Graphene-polymer composite: extraction of polycyclic aromatic hydrocarbons from samples by stir rod sorptive extraction

Advances and Applications of Hybrid Graphene-Based Materials as Sorbents for Solid Phase Microextraction Techniques

The advancement of traditional sample preparation techniques has brought about miniaturization systems designed to scale down conventional methods and advocate for environmentally friendly analytical approaches. Although often referred to as green analytical strategies, the effectiveness of these methods is intricately linked to the properties of the sorbent utilized. Moreover, to fully embrace implementing these methods, it is crucial to innovate and develop new sorbent or solid phases that enhance the adaptability of miniaturized techniques across various matrices and analytes. Graphene-based materials exhibit remarkable versatility and modification potential, making them ideal sorbents for miniaturized strategies due to their high surface area and functional groups. Their notable adsorption capability and alignment with green synthesis approaches, such as bio-based graphene materials, enable the use of less sorbent and the creation of biodegradable materials, enhancing their eco-friendly aspects towards green analytical practices. Therefore, this study provides an overview of different types of hybrid graphene-based materials as well as their applications in crucial miniaturized techniques, focusing on offline methodologies such as stir bar sorptive extraction (SBSE), microextraction by packed sorbent (MEPS), pipette-tip solid-phase extraction (PT-SPE), disposable pipette extraction (DPX), dispersive micro-solid-phase extraction (d-µ-SPE), and magnetic solid-phase extraction (MSPE).

Preparation of COF-coated nickel foam adsorbents for dispersive solid-phase extraction of 16 polycyclic aromatic hydrocarbons from Chinese herbal medicines

Covalent organic framework coated nickel foam (NF@COF) was prepared as a sorbent for the dispersive solid phase extraction (DSPE) of polycyclic aromatic hydrocarbons (PAHs) from Chinese herbal medicines (CHMs) prior to their determination by gas chromatography-mass spectrometry (GC-MS). The structure and morphology of the as-synthesized NF@COF were characterized by different techniques. Various key parameters affecting the performance of the DSPE method, including the amount of sorbent, desorption solvent, desorption volume and time, extraction time, and sample volume, were investigated. Under the optimized conditions, NF@COF combined with GC-MS was successfully applied to the determination of 16 PAHs in CHMs. The method showed wide linearity (20-2000 ng mL-1), low limits of determination (0.3-2.7 ng mL-1), and high recoveries (78.0-124%). These results revealed that NF@COF has the potential for efficient extraction of PAHs from complex samples.

Application of an in-house packed octadecylsilica-functionalized graphene oxide column for capillary liquid chromatography analysis of hormones in urine samples

Graphene oxide-based LC stationary phases were developed and applied for separating hormones from urine using capillaryLC-MS/MS. Using two analytical approaches - direct injection and column-switching arrangement - it was possible to evaluate the chromatographic parameters and perform tests on the raw biological fluid. Two stationary phases (SPs) were produced, varying the amino silica support particle diameter (Si, 5, and 10 μm). Graphene oxide was covalently bonded to the surface of Si particles, and this material was functionalized by the insertion of octadecylsilica groups, generating the SiGO-C18. Infra-red spectroscopy assays revealed that both steps were successful - supporting GO onto Si and further C18 customization. Scanning electron microscopy showed spherical geometries with minor irregularities and narrow particle size distribution for the produced SPs. The GO-coating rate was higher on the Si particles of 10 μm. As a result, the 10 μm produced column reported better resolution, efficiency, and peak capacity. Therefore, this SiGO-C18 capillary column (100 mm × 0.32 mm i.d., 10 μm dp) was applied successfully in a column-switching method to separate hormones in urine. Linearity (R2 above 0.99), quantification limits (between 1.0 and 5 μg/L), and other figures of merit of the method were determined. It is worth mentioning that the SiGO-C18 capillaryLC column performed adequately, separating the target compounds in less than 6 min. We hope this work could significantly contribute to shedding some light on graphene-based materials as a promising class of stationary phase for miniaturized liquid chromatography.

Magnetic covalent organic framework nanocomposites as a new adsorbent for the determination of polycyclic aromatic hydrocarbons in water and food samples

A magnetic covalent organic framework nanocomposite (Fe₃O₄@COF(Tp-NDA)) was synthesized via a solvothermal method, used as a magnetic adsorbent for the extraction of polycyclic aromatic hydrocarbons (PAHs) from lake water, tea, coffee, and fried chicken, and detected using a high performance liquid chromatography-ultraviolet detector. The synthesized magnetic adsorbent was characterized via transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption-desorption isotherm analysis and vibrating sample magnetometry. Parameters that affected the extraction conditions and desorption conditions were optimized. Adsorption equilibrium could be attained within 3 min. The prepared magnetic material could be reused 10 times. The limits of detection and quantification were 0.05-0.25 μg L^-1 and 0.17-0.83 μg L^-1, respectively. The recovery was 74.6-101.8% with a relative standard deviation of below 4.2%. The method was successfully used to detect PAHs in various samples.

Graphene-nucleic acid biointerface-engineered biosensors with tunable dynamic range

Programmed biosensors with tunable quantification range and sensitivity would greatly broaden their application in medical diagnosis, food safety and environmental analysis. Herein, we proposed a graphene-nucleic acid biointerface-engineered biosensor, allowing target molecules to be detected with adjustable dynamic ranges and sensitivities. The biosensors were programmed by simply tuning the poly A tail of aptamer probes. The tuning of the poly A tail would allow the interaction between aptamer probes and graphene oxide (GO) to be modulated, in turn programing the competitive binding processes of aptamer probes to target molecules and GO. The biosensors, termed affinity-tunable aptasensors (atAptasensors) could be easily tuned with different dynamic ranges by using aptamer probes with different tail lengths, and the dynamic range could be extended to be over 3 orders by a combined use of multiple aptamer probes. Remarkably, the specificity of aptamer probes could be increased by increasing the interaction between aptamer probes and GO. Reliability of atAptasensor for ATP detection was tested in serum and milk samples, and we also applied atAptasensor for culture-independent analysis of microorganism pollution.

Graphene oxide-iron modified clinoptilolite based composites for adsorption of arsenate and optimization using response surface methodology

In this study, graphene oxide and composites of graphene oxide-iron modified clinoptilolite were synthesized and used for arsenate removal from aqueous solution. All adsorbents were characterized using X-ray diffraction and specific surface area analysis. The specific surface areas of composites were found to be less than the iron modified clinoptilolite. The time required to reach equilibrium was determined as 3 hours for all adsorbents. The Box-Behnken statistical experiment design method was used to determine the effects of initial arsenate concentration, pH and the amount of adsorbent on the percent arsenate removal. Graphene oxide was not as effective as composites for arsenate adsorption from water. Arsenate adsorption on composites was showed good compatibility with the Freundlich isotherm. The maximum arsenate uptake was realized at pH 4 for graphene oxide and at pH 7 for composites. The maximum adsorption capacities obtained at the optimum points determined by using the Box-Behnken design method were calculated as 39.49, 117.98 and 124.64 µg.g^-1 for graphene oxide and composites, respectively.

The Current Role of Graphene-Based Nanomaterials in the Sample Preparation Arena

Since its discovery in 2004 by Novoselov et al., graphene has attracted increasing attention in the scientific community due to its excellent physical and chemical properties, such as thermal/mechanical resistance, electronic stability, high Young's modulus, and fast mobility of charged atoms. In addition, other remarkable characteristics support its use in analytical chemistry, especially as sorbent. For these reasons, graphene-based materials (GBMs) have been used as a promising material in sample preparation. Graphene and graphene oxide, owing to their excellent physical and chemical properties as a large surface area, good mechanical strength, thermal stability, and delocalized π-electrons, are ideal sorbents, especially for molecules containing aromatic rings. They have been used in several sample preparation techniques such as solid-phase extraction (SPE), stir bar sorptive extraction (SBSE), magnetic solid-phase extraction (MSPE), as well as in miniaturized modes as solid-phase microextraction (SPME) in their different configurations. However, the reduced size and weight of graphene sheets can limit their use since they commonly aggregate to each other, causing clogging in high-pressure extractive devices. One way to overcome it and other drawbacks consists of covalently attaching the graphene sheets to support materials (e.g., silica, polymers, and magnetically modified supports). Also, graphene-based materials can be further chemically modified to favor some interactions with specific analytes, resulting in more efficient hybrid sorbents with higher selectivity for specific chemical classes. As a result of this wide variety of graphene-based sorbents, several studies have shown the current potential of applying GBMs in different fields such as food, biological, pharmaceutical, and environmental applications. Within such a context, this review will focus on the last five years of achievements in graphene-based materials for sample preparation techniques highlighting their synthesis, chemical structure, and potential application for the extraction of target analytes in different complex matrices.

Recent Advances in the Extraction of Polycyclic Aromatic Hydrocarbons from Environmental Samples

Polycyclic aromatic hydrocarbons (PAHs) comprise a group of chemical compounds consisting of two or more fused benzene rings. PAHs exhibit hydrophobicity and low water solubility, while some of their members are toxic substances resistant to degradation. Due to their low levels in environmental matrices, a preconcentration step is usually required for their determination. Nowadays, there is a wide variety of sample preparation techniques, including micro-extraction techniques (e.g., solid-phase microextraction and liquid phase microextraction) and miniaturized extraction techniques (e.g., dispersive solid-phase extraction, magnetic solid-phase extraction, stir bar sorptive extraction, fabric phase sorptive extraction etc.). Compared to the conventional sample preparation techniques, these novel techniques show some benefits, including reduced organic solvent consumption, while they are time and cost efficient. A plethora of adsorbents, such as metal-organic frameworks, carbon-based materials and molecularly imprinted polymers, have been successfully coupled with a wide variety of extraction techniques. This review focuses on the recent advances in the extraction techniques of PAHs from environmental matrices, utilizing novel sample preparation approaches and adsorbents.

Preparation and characterization of magnetic nanomaterial and its application for removal of polycyclic aromatic hydrocarbons

Fe₃O₄@polyaniline, a Fe₃O₄-based magnetic core-shell material, was synthesized and its morphology and microstructure were characterized with transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometry. Polyaniline was modified onto the surface of Fe₃O₄ nanoparticles by a self-assembly method based on a two-step oxidative polymerization method. The new materials exhibited good adsorption to polycyclic aromatic hydrocarbons such as fluoranthene, pyrene and benzo[a]pyrene from environmental water samples due to the high affinities of polyaromatic hydrocarbons to polyaniline via π-π and van der Waals interactions. The experimental results indicate that the adsorption of polyaromatic hydrocarbons follows pseudo-second order kinetics and the adsorption isotherms conform to a Langmuir isotherm model. The thermodynamic parameters for polyaromatic hydrocarbons indicate that the adsorption process is spontaneous and endothermic in nature, but adsorption occurs via non-covalent interactions. This study indicated that the Fe₃O₄@polyaniline hybrid core-shell structure was proved to be a good adsorbent for polyaromatic hydrocarbons while exhibiting simple preparation, easy separation, low cost, high reusability and great potential applicability for removal of polyaromatic hydrocarbons from water.

Synthesis of fly ash based zeolite-reduced graphene oxide composite and its evaluation as an adsorbent for arsenic removal

A zeolite-reduced graphene oxide (ZrGO) based composite was synthesized to remove arsenic from water. To make a low-cost adsorbent, zeolite was synthesized using an inexpensive waste material; fly ash, which was further used to produce the ZrGO composite. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Raman spectra were used to characterize the morphology and surface composition of the synthesized materials. Synthesized materials: zeolite, rGO and ZrGO were evaluated as an adsorbent to remove arsenic from water. The results indicated that all three were able to adsorb arsenic from water but the removal efficiency of ZrGO was the best as it was able to bring down the arsenic concentration within the WHO permissible limits. The maximum adsorption capacity for 100 μg/L of initial arsenic concentration was found to be 49.23 μg/g. Results indicate that pseudo second order kinetics describes the arsenic adsorption on ZrGO. Adsorption isotherm study for ZrGO shows best fit for Redlich-Peterson model of adsorption.

Reduced graphene oxide as an efficient sorbent in microextraction by packed sorbent: Determination of local anesthetics in human plasma and saliva samples utilizing liquid chromatography-tandem mass spectrometry

Herein, reduced graphene oxide (RGO) has been utilized as an efficient sorbent in microextraction by packed sorbent (MEPS). The combination of MEPS and liquid chromatography-tandem mass spectrometry has been used to develop a method for the extraction and determination of three local anesthetics (i.e. lidocaine, prilocaine, and ropivacaine) in human plasma and saliva samples. The results showed that the utilization of RGO in MEPS could minimize the matrix effect so that no interfering peaks at the retention times of the analytes or internal standard was observed. The high extraction efficiency of this method was approved by mean recoveries of 97.26-106.83% and 95.21-105.83% for the studied analytes in plasma and saliva samples, respectively. Intra- and inter-day accuracies and precisions for all analytes were in good accordance with the international regulations. The accuracy values (as percentage deviation from the nominal value) of the quality control samples were between -2.1 to 13.9 for lidocaine, -4.2 to 11.0 for prilocaine and between -4.5 to -2.4 for ropivacaine in plasma samples while the values were ranged from -4.6 to 1.6 for lidocaine, from -4.2 to 15.5 for prilocaine and from -3.3 to -2.3 for ropivacaine in human saliva samples. Lower and upper limit of quantification (LLOQ, ULOQ) were set at 5 and 2000 nmol L^-1 for all of the studied drugs. The correlation coefficients values were ≥0.995. The limit of detection values were obtained 4 nmol L^-1 for lidocaine and prilocaine, and 2 nmol L^-1 for ropivacaine.

Three-dimensional ionic liquid-ferrite functionalized graphene oxide nanocomposite for pipette-tip solid phase extraction of 16 polycyclic aromatic hydrocarbons in human blood sample

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitously found in the environment and have been proved to be prospectively associated with the risk of cancer. In this study, a simple method based on pipette-tip solid phase extraction (PT-SPE) and gas chromatography-mass spectrometry (GC-MS) has been firstly developed for the determination of 16 PAHs in human whole blood. Three-dimensional ionic liquid-ferrite functionalized graphene oxide nanocomposite (3D-IL-Fe₃O₄-GO) was used as sorbent in PT-SPE. Compared with conventional SPE method, the PT-SPE method was solvent-saving (1.0 mL), reusable (at least 10 times) and required less blood sample (200 μL). Affecting parameters on extraction efficiency were investigated and optimized. Under the optimized conditions, a good linearity was obtained and the recoveries of 16 PAHs at three spiked levels ranged from 85.0% to 115%. The limits of quantification (LOQs) were in the range of 0.007-0.013 μg/L. Furthermore, the developed method was successfully applied to the analysis of 16 PAHs in 14 human blood samples. The results showed that the predominant PAHs in human whole blood was low-molecular-weight PAHs, with the rank order phenanthrene (PHE)> naphthalene (NAP)> fluorene (FLU)> fluoranthene (FLT)> pyrene (PYR). Because of its simplicity, accuracy and reliability, the PT-SPE method combined with GC-MS demonstrated the applicability for clinical analysis and provided more information for PAHs exposure studies.

Raman spectroscopy of graphene-based materials and its applications in related devices

Graphene-based materials exhibit remarkable electronic, optical, and mechanical properties, which has resulted in both high scientific interest and huge potential for a variety of applications. Furthermore, the family of graphene-based materials is growing because of developments in preparation methods. Raman spectroscopy is a versatile tool to identify and characterize the chemical and physical properties of these materials, both at the laboratory and mass-production scale. This technique is so important that most of the papers published concerning these materials contain at least one Raman spectrum. Thus, here, we systematically review the developments in Raman spectroscopy of graphene-based materials from both fundamental research and practical (i.e., device applications) perspectives. We describe the essential Raman scattering processes of the entire first- and second-order modes in intrinsic graphene. Furthermore, the shear, layer-breathing, G and 2D modes of multilayer graphene with different stacking orders are discussed. Techniques to determine the number of graphene layers, to probe resonance Raman spectra of monolayer and multilayer graphenes and to obtain Raman images of graphene-based materials are also presented. The extensive capabilities of Raman spectroscopy for the investigation of the fundamental properties of graphene under external perturbations are described, which have also been extended to other graphene-based materials, such as graphene quantum dots, carbon dots, graphene oxide, nanoribbons, chemical vapor deposition-grown and SiC epitaxially grown graphene flakes, composites, and graphene-based van der Waals heterostructures. These fundamental properties have been used to probe the states, effects, and mechanisms of graphene materials present in the related heterostructures and devices. We hope that this review will be beneficial in all the aspects of graphene investigations, from basic research to material synthesis and device applications.

In Situ Synthesis of a Magnetic Graphene Platform for the Extraction of Benzimidazoles from Food Samples and Analysis by High-Performance Liquid Chromatography

A novel method was proposed for the determination of five benzimidazoles (oxfendazole, mebendazole, flubendazole, albendazole, and fenbendazole) using magnetic graphene (G-Fe3O4). G-Fe3O4 was synthesized via in situ chemical coprecipitation. The properties of G-Fe3O4 were characterized by various instrumental methods. G-Fe3O4 exhibited a great adsorption ability and good stability towards analytes. Various experimental parameters that might affect the extraction efficiency such as the amount of G-Fe3O4, extraction solvent, extraction time, and desorption conditions were evaluated. Under the optimized conditions, a method based on G-Fe3O4 magnetic solid-phase extraction coupled with high-performance liquid chromatography was developed. A good linear response was observed in the concentration range of 0.100-100 μg/L for the five benzimidazoles, with correlation coefficients ranging from 0.9966 to 0.9998. The limits of detection (S/N = 3) of the method were between 17.2 and 32.3 ng/L. Trace benzimidazoles in chicken, chicken blood, and chicken liver samples were determined and the concentrations of oxfendazole, mebendazole, flubendazole, and fenbendazole in these samples were 13.0-20.2, 1.62-4.64, 1.94-6.42, and 0.292-1.04 ng/g, respectively. The recovery ranged from 83.0% to 115%, and the relative standard deviations were less than 7.9%. The proposed method was sensitive, reliable, and convenient for the analysis of trace benzimidazoles in food samples.

Linear Graphene Nanocomposite Synthesis and an Analytical Application for the Amino Acid Detection of Camellia nitidissima Chi Seeds

Husk derived amino modified linear graphene nanocomposites (aLGN) with a diameter range of 80-300 nm and a length range of 100-300 μm were prepared by a modified Hummers method, ammonia treatment, NaBH₄ reduction and phenylalanine induced assembly processes, etc. The resulting composites were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), scanning electron microscopy (SEM), biological microscope (BM), and X-ray diffraction spectroscopy (XRD), etc. Investigations found that the aLGN can serve as the novel coating of stir bar sorptive extraction (SBSE) technology. By combing this technology with gas chromatography-mass spectrometry (GC-MS), the combined SBSE/GC-MS technology with an aLGN coating can detect seventeen kinds of amino acids of Camellia nitidissima Chi seeds, including Ala, Gly, Thr, Ser, Val, Leu, Ile, Cys, Pro, Met, Asp, Phe, Glu, Lys, Tyr, His, and Arg. Compared to a conventional polydimethylsiloxane (PDMS) coating, an aLGN coating for SBSE exhibited a better thermal desorption performance, better analytes fragmentation depressing efficiencies, higher peak intensities, and superior amino acid discrimination, leading to a practicable and highly distinguishable method for the variable amino acid detection of Camellia nitidissima Chi seeds.

Fe3O4/Reduced Graphene Oxide Nanocomposite: Synthesis and Its Application for Toxic Metal Ion Removal

The synthesis of reduced graphene oxide modified by magnetic iron oxide (Fe3O4/rGO) and its application for heavy metals removal were demonstrated. The obtained samples were characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and magnetic measurement. The results showed that the obtained graphene oxide (GO) contains a small part of initial graphite as well as reduced oxide graphene. GO exhibits very high surface area in comparison with initial graphite. The morphology of Fe3O4/rGO consists of very fine spherical iron nanooxide particles in nanoscale. The formal kinetics and adsorption isotherms of As(V), Ni(II), and Pb(II) over obtained Fe3O4/rGO have been investigated. Fe3O4/rGO exhibits excellent heavy metal ions adsorption indicating that it is a potential adsorbent for water sources contaminated by heavy metals.

Preparation of magnetic nanographene sorbent for extraction and quantification of targeted PPCPs in environmental water samples

Nano MGO provides the advantages of large surface area and reusability property for enrichment of selected PPCPs.

Magnetic graphene as modified quick, easy, cheap, effective, rugged and safe adsorbent for the determination of organochlorine pesticide residues in tobacco

In this study, magnetic graphene was used as modified quick, easy, cheap, effective, rugged and safe (QuEChERS) adsorbent for the determination of organochlorine pesticide (OCPs) residues in tobacco. To achieve the optimum conditions of modified QuEChERS procedure toward target analytes, several parameters affecting the clean-up efficiency including the amount of the adsorbent and clean-up time were investigated. Under the optimized conditions, a method for the determination of 26 OCPs residues in tobacco was established by coupling the modified QuEChERS procedure to on-line gel permeation chromatography-gas chromatography-tandem mass spectrometry (on-line GPC-GC-MS(2)). The limits of detection of proposed method for 26 OCPs residues ranged from 0.01275 to 3.150ng/g. And good linearities of the proposed method were obtained with coefficients of determination (R(2)) greater than 0.9985 for all target analytes. Good reproducibility of method was obtained as intra- and inter-day precisions, the relative standard deviations were less than 11.1 and 15.0%, respectively. The apparent recoveries were in the range of 64-126% at different concentrations for real samples. Compared with the reported methods for the determination of OCPs residues in tobacco, the proposed method has the advantages of simple to operate, low cost and high clean-up ability. Finally, the method was successfully applied to the analysis of OCPs residues in real samples.

Spectrophotometric determination of basic fuchsin from various water samples after vortex assisted solid phase extraction using reduced graphene oxide as an adsorbent

In this study, a fast and simple vortex assisted solid phase extraction method was developed for the separation/preconcentration of basic fuchsin in various water samples. The determination of basic fuchsin was carried out at a wavelength of 554 nm by spectrophotometry. Reduced graphene oxide which was used as a solid phase extractor was synthesized and characterized by X-ray diffraction, scanning electron microscopy and the Brunauer, Emmett and Teller. The optimum conditions are as follows: pH 2, contact times for adsorption and elution of 30 s and 90 s, respectively, 10 mg adsorbent, and eluent (ethanol) volume of 1 mL. The effects of some interfering ions and dyes were investigated. The method was linear in the concentration range of 50-250 μg L(-1). The adsorption capacity was 34.1 mg g(-1). The preconcentration factor, limit of detection and precision (RSD, %) of the method were found to be 400, 0.07 μg L(-1) and 1.2%, respectively. The described method was validated by analyzing basic fuchsin spiked certified reference material (SPS-WW1 Batch 114-Wastewater) and spiked real water samples.

PAMAM dendrimers and graphene: materials for removing aromatic contaminants from water

We present results from experiments and atomistic molecular dynamics simulations on the remediation of naphthalene by polyamidoamine (PAMAM) dendrimers and graphene oxide (GrO). Specifically, we investigate 3rd-6th generation (G3-G6) PAMAM dendrimers and GrO with different levels of oxidation. The work is motivated by the potential applications of these emerging nanomaterials in removing polycyclic aromatic hydrocarbon contaminants from water. Our experimental results indicate that GrO outperforms dendrimers in removing naphthalene from water. Molecular dynamics simulations suggest that the prominent factors driving naphthalene association to these seemingly disparate materials are similar. Interestingly, we find that cooperative interactions between the naphthalene molecules play a significant role in enhancing their association to the dendrimers and GrO. Our findings highlight that while selection of appropriate materials is important, the interactions between the contaminants themselves can also be important in governing the effectiveness of a given material. The combined use of experiments and molecular dynamics simulations allows us to comment on the possible factors resulting in better performance of GrO in removing polyaromatic contaminants from water.

Graphene-enhanced visible-light photocatalysis of large-sized CdS particles for wastewater treatment

The hybrid composites of graphene decorated by large-sized CdS particles (G/M-CdS) were prepared by a one-pot solvothermal route in which the reduction of graphite oxide into graphene was accompanied by the generation of microsized CdS particles. The structure and composition of the obtained nanocomposites were studied by means of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The CdS particles with the average sizes of approximately 640 nm were formed on graphene sheets. The as-prepared composite was used as adsorbent to remove dye from wastewater using the organic dye Rhodamine B as the adsorbate. The G/M-CdS composite reveals a high photodegradation rate under visible light irradiation. Our results demonstrate that the G/M-CdS is very promising for removing organic dyes from wastewater.