scholarly journals Electrochemical Evaluation of Selenium (IV) Removal from Its Aqueous Solutions by Unmodified and Modified Graphene Oxide

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1063
Author(s):  
Zuzana Koudelkova ◽  
Zuzana Bytesnikova ◽  
Kledi Xhaxhiu ◽  
Monika Kremplova ◽  
David Hynek ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Iron Oxide ◽  
Adsorption Capacity ◽  
Selenium Concentration ◽  
Stripping Voltammetry ◽  
World Health ◽  
Maximum Adsorption Capacity ◽  
Adsorption Model ◽  
Graphene Oxides ◽  
Modified Graphene Oxide

The removal of selenium from superficial and waste water is a worldwide problem. The maximum limit according to the World Health Organization (WHO) for the selenium in the water is set at a concentration of 10 μg/L. Carbon based adsorbents have attracted much attention and recently demonstrated promising performance in removal of selenium. In this work, several materials (iron oxide based microparticles and graphene oxides materials) and their composites were prepared to remove Se(IV) from water. The graphene oxides were prepared according to the simplified Hummer’s method. In addition, the effect of pH, contact time and initial Se(IV) concentration was tested. An electrochemical method such as the differential pulse cathodic stripping voltammetry was used to determine the residual selenium concentration. From the experimental data, Langmuir adsorption model was used to calculate the maximum adsorption capacity. Graphene oxide particles modified by iron oxide based microparticles was the most promising material for the removal of Se(IV) from its aqueous solution at pH 2.0. Its adsorption efficiency reached more than 90% for a solution with given Se(IV) concentration, meanwhile its maximal recorded adsorption capacity was 18.69 mg/g.

Synthesis and characterization of a new magnetic adsorbent for removal of 4-nitrophenol: application of response surface methodology

2019 ◽  
Vol 80 (8) ◽  
pp. 1430-1442
Author(s):  
Reza Gholamnia ◽  
Mehrnoosh Abtahi ◽  
Reza Saeedi ◽  
Shokooh Sadat Khaloo
Keyword(s):  
Graphene Oxide ◽  
Adsorption Capacity ◽  
Response Surface ◽  
Second Order ◽  
Quadratic Model ◽  
Maximum Adsorption Capacity ◽  
Modified Graphene Oxide ◽  
Pseudo Second Order ◽  
Modified Graphene ◽  
Graphene Oxide Sheets

Abstract Magnetic modified graphene oxide was synthesized as a new modified magnetic nano-composite (MMNC) by a simple sonochemical–hydrothermal method. The sonochemical reaction was employed to exfoliate, functionalize and decorate neomycin on graphene oxide sheets. Nickel ferromagnetic particles were synthesized by hydrothermal co-precipitation method and decorated on neomycin-modified graphene oxide. The morphology and chemical structure of MMNC were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction spectroscopy. The adsorption capability of MMNC for removal of phenolic compounds was assessed through adsorption of 4-nitrophenol (4-NP) from aqueous solution. The three-factor Box–Behnken design coupled with response surface method was applied to evaluate and optimize the important variables which affect the adsorption process. A significant quadratic model (p-value <0.05, R2(adj) = 0.9593) was derived using analysis of variance. The maximum adsorption capacity of 125.4 mg 4-NP/g MMNC at pH 6 was obtained, which was comparable in some cases and higher than most adsorbents reported in the literature. The presence of neomycin on graphene oxide sheets improved the maximum adsorption capacity of the nano-sorbent up to 28% (from 98.7 to 125.4 mg 4-NP/g adsorbent). The adsorption isotherms fitted well with the Langmuir model (Langmuir constant b = 0.064 l/mg, R2 = 0.9989) and the kinetic study showed that the nitrophenol uptake process followed the pseudo-second-order rate expression (R2 ≥ 0.9960, pseudo-second-order constant K2 ≥ 1.7 × 10−3).

scholarly journals Directionally-Grown Carboxymethyl Cellulose/Reduced Graphene Oxide Aerogel with Excellent Structure Stability and Adsorption Capacity

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2219
Author(s):  
Mengke Zhao ◽  
Sufeng Zhang ◽  
Guigan Fang ◽  
Chen Huang ◽  
Ting Wu
Keyword(s):  
Graphene Oxide ◽  
Adsorption Capacity ◽  
Reduced Graphene Oxide ◽  
Carboxymethyl Cellulose ◽  
Organic Dyes ◽  
Structure Stability ◽  
Maximum Adsorption Capacity ◽  
Adsorption Model ◽  
Composite Aerogel ◽  
Reduced Graphene

A novel three-dimensional carboxymethyl cellulose (CMC)/reduced graphene oxide (rGO) composite aerogel crosslinked by poly (methyl vinyl ether-co-maleic acid)/poly (ethylene glycol) system via a directional freezing technique exhibits high structure stability while simultaneously maintaining its excellent adsorption capacity to remove organic dyes from liquid. A series of crosslinked aerogels with different amounts of GO were investigated for their adsorption capacity of methylene blue (MB), which were found to be superb adsorbents, and the maximum adsorption capacity reached 520.67 mg/g with the incorporation of rGO. The adsorption kinetics and isotherm studies revealed that the adsorption process followed the pseudo-second-order model and the Langmuir adsorption model, and the adsorption was a spontaneous process. Furthermore, the crosslinked aerogel can be easily recycled after washing with dilute HCl solution, which could retain over 97% of the adsorption capacity after recycling five times. These excellent properties endow the crosslinked CMC/rGO aerogel’s potential in wastewater treatment and environment protection.

scholarly journals A Composite of Hyaluronic Acid-Modified Graphene Oxide and Iron Oxide Nanoparticles for Targeted Drug Delivery and Magnetothermal Therapy

ACS Omega ◽  
2019 ◽  
Vol 4 (5) ◽  
pp. 9284-9293 ◽  
Author(s):  
Nilkamal Pramanik ◽  
Santhalakshmi Ranganathan ◽  
Sunaina Rao ◽  
Kaushik Suneet ◽  
Shilpee Jain ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Graphene Oxide ◽  
Hyaluronic Acid ◽  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Targeted Drug Delivery ◽  
Oxide Nanoparticles ◽  
Modified Graphene Oxide ◽  
Targeted Drug ◽  
Modified Graphene

Preparation of Graphene Oxide Modified Rice Husk for Cr(VI) Removal

2019 ◽  
Vol 19 (11) ◽  
pp. 7035-7043 ◽  
Author(s):  
Tong Ouyang ◽  
Jidan Tang ◽  
Fang Liu ◽  
Chang-Tang Chang
Keyword(s):  
Graphene Oxide ◽  
Adsorption Capacity ◽  
Rice Husk ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Adsorption Sites ◽  
Equilibrium Data ◽  
Order Kinetic Model ◽  
Alkaline Conditions ◽  
Rice Husk Biochar

The objective of this paper is to study the removal of Cr(VI) in aqueous solution by using a new graphene oxide-coated rice husk biochar composite (GO-RHB). GO-RHB is a synthetic material having a porous structure with lots of oxygen-containing functional groups and a large surface area that provide effective adsorption sites. Experiments showed that GO-RHB had higher adsorption capacity under acidic than under alkaline conditions. At pH of 2, GO-RHB has the maximum adsorption capacity(48.8 mg g−1). Equilibrium data obtained by fitting with the Langmuir and Freundlich models indicate that the reaction process was monolayer adsorption. The adsorption of Cr(VI) followed the pseudo-second-order kinetic model that illustrates chemical adsorption. Intraparticlediffusion studies further revealed that film diffusion was taking place. Moreover, the results of thermodynamics showed that the adsorption process was endothermic and spontaneous in nature. The removal mechanism of Cr(VI) was also explained in detail. The prepared adsorbent is highly efficient and might be useful than many other conventional adsorbent used for the removal of Cr(VI) from wastewater.

scholarly journals Cotransport of Cu with Graphene Oxide in Saturated Porous Media with Varying Degrees of Geochemical Heterogeneity

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 444 ◽  
Author(s):  
Jianzhou He ◽  
Dengjun Wang ◽  
Tingting Fan ◽  
Dongmei Zhou
Keyword(s):  
Heavy Metals ◽  
Porous Media ◽  
Graphene Oxide ◽  
Iron Oxide ◽  
Colloidal Stability ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Physicochemical Conditions ◽  
Subsurface Environment ◽  
Geochemical Heterogeneity

Graphene oxide (GO) is likely to encounter heavy metals due to its widespread use and inevitable release into the subsurface environment, where the ubiquitous presence of iron oxides (e.g., hematite) would affect their interaction and transport. The present study aimed to investigate the cotransport of GO (20 mg L−1) and copper (0.05 mM CuCl2) in the presence of varying degrees of geochemical heterogeneity represented by iron oxide-coated sand fractions (ω = 0‒0.45) in water-saturated columns under environmentally relevant physicochemical conditions (1 mM KCl at pH 5.0‒9.0). The Langmuir-fitted maximum adsorption capacity of Cu2+ by GO reached 137.6 mg g−1, and the presence of 0.05 mM Cu2+ decreased the colloidal stability and subsequent transport of GO in porous media. The iron oxide coating was found to significantly inhibit the transport of GO and Cu-loaded GO in sand-packed columns, which can be explained by the favorable deposition of the negatively charged GO onto patches of the positively charged iron oxide coatings at pH 5.0. Increasing the solution pH from 5.0 to 9.0 promoted the mobility of GO, with the exception of pH 7.5, in which the lowest breakthrough of GO was observed. This is possibly due to the fact that the surface charge of iron oxide approaches zero at pH 7.5, suggesting that new “favorable” sites are available for GO retention. This study deciphered the complicated interactions among engineered nanomaterials, heavy metals, and geochemical heterogeneity under environmentally relevant physicochemical conditions. Our results highlight the significant role of geochemical heterogeneity, such as iron oxide patches, in determining the fate and transport of GO and GO-heavy metal association in the subsurface environment.

scholarly journals Silica-Coated Magnetic Nanocomposites for Pb2+ Removal from Aqueous Solution

2020 ◽  
Vol 10 (8) ◽  
pp. 2726 ◽  
Author(s):  
Roxana Nicola ◽  
Otilia Costişor ◽  
Mihaela Ciopec ◽  
Adina Negrea ◽  
Radu Lazău ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Adsorption Capacity ◽  
Aqueous Media ◽  
Physical Stability ◽  
Absorption Capacity ◽  
Maximum Adsorption Capacity ◽  
X Ray Diffraction ◽  
Similar Materials ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Magnetic iron oxide-silica shell nanocomposites with different iron oxide/silica ratio were synthesized and structurally characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), small-angle neutron scattering, magnetic and N2-sorption studies. The composite that resulted with the best properties in terms of contact surface area and saturation of magnetization was selected for Pb2+ adsorption studies from aqueous media. The material presented good absorption capacity (maximum adsorption capacity 14.9 mg·g−1) comparable with similar materials presented in literature. Its chemico-physical stability and adsorption capacity recommend the nanocomposite as a cheap adsorbent material for lead.

scholarly journals Sodium hydroxide modified rice husk for enhanced removal of copper ions

2018 ◽  
Vol 78 (7) ◽  
pp. 1615-1623 ◽  
Author(s):  
N. Priyantha ◽  
H. K. W. Sandamali ◽  
T. P. K. Kulasooriya
Keyword(s):  
Heavy Metal ◽  
Adsorption Capacity ◽  
Rice Husk ◽  
Copper Ions ◽  
Maximum Adsorption Capacity ◽  
Adsorption Model ◽  
Natural Form ◽  
Langmuir Adsorption ◽  
Pseudo Second Order ◽  
Heavy Metal Adsorbent

Abstract Although rice husk (RH) is a readily available, natural, heavy metal adsorbent, adsorption capacity in its natural form is insufficient for certain heavy metal ions. In this context, the study is based on enhancement of the adsorption capacity of RH for Cu(II). NaOH modified rice husk (SRH) shows higher extent of removal for Cu(II) ions than that of heated rice husk (HRH) and HNO3 modified rice husk (NRH). The extent of removal of SRH is increased with the concentration of NaOH, and the optimum NaOH concentration is 0.2 mol dm−3, used to modify rice husk for further studies. The surface area of SRH is 215 m2 g−1, which is twice as much as that of HRH according to previous studies. The sorption of Cu(II) on SRH obeys the Langmuir adsorption model, leading to the maximum adsorption capacity of 1.19 × 104 mg kg−1. Kinetics studies show that the interaction of Cu(II) with SRH obeys pseudo second order kinetics. The X-ray fluorescence spectroscopy confirms the adsorption of Cu(II) on SRH, while desorption studies confirm that Cu(II) adsorbed on SRH does not leach it back to water under normal conditions.

scholarly journals Selenate Adsorption from Water Using the Hydrous Iron Oxide-Impregnated Hybrid Polymer

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1630
Author(s):  
Vesna Marjanovic ◽  
Aleksandra Peric-Grujic ◽  
Mirjana Ristic ◽  
Aleksandar Marinkovic ◽  
Radmila Markovic ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Adsorption Capacity ◽  
Ph Value ◽  
Xrd Analysis ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Adsorbent Regeneration ◽  
Desorption Efficiency ◽  
Hydrous Iron Oxide ◽  
The Cross

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.

Preparation, characterization, and chemical-induced hydrophobicity of thermostable amine-modified graphene oxide

RSC Advances ◽  
2015 ◽  
Vol 5 (127) ◽  
pp. 105393-105399 ◽  
Author(s):  
Jing Wang ◽  
Hong-Zhang Geng ◽  
Zhi-Jia Luo ◽  
Songting Zhang ◽  
Jinqiu Zhang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Graphene Oxide ◽  
Small Molecule ◽  
Contact Angles ◽  
Oxide Surfaces ◽  
Graphene Oxides ◽  
Excellent Thermal Stability ◽  
Modified Graphene Oxide ◽  
Modified Graphene

A small molecule was grafted onto the graphene oxide surfaces using two different approaches and the obtained amine-modified graphene oxides have excellent thermal stability and significantly enhanced water/air contact angles.

scholarly journals Graphene Oxide Adsorption Enhanced by Attapulgite to Remove Pb (II) from Aqueous Solution

2019 ◽  
Vol 9 (7) ◽  
pp. 1390 ◽  
Author(s):  
Bigui Wei ◽  
Xiabing Cheng ◽  
Gang Wang ◽  
Hua Li ◽  
Xiaosan Song ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Graphene Oxide ◽  
Adsorption Capacity ◽  
High Efficiency ◽  
Separation Efficiency ◽  
Hydrothermal Reaction ◽  
Adsorption Properties ◽  
Maximum Adsorption Capacity

To improve the adsorption and separation efficiency of lead-containing wastewater by graphene oxide (GO), attapulgite (ATP) was used through a simple hydrothermal reaction. The prepared GO was characterized by SEM, TEM, FTIR, and XPS. The adsorption properties of the prepared GO were investigated. The maximum adsorption capacity of Pb2+ on as-prepared GO at pH 5 and 25 °C was 450.9 mg/g. It is concluded that the as-prepared GO can be used as a high-efficiency adsorbent for lead-containing wastewater.

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