Introduction

Mesoporous materials are those formed by pores with a diameter between 20 and 500 Å, according to IUPAC (El-Sharkawy et al. 2007; Pizarro et al. 2015). However, due to the limitation of analytical techniques of that time, the authors were not able to recognize the remarkable features of its products. In 1992, the introduction of micellar aggregates as structural driver agents enabled the synthesis of a new family of mesoporous silica and aluminosilicate compounds, named as M41S. The M41S family of materials consists of three basic members: mobil composition of matter no. 41 (MCM-41) having hexagonal phase, MCM-48 having cubic phase, and MCM-50 material of lamellar phase with poor stability (Vartuli et al. 1994). The porous materials usually present high thermal, hydrothermal, and mechanical stability. Moreover, these materials have a wide application as catalysts and adsorbents, mainly due to its porosity associated with high surface area (Pal and Bhaumik 2013).

The molecular sieve MCM-41 is one of the most studied porous materials. This silica has an arrangement of hexagonal channel of unidirectional, uniform, and not interconnected pores. This material presents some interesting features to adsorptive and catalytic applications, such as (i) well-defined pores with a narrow size distribution (between 1.5 and 10 nm), (ii) possibility of adjusting the pore size, (iii) large pore volume (more than 1 cm3), (iv) high surface area (700–1500 m2 g−1), (v) high density of internal silanol groups (40–60 %) with passive surface for modification, and (vi) good thermal, hydrothermal, mechanical, and acidity stability (Li et al. 2015; Qin et al. 2015). Furthermore, this material can be prepared from a variety of experimental conditions by varying pH, concentration, composition, temperature, and synthesis time.

Different mesoporous materials have been synthesized by the sol-gel method. Some works show (Kresge et al. 1992; Putz et al. 2015) that it is possible to obtain homogeneous materials with great purity at low temperatures using driver agents. The role of surfactant is critical to the formation of the M41S materials. When in aqueous solution, these drivers form micelle agents, around which occurs the condensation of the inorganic precursor. For this, it is necessary that the surfactant molecules be in a sufficient concentration to form a liquid crystal structure. Loads of this surfactant added is balanced by inorganic anions of silicates. Finally, the driver is removed by calcination resulting in a mesoporous material with high specific area (Voss 1999).

The degradation of effluents from the dyeing process is one of the main problems of the textile industry, not only because the criteria for color removal in effluents on the aquatic environment are increasingly demanding but also because their removal is essential for the water reuse in the industrial process.

Another important class of contaminants is that from petroleum-derived liquid fuels such as nitrogenous contaminants. Quinoline is a major nitrogenous organic contaminants present in the oil and its derivatives. The presence of nitrogen compounds adversely influences the stability of fuel and increase water retention even further; its combustion produces harmful air pollutants and precursor species of acid rain. Thus, the removal of these contaminants has remarkable economic and environmental relevance (Mambrini et al. 2013).

Several waste treatment techniques have been developed, such as absorption and filtration (Gad and El-Sayed 2009), biological degradation (Paździor et al. 2009), and advanced oxidation processes (AOPs) (Rahim Pouran et al. 2015). AOPs are one of the most promising technologies to degrade aromatic organic compounds with high molecular stability. The AOPs are physico-chemical processes based on the in situ generation of intermediate species able to promote the oxidation and/or mineralization of toxic organic compounds. Among the AOPs, Fenton-like reactions are the most promising. The Fenton mechanism is based on the generation of hydroxyl radical (•OH) from hydrogen peroxide (H2O2), catalyzed by iron(II) ions, and has been widely explored in the oxidation of organic compounds, especially textile dyes and contaminants from liquid fuels (Borràs et al. 2013; Martins et al. 2015; Rahim Pouran et al. 2015; Teixeira et al. 2012) (Fig. 1).

Fig. 1
figure 1

Schematic representation of Fenton process catalyzed by metal nuclei on MCM-41

Full size image

As far as we know, this is the first time that materials combining MCM-41 matrix, Fe supported on their surface and partial carbon coating are applied in adsorption and oxidation of quinoline and/or organic dyes.

Experimental

Synthesis of MCM-41

The synthesis of MCM-41 was based on a modification of the synthesis described by Grün et al. (Grün et al. 1999), in which the cetyltrimethylammonium bromide (CTAB) was used as surfactant, tetraethylorthosilicate (TEOS) as silica source, sodium hydroxide (NaOH) as catalyst, and deionized water as solvent. These reactants were added in accordance with the following molar ratio: 0.12 CTAB/1 TEOS/0.6 NaOH/100 H2O.

The synthesis involved the following steps: (a) dissolution of the CTAB in aqueous NaOH (1 mol L−1); (b) adding the TEOS under stirring at room temperature; (c) washing the resulting material with milli-Q water; (d) drying the solid (MCM-41 precursor) for 12 h at 60 °C; (e) calcination of this precursor at 550 °C for 6 h under air flow, thereby obtaining MCM-41.

Modifications on MCM-41

Two groups of materials were prepared by different surface modifications: (i) iron impregnation and (ii) carbon deposition. Iron was used as metal catalyst and was supported by wet impregnation on MCM-41 in different mass ratios, i.e., 2.5, 5.0, or 10.0 %. An alcoholic solution of FeCl3·6H2O salt (Synth) was added to the MCM-41 dispersion, and the system was left under stirring for 24 h for complete evaporation of the solvent. The solid obtained was calcined at 300 °C for 60 min under air flow. The materials were named by their iron content: MCM41/Fe2.5, MCM41/Fe5, and MCM41/Fe10.

These materials impregnated with different proportions of Fe underwent a hydrophobization process for carbon deposition on their surface. The carbon deposition should increase the hydrophobic character of the materials, as well as stabilize the iron particles on the materials’ surface and increase the formation of active species that favors the adsorption (Calvete et al. 2010; Purceno et al. 2011) and oxidation processes (Lima et al. 2008). The hydrophobized materials were named according to the iron content, MCM41/Fe2.5/C, MCM41/Fe5/C, and MCM41/Fe10/C. The hydrophobization were performed via chemical vapor deposition (CVD) process (Manikandan et al. 2013), using ethanol as carbon source. The carbon deposition occurred in a reactor consisting of a quartz tube in a tubular furnace. The materials impregnated with iron were heated to 700 °C at 10 °C min−1 under ethanol/N2 flow of 50.0 mL min−1.

Carbon deposits were produced from ethanol decomposition. The thermal decomposition of ethanol occurs typically above 650 °C but iron nuclei reduce this temperature, since they act in the dehydrogenation of ethanol and in the nucleation and growth of carbon nanostructures (Oliveira et al. 2011; Pinilla et al. 2011).

Characterization of the materials

The materials were characterized by a variety of techniques: CHN elemental analysis (Perkin-Elmer-Séries II-CHNS/O Analyzer 2400, with a combustion chamber temperature near to 926 °C), thermogravimetric (TG) analysis (in air flow, 100 mL min−1, heating rate of 10 °C min−1 up to 900 °C in an DTG-60 Shimadzu), Mössbauer spectroscopy (room temperature in a spectrophotometer CMTE MA250, with constant acceleration, Co source, Rh matrix, and α-Fe as reference), transmission electron microscopy coupled with energy-dispersive spectroscopy (TEM and EDS) (microscope Tecnai G2-20-SuperTwin FEI-200 kV, samples dispersed in acetone and deposited on a Cu screen), Raman spectroscopy (Bruker spectrometer SENTERRA, equipped with a CCD detector, using a laser with λ = 633 nm), specific surface area and porosity—N2 adsorption/desorption (Autosorb-1MP equipment, Quantachrome Instruments Corp. at −196 °C, samples previously degasified at 150 °C for 8 h), and zeta potential at different pHs (ZetaSiker equipment, Malvern Instruments—with composites dispersed in deionized water).

Application of the materials

Dye adsorption tests were carried out using methylene blue (MB) as a cationic molecule model and indigo carmine (IC) as anionic molecule model (IC). The adsorption experiments were performed with 10.0 mL of a 100.0 mg L−1 MB solution and 20.0 mg of the materials (adsorbents). Adsorption of the dyes was monitored by the MB or IC decolorization using a UV-vis spectrophotometer 2550—Shimadzu at 664 and 365 nm wavelengths, respectively. Adsorption of methylene blue and indigo carmine was carried out using a calibration curve in the range of 10–200 ppm of each dye in water. During the adsorption tests, the absorbance of the dyes was compared to absorbance values of the standard solutions in the calibration curve. The adsorption promoted by the materials was determined by the difference between the initial concentration of the solution and the concentration determined after contact between the adsorbent and the dye solution.

The catalytic activity of the materials produced was evaluated in the oxidation of MB in an aqueous medium, using 1.0 mL of hydrogen peroxide as oxidizing agent, 10.0 mL of a 30.0 mg L−1 dye solution, and 20.0 mg of material. Initially, the adsorption effect was eliminated during a 24-h contact of the materials to a 500.0 mg L−1 dye solution. Then, these materials were filtered off and, only after drying, were used in oxidation reactions. The oxidation was monitored by discoloration of the solutions using an UV-vis spectrophotometer 2550—Shimadzu (λ = 664 nm).

The nitrogen oxidation tests were performed using the quinoline as a model molecule. Initially, the materials were left in contact with a quinoline solution (500.0 mg L−1 of nitrogen) for 24 h so that the effect of adsorption was eliminated. After filtered and dried, the materials were used in oxidation reactions.

The procedures were carried out using 10.0 mL of a 30.0 mg L−1 of quinoline solution, 1.0 mL of oxidation mixture (1 H2O2/1 HCOOH), and 30.0 mg of the material. The quinoline oxidation reactions were followed by mass spectrometry with electrospray ionization—Thermo LCQ Fleet.

Results and discussion

Characterization of the materials

The materials based on MCM-41 were first characterized with respect to the iron phases by Mössbauer spectroscopy (Fig. 2). The hyperfine parameters used for phase identifications are shown in Table 1.

Fig. 2
figure 2

57Fe room temperature Mössbauer spectra of MCM-41-based materials: a after iron impregnation and b after carbon deposition materials

Full size image
Table 1 Mössbauer hyperfine parameters determined for iron phases in MCM41/Fe and MCM41/Fe/C samples
Full size table

The iron impregnation was prepared with FeCl3 salt, which means that all iron was supported as Fe3+. It is observed that after CVD process, part of the iron present on MCM-41 is reduced to Fe2+, i.e., 26, 16, and 40 % of Fe2+ on MCM41/Fe2.5/C, MCM41/Fe5/C, and MCM41/Fe10/C, respectively. In addition, we may infer that the iron is supported as very small particles without expressive formation of well-defined phases, such as iron silicate or iron oxide. Only the material with 10 % of iron was capable of producing a well-defined phase, α-Fe2O3, with 20 % of relative area (Table 1).

The sample MCM41/Fe2.5/C has shown a greater concentration of reduced iron in relation to the sample MCM41/Fe5/C. This behavior may be related to the formation of iron particles slightly larger in the sample MCM41/Fe5/C with lower availability of metal sites on the surface of this material compared to MCM41/Fe2.5/C. The sample MCM41/Fe10/C showed a greater content of Fe2+, as expected, due to its higher iron content.

The CHN elemental analysis was carried out to determine the carbon content in the composition of the materials. It was found that MCM41/Fe2.5/C, MCM41/Fe5/C, and MCM41/Fe10/C present 12, 13, and 15 % C, respectively. The carbon content is enhanced in materials with more iron; however, this increase cannot be linearly related to the iron content.

TG experiments were conducted to study the thermal behavior of the samples and to verify the efficiency of the CVD process on the carbon formation. The thermogravimetric curves for pure MCM-41 and for carbon materials MCM41/Fe/C are shown in Fig. 3.

Fig. 3
figure 3

a TG profiles obtained for pure MCM-41 and carbon composites, under air atmosphere, and b DTG curves for MCM41/Fe2.5/C, MCM41/Fe5/C, and MCM41/Fe10/C

Full size image

Two events of weight loss can be seen in the TG profile of pure MCM-41: The first one, before 100 °C, related to surface water desorption (∼5 %), and the second event at 150–350 °C associated with the dehydroxylation of silanol groups (around 20 %). For the materials prepared after CVD, the TG profiles also show the water desorption before 100 °C. For the materials with carbon, it was possible to observe that a weight loss from 300 °C related two simultaneous events. According to Mössbauer results, the catalysts prepared by CVD present Fe2+ species, which can be oxidized to form Fe2O3, resulting in a TG weight gain. Simultaneously, the carbon present in the materials can be oxidized to form CO and CO2, resulting a weight loss between 400 and 600 °C. Since the amount of carbon deposited on the material is higher than the amount of iron, the weight loss event is evidenced.

Regarding the derivative of TG profiles (DTG curves—Fig. 3b), the curves obtained for all the materials produced show the isothermic peak for water dessorption centered at 50 °C. Moreover, only in the profile of MCM41/Fe5/C sample is observed a fairly sharp and intense peak at 750 °C, which might be related to the burn off of organized carbon structure, such as graphitic carbon. Graphite is more stable than a defected carbon, which should be oxidized at lower temperatures, for example, 350–550 °C (Nxumalo et al. 2010).

In Fig. 4, the Raman spectra obtained for the series of MCM41/Fe/C materials are shown. Raman spectroscopy is important to characterize the quality of the carbonaceous structures produced on the surface of the materials. Different carbon structures exhibit characteristic vibrational modes that may be identified in different regions of a Raman spectrum (Dresselhaus et al. 2008).

Fig. 4
figure 4

Raman spectra (λ = 633 nm) obtained for samples MCM-41 and MCM41/Fe/C series

Full size image

In the frequency region between 1500 and 1600 cm−1 of Raman spectra (Fig. 4), we may see the G band, mainly related to a vibrational mode characteristic of organized graphitic carbon. This vibrational mode is caused by the tangential vibration of two carbon atoms, one against the other, in organized structures (Dresselhaus et al. 2008). On the other hand, defective or disorganized carbon is identified by the D band that is typically between 1300 and 1400 cm−1. Pure support MCM-41 and iron phases present no bands in the frequency region analyzed, so we may infer that all bands observed in the spectra obtained are due to the carbon deposits. It is observed that G band is narrower than D, also more intense and better defined as the Fe content increases.

The ratio of the relative intensities of G and D bands (I G/I D) can be analyzed as a measure of the carbon structures’ organization/quality (Oliveira et al. 2013a; Wang et al. 2015). The I G/I D ratio calculated for MCM41/Fe2.5/C, MCM41/Fe5/C, and MCM41/Fe10/C are 1.1, 1.6, and 1.5, respectively. These values indicate that the amount of graphitic carbon formed on the materials is greater than the amount of disorganized/defective carbon in all materials. Even if the MCM41/Fe10/C material gives the largest amount of carbon deposited, this material does not have the highest I G/I D ratio, because when the iron content is much higher, it is harder to control carbon growth.

The structure of the materials was studied by TEM. All materials of the series MCM41/Fe/C show similar TEM images, as represented by MCM41/Fe10/C in Fig. 5. In general, it was observed that the MCM-41 support presents slightly organized and porous structure (Fig. 5a). In the materials prepared after Fe impregnation and CVD with ethanol, some twisted filaments can be seen with diameters of approximately 30 nm (Fig. 5b). Metallic and dense particles may also be observed in TEM images, likely supported iron nanoparticles (Fig. 5c).

Fig. 5
figure 5

TEM images obtained for the material MCM41/Fe10/C

Full size image

EDS spectra were obtained from the TEM images. The EDS microanalysis of MCM41/Fe10/C (Fig. 6) indicates a more intense peak on silica beyond the presence of iron and carbon as expected. The signal of cupper is found due to the sample port of the equipment. The EDS spectra confirmed an oxidation of ethanol by the presence of iron in the MCM-41, forming carbon.

Fig. 6
figure 6

EDS spectrum of MCM41/Fe10/C material

Full size image

The N2 adsorption/desorption isotherms and the BJH pore size distribution are shown in Fig. 7.

Fig. 7
figure 7

a N2 adsorption/desorption isotherms and b pore size distribution for pure MCM-41 and hydrophobized materials

Full size image

The isotherms shown in Fig. 7a are type IV, exhibiting a hysteresis for p/p 0 close to 0.40, characteristic of mesoporous materials (El-Sharkawy et al. 2007; Luan et al. 1995). The hysteresis of type IV exhibits a loop, i.e., the adsorption and desorption isotherms do not coincide over a certain region of external pressures (Sing et al. 2008). At low pressures, first, an adsorbate monolayer is formed on the pore surface, which is followed by the multilayer formation. The point p/p 0 = 0.4 indicates the stage at which the monolayer coverage is complete. In the range of 0.0–0.4 p/p 0, the surface area is determined by the BET method.

From Fig. 7b, we may see that the average pore diameter of pure MCM-41 and hydrophobized materials is approximately 40 Å, and it does not change after CVD reaction. It can be observed in Table 2 that all materials produced present a high specific surface area, especially MCM-41. However, the materials present a decrease in the surface area and pore volume from pure support. This decrease might be related to the occupation of MCM-41 pores by iron nanoparticles and carbon structures produced during CVD process. Furthermore, the thermal treatment can also contribute to these decreases in the specific surface area and pore volume by destroying some pores, although according to Chen and coworkers (Chen et al. 1993), pure silica MCM-41 can be heated to at least 850 °C before its structure collapses. The CVD process was conducted at 700 °C because it is known that ethanol decomposition at this temperature leads to carbon deposition as organized structures on the surface of the matrix (Oliveira et al. 2011).

Table 2 Specific surface area of the materials studied determined by the BET method
Full size table

Application of the materials

The adsorption kinetic of the MCM-41-based materials was investigated using MB and IC dyes. The behavior of each material for dye adsorption is shown in Fig. 8.

Fig. 8
figure 8

Adsorption monitoring of a methylene blue and b indigo carmine, by the MCM-41 and hydrophobized materials

Full size image

It can be seen in Fig. 8a that over 180 min, the materials prepared reach 79, 74, 88, and 94 % of MB removal for MCM-41, MCM41/Fe2.5/C, MCM41/Fe5/C, and MCM41/Fe10/C, respectively. Pure MCM-41 is a good adsorbent for MB, since it removes 79 % within 180 min of contact. This is likely related to the high specific surface area of this material, i.e., 1080 m2 g−1. However, it is observed that materials prepared with 5 and 10 % of iron and carbon exhibit higher activities than pure MCM-41, up to 88 and 94 %, even though they present lower surface areas, i.e., 775 and 201 m2 g−1. Therefore, the adsorption process is not related only to the physical morphology of the materials but also to a chemical component. It seems that the greater the iron and carbon content on the adsorbent, the more MB is removed from the liquid phase. It is proposed that the carbonaceous structures on the surface of the materials favor adsorption since they interact better with the nonpolar portion of the dye molecule (Oliveira et al. 2015).

Figure 8b shows the adsorption of indigo carmine (a negatively charged molecule) for the series of MCM41/Fe/C materials. According to data of Fig. 8b, the materials MCM-41, MCM41/Fe2.5/C, MCM41/5Fe/C, and MCM41/Fe10/C adsorb 5, 21, 18, and 13 % of the dye in 180 min, respectively. The dye adsorption capacity does not follow the increase on surface area or even the porosity (pore volume and size), so the adsorption of this series of materials should also be influenced by other factors, such as the charge generated on their surface in aqueous media and the availability of adsorption centers. Therefore, the iron species and the carbon structures might contribute to those main changes on the surface of the materials, thus increasing the methylene blue adsorption. Moreover, it is observed that the adsorption capacity is inversely proportional to the amount of metal supported, so this metal is expected to generate negative charges that repel the anionic molecules of IC, which corroborates the results for the adsorption of methylene blue dye (cationic dye—Fig. 8). These results suggest that surface charges generated on the materials in aqueous medium may be significantly contributing to the adsorption results observed for the different dyes, methylene blue (cationic) and indigo carmine (anionic) (Mambrini et al. 2012).

In order to understand these electrostatic interactions between the dyes and the hidrophobized materials, zeta potential measurements at different pH were carried out (Fig. 9). The zeta potential at different pH curves allows the determination of the point of zero charge (PZC) of the materials and an evaluation of the surface charge of the particles under study.

Fig. 9
figure 9

Zeta potential measurements for MCM-41 and hydrophobized materials obtained after ethanol/CVD process at 800 °C

Full size image

Figure 9 shows a PZC at pH 3 for the MCM-41 and MCM41/Fe10/C materials. The MCM41/Fe2.5/C and MCM41/Fe5/C materials presented negatively charged throughout the pH range. Since the initial pH of the dye solutions was 7.0, those results indicated that the surface of the materials is negatively charged and therefore preferentially adsorb positively charged molecules such as methylene blue dye. The MCM41/Fe10/C material has lower specific area, but the highest negative charge value at pH 7, which justifies the higher adsorption of methylene blue for this material. On the other hand, the materials negatively charged showed very low adsorption for the negative IC.

The materials were also tested as catalysts for the methylene blue oxidation reaction with H2O2. In this case, the adsorption effect was previously eliminated during a 24-h contact of the materials to a very concentrated solution of the dye, i.e., 500.0 mg L−1. These materials were then filtered, dried, and used in a fresh MB solution for the oxidation reactions. After addition of hydrogen peroxide, it is observed (Fig. 10) that the MCM-41 promotes low color removal, approximately 15 % after 60 min. On the other hand, MCM41/Fe2.5/C, MCM41/Fe5/C, and MCM41/Fe10/C remove in 60 min 64, 63, and 72 %, respectively. Similar materials have reached lower activities in the same experimental conditions (Rahim Pouran et al. 2015).

Fig. 10
figure 10

Methylene blue discoloration catalyzed by the MCM-41-based materials

Full size image

The highest catalytic activity of MCM41/Fe10/C was expected and may be mainly related to two factors: (i) greater amount of carbon on this material in relation to MCM41/Fe5/C and MCM41/Fe2.5/C, which facilitates the adsorption of the contaminant on the catalyst surface, and (ii) higher Fe2+ content, which is the most active iron phase for oxidation reactions in Fenton-like process.

After 180 min of reaction, the oxidation products were determined by mass spectrometry with electrospray ionization (ESI/MS) (Fig. 11).

Fig. 11
figure 11

Monitoring of methylene blue oxidation in the presence of MCM41/Fe10/C catalyst, by ESI-MS

Full size image

From the ESI-MS data, it is observed that methylene blue produces a characteristic signal m/z = 284. After 180-min reaction with hydrogen peroxide in the presence of the catalyst MCM41/Fe10/C, new signals are shown in the ESI-MS spectra, i.e., m/z = 162, 270, and 301. We suggest that the available iron species dispersed on the surface of the MCM-41 can promote the generation of •OH radicals, favoring the oxidation of the methylene blue molecules. The new peaks observed in the presence of the MCM41/Fe10/C catalyst prove that not only the solution discoloration occurs but also MB (m/z 284) is oxidized in the presence of the material, which does not occur in the presence of pure MCM-41.

In Fig. 12 are shown the proposed initial oxidation mechanism with the structural formulas of the products identified by ESI-MS. The molecule m/z = 301 is the product of the dye hydroxylation, while the m/z = 270 is related to the loss of a methyl radical, and m/z = 162 is the molecule formed due to the break of methylene blue chain (Costa et al. 2015; Esteves et al. 2008).

Fig. 12
figure 12

Intermediates of methylene blue oxidation in the presence of the MCM catalysts

Full size image

Quinoline (QN) was tested in the oxidation experiments as model nitrogen contaminant present in liquid fuels. Quinoline oxidation was monitored by ESI-MS after 180 min with hydrogen peroxide in the presence of pure MCM-41 and MCM41/Fe10/C catalyst (Fig. 13).

Fig. 13
figure 13

Monitoring of quinoline oxidation in the presence of MCM41/Fe10/C catalyst, by ESI-MS

Full size image

In ESI-MS results obtained for quinoline, it is observed a rather intense signal ratio m/z = 130 corresponding to the protonated quinoline structure. After 180-min reaction, new signals appear in the spectrum only for MCM41/Fe10/C catalyst, i.e., m/z = 146, 176, and 278, referring to quinoline oxidation products.

The product with m/z = 146 corresponds to the input of the hydroxyl quinoline structure, suggesting the formation of •OH radicals promoted by the decomposition reaction of hydrogen peroxide catalyzed by the material MCM41/Fe10/C. The signal ratio m/z = 176 should be related to the oxidation of hydroxyl groups, leading to the formation of ketones. Figure 14 shows a proposal for the formation of possible intermediate of quinoline oxidation reaction. The formation of these oxidized intermediates is reported in the literature by Oliveira et al. and Souza et al. (de Souza et al. 2010; Oliveira et al. 2013b).

Fig. 14
figure 14

Intermediates for quinoline oxidation reaction in the presence of the catalyst MCM41/Fe10/C

Full size image

Conclusions

Mesoporous silica MCM-41 was produced via sol-gel process and modified by CVD. The surface modifications transformed this material into versatile mesoporous materials with great potential to be used in different technological applications, such as adsorption and catalysis. Iron was first supported on the surface of MCM-41 to catalyze the CVD reaction with ethanol as carbon source. The materials prepared with different iron contents, i.e., 2.5, 5, and 10 % and after partial hydrophobization (12–15 % C), were extensively characterized. The materials have shown to be very active as methylene blue and indigo carmine adsorbents due to their mesoporous structure and high specific surface area, i.e., up to 1080 m2 g−1. Preliminary studies on the catalysis of dyes and quinoline removal showed very promising results. It was shown that the iron species formed during the hydrophobization process (especially Fe2+) play important roles in the mechanism of these oxidation reactions.