Carboxylated Graphene Oxide Research Articles

Optimization of carboxylated graphene oxide (C-GO) content in polymer matrix: Synthesis, characterization, and application study

Carboxylated graphene oxide (C-GO) embedded in polysulfone (PSF) membrane composites were prepared with different wt. % (i.e., 0.2% M − 1, 0.3% M − 2, 0.4% M − 3, and 0.5% M − 4) using non-solvent induced phase separation (NIPS) method and ultrafiltration assembly was applied for the removal of dye effluents. The optimization of C-GO content into polymer matrix was found influencing factor in determining the composite membranes efficiency and application in various research fields. The membranes were characterized in terms of surface morphology (SEM), crystallinity (XRD), and functional groups identification (FTIR). The water permeability of the developed membranes was analyzed, and it is observed that increasing the content of C-GO in PSF membranes imposed a positive impact on permeation performance. M − 3 was found to be a potential candidate among all the membranes with a maximum water flux of about 183 LMH which is considerably higher as compared to the pristine PSF membrane's water flux (i.e., 27 LMH). Moreover, contact angle measurements of membranes were also checked to assess the hydrophilicity of PSF membranes. The results of contact angle also support the water permeability and efficient correlation was observed as contact angle decreases with increasing the content of C-GO. The minimum contact angle with excellent hydrophilicity was shown by the M − 3 membrane and it was found of about ±58.19° and this value is close to the M − 4 membrane having maximum C-GO content. The photocatalytic performance of the M − 3 membrane was checked under UV-254 nm using methylene blue dye and 97% dye removal was achieved within 220 min of reaction time under neutral pH conditions. The M − 3 membrane having C-GO content of 0.4% was found to be the best membrane with high pure water flux (183 LMH) and efficient dye rejection (82%) capability.

The development of high sensitive alpha-fetoprotein immune-electrochemical detection method using an excellent conductivity 3D-CuFC-C nanocrystals synthesized by solution-grown at room temperature

A novel 3D C-based nano Cu2[Fe(CN)6]-C (C–CuFC) nanocrystals with unusually electrical-conductivity was synthesized based on reduced carboxylated graphene oxide (COOH-rGO) and copper nanoparticles (CuNPs) by using room temperature (RT) K3[Fe(CN)6]-solution growth. During the fabrication of C–CuFC electrode, rGO-COOH enabled the Cu2+ to tunnel the electrons, which contributed to form a 3D petal-liked structure (Flo.-C), meanwhile, the synthetic 3D Flo.-C induced crystal of the electroactive cubic CuFC–C in K3[Fe(CN)6] solution. Another, the [Cu(CN)4]2-, [Fe(CN)6]4- and quinones with high conductivity were produced, and the free Fe2+ and Cu2+ existed on solid (electrode)−liquid (electrolyte) interface also increased the electric signal directly, so this CuFC–C showed amazing electrochemical current, which was 29-folds larger than the current intensity of bare electrode. With attaching on electrode, CuFC–C nanomaterial can significantly improve the electrical conductivity of sensor. Impressively, such 3D-CuFC-C nanocrystals shows excellent anchoring ability toward the AFP-antibodies (Ab) ascribed to the unreduced COOH-group of CuFC–C. Hence, a 3D Ab/CuFC–C/GCE electrochemical immunosensor was constructed based the promising conductivity and biocompatibility. Meanwhile, the Ab/CuFC–C/GCE biosensor exhibited ultra-low detection limit (LOD: 1.40 × 10−8 ng mL−1) and a fast response time (0.4 min). Additionally, the developed biosensor displayed excellent stability and good recovery (92.07%–101.91%) for AFP in human serum. Therefore, this sensing-platform has great potential in rapidly and sensitively detecting biomarkers and the other race targets.

High-performance CO2 separation membranes: comparison of graphene oxide and carboxylated graphene oxide nanofillers

High-performance CO2 separation membranes: comparison of graphene oxide and carboxylated graphene oxide nanofillers

Study on the difference in adsorption performance of graphene oxide and carboxylated graphene oxide for Cu(II), Pb(II) respectively and mechanism analysis

Graphene oxide has been widely studied as a new type of adsorbent due to its strong affinity for heavy metal ions. However, limited by the number of oxygen-containing functional groups on its surface, there are still some defects in the field of heavy metal ion adsorption. In this paper, graphene oxide (GO) was prepared by modified Hummers method, and carboxylated graphene oxide (GO-COOH) was further synthesized by the derivatization reaction of bromoacetic acid with hydroxyl group under strong alkali conditions. The physical and chemical properties of the material were characterized by XRD, SEM, TEM, XPS and FT-IR. Taking copper and lead ion solutions as pollution models, the adsorption behaviors of the two heavy metal ions solutions on GO were investigated through batch adsorption experiments, adsorption kinetic model, adsorption isotherm model and Van't Hoff equation. The experimental results showed that the maximum adsorption capacity of GO for Cu(II) after carboxyl group treatment increased from 55.47 mg/g to 62.02 mg/g, and the maximum adsorption capacity of GO-COOH for Pb(II) increased from 85.17 mg/g to 96.21 mg/g. In this paper, the reasons for the difference in the adsorption capacity of GO for Cu(II) and Pb(II) and the significant enhancement of the adsorption performance of GO-COOH were discussed, and the possible adsorption mechanism was proposed. The research in this paper provides a new way to realize the efficient utilization of graphene oxide materials in the purification process of water environment and the development of modern materials science.

Graphene oxide modification enhances the activity of chitosan against Fusarium graminearum in vitro and in vivo

Fusarium graminearum (F. graminearum), a pathogen for Fusarium head blight (FHB) on wheat, significantly reduces wheat yield and poses potential threats to human food safety. In this study, graphene oxide (GO) modified chitosan (GO-CS composite) was synthesized and its antifungal activity against F. graminearum in vitro and in vivo was evaluated. The 1HNMR and FTIR results revealed the reaction between the carboxyl groups in GO and the amino groups in chitosan (CS). In vitro, the combination of GO and CS resulted in a significant synergistic inhibitory effect on the mycelial growth of F. graminearum relative to single GO or CS. The EC50 value of the GO-CS composite was 14.07 μg/mL, which was much lower than that of GO or CS alone. In vivo, the GO-CS composite significantly reduced the disease incidence and severity compared with single GO or CS, and the control efficacy could reach 60.01 %. Microbial cells might be ultimately damaged when interacting with GO-CS due to various mechanisms such as biological effects and physical barriers. Overall, the combination of GO and CS provides new opportunities for their application in the control of fungi.

Carboxylated graphene oxide nanosheets as efficient electrodes for high-performance supercapacitors.

In the presence of dry ice, a series of graphitic materials with carboxylated edges (ECGs) were synthesized by ball milling graphite for varied times (24, 36, and 46 h). The influence of carboxylation on the physiochemical characteristics and electrochemical performance as effective electrodes for supercapacitors were assessed and compared with pure graphite. Several characterization techniques were employed to investigate into the morphology, texture, microstructure, and modification of the materials. Due to its interconnected micro-mesoporous carbon network, which is vital for fast charge-discharge at high current densities, storing static charges, facilitating electrolyte transport and diffusion, and having excellent rate performance, the ECG-46 electrode among the investigated samples achieved the highest specific capacitance of 223 F g−1 at 0.25 A g−1 current density and an outstanding cycle stability, with capacitance retention of 90.8% for up to 10,000 cycles. Furthermore, the symmetric supercapacitor device based on the ECG-46 showed a high energy density of 19.20 W h kg−1 at 450.00 W kg−1 power density. With these unique features, ball milling of graphitic material in dry ice represents a promising approach to realize porous graphitic material with oxygen functionalities as active electrodes.

Synthesis of Functionalized Carboxylated Graphene Oxide for the Remediation of Pb and Cr Contaminated Water.

With the growing scarcity of water, the remediation of water polluted with heavy metals is the need of hour. The present research work is aimed to address this problem by adsorbing heavy metals ions (Pb (II) and Cr (VI)) on modified graphene oxide having an excess of carboxylic acid groups. For this, graphene oxide (GO) was modified with chloroacetic acid to produce carboxylated graphene oxide (GO-COOH). The successful synthesis of graphene oxide and its modification has been confirmed using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray Diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and Transmission electron microscopy (TEM). The increase in surface area of graphene oxide after treatment with chloroacetic acid characterized by BET indicated its successful modification. A batch experiment was conducted to optimize the different factors affecting adsorption of both heavy metals on GO-COOH. After functionalization, we achieved maximum adsorption capacities of 588.23 mg g−1 and 370.37 mg g−1 for Pb and Cr, respectively, by GO-COOH which were high compared to the previously reported adsorbents of this kind. The Langmuir model (R2 = 0.998) and Pseudo-second-order kinetic model (R2 = 0.999) confirmed the monolayer adsorption of Pb and Cr on GO-COOH and the chemisorption as the dominant process governing adsorption mechanism. The present work shows that the carboxylation of GO can enhance its adsorption capacity efficiently and may be applicable for the treatment of wastewater.

In Vivo Detection of Glutamate in Tomatoes by an Enzyme-Based Electrochemical Biosensor.

The in vivo and on-site detection of key physiology parameters in plants will be of great relevance for precision agriculture and food technology. In this work, a sensitive enzymatic glutamate sensor was successfully developed. To enhance the conductivity and catalytic ability and to fix the glutamate oxidase, Au–Pt nanoparticles were first deposited on screen-printed electrodes, and then carboxylated graphene oxide and carboxylated multiwalled carbon nanotubes were fabricated for the synthesis of the electrode. The detection range of the glutamate sensor is widest (2 μM to 16 mM) up to date, and its detection limit is relatively low (0.14 μM). A number of standard curves were built in the pH range of 3.5–7.5, which can be applied in various plants and fruits. Using this sensor, the glutamate level in tomatoes was determined in vivo. This glutamate sensor has important practical value in precision agriculture. Our strategy also provides a way to establish the detection modes for other biomolecules in plants.

Carboxylated Graphene Oxide as a Nanocarrier for Drug Delivery of Quercetin as an Effective Anticancer Agent

Background:Enhancing the therapeutic profile of hydrophobic drugs using the development of biocompatible drug delivery systems is an urgent need. Many types of research have been conducted on graphene derivatives owing to their unique characteristics. Methods:In this survey, QUER, a natural medicine, was loaded on carboxylated GO, and cytotoxicity assay and the uptake of QUER into prostate cancer cells (PC3) were evaluated.Results:The release behavior of QUER was temperature- and pH-sensitive. Although QUER was loaded with high efficiency, the released rate was low (23.25% at pH 5.5 and 42 °C). The toxicity and intensity of fluorescence in the FREE QUER were higher than the loaded form. Conclusion: High-capacity loading and controlled release of GO QUER can be recognized as a proper candidate in treating cancer.

Enhanced Antibacterial Activity through Silver Nanoparticles Deposited onto Carboxylated Graphene Oxide Surface.

The strong bactericidal action of silver nanoparticles (AgNPs) is usually limited by their degree of aggregation. Deposition of AgNPs onto a graphene oxide (GO) surface to generate GO-Ag hybrids has been shown to be an effective method of controlling these aggregation problems. In this sense, a novel carboxylated graphene oxide–silver nanoparticle (GOCOOH-Ag) material has been synthesized, and their antibacterial and biofilm formation inhibitions have been studied. AgNPs decorating the GOCOOH surface achieved an average size of 6.74 ± 0.25 nm, which was smaller than that of AgNPs deposited onto the GO surface. In addition, better distribution of AgNPs was achieved using carboxylated material. It is important to highlight the main role of the carboxylic groups in the nucleation and growth of the AgNPs that decorate the GO-based material surface. In vitro antibacterial activity and antibiofilm-forming action were tested against Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli). Both GO-Ag and GOCOOH-Ag reduced bacterial growth, analyzed by time–kill curves. However, the minimum inhibitory concentration and the minimum bactericidal concentration of GOCOOH-Ag were lower than those of GO-Ag for all strains studied, indicating that GOCOOH-Ag has better antibacterial activity. In addition, both nanomaterials prevent biofilm formation, with a higher reduction of biofilm mass and cell viability in the presence of GOCOOH-Ag. The carboxylation functionalization in GO-based materials can be applied to improve the bactericidal and antibiofilm-forming action of the AgNPs.

Covalent immobilization of graphene oxide on biomedical grade CoCr alloy by an improved multilayer system assembly via Silane/GO bonding

Improvements in durable lubrication together with minimized wear are essential for obtaining long-term, functioning metallic joint prostheses. To achieve this objective, CoCr surface was functionalized with Graphene Oxide (GO) and characterized by FTIR and XPS. CoCr alloy was subjected to alkalinization in order to generate high hydroxyl content on the surface. FTIR and XPS revealed reactive OH groups, enabling intermediate coupling via (3-aminopropyl) triethoxysilane (APTES), which was cured at 45 °C and 75 °C for 24 h and 30 min, respectively. FTIR revealed cross-linked films (Si–O–Si), inferring condensation and self-assembly of silane layers, while XPS revealed the presence of NH2, enabling chemical binding of GO. Silane-coated CoCr disks were immersed in GO solution at 60 °C for 12h and 24h, respectively. FTIR displayed CC band confirming the assembly of GO on silane-coated CoCr surfaces. XPS revealed three possible surface mechanisms: (1) reaction between primary amines of APTES and epoxy groups of GO; (2) free –OH groups in APTES and carboxyl groups in GO; and (3) reaction between APTES primary amines and –OH from carboxyl groups of GO. Overall, the multilayer system CoCr–OH–Si45-GO24h showed covalent functionalization of metal substrate with GO to a large extension of surface area among all the multilayer systems studied.

Ultrasensitive molecularly imprinted electrochemiluminescence sensor based on highly-conductive rGO-COOH synergically amplify TCPP luminophor signal in aqueous phase system for “switches-controlled” detection of tryptamine

An efficient and innovative molecularly imprinted electrochemiluminescence sensor (MIECLS) based on the reduced carboxylated graphene oxide (rGO-COOH) amplifying aqueous phase meso-tetra(4-carboxyphenyl)porphyrin (TCPP) signal was constructed for “switches-controlled” detection of tryptamine (Tryp). The conductive rGO-COOH uninterruptedly accelerated the high-energy electrons injection into the aqueous co-reaction system of green metal-free TCPP, and more excited state molecules (TCPP*) were generated to obtain excellent ECL signal. Benefiting from the large specific surface area provided by rGO-COOH, molecularly imprinted polymer (MIP) with specific recognition cavities can be firmly electropolymerized on the surface of rGO-COOH/glassy carbon electrode (GCE), which regulated electrons transfer rate to realize “switches-controlled” detection by elution and recombination of Tryp. Under optimal conditions, the MIECLS exhibited a favorable linear relationship with Tryp in the concentration range of 1 × 10−9–1 × 10−4 mol L−1 and the limit of detection (LOD) was 0.25 × 10−9 mol L−1. The MIECLS was used for Tryp detection in actual samples with the satisfactory results (recovery rate, 83.19–91.32%) and consistent with that of HPLC. The dual application of TCPP and MIP/rGO-COOH/GCE can create nicely synergistic effect for the Tryp detection, making a novel avenue to the rapid analysis of other food hazards.

Performance of the illumination dependent electrical and photodiode characteristic of the Al/(GO:PTCDA)/p-Si structures

In this our study, we fabricated an Al/p-Si metal semiconductor (MS) structure with perylenetetra carboxylic dianhydride (PTCDA) and graphene oxide (GO) interface. The morphology of the PTCDA and GO organic semiconductor powder structures were examined by scanning electron microscopy (SEM).The main values such as ideality factors (n), rectification ratios (RR), saturation currents (I0) and barrier heights (Φbo) were extracted from I–V characteristics and discussed in details by thermionic emission (TE) theory in the various illumination conditions. The illumination dependent photodiode and photoresponsitity properties of Al/(GO:PTCDA)/p-type Si photo diode structures were investigated using current–voltage (I–V) characteristics in dark, room light and different light intensities, in the illumination range of 20–100 mW cm−2 by increments of 20 mW cm−2at room temperature (300 K).The photodiodes produced had good rectifying characteristics, however the value of rectifying ratios (RR) dropped as the light power intensity increased. According to the results, the photodiodes had a linear photocurrent (Iph), excellent detectivity and responsivity. Furthermore, the some basic electrical and photovoltaic values such as n, I0, Φbo, Voc, Isc, and Pmaxwere acquired as 5.82, 7.64×10−7A, 0.624 eV, 0.33 V, 2.24×10−5A and 3.41×10−6W under 100 mW/cm2light intensity, respectively. Therefore, the experimental research shown that Al/PTCDA:GO/p-Si photodiode structures can be improved for photodiode applications.

In situ cross‐linking capability of novel amine‐functionalized graphene with epoxy nanocomposites

AbstractIn situ chemical linkage between nanofillers and polymer is challenging, but it is an effective process for enhancing the mechanical and thermal properties of polymer nanocomposites. Herein, novel amine‐functionalized graphene is designed and developed to show the in situ chemical interaction with epoxy matrix. Three different graphene materials, graphene oxide (GO), carboxylic graphene oxide (GOCOOH), and ethylenediamine substituted graphene oxide (GOCONHCH2CH2NH2) is synthesized chemically, and epoxy nanocomposite with different wt% is fabricated. FTIR showed the presence of hydroxyl and amide bond formation, confirmed by 13C‐NMR, where the carboxylic carbon peak of GO at 193 ppm shifted to 184 ppm for GOCONHCH2CH2NH2. Elemental analysis by XPS showed that C: O: N of GO changed from 70:30:0 to 79:13:8 for GOCONHCH2CH2NH2. Three‐point bending studies revealed that maximum flexural strength and modulus for GOCONHCH2CH2NH2 incorporated epoxy polymer composite because of intermolecular chemical bond formation between the epoxy resin and GOCONHCH2CH2NH2. The formation of a chemical bond between GOCONHCH2CH2NH2 and epoxy polymer is confirmed by Raman spectroscopy and XPS analysis. The mechanism of forming an in situ chemical bond between amine‐functionalized graphene and the epoxy polymer is derived based on experimental evidence.

Construction of facilitated mass transfer composite membranes with triple-layer water nanochannel architecture for forward osmosis process using cGO-coated polysulfone separation membrane as the substrate

Forward osmosis (FO) composite membrane with triple-layer water nanochannel architecture was constructed using carboxylated graphene oxide (cGO)-polyamide (PA) composite through interfacial polymerization (IP) to improve membrane permeability.

A probe-free electrochemical immunosensor for methyl jasmonate based on a Cu-MOF-carboxylated graphene oxide platform.

Methyl jasmonate (MeJA) is an important phytohormone which can regulate plant growth and stress tolerance. It is very necessary to develop sensitive and accurate detection methods for MeJA. In this work, a probe-free electrochemical immunosensor for MeJA detection was developed based on a Cu-MOF–carboxylated graphene oxide (COOH-GO) platform. The Cu2+ in the Cu-MOFs was used to provide redox signals, which avoids the application of an external redox probe in the electrolyte solutions as conventional immunosensors. COOH-GO was used to improve the structural stability and provide more sites for binding MeJA antibodies. The linear range of the MeJA immunosensor is from 10 pM to 100 μM, which can cover the whole concentration range of MeJA in most plants. And its detection limit is very low (0.35 pM), and it can detect very low concentrations of MeJA. This immunosensor is simple, low cost, and does not need redox probe solutions for measurements. It shows remarkable potential for on-site application in precision agriculture.

SiRNA Mediated GSK3β Knockdown Targets Insulin Signaling Pathway and Rescues Alzheimer's Disease Pathology: Evidence from In Vitro and In Vivo Studies.

Sporadic Alzheimer's disease (sAD) is a progressive neurodegenerative disorder with dysfunctional insulin signaling and energy metabolism. Emerging evidence suggests impairments in brain insulin responsiveness, glucose utilization, and energy metabolism may be major causes of amyloid precursor protein mishandling. The support for this notion comes from the studies wherein streptozotocin (STZ) induced brain insulin resistance in rodent model resulted in sAD-like neuropathology with cognitive decline. Our previous study showed a compromised insulin signaling pathway, glucose uptake, glucose metabolism, and energy homeostasis in STZ-induced glial-neuronal coculture and in vivo model of sAD. Various components of insulin signaling pathway were examined to understand the metabolic correlation, and GSK3β was selected for gene knockdown strategy to reverse sAD pathology based on the data. In the present study, we have synthesized carboxylated graphene oxide (GO) nanosheets functionalized with PEG and subsequently with polyethylenimine (PEI) to provide attachment sites for GSK3β siRNA. Our results showed that siRNA mediated knockdown of the GSK3β gene reduced expression of amyloid pathway genes (APP and BACE1), which was further confirmed by reduced amyloid beta (Aβ) levels in the in vitro STZ-induced sAD model. GSK3β knockdown also restored insulin signaling, AMPK and Mapk3 pathway by restoring the expression of corresponding candidate genes in these pathways (IR, Glut1/3, Prkaa1/2, Mapk3, BDNF) that reflected improved cellular energy homeostasis, neuronal proliferation, differentiation, maturation, and repair. Behavioral data from Morris water maze (MWM), open field (OF), novel object recognition (NOR), Y maze, and radial arm maze (RAM) tests showed that 0.5 μg nanoformulation (GOc-PP-siRNAGSK3β) intranasally for 7 days improved spatial memory, rescued anxiety like behavior, improved visual and working memory, and rescued exploratory behavior in STZ-induced sAD rats. GSK3β silencing resulted in decreased BACE1 expression and prevented accumulation of Aβ in the cortex and hippocampus. These molecular findings with improved behavioral performances were further correlated with reduced amyloid beta (Aβ) and neurofibrillary tangle (NFTs) formation in the cortex and hippocampus of GOc-PP-siRNAGSK3β administered sAD rats. Therefore, it is conceivable from the present study that nanoparticle-mediated targeting of GSK3β in the sAD appears to be a promising strategy to reverse sAD pathology.

Amelioration of adsorptive efficacy by synergistic assemblage of functionalized graphene oxide with esterified cellulose nanofibers for mitigation of pharmaceutical waste

An effort has been undertaken for valorization of surplus biomass to synthesize sustainable and commercially competitive nanoadsorbents utilizing green synthetic strategies. This study encompasses a pioneering research on the comparative adsorption analysis of different modified forms of graphene oxide (GO) combined with functionalized cellulose nanofibers (CNF) derived from surplus biomass for elimination of noxious drug species from aqueous environment with a comprehensive study for evaluating the effect of loading percentage of functionalized GO. Characteristic assessments of the prepared nanocomposites were performed using FT-IR studies, powder XRD studies, FESEM analysis, EDS analysis and BET studies. The prepared nanohybrids were evaluated for their adsorptive performance for elimination of ciprofloxacin and ofloxacin and their performance was optimized in terms of adsorbent loading, pH and initial drug concentration. Further, investigation of adsorbent properties and the adsorption process was undertaken by studying different kinetic and isotherm models of adsorption. The adsorption potential of functionalized CNF was substantially ameliorated through its facile assemblage with functionalized GO. The experimental outcomes revealed that 20 wt% loading of carboxylated graphene oxide within the perforated surface of esterified cellulose nanofibres exhibited best adsorption performance with maximum removal capacity of 45.04 mg g−1 and 85.30 mg g−1 for ciprofloxacin and ofloxacin, respectively. The outstanding regenerability and reusability of nanocomposites present tremendous potential for development of inexpensive and sustainable sorbent materials for managing pharmaceutical pollution. Literature presents scarce data and insufficient number of reports which thoroughly compares the role of differently functionalized GO to potentiate the adsorptive performance of biomass based nanocellulose and its broad application prospects in wastewater remediation. This marks the novelty of the present investigation.

DFT assisted study on activation of surface acidic –COOH debris in graphene oxide supported catalyst for benzyl alcohol oxidation

This study is aimed to elucidate the deep intuitive understanding of whether carboxyl groups of graphene oxide (GO) are worth modifying for the selective oxidation of benzyl alcohol (BzA) to benzaldehyde (BzH). In this work, for the first time, Cu-salen complex (Where Salen = N,N’-bis(4-hydroxysalicylaldehyde)ethylenediamine) was grafted on chloro- modified GO nanosheets forming a heterogeneous catalyst (Cu-f-GO). First principles-based density functional theory (DFT) has been performed to inspect structural and electronic properties, binding mechanism of SOCl2 with each available functional group of GO. Besides, other parameters like HOMO, LUMO, energy bandgap (Eg), adsorption energy (Ead), electronegativity (χ), chemical potential (μ), and global electrophilicity were also calculated. The catalytic results show that the as-prepared catalyst demonstrated petite performance. This poor performance might be due to lesser acidic sites available on the surface of the catalyst. Hence, it was decided to substantiate the hypothesis, we have conducted the catalytic reaction using a few drops of concentrated H2SO4 as a precursor. The use of precursor had resulted in optimal activity with 100% conversion and 98.64% selectivity to BzH within 1 h.

Highly Efficient Removal for Methylene Blue and Cu2+ onto UiO-66 Metal-Organic Framework/Carboxylated Graphene Oxide-Incorporated Sodium Alginate Beads.

Herein, we report a new metal–organic framework (MOF)-based composite beads adsorbent made via incorporating UiO-66 MOF, carboxylated graphene oxide (GOCOOH) into sodium alginate for efficient removal of methylene blue dye, and Cu2+ ions. The successful fabrication of the synthesized UiO-66/GOCOOH@SA composite beads was confirmed by means of X-ray diffraction, Fourier transform infrared, scanning electron microscopy, zeta potential, X-ray photoelectron spectroscopy analysis, and thermogravimetric analysis and BET measurement. The incorporation of both UiO-66 and GOCOOH into SA beads greatly increased their adsorption efficiency for the removal of both MB and Cu2+ with maximum adsorption capacities of 490.72 and 343.49 mg/g, respectively. The removal process of both MB and Cu2+ follows the pseudo-second-order model and Freundlich isotherm model. A plausible adsorption mechanism was discussed in detail. Regeneration tests clarified that the removal efficiencies toward both MB and Cu2+ remained higher than 87% after five cycles. These results reveal the potentiality of UiO-66/GOCOOH@SA beads as an excellent adsorbent.