Design,synthesis, and nanoengineered modification of spherical graphene surface by layered double hydroxide (LDH) for removal of As(III) from aqueous solutions

In this study, new nano spherical graphene modified with LDH (Layered Double Hydroxide) was prepared and used to remove As(III) ion from aqueous solutions. At first, graphene oxide was synthesized from graphite using a well-known Hammer method. The obtained graphene oxide solution was sprayed in octanol solution under different temperatures and sprayed speed as influenced variables. The structure and physical characterization of synthesized spherical graphene oxide were determined by various techniques, including FT-IR, N₂ adsorption–desorption, SEM, TEM, and EDX. In the next step, the hydrothermal method was applied to deposition LDH on the spherical graphene oxide. The synthesized spherical graphene modified by LDH was used to remove As(III) as a toxic heavy metal ion. The effect of influenced variables including pH, contact time, amount of sorbent, and type eluent studied and the optimum values were as 8, 30, 50, and HCl (0.5 mol·L^-1), respectively. After optimization, the studied sorbent was shown a high adsorption capacity (149.3 mg·g^-1). The adsorption mechanism and kinetic models exhibited good agreement with the Langmuir isotherm and pseudo-second-order trends, respectively. Besides, the synthesized product was tested for seven times without significant loss in its sorption efficiency.     

Radiation synthesis of graphene oxide/composite hydrogels and their ability for potential dye adsorption from wastewater

A high yield of graphene oxide (GO) was chemically synthesized from graphite powder utilizing adjusted Hummer's method. The contents of acidic functional groups in GO were determined using potentiometric titration. Composite hydrogels dependent on graphene oxide/poly(2-acrylamido-2-methylpropanesulfonic acid)/polyvinyl alcohol (GO/PAMPS/PVA) were synthesized utilizing a ⁶⁰Co gamma irradiation source at different doses. The synthesized graphene oxide and composite hydrogels were portrayed via X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared analysis. The morphology of composite hydrogels was characterized by scanning electron microscope. The gel % and swelling % for the prepared hydrogel demonstrated that the swelling % of hydrogel increased with raising AMPS content. Whereas the increment of GO and increasing the irradiation dose lead to a reduction in the swelling %. The influences of pH, GO percentage, initial dye concentration, the adsorbent dosage, contact time, and temperature on the adsorption of basic blue 3 dye were evaluated and the adsorption capacity was 194.6 mg/g at optimum conditions; pH = 6, GO/PAMPS/PVA composite hydrogels with 5 wt% of GO, initial dye concentration = 200 mg/L, adsorbent dose = 0.1 g, solution volume = 50 mL after 360 min at room temperature (25°C). The adsorption of dye onto the GO/PAMPS/PVA composite hydrogels follows Pseudo-second-order adsorption kinetics, fits the Freundlich adsorption isotherm model.     

Convenient method for preparation of a new absorbent based on biofunctionalized graphene oxide hydrogels using nitrene chemistry and click reaction

A new graphene oxide (GO)-based hydrogel was synthesized through cross-linking of biofunctionalized graphene oxide nanosheets by di-alkyne polyethylene glycol as cross-linking agent. In this respect, nitrene chemistry as a convenient and straightforward protocol was developed for biofunctionalization of GO using an azido-starch as an eco-friendly, biodegradable and cost-effective material. In the next step, 1,3-dipolar cycloaddition chemistry, a green and highly efficient approach was utilized in cross-linking of functionalized GO by PEG through click reaction between remaining azido groups of starch on the surface of GO sheets and terminal alkyne groups of polyethylene glycol. Formation of aziridine and triazole rings during functionalization and cross-linking in this method could evidently improve biological activities of the obtained hydrogel compared to the conventional methods. The antibacterial activity of the new compounds was explored. The synthesized hydrogel showed antibacterial properties against Gram-positive and Gram-negative bacteria due to the presence of triazole rings. Also, the resulting hydrogel exhibited high dye removal efficiency and it can be utilized in water treatment effectively. The adsorption kinetics was analyzed through the effects of adsorption time and the dye concentration on the adsorption capacity. Kinetic data were accurately described by a pseudo-second-order model.     

A novel and simple approach for the synthesis of Fe3O4-graphene composite

High crystalline Fe₃O₄-graphene composite has been successfully synthesized via one-step thermolysis reaction. The results demonstrated that the attachment of iron-organic complex with graphene oxide sheets can facilely lead to magnetic graphene composites with a time-dependent calcination process. The composite was characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The high efficient removal of methylene blue determined that Fe₃O₄-graphene is a promising sorbent material for wastewater treatment.     

低温净水破乳剂的合成及性能研究

为了解决原油乳状液低温情况下难于破乳的问题,合成了一种复配型低温净水破乳剂。ARB-01破乳剂以多胺为起始剂,具有星型结构的聚氧乙烯聚氧丙烯嵌段共聚物。PJN-01絮凝剂采用胺类化合物和卤代环醚进行反应,生成高效阳离子絮凝剂。将上述ARB-01和PJN-01组分进行复配使用,研制出CP903DW,与现场使用的破乳剂相比,破乳效果好,脱水速度快。     

Facile fabrication of graphene oxide-polyethylenimine composite and its application for the Cr(VI) removal

A binary composite consisting of graphene oxide (GO) and polyethylenimine (PEI) was fabricated by a facile physical mixing. Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Zeta potential were used to characterize the prepared graphene oxide-polyethylenimine composite (GOPC). A series of experiments were carried out to investigate the effects of some important parameters, such as molecular weight of PEI, pH, time and temperature, on the adsorption efficiency of GOPC. Due to the high amine density of GOPC, its adsorption for Cr(VI) occurred more easily at lower pH mainly via electrostatic interaction. The adsorption process matched well with the Langmuir isotherm model and the pseudo-second-order kinetic model. The maximum adsorption capacity from the Langmuir model was 370.37 mg/g at pH 2.0 and 45°C for GOPC. Thermodynamic parameters revealed spontaneous and endothermic nature of the Cr(VI) adsorption onto GOPC. The main adsorption mechanism of GOPC toward Cr(VI) was electrostatic interaction. The adsorption-desorption experiments suggested GOPC was easily recycled and its stable adsorption capacity endowed it great potential as an adsorbent of Cr(VI) from wastewater.     

近红外光响应氧化石墨烯/微凝胶复合智能水凝胶

设计合成了一种包含氧化石墨烯（GO）片层、聚（N-异丙基丙烯酰胺）（PNIPAM）微凝胶球体和PNIPAM链段的复合结构水凝胶。通过控制聚合时间得到负载双键且粒径不同的PNIPAM微凝胶,将其作为交联点与N-异丙基丙烯酰胺（NIPAM）聚合,GO作为纳米填料掺入水凝胶体系,GO片层上的含氧基团与NIPAM上的胺基产生氢键物理交联。此方法制备的复合水凝胶同时具有温度敏感和近红外光敏感特性,通过改变GO浓度、微凝胶的合成时间、NIPAM浓度等条件,水凝胶的光敏感性和温度敏感性得到提升。相比于传统PNIPAM水凝胶,此种复合水凝胶能够对光响应,实现非接触式控制形变,且响应速率快、响应程度高,可应用于光控开关等领域。     

镍负载二氧化钛/PEI/石墨烯纳米复合催化剂的制备与研究

首先采用改进的Hummers法制备了氧化石墨烯(GO),再以聚乙烯亚胺(PEI)修饰的氧化石墨烯为载体,并以硫酸钛和氯化镍为前驱体,利用水热法在180 ℃下以PEI为交联剂制得镍负载的TiO2/PEI/石墨烯纳米复合催化剂。通过紫外可见分光光度计(UV-vis)、傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)等测试手段对催化剂进行了表征。结果表明,Ni-TiO2/PEI/RGO纳米复合催化剂中镍负载TiO2纳米粒子与石墨烯能够均匀复合,并具有较小的晶粒尺寸。以对硝基苯酚(4-NP)为降解目标物,考察了该催化剂在NaBH4存在下还原4-NP的催化活性。结果表明,镍负载的TiO2/PEI/石墨烯纳米复合催化剂具有良好的重复催化活性,其降解率为98%,催化剂重复使用10次后,降解率仍能保持90%以上。     

Preparation and characterization of cotton fibers coated with AA-IA hydrogel containing silver/graphene or graphene oxide nanoparticles

This study presents the fabrication and characterization of cotton textile fibers coated with hydrogels containing silver and Graphene or Graphene Oxide nanoparticles using 1-hexyl-3-methyl-imidazolium (HMIMPF6) ionic liquid (IL) as carbon filler dispersant. Acrylic acid/Itaconic acid (AA-IA) hydrogels are synthesized by polymerizing an acrylic acid-itaconic acid aqueous (80/20 v/v) solution and mixed with 2-2-Azobis (2-methylpropionamide) diclorohydrate, and N,N´-methylenbis (acrylamide). Then silver nanoparticles are generated throughout the hydrogel networks using in situ method by incorporating the silver ions and subsequent reduction with sodium borohydride. Then a cotton textile fiber substrate was coated with this hydrogel. Finally, graphene or graphene oxide was added to the textile substrate already impregnated with hydrogel and silver nanoparticles. In order to favor the dispersion of the carbon nano-structures in the system, an IL was used. The influence of these nanocomposite hydrogels on the properties of textile fiber were investigated by infrared spectroscopy (ATR), scanning electron microscopy (SEM), inductively coupled plasma mass spectroscopy (ICP) and antibacterial tests against Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). The effect of each and combined fillers dispersion on antimicrobial properties were determined. Cotton fibers coated with hydrogel containing silver nanoparticles and graphene showed better results when the ionic liquid was used. Graphene showed greater antimicrobial efficiency than graphene oxide. It was proved that the textiles coated with hydrogels containing these fillers had an excellent antibacterial ability and are a good option to be used for medical applications such as wounds and burns dressing.     

超疏水高强度石墨烯油水分离材料的制备及应用

使用较为环保的手段对表面进行修饰,使用氧化石墨烯(GO)对三聚氰胺海绵(MS)进行进一步的表面改性,对超疏水的还原氧化石墨烯/三聚氰胺海绵(RGO-MS)进行制备。使用一些列手段对制备的RGO-MS的结构、形态、组分进行了研究。结果表明,海绵骨架与还原氧化石墨烯表面有十分密切的关系;超疏水的还原氧化石墨烯/三聚氰胺海绵对高密度与低密度的原油都有较好的吸附能力,而且在多次吸附工作后仍然具有百分之九十以上的吸附能力,对油水混合物的分离效率较高。     

Chemically clean synthesis and characterization of graphene oxide‐poly(acrylic acid–sodium styrene sulfonate) composite thermostable elastic gel encapsulating copper nanoparticles for efficient catalytic reduction of 4‐nitrophenol

The thermostable chemically blended elastic poly‐(acrylic acid–sodium‐styrene‐sulfonate–graphene oxide) super‐absorbent hydrogel was synthesized by additive‐free gamma‐radiation induced polymerization followed by crosslinking method. It showed the best swelling ratio in water due to its porous nature. The composite material adsorbed 98 mg/g Cu(II) at room temperature from the aqueous solution of Cu(II) at pH 5 by the chemi‐adsorption of Cu(II) ions at several energetically heterogeneous functional groups. The copper nanoparticles (CuNPs) of size 12 ± 8 nm had been synthesized in situ by chemical reduction of the pre‐adsorbed Cu(II) ions. The functional groups of composite hydrogel served as complexing agent and nano‐reaction sites. Avoiding any pre‐reduction induction time, the inexpensive CuNPs catalytically completely decolorized the aqueous solution of 4‐nitrophenol (4‐NP) within 60 s in the presence of NaBH₄ at a promising calculated rate constant (9.0 × 10^?2/s) ever reported in the literatures. It is in contrast to the commonly noticeable phenomenon for other CuNPs‐based catalysis of 4‐NP. The composite hydrogel matrix helped to retain the catalytic activity of CuNPs and simultaneously it helped in the osmotic inclusion of 4‐NP into the reaction cites. This composite hydrogel synthesized through a chemically clean method could be utilized for efficient conversion of hazardous chemical 4‐NP to industrially important chemical 4‐aminophenol. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46200.     

Hierarchical MnNiCo ternary metal oxide/graphene nanoplatelets composites as high rated electrode material for supercapacitors

For achieving a higher supercapacitor performance, electrode material with high surface area and conductivity such as graphene, graphene nanoplatelets (GNP), and carbon nanotubes along with Transition Metal oxides (TMO) can be used. Herein, the composite of graphene nanoplatelets with ternary metal oxide of manganese, nickel, and cobalt (MNC) is synthesized through a facile cost-effective hydrothermal process and its compositional, morphological, and electrochemical properties are investigated. As-synthesized MNC-GNP composite showed excellent electrochemical properties owing to the high porosity offered by graphene nanoplatelets and synergistic effects produced by individual components of the composite. For comparative studies, ternary oxide MNC was prepared by the same hydrothermal route. The cubic structure of the MNC-GNP composite is confirmed by X-ray diffraction (XRD). Scanning Electron Microscope (SEM) showed distinct hierarchical dendritic structures which showed an increase in density by the addition of graphene nanoplatelets. Electrochemical testing revealed that MNC-GNP exhibited an enhanced specific capacity of 605 mAh g^-1 which is higher compared to MNC which exhibited 243 mAh g^-1 at a current density of 2 mV s^-1. GCD also depicted an increased charge-discharge time in the case of MNC-GNP as compared to its counterpart. MNC-GNP has also shown charge stability up to 99.5 % of capacity retention up to 1000 cycles. Hence, synthesized composite shows to be an effective electrode material for supercapacitors owing to enhanced electrochemical properties.     

Laboratory scale study on rheological behavior,morphological and structural properties of crosslinked polyacrylamide composite hydrogels embedded with date seed powder

Incorporation of biofillers in polymeric hydrogels has continued to receive great attention in recent times because of their excellent properties. In this study, polyacrylamide (PAM) and polyethyleneimine (PEI) were used to develop novel composite hydrogels filled with date seed powder (DSP) via chemical crosslinking technique. Pristine PAM/PEI hydrogel and PAM/PEI‐DSP hydrogels at various DSP loadings were fabricated and subjected to gelation at 40°C for 24 h. The impact of various DSP loadings on the hydrogel samples developed was investigated using hybrid rheometer, SEM, XRD, and FTIR instruments, respectively. Rheological measurements confirmed the viscoelastic responses of the neat PAM/PEI hydrogel and the PAM/PEI‐DSP hydrogels reinforced with various DSP contents (0.8, 2.4, and 4 wt %). The dynamic strain, dynamic frequency and time sweep tests demonstrated that PAM/PEI‐DSP hydrogels were slightly more elastic than the virgin PAM/PEI hydrogel. The SEM characterization revealed the surface micrographs of the neat PAM/PEI hydrogel and the PAM/PEI‐DSP hydrogels at different DSP loadings to be smooth, homogeneous, and dense. Besides, the SEM micrographs supported the incorporation of DSP in the PAM/PEI‐DSP hydrogel samples. XRD analysis showed that the structures of neat PAM/PEI hydrogel and PAM/PEI‐DSP hydrogels filled with various DSP contents were predominantly amorphous while FTIR results confirmed the functional groups and evidence of crosslinking in the neat PAM/PEI hydrogel and the PAM/PEI‐DSP hydrogels embedded with different DSP contents. It is believed that these new hydrogels have huge development potentials and promising future in wastewater treatment and removal of heavy metal ions in aqueous solutions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42110.     

Application of Novel Modified Chitosan Hydrogel Composite for the Efficient Removal of Eriochrome Black T and Methylene Blue Dyes from Aqueous Media

Journal of Inorganic and Organometallic Polymers and Materials - In this paper, chitosan/Fe3O4/graphene oxide hydrogel was synthesized then modified with 2,6-pyridinedicarbonyl dichloride to obtain...     

Co负载TiO2/氧化石墨烯纳米复合材料的水热法合成及光催化性能

首先采用改进的Hummers法制得氧化石墨烯(GO)，再利用氧化石墨烯为基体，硫酸钛和氯化钴为前驱体，并通过修饰石墨烯的聚乙烯亚胺(PEI)为交联剂，采用一步水热法成功合成了三维柱状自组装的钴负载TiO2/氧化石墨烯纳米复合材料(Co@/TiO2/PEI/RGO)。通过紫外-可见吸收光谱法、X射线衍射、透射电子显微镜和X射线光电子能谱对复合材料的结构和光电性能进行了表征。在紫外和可见光照条件下，研究了复合材料的光催化降解亚甲基蓝(MB)的性能。结果表明钴负载TiO2/RGO纳米复合材料具有较高的光催化活性，在60min内降解率为99%，可循环至少10次。     

CuO/graphene composite as anode materials for lithium-ion batteries

CuO/graphene composite is synthesized from CuO and graphene oxide sheets following reduced by hydrazine vapor. As the electrode material for lithium-ion batteries, CuO nanoparticles with sizes of about 30 nm homogeneously locate on graphene sheets, and act as spacers to effectively prevent the agglomeration of graphene sheets, keeping their high active surface. In turn, the graphene sheets with good electrical conductivity server as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during discharge/charge process. The synergetic effect is beneficial for the electrochemical performances of CuO/graphene composite, such as improved initial coulombic efficiency (68.7%) and reversible capacity of 583.5 mAh g⁻¹ with 75.5% retention of the reversible capacity after 50 cycles.     

Synthesis of polyaniline/electrochemically exfoliated graphene composite as counter-electrode in dye-sensitized solar cell

ABSTRACT

Polyaniline (PANI)/graphene composite is a good candidate for the counter-electrode in a Pt-free DSSC. In this study, the electrochemically exfoliated graphene (EEG) from the used-battery graphite rod was produced. DC measurement reveals that EEG has a relatively low sheet resistance of 502.72 Ω/square. EEG suspension in DMF was used as synthesis media of PANI/EEG composite using the direct mixing method. Raman spectra show that the PANI/EEG composite was successfully synthesized as indicated by the presence of their characteristic peaks. Current density-voltage (J-V) measurements show that the power conversion efficiency of PANI/EEG composite better than the PANI-based counter-electrode.     

二氧化钛/氧化石墨烯复合光催化剂的合成

采用水热法,以钛酸四正丁酯及氧化石墨烯（GO）为原料,在水性体系中合成了一系列具有不同GO质量分数的TiO2/GO复合光催化剂。FE-SEM分析结果表明,分散的钛酸四正丁酯以多分子层的形式吸附到氧化石墨烯的表面,最后在水热过程中转化为锐钛型TiO2粒子。当氧化石墨烯的质量分数低于3%时,产物中含有纯TiO2微球及TiO2/GO复合物;当氧化石墨烯质量分数大于5%时,产物为单纯的TiO2/GO复合物。电化学性能测试结果表明,GO复合后,TiO2电极中载流子的传输效率提高。氧化石墨烯复合量为10%时,复合光催化剂显示了对亚甲基蓝最佳的光催化活性。当复合氧化石墨烯转化为石墨烯后,其光催化活性可得到进一步大幅度的提高。     

Enhancement of Pb(II) Adsorption and Antibacterial Performances of Sodium Alginate/Acrylic Acid Composite Hydrogel via Snowflake-like ZnO Modification

ABSTRACT

Hydrogel materials, due to their special three-dimensional network structure that can be used as adsorbents. The hydrogel combined with the inorganic nanomaterials has superior adsorption performance. Herein, we report that a snowflake-like nZnO/SA-co-AA composite hydrogel (NZCH) with a double network structure is synthesized via graft copolymerization of nano zinc oxide (nZnO) with sodium alginate (SA) and acrylic acid (AA). The hydrogel exhibits the adsorption efficiency of 200 mg/g, has a good effect in adsorbing Pb(II). Meanwhile, the hydrogel has an antibacterial activity against Escherichia coli of 99%. It holds broad prospects for obtaining this multifunctional hydrogel in the field of adsorbing Pb(II).     

石墨烯负载二氧化钛复合材料及光催化降解甲基橙

以天然鳞片石墨为原料,用改进的Hummers法氧化制备氧化石墨烯,然后用葡萄糖还原制得石墨稀,再用溶胶一凝胶法复合制备了TiO2／2;墨烯的复合材料。用FI-IR、Raman、AFM、SEMvR）3LTGA对石墨烯和TiO2／2;墨烯复合材料进行了表征,并在紫外光照射条件下对比石墨烯、TiO2、TiO：／2;墨烯复合材料对甲基橙的降解效果。结果表明,在紫外光照射下,TiO2的负载率为35％时,TiO2／2;墨烯复合材料光催化降解甲基橙的催化效率明显大于单纯TiO2及石墨烯,光催化4小时后,脱色率达到85％。TiO2／2;墨烯复合材料不失为一种有潜力的光催化降解染料废水催化材料。