Removal of molybdenum(VI) from aqueous solutions using nano zero-valent iron supported on biochar enhanced by cetyl-trimethyl ammonium bromide: adsorption kinetic, isotherm and mechanism studies

2018 ◽  
Vol 2017 (3) ◽  
pp. 859-868 ◽  
Author(s):  
J. J. Lian ◽  
Y. G. Huang ◽  
B. Chen ◽  
S. S. Wang ◽  
P. Wang ◽  
...  

Abstract A new carbonized pomelo peel biosorbent (MCPP) modified with nanoscale zero-valent iron (NZVI) and cetyl-trimethyl ammonium bromide was prepared and employed for the adsorption of molybdate (Mo(VI)) from aqueous solution. We investigated the effects of various conditions on Mo(VI) adsorption and evaluated the results based on adsorption kinetics models and isotherm equations. The kinetic data fitted to the pseudo-second-order model. The Langmuir model best described the adsorption of Mo(VI) on MCPP. The values of changes in Gibbs free energy, standard enthalpy, and standard entropy revealed that the adsorption process was feasible, spontaneous and endothermal. X-ray diffraction, Fourier transform infrared and X-ray photoelectron spectroscopy measurements suggested that Mo(VI) adsorption occurred via both the reduction and surface adsorption. Thus, biochar, prepared from fruit residue, can be applied to remove Mo(VI) from aqueous solutions. More importantly, our results provide a sustainable approach for Mo(VI) removal from wastewater by means of functional modification.

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1617
Author(s):  
Silviu-Adrian Predoi ◽  
Carmen Steluta Ciobanu ◽  
Mikael Motelica-Heino ◽  
Mariana Carmen Chifiriuc ◽  
Monica Luminita Badea ◽  
...  

In the present study, a new low-cost bioceramic nanocomposite based on porous hydroxyapatite (HAp) and cetyl trimethyl ammonium bromide (CTAB) as surfactant was successfully obtained by a simple chemical co-precipitation. The composition and structure of the HAp-CTAB were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) spectrometer, and N2 adsorption/desorption analysis. The capacity of HAp-CTAB nanocomposites to remove the lead ions from aqueous solutions was studied by adsorption batch experiments and proved by Langmuir and Freundlich models. The Pb2+ removal efficiency of HAp-CTAB biocomposite was also confirmed by non-destructive ultrasound studies. The cytotoxicity assays showed that the HAp-CTAB nanocomposites did not induce any significant morphological changes of HeLa cells after 24 h of incubation or other toxic effects. Taken together, our results suggests that the obtained porous HAp-CTAB powder could be used for the decontamination of water polluted with heavy metals, such as Pb2+.


Author(s):  
Haixia Wang ◽  
Mingliang Zhang ◽  
Hongyi Li

Maize straw biochar-supported nanoscale zero-valent iron composite (MSB-nZVI) was prepared for efficient chromium (Cr) removal through alleviating the aggregation of zero-valent iron particles. The removal mechanism of MSB-nZVI was investigated by scanning electron microscopy with energy dispersive X-ray (SEM-EDX), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). Cr(VI) removal from aqueous solution by MSB-nZVI was greatly affected by pH and initial concentration. The removal efficiency of Cr(VI) decreased with increasing pH, and the removal kinetics followed the pseudo-second-order model. XRD patterns of MSB-nZVI before and after reaction showed that reduction and precipitation/co-precipitation (FeCr2O4, Fe3O4, Fe2O3) occurred with the conversion of Cr(VI) to Cr(III) and Fe(0) to Fe(II)/Fe(III). The produced precipitation/co-precipitation could be deposited on the MSB surface rather than being only coated on the surface of nZVI particles, which can alleviate passivation of nZVI. For remediation of Cr(VI)-contaminated saline–alkali soil (pH 8.6–9.0, Cr 341 mg/kg), the released amount of Cr(VI) was 70.7 mg/kg, while it sharply decreased to 0.6–1.7 mg/kg at pH 4.0–8.0, indicating that the saline–alkali environment inhibited the remediation efficiency. These results show that MSB-nZVI can be used as an effective material for Cr(VI) removal from aqueous solution and contaminated soil.


RSC Advances ◽  
2014 ◽  
Vol 4 (93) ◽  
pp. 51244-51255 ◽  
Author(s):  
Santosh K. Gupta ◽  
P. S. Ghosh ◽  
A. Arya ◽  
V. Natarajan

Nanorods of ThO2 were synthesized in a reverse micelle technique using cetyl trimethyl ammonium bromide as a surfactant and characterized by X-ray diffraction and transmission electron microscopy.


2014 ◽  
Vol 609-610 ◽  
pp. 346-350 ◽  
Author(s):  
Yu Rong Zhong ◽  
Man Zhao ◽  
Bao Long Xu

Europium-doped lutetium (Lu2O3:Eu3+ ) powders were prepared by micro-emulsion method. A small amount of an aqueous solution of Lu(NO3)3, Eu(NO3)3 and aqueous ammonia was slowly dropped into the water-in-oil micro-emulsion system (water / cetyl trimethyl ammonium bromide (CTAB) / n-butyl alcohol and cyclohexane) under vigorous stirring at 80 °C. The precipitates were obtained by Ostwald’s ripening at 250 °C for 6 h, which were then heated at 400 °C, 600 °C and 800 °C. The SEM morphology showed that the powders were rods of about few hundred nanometers in length and 40 nm in diameter. The spectrograms of X-ray diffraction (XRD) demonstrated that the Lu2O3:Eu3+ crystallinity was enhanced with the increasing of temperature. The photoluminescence results revealed that the intense emission bands centered at 612 nm. This method provides a new way to obtain different morphology and luminescent properties of Lu2O3:Eu3+ powder.


1984 ◽  
Vol 62 (1) ◽  
pp. 51-55 ◽  
Author(s):  
Kamal Shakir ◽  
Kamal Benyamin ◽  
Mourad Aziz

Foam separation investigations over the 2.5–10.5 pH range show that U(VI) can be successfully separated from aqueous solutions by precipitation with oxine and subsequent flotation of the precipitate, either in absence or in presence of surfactant collectors. Collectors tested were: cetyl trimethyl ammonium bromide (CTAB) and sodium lauryl sulphate (NaLS). The extent of removal depends on many factors and removals as high as 98% could be achieved when uranyl oxinate precipitate was floated, under certain controlled conditions, in the presence of CTAB. Factors affecting the percentage removal were investigated and the best conditions were selected. The results obtained are discussed in terms of the hydrolytic behaviour of U(VI).


Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 131 ◽  
Author(s):  
Lie Yang ◽  
Hong Li ◽  
Jianming Xue ◽  
Liuyang He ◽  
Yongfei Ma ◽  
...  

The efficiencies of the nanoscale zero-valent iron (nZVI) and hydrothermal and nZVI-heat activation of peroxydisulfate (PS) were studied for the decomposition of chloramphenicol (CAP) in aqueous solutions. The nZVI heat combined with activation of PS provided a significant synergistic effect. A central composite design (CCD) with response surface methodology (RSM) was employed to explore the influences of single parameter and interactions of selected variables (initial pH, PS concentration, nZVI and temperature) on degradation rates with the purpose of condition optimization. A quadratic model was established based on the experimental results with excellent correlation coefficients of 0.9908 and 0.9823 for R2 and R2adj. The optimized experimental condition for 97.12% CAP removal was predicted with the quadratic model as 15 mg/L, 0.5 mmol/L, 7.08 and 70 °C for nZVI dosage, PS, initial pH, and temperature, respectively. This study demonstrated the effectiveness of RSM for the modeling and prediction of CAP removal processes. In the optimal condition, Fe2O3 and Fe3O4 were the predominant solid products after reactions based on X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis, which could also act as the activators along with the reaction. Overall, it could be concluded that hydrothermal enhanced nZVI activation of PS was a promising and efficient choice for CAP degradation.


2019 ◽  
Vol 14 (12) ◽  
pp. 1759-1765 ◽  
Author(s):  
N. Prakash ◽  
C. Narendhar ◽  
E. Muthusankar ◽  
D. Ragupathy

In this paper, KIT: Korea Advanced Institute of Science and Technology No. 6 (KIT-6) and MCM: Mobil Composition of Matter No. 48 (MCM-48) mesoporous silica templates were prepared by wrapping Pluronic (P123) and Cetyl trimethyl ammonium bromide (CTAB). Mesoporous Co3O4 geometry tailored KIT-6 and MCM-48 with different porosity were synthesized via reflux technique. Crystal geometry, morphology, molecular vibrations and pore structure were analyzed by X-Ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and Brunauer-Emmett-Teller (BET) method based N2 adsorption–desorption for the modified materials. As expected, MCM-48 micropore-dominated electrode exhibited higher specific capacitance (442.5 F/g) which is much superior to that of KIT-6 (88.9 F/g). Outstanding electrochemical execution is due to the mesoporous tailored architecture (average pore diameter of 6.1 nm) and synergistic contribution of MCM-48 architectured with a Co3O4 core. This promising electrode material opens up a new platform for high-performance supercapacitors.


2015 ◽  
Vol 4 (4) ◽  
pp. 19-31 ◽  
Author(s):  
Ali Ġmran Vaġzoğullar ◽  
Mehmet Uğurlu ◽  
Ġbrahim Kula

In our study adsorption of Hg+2 ions from water solutions on Sepiolite (Sep) and Modified Sepiolite (MSep) with cationic surfactants namely cetyl trimethyl ammonium bromide CTAB was investigated. Different parameters were used to investigate such as contact time, pH and adsorbent dosage. The adsorption capacity of MSep and Sep was examined. Both particles were characterized with FTIR spectrum. According to the our results the equilibrium adsorption data corresponded to the Langmuir isotherm and qmax was 54,7 mg/g and 104,1 mg/g for Sep and MSep respectively. Kinetic parameters showed that pseudo-second-order adsorption kinetic model was the best model than the pseudo-first-order. MSep is more active adsorbent than Sep and it can be the best alternative adsorbent for removing of heavy metal from industrial waste water. In addition MSep can be used as adsorbent for removal of nonpolar toxic organic molecules, because sepiolite surface can be converted from hydrophilic form to hydrophobic form by CTAB resulting in increased the adsorption capacity.International Journal of Environment Vol.4(4) 2015: 19-31


2014 ◽  
Vol 1073-1076 ◽  
pp. 8-11 ◽  
Author(s):  
Bin Huang ◽  
Li Li ◽  
Ya Ping Jiang ◽  
Shi Xiong Hao

Nano-titanium dioxide was prepared in a microemulsion system by solvothermal method. The microemulsion system is composed of ammonium hexafluorotitanate((NH4)2TiF6) used as titanium source, water, cetyl trimethyl ammonium bromide (CTAB), n-butanol, and cyclohexane. The influences of reaction time, amount of urea added and the mole ratio of water to CTAB (ω) on particle size, and photocatalytic activity were investigated by photocatalytic degrading methyl orange and X-ray diffraction (XRD) characterization. The results show that the optimum preparation conditions are that reaction time 12 h, the amount of urea added 1.5 g, and the ratio of water to CTAB ratio (ω) 18:1.


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