temperature, adsorbent dosage, and initial phenol concentration. Therefore, the models can be used to predict the interaction of the process variables. Optimization tests showed that the optimum operating conditions for the adsorption process occurred at initial solute concentration of 40.61 mg/L, pretreatment temperature of 441.46°C, adsorbent dosage 4 g, adsorption capacity of 0.9595 mg/g, and removal efficiency of 97.16%. These optimum operating conditions were experimentally validated.


2015 ◽  
Vol 10 (1) ◽  
pp. 121
Author(s):  
Keat Khim Ong ◽  
A. T. Ahmad Farhan ◽  
W. M. Z. Wan Yunus ◽  
Ahmad Mujahid Ahmad Zaidi ◽  
M. L. Jabit ◽  
...  

<p class="zhengwen"><span lang="EN-GB">Adsorption of Zn(II) ions from aqueous solutions by thermally treated rice husk was investigated using factorial experimental design to study effects of heating temperature and period of rice husk, pH, initial Zn(II) ion concentration, adsorption temperature and contact time, and adsorbent dosage. Main and interaction effects of these factors were analyzed using statistical techniques and the results were analyzed statistically using the Student’s t-analysis and analysis of variance which were used to determine significant factors that affect the percentage removal of Zn(II). These significant factors were heating temperature of rice husk, pH, initial metal concentration, contact time, and adsorbent dosage. The interaction between two different effects also affects the percentage removal of Zn(II) ions. These include the interactions between heating temperature of rice husk and initial metal concentration, pH and initial metal concentration, and pH and the adsorbent dosage.</span></p>


2018 ◽  
Vol 78 (3) ◽  
pp. 708-720 ◽  
Author(s):  
B. Rouhi Broujeni ◽  
A. Nilchi ◽  
A. H. Hassani ◽  
R. Saberi

Abstract In this study, novel chitosan/Fe2O3nano composite Ch/Fe-Onc was synthesized and evaluated as an adsorbent for removing thorium (IV) (Th4+) ion from aqueous solution. The Ch/Fe-Onc was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Response surface methodology (RSM) was used in the optimization of Th4+ adsorption for parameters such as pH, the initial metal ion concentration (Th4+ concentration) and contact time. The statistical measures (i.e. analysis of variance, R2, the lack of fit test and the P value) specify that the developed model is proper. Furthermore, the adsorption kinetics was well defined by the pseudo-second-order equation, while the adsorption isotherms were better fitted by the Langmuir model. The adsorption capacity of Ch/Fe-Onc was 430 mg Th4+g−1 composite which leads to 99% removal at 25 °C. Moreover, thermodynamic parameters which state the natural and endothermic nature of the reactions were determined. The loaded Th4+ can be easily regenerated with HNO3 and the Ch/Fe-Onc can be used repeatedly without any significant reduction in its adsorption capacity. The desorption level of Th4+ from the Ch/Fe-Onc by using 0.1 M HNO3, was more than 95%.


Author(s):  
E. S. Isagba ◽  
S. Kadiri ◽  
I. R. Ilaboya

This paper investigated the use of yam peel as a natural adsorbent for the removal of Copper (Cu) and Manganese (Mn) from waste water. The yam peels were thoroughly washed with distilled water, dried, pulverized and carbonized. The carbonized yam peel was then characterized for its particle sizes, moisture content, ash content, volatile matter, Methylene Blue number, Iodine number. The raw yam peels were prepared using the same procedure, but was not carbonized. The adsorption of Mn(II) and Cu(II) ions were investigated using adsorption experiment at room temperature. The effect of contact time, metal ion concentration and dosage were evaluated. The residual concentrations of the metal ions were determined by Atomic Absorption Spectrophotometer (AAS). Experimental data obtained were analyzed using Kinetic models and Isotherms such as Pseudo- First order kinetic models, Pseudo-second order kinetic models, Langmuir isotherms and Freundlich isotherm. The analysis showed that the pseudo-second order kinetic model best described the adsorption of the metal ions; ( Cu; r2 = 0.991 for RYP and r2 = 0.834 for AYP) and (Mn; r2 = 0.958 for RYP and r2 = 0.896 for AYP) and the experimental data best fit the Freundlich model; (Cu; r2 = 0.564 for RYP and r2 = 0.871 for AYP) and (Mn; r2 = 0.685 for RYP and r2 = 0.736 for AYP). Finally, optimum removal efficiencies of 30.54% for Mn(II) and 39.62% for Cu(II) were obtained for AYP at concentrations of 50mg/l and mass dosage of 1.0g, 120 minutes contact time and a pH of 6.8.


Author(s):  
G. G. Oseke ◽  
M. T. Isa ◽  
M. S. Galadima ◽  
A. O. Ameh

This study was aimed at developing chitosan-rice husk ash adsorbent for the removal of crude oil from contaminated water. Design Expert software 6.06 was used to design the adsorption experiment. The adsorption was tested for Langmuir, Freundlich and Temkin isotherms and the kinetic studies also carried out. The effect of influencing parameters such as contact time, adsorbate concentration, adsorbent dosage and formulation ratio were studied. It was generally shown that adsorption process increased with time and adsorbate concentration and decreased with adsorbent dosage. Models for the prediction of adsorption capacity for the composite was significant with R2 value of 0.8382 and P-value of 0.0017. Optimum conditions were found to be 0.90 wt/wt chitosan/silica ratio, contact time of 5 min, and oil/water ratio of 0.25 v/v, which gave 20.66 g/g sorption capacity respectively. Adsorption isotherm studies of Langmuir, Freundlich and Temkin were carried out for the chitosan-rice husk ash composite. Temkin isotherm best fitted with R2 value of 0.9999. The adsorption capacity of composite from isotherm studies was obtained to be 18.85 g/g adsorbent. The heat of adsorption bT (kJmol-1) obtained from Temkin isotherm study was -48.67 kJ/mol indicating physisorption of adsorbents to the crude oil.  Kinetic studies indicated that the pseudo-second order model suitably described the removal of crude oil by the composite with R2 value 0.9999.


BioResources ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 22-33
Author(s):  
Mahnaz Mahdavi ◽  
Mansor B. Ahmad ◽  
Md Jelas Haron ◽  
Mohamad Zaki Ab. Rahman

Cr(III) ions were adsorbed onto polyacrylamide-grafted rubberwood fibre, and effects of aqueous conditions were evaluated. The adsorbent was prepared via graft copolymerization of acrylamide (Am) onto rubberwood fibre (RWF), using ceric ammonium nitrate as an initiator. Fourier transform infrared spectroscopy was used to confirm the formation of PAm-g-RWF. Various variables affecting the adsorption capacity such as the pH of the solution, adsorption time, initial metal ion concentration, and temperature were investigated. The Cr(III) was up to 92% removed by PAm-g-RWF from an initial concentration of 10 mg/L at pH 5.0. Kinetic data fitted very well to a pseudo-second-order rate expression and less well to a pseudo-first-order equation. The equilibrium parameters for adsorption isotherms of the metal ions on the grafted fibre were obtained using Langmuir and Freundlich models, and the Langmuir model was found to be in better correlation with the experimental data with a maximum adsorption capacity of 18.24 mg/g. Thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°), and entropy change (ΔS°) were calculated; the adsorption process was spontaneous and endothermic.


2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Ying Zhang ◽  
Ru Zheng ◽  
Jiaying Zhao ◽  
Yingchao Zhang ◽  
Po-keung Wong ◽  
...  

In this study, adsorption of zinc onto the adsorbent (untreated rice husk and NaOH-treated rice husk) was examined. During the removal process, batch technique was used, and the effects of pH and contact time were investigated. Langmuir isotherm was applied in order to determine the efficiency of NaOH-treated rice husk used as an adsorbent. The zinc adsorption was fast, and equilibrium was attained within 30 min. The maximum removal ratios of zinc for untreated rice husk and NaOH-treated rice husk after 1.5 h were 52.3% and 95.2%, respectively, with initial zinc concentration of 25 mg/L and optimum pH of 4.0. Data obtained from batch adsorption experiments fitted well with the Langmuir isotherm model. Maximum adsorption capacity of zinc onto untreated rice husk and NaOH-treated rice husk was 12.41 mg/g, and 20.08 mg/g respectively, at adsorbent dosage of 1 g/L at 25°C. The nature of functional groups (i.e., amino, carboxyl, and hydroxyl) and metal ion interactions was examined by the FT-IR technique. It was concluded that the NaOH-treated rice husk had stronger adsorption capacity for Zn2+compared with the untreated rice husk. The NaOH-treated rice husk is an inexpensive and environmentally friendly adsorbent for Zn2+removal from aqueous solutions.


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