Adsorption of rhodamine B and Cr3+ ion onto graphene/chitosan composite

Author(s):  
Yanji Li ◽  
Meng Ni ◽  
Qiang He ◽  
Xiang Li ◽  
Wei Zhang ◽  
...  

Graphene and chitosan acted as the adsorbents for simulated wastewater with rhodamine B. The novel material produced by freeze-drying obviously outperformed graphene and chitosan in treating rhodamine B. Factors (e.g., contaminant concentration, reaction time, solution pH value, adsorption dose and temperature) overall impacted the adsorption. The optimal conditions for graphene-chitosan treatment of dyes included the concentration of pollutants at 400 mg/L, the dose of adsorbent as 5 mg, the solution pH at 4 and at 25∘C, and for 12 h, in which the maximal treatment amount reached 858.00 mg/g. The adsorption processes of Chitosan/graphene composites and magnetic Chitosan/graphene composites for simulated wastewater from Rhodamine B reactor followed Langmuir and Freundlich models, respectively. The in-particle diffusion model shows that the adsorption process of the composites for Rhodamine B simulated wastewater is not determined by either surface diffusion or in-particle diffusion. The magnetic Chitosan/graphene composites exhibit high recyclability, which can be respectively reused 3 times and 5 times and retain 80% adsorption capacity after being administrated with Rhodamine B simulated wastewater. By analyzing grey correlation degree, it is demonstrated that the concentration of pollutants and the reaction temperature critically affect the adsorption capacity. The electrochemical treatment with graphite rod for the Cr3+ was under the initial voltage of 30.6 V, at the pH of 5.59, and at the temperature of 18.5∘C; the removal rate of the samples was nearly 62.35% with the chromium ion concentration declined from 0.3333 g/L to 0.1255 g/L.

2018 ◽  
Vol 788 ◽  
pp. 83-88
Author(s):  
Oskars Leščinskis ◽  
Ruta Švinka ◽  
Visvaldis Švinka

Clays are materials consisting of clay minerals and non-clay minerals. Clay mineral fraction is considered to be a nanofraction. Clay minerals can be used for water purification and treatment. Description and characterization of 3 different Latvian clay nanosized minerals from 3 different geological periods (clay Liepa from Devonian period, clay Vadakste from Triassic period and clay Apriki from Quaternary period) as well as their adsorption capacity concerning organic compounds such as methyl orange and rhodamine B are summarized. Nanosized clay mineral particles were obtained using sedimentation method. Particle size distribution, zeta potential and FTIR spectra is given. The adsorption tests of above mentioned organic compounds were carried out in water solutions at 3 different pH values. The adsorption values were determined by means of UV-spectrophotometric technique. Zeta potential values for clay minerals Apriki, Liepa and Vadakste are -40.9 mV, -49.6 mV and -43.0 mV, respectively. FTIR spectra show similar tendencies for all 3 clay minerals. The best adsorption capacity concerning methyl orange and rhodamine B were in solutions with a pH value of 2, whereas at neutral and alkaline pH values adsorption in 24 hours was not observed.


BioResources ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. 6100-6120
Author(s):  
Yinan Hao ◽  
Yanfei Pan ◽  
Qingwei Du ◽  
Xudong Li ◽  
Ximing Wang

Armeniaca sibirica shell activated carbon (ASSAC) magnetized by nanoparticle Fe3O4 prepared from Armeniaca sibirica shell was investigated to determine its adsorption for Hg2+ from wastewater. Fe3O4/ASSAC was characterized using XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), and BET (Brunauer–Emmett–Teller). Optimum adsorption parameters were determined based on the initial concentration of Hg2+, reaction time, reaction temperature, and pH value in adsorption studies. The experiment results demonstrated that the specific surface area of ASSAC decreased after magnetization; however the adsorption capacity and removal rate of Hg2+ increased 0.656 mg/g and 0.630%, respectively. When the initial concentration of Hg2+ solution was 250 mg/L and the pH value was 2, the adsorption time was 180 min and the temperature was 30 °C, and with the Fe3O4/ASSAC at 0.05 g, the adsorption reaching 97.1 mg/g, and the removal efficiency was 99.6%. The adsorption capacity of Fe3O4/ASSAC to Hg2+ was in accord with Freundlich isotherm models, and a pseudo-second-order kinetic equation was used to fit the adsorption best. The Gibbs free energy ΔGo < 0,enthalpy change ΔHo < 0, and entropy change ΔSo < 0 which manifested the adsorption was a spontaneous and exothermic process.


2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Ali Baddouh ◽  
Brahim El Ibrahimi ◽  
Elhassan Amaterz ◽  
M. Mohamed Rguiti ◽  
Lahcen Bazzi ◽  
...  

The electrochemical oxidation of the Rhodamine B dye (Rh-B) was carried out using dimensionally stable type anode (DSA, Ti/Ru0.3Ti0.7O2). The work was performed using the electrochemical flow cell system. The effect of several operating factors, such as supporting electrolytes, current density, electrolysis time, temperature, and initial concentration of Rh-B dye, were investigated. The UV-visible spectroscopy and chemical oxygen demand (COD) measurements were conducted to monitor the removal and degradation of Rh-B. The best color removal achieved was found to be 98.3% after 10 min applying 3.9 mA·cm−2 as a current density using 0.07 mol·L−1 of NaCl. Meanwhile, the highest COD removal rate (93.0%) was obtained for an applied current density of 3.9 mA·cm−2 as the optimal operating condition after 180 min reaction time, with 2.98 kW h·m−3 as energy consumption. This shows that the best conditions for color removal are not certainly the same as those for the COD removal. The rises in the concentration of NaCl, and applied current increased the Rh-B color removal rate. The decline in Rh-B dye concentration followed pseudo-first-order kinetics. The obtained values of apparent rate constant were increased by increasing chloride ion concentration. It is concluded that the electro-oxidation on DSA electrode using a flow cell is a suitable process for the removal of Rh-B dye in aqueous solutions.


e-Polymers ◽  
2016 ◽  
Vol 16 (2) ◽  
pp. 99-109 ◽  
Author(s):  
Xiu-Juan Wu ◽  
Ji-De Wang ◽  
Li-Qin Cao

AbstractNovel chitosan/diatomite (CS/DM) membranes were prepared by phase inversion technique to remove anionic azo dyes from wastewater. The fabricated composite membranes exhibited the combined advantages of inorganic substances, diatomites, and polysaccharides. These composite membranes were characterized through Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. The mechanical properties of the membranes were also evaluated. Adsorption experiments were conducted under varied initial dye concentration, solution pH values, contact time, and adsorbent dosage. The results indicate that pH 3 is the optimal pH value for Orange G adsorption. The CS/DM membranes exhibit the highest adsorption capacity of 588 mg g-1 and removal rate of 94% under an initial dye concentration of 200 mg l-1, contact time of 6 h, and membrane dosage of 8 mg. Langmuir, Freundlich and Redlich-Peterson adsorption models were applied to describe the equilibrium isotherms at different dye concentrations. The equilibrium data was found to be fitted well to the Redlich-Peterson isotherm. Pseudo-first-order and pseudo-second-order kinetics models were used to describe the adsorption of membranes. The adsorption data were well explained by pseudo-second-order models, and also followed by the Elovich model. In addition, these membranes display high adsorption capacity and mechanical performance even after reused for seven times.


Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1630
Author(s):  
Vesna Marjanovic ◽  
Aleksandra Peric-Grujic ◽  
Mirjana Ristic ◽  
Aleksandar Marinkovic ◽  
Radmila Markovic ◽  
...  

Hybrid adsorbent, based on the cross-linked copolymer impregnated with hydrous iron oxide, was applied for the first time for Se(VI) adsorption from water. The influence of the initial solution pH, selenate concentration and contact time to adsorption capacity was investigated. Adsorbent regeneration was explored using a full factorial experimental design in order to optimize the volume, initial pH value and concentration of the applied NaCl solution as a reagent. Equilibrium state was described using the Langmuir model, while kinetics fitted the pseudo-first order. The maximum adsorption capacity was found to be 28.8 mg/g. Desorption efficiency increased up to 70%, and became statistically significant with the reagent concentration and pH increase, while the applied solution volume was found to be insignificant in the investigated range. Based on the results obtained, pH influence to the adsorption capacity, desorption efficiency, Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis of loaded adsorbent, it was concluded that the outer- and inner-sphere complexation are mechanisms responsible for Se(VI) separation from water. In addition to the experiments with synthetic solutions, the adsorbent performances in drinking water samples were explored, showing the purification efficiency up to 25%, depending on the initial Se(VI) concentration and water pH. Determined sorption capacity of the cross-linked copolymer impregnated with hydrous iron oxide and its ability for regeneration, candidate this material for further research, as a promising anionic species sorbent.


2013 ◽  
Vol 791-793 ◽  
pp. 24-27
Author(s):  
Qing Shan Pan ◽  
Dai Qi Li ◽  
Jian Qiang Li ◽  
Wei Liu ◽  
Mei Gui Ma ◽  
...  

Peanut shell Cellulose Xanthate (PCX) was prepared by reacting with carbon disulphide after mercerized by sodium hydroxide solution. The preparing conditions (hydroxide solution concentration, carbon disulphide dosage, temperature) were optimized in this study. And the effects of PCX amount and contact time on the removal of Cd (II) ion from aqueous solution was studied,the results indicated that when the initial Cd (II) ion concentration was 10mg/L, the adsorption capacity of PXC was high effective with the PCX amount was 1g/L and the contact time was 1.5h,the equilibrium adsorption capacity of PCX was 9.87 mg/g and the removal rate of Cd (II) ion was 98.72%.Then the regeneration capacities of PCX adsorbent was investigated, the results indicated that the removal rate of Cd (II) ion was more than 75% after regeneration. All the results indicated that the PCX can be used as a low cost but effective biosorbent for heavy metals remediation.


2012 ◽  
Vol 518-523 ◽  
pp. 121-124
Author(s):  
Hong Xia Xia ◽  
Qi Hong Zhu

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..


2012 ◽  
Vol 518-523 ◽  
pp. 3204-3207 ◽  
Author(s):  
Hui Tian ◽  
Ya Na Liu

The methyl violet dye as the main research subjects. The concentration of H2O2, ferrous ion concentration, pH value and the type of dyes and so on be research the influence on the rate. The result shown: the greater dose of H2O2, the greater removal of methyl violet dye. when the dose of H2O2reach to a certain amount, keep increase the dose , but the increase was not obvious. In a certain concentration range, when the higher concentration of ferrous ions, the higher degradation rate of methyl viologen.When more than the certain concentration, the degradation rate began to decline. The removal efficiency is better when the ratio of ferrous ions and H2O2is 1:10..A large removal rate is controlled in the temperature of 20 to 60 as well as the pH is from 3 to 5. After changing the type of dye,beside the Alizarin Red,the removal of Methylene blue, Rhodamine, methyl violet are all high.


2012 ◽  
Vol 446-449 ◽  
pp. 2800-2808
Author(s):  
Guo Jing Yang ◽  
Shuang Shuang Chen ◽  
Wei Hong Wu ◽  
Jian Zhou

The process optimization and characteristics of electrode-biofilm for the treatment of copper pickling wastewater in the self-designed reactor were experimentally investigated. Carbon electrodes were installed in the reactor as the anode and cathode and denitrifying microorganisms were fixed on the surface of the cathode. The results showed that neutralization, copper ion removal, denitrification proceeded simultaneously and no secondary pollution existed. The removal rate of total nitrogen and copper ion in the effluent water reached 98% and 97% at 30mg/L of copper ion concentration and 100mg/L of nitrate nitrogen when the conditions were controlled at temperature 35°C, current density 0.1mA/cm2, hydraulic retention time 11h and C/N ration 1.07. The pH value of the treated water was increased almost to neutral. In addition, copper ion solution of certain concentration and purity could be made by exchanging the polarity of anode and cathode to recycle copper in this research.


2013 ◽  
Vol 545 ◽  
pp. 101-108 ◽  
Author(s):  
Kitirote Wantala ◽  
Nusavadee Pojananukij ◽  
Pongsert Sriprom ◽  
Tinnakorn Kumsaen ◽  
Arthit Neramittagapong ◽  
...  

Adsorption of Zn(II) and Pb(II) from aqueous solution were studied by using modified coir pith as an adsorbent. The extended adsorption conditions were investigated as a function of calcination temperature, contact time, adsorbent size, initial pH of solution and initial Zn(II) and Pb(II) concentrations. The adsorption capacity increased rapidly in first 5 minute and reached equilibrium in 120 minutes for Zn(II) and 10 minutes for Pb(II). In case of Zn(II); the results showed that the calcination temperature of modified coir pith above 600oC gave the higher adsorption capacity. The sizes of modified coir pith have no effect on the adsorption capacity. The adsorption capacity increased with increasing initial solution pH value. In case of Pb(II); the calcination temperature of modified coir pith showed no effect on the adsorption capacity. The sizes of modified coir pith showed a little effect on the adsorption capacity. The adsorption capacity increased with increasing of initial solution pH value up to pH of 3 and then stable. The results also corresponded with the Langmuir and Freundlich isotherms and pseudo second order kinetic adsorption models. The modified coir pith gave a higher Zn(II) and Pb(II) adsorption capacity of 29.33 mg Zn(II)/g adsorbent and 36.50 mg Pb(II)/g adsorbent, respectively.


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