Adsorption Of Dimethyl Phthalate Research Articles

One-step preparation of highly efficient adsorbents: Adsorption study of DMP on porous carbon macrobody based on sodium alginate

Porous carbon is a carbon material with a high surface area and abundant pore structure, holding extensive potential applications in the adsorption field. However, current porous carbon materials are complicated to prepare, and most are in powder form, making them difficult to separate from water after adsorption and prone to secondary pollution. This study uses sodium alginate (SA) as a precursor and K2CO3 one-step method to prepare sodium alginate-based macromaterials that can skillfully solve the above problems and explore its adsorption kinetics and thermodynamic characteristics for dimethyl phthalate (DMP). This study's meticulous control of experimental details enabled the fabrication of macroscopic materials. The appropriate temperature and activator blending ratio are critical to material agglomeration. (At 800°C in a small ceramic boat, macroscopic material C800-2 was prepared with an activator ratio of K2CO3: sodium alginate at 2:1 and under low acid concentration acid washing (0.2mol/L HCl)). Excessive pyrolysis temperature can lead to severe chemical bond loss, potentially preventing material agglomeration. Excessive doping of the activator may result in carbon framework collapse. While maintaining the macroscopic structure, C800-2 enhanced a 3.8-fold increase in total pore volume and a 4.6-fold increase in surface area. Moreover, at 313K, its saturated adsorption of DMP reached an impressive 614.98mg/g. C800-2 material exhibits excellent interference resistance and regeneration capability. The study achieves one-step fabrication of macroscopic materials while retaining superior adsorption performance, providing fundamental data for material engineering applications.

Revolutionizing conventional adsorbents: Strengthening dimethyl phthalate adsorption through N/P co-doping macroscopic robust porous carbon

Conventional powdered porous carbon materials face serious challenges, such as difficult recycling, easy clogging, and potential secondary pollution, and thus are not ideal for practical engineering applications. Endeavoring to address these issues, a fortuitous revelation emerged: the deliberate modulation of experimental parameters yields macroscopic materials of heightened stability, affording the distinct advantage of facile separation and recyclability. This investigative pursuit employed sodium alginate (SA) as the carbon precursor, K2CO3 as the activating agent, and ammonium polyphosphate (APP) as an N/P co-doping agent. Through a meticulously executed one-step pyrolysis process, macroscopic materials rooted in N/P co-doped sodium alginate (C/N/P-0.3) were skillfully synthesized. Comprehensive SEM and BET analyses elucidate that N/P co-doping amplifies the genesis of defects and active sites during activation, surpassing the impact of K2CO3 in isolation. This strategic co-doping approach results in a notable 1.30-fold augmentation in specific surface area and a concurrent 1.34-fold expansion in the total pore volume of the material, thereby culminating in a substantial 25.39% elevation in the adsorption of dimethyl phthalate (DMP). Furthermore, corroborative assessments utilizing XPS, FTIR, and allied methodologies substantiate that the synergistic interplay under specific experimental conditions fortifies the stability of their layered structure, concurrently enhancing material mechanical properties by an appreciable 59.8%. Notably, the exceptional regenerative performance of C/N/P-0.3 was validated through four experimental cycles. This study posits that these innovative porous carbon materials, predicated upon their copious internal pore architecture and steadfast macroscopic morphology, harbor substantial promise for multifarious engineering applications.

Transport of dimethyl phthalate on loess with modified bentonite: A batch and column test investigation

Phthalic acid ester (PAE) is a toxic pollutant commonly found in high concentrations in municipal solid waste landfills. Soil–bentonite is widely used as a barrier material to control groundwater contaminants from landfill leachates. Traditional soil–bentonite materials always have a limited capacity for organic pollutant adsorption. To address this issue, the adsorption and transport behavior of dimethyl phthalate (DMP) on loess amended with two kinds of modified bentonite (HTMAC-B, modified with hexadecyltrimethylammonium chloride; CMC-B, modified with hydrophobic cationic surfactant, and carboxymethyl cellulose) were investigated. The kinetics of DMP adsorption indicates that film diffusion contributes significantly to the kinetic adsorption of DMP on HTMAC-B. The adsorption isotherm results showed that partitioning dominated DMP adsorption on loess with both modified bentonites. Owing to the in-ionic sites in HTMAC-B, which attracted hydrophobic compounds such as DMP, the adsorption capacity of 5 % HTMAC-B-amended loess (LH) was increased by a factor of 3.2. However, because CMC-B provided mostly ionic sites, 5 % CMC-B-amended loess (LC) had a little effect on DMP adsorption. The hydraulic conductivity values of LH and LC were 5.95 × 10−10 and 1.65 × 10−11 m/s, respectively. The X-CT result showed that there is a significant porosity change for both LH and LC. Dual-porosity model reveals that the leaching process primarily affects micro-pores, rather than larger pores in the soil matrix. The predicted retardation factors for LH and LC were 38.89 and 9.67, respectively. When using loess-bentonite as barrier material, the amendment of HTMAC-B and CMC-B can help to increase the retardation ability and reduce the permeability, respectively.

Biochar Derived from Treated Lotus Stem and Adsorption of Phthalic Acid Esters

Phthalic acid ester (PAE), a plasticizer, is increasingly being detected in different environments. These compounds can gravely affect the human endocrine system. The present study aims to prepare adsorbents that can effectively adsorb PAE pollutants. To fabricate a better carbon structure than conventional biochar, the sodium hydroxide solution was used as a hydrolyzing agent to pretreat the biomass in order to weaken the bonds in lignin, cellulose, and hemicellulose. As a result, biochar with a special porous carbon structure is obtained. To study the characteristics of the biochar and its adsorption properties, dimethyl phthalate (DMP)—a PAE—was selected as the adsorbate. The morphology and structural composition of the biochar were examined via an environment scanning electron microscope with a field emission gun (SEM), surface area analyzer (BET), Fourier transform infrared spectrometer (FTIR), thermal gravimetry (TG/DTG), X-ray diffractometry (XRD), and Raman spectroscopy. The BET data of the biochar increased by 125.3 times than that of the original biochar. The layer spacing and the surface functional groups of the pretreated biochar also increased. After performing the micro-morphological regulation of biomass using sodium hydroxide, the adsorption performance of biochar with regard to PAE effectively improved and an adsorption capacity of 125 mg/g was observed for DMP. The adsorption kinetics and thermodynamic experiments showed that DMP adsorption by biochar follows the Langmuir and pseudo-second-order models.

Defective UiO-67 for enhanced adsorption of dimethyl phthalate and phthalic acid

It is imperative to remove endocrine disrupting compounds (EDCs) from water because of their damage to human health via drinking, eating and skin contacting. Herein, a variety of UiO-67 samples, with different numbers of defects were screened for the adsorption elimination of dimethyl phthalate (DMP) and phthalic acid (PA) in aqueous solution. UiO-67-30BA (benzoic acid regulator with 30 times molar number of ligands) which had the greatest number of missing-links and the highest specific surface area, was determined by thermogravimetric analysis (TGA), nuclear magnetic resonance (1H‐NMR), and energy-dispersive X-ray spectroscopy (EDS) and N2 adsorption-desorption. The adsorption kinetics of PA and DMP on UiO-67-30BA well obeyed pseudo-first-order kinetic model and the adsorption isotherms well followed Langmuir model. Adsorption thermodynamics indicated that the adsorption process was an exothermic and spontaneous process. Remarkably, UiO-67-30BA with the most defects showed the third highest PA and highest DMP adsorption capacity compared with reported MOFs materials, which were 434.0 and 228.1 mg/g, respectively. Furthermore, the dominant interactions between PA and UiO-67 samples were electrostatic interaction and π-π interaction, while the adsorption of DMP depended on π-π interaction. The introduction of missing-links not only provided an outstanding adsorbent UiO-67-30BA for DMP and PA, but also revealed the different adsorption mechanisms of the adsorbents.

Preparation of multi-walled carbon nanotubes based magnetic multi-template molecularly imprinted polymer for the adsorption of phthalate esters in water samples.

Taking the advantages of surface imprinting, multi-template imprinting and magnetic separation, a novel magnetic multi-template molecularly imprinted polymer (mag-MMIP@MWCNTs) was prepared by using MWCNTs as support material, Fe3O4 as magnetic core, and dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBP) as template molecules. This composite was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and the Brunauer-Emmett-Teller (BET) analysis, and was used for the simultaneous adsorption of DMP, DEP, and DBP in aqueous solution. The effects of solution pH, contact time, PAEs initial concentration, temperature, adsorption selectivity, and reusability were investigated and discussed in detail. The results demonstrated that mag-MMIP@MWCNTs exhibited fast kinetics, good magnetic separation, and excellent selectivity for the adsorption of three phthalate esters (PAEs). The adsorption kinetics followed pseudo second-order kinetic model and the adsorption thermodynamics followed Langmuir isothermal model very well, and the maximum adsorption capacities (Qmax) of DMP, DEP, and DBP were obtained as 0.95, 1.38, and 7.09 mg g-1, respectively. The Scatchard analysis revealed that the template-polymer system had a two-site binding behavior. The adsorption thermodynamic studies indicated that the adsorption processes were exothermic and spontaneous, and dominated by physical adsorption relying on hydrogen bond, hydrophobic interaction, and van der Waals force. Mag-MMIP@MWCNTs also showed good reproducibility and reusability for simultaneous adsorption of the three PAEs. The potential application of mag-MMIP@MWCNTs was proved by the removal of DMP, DEP, and DBP spiked in environmental water samples.

Effect of the composition and surface functional groups of Fe-Ni bimetal oxides catalysts in catalytic ozonation process

In this study, Fe-Ni bimetal oxides (Fe-NiO x ) catalysts were used to activate O 3 in a heterogeneous system. This research focuses on the degradation mechanism of dimethyl phthalate (DMP) by adding Fe-NiO x catalysts which activated the O 3 decomposition to generate strong oxidative hydroxyl radicals (•OH). The experimental results showed that O 3 /Fe-NiO x catalyst calcinated under 500 °C achieved 47.75% higher DMP removal efficiency when compared with ozonation of DMP without the catalyst. Besides, control experimental data suggested that the adsorption of DMP was negligible ( x . Thus, it was concluded that the removal of DMP was due to the catalytic ability of Fe-NiO x rather than the adsorption of DMP onto the catalysts. Moreover, the unsatisfactory performance of Fe-NiO x catalysts calcinated in the presence of N 2 revealed that O 2 played an important part in affecting the crystalline degree of catalysts during the synthesis process. Meanwhile, the X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FT-IR) characterization analysis indicated that calcination temperature was an indispensable factor that influenced the relative content of Ni 2+ and hydroxyl groups (−OH) in Fe-NiO x catalysts. Furthermore, the relative content of Ni 2+ had a greater effect on catalysts9 activity because of the electron transfer between multivalent metal states.

Biochar preparation from Solidago canadensis and its alleviation of the inhibition of tomato seed germination by allelochemicals.

Solidago canadensis is a malignant invasive plant widely distributed in China. In this study, it was used as a biomass source to prepare biochar via an oxygen-limited pyrolysis method. The effect of temperature, heating rate and pyrolysis time on the yield and surface characteristics of the biochar was identified. The adsorption properties for dimethyl phthalate (DMP), a typical allelochemical of Solidago canadensis, of the biochar were explored. In addition, a pot experiment was conducted to reveal the effect of the biochar on tomato seed germination in the presence of allelochemicals. The maximum yield of the biochar was observed when Solidago canadensis was pyrolyzed at 300 °C for 2 h, with a heating rate of 8 °C min−1. Variation of pyrolysis conditions had little influence on the surface characteristics of the biochar. The adsorption of DMP on the biochar could be well described by the Langmuir model, with a maximum adsorption capacity of 59.37 mg kg−1. The addition of biochar to the soil could promote tomato seed germination in the presence of allelochemicals. Therefore, the biochar prepared from Solidago canadensis can be used for soil amendment for invaded sites.

Photodegradation of dimethyl phthalate (DMP) by UV–TiO2 in aqueous solution: operational parameters and kinetic analysis

In this paper, the adsorption and degradation phenomenon involved in the photocatalytic degradation of dimethyl phthalates (DMPs) by titanium dioxide (TiO2) was studied. A variety of operating variables were selected firstly. Then, it was proved that even for such weak adsorption properties molecules as DMP, adsorption was still an important prerequisite for photolysis. A surface-mediated reaction process was proposed that the photodegradation of DMP assisted by TiO2 particles occurred primarily at the surface of the photocatalyst rather than in the homogeneous phase. According to Langmuir–Hinshelwood model, the adsorption constant determined from the dark adsorption was far less than that obtained in the light condition. Enhanced DMP adsorption on the surface of TiO2 under irradiation was the possible reason for the improvement of photodegradation efficiency. Under the irradiation of light, a synergistic mechanism of adsorption and photocatalysis was responsible for DMP degradation. The quantitative analysis by adding scavengers indicated that ·OH radical was primarily responsible for the photodegradation of DMP. It was further verified that ·OH was produced much more from conduction band electrons rather than valance band holes toward photodegradation of DMP by adding foreign Cu2+.

Efficient removal of dimethyl phthalate with activated iron-doped carbon aerogel through an integrated adsorption and electro-Fenton oxidation process

A promising activated iron-doped carbon aerogel (AFeC) possessing high adsorption capacity and “self-cleaning” ability via generated OH radicals was fabricated and applied to remove dimethyl phthalate (DMP). Around 90% of the DMP (50 ppm) was first adsorbed on the surface of a DMP-imprinted AFeC electrode and then further catalytically oxidized by surface OH produced via an electro-Fenton reaction. DMP removal of 98% can be achieved in 150 min in the heterogeneous electro-Fenton process. The addition of Fe0 favoured the generation of graphene sheets of amorphous carbon and then provided strong π-π interaction with aromatic pollutants. In addition to iron, a DMP molecular template was also introduced to AFeC to create special molecular imprinting affinity for DMP. The CO2-N2 activation treatment increased the porosity and enriched the hydroxyl and quinone groups (C-O and C=O). The high DMP adsorption capacity of the DMP-imprinted AFeC electrode can be ascribed to the following mechanism: (i) electrostatic interaction; (ii) hydrophobic interaction; (iii) π-π electron-donor-acceptor interactions; (iv) molecular imprinting affinity between template molecules and imprinted sites. Thus, this carbon-based material is promising to be potentially applied in the removal of DMP containing wastewater through integrated adsorption and degradation.

Study of adsorption and degradation of dimethylphthalate on TiO2-based photocatalysts

This work studied the degradation and adsorption of dimethylphthalate (DMP) using various TiO2-based photocatalysts: TiO2 Aeroxide P25, Kronos vlp7000, Hombikat UV-100, Kemira 650 and a synthesized photocatalyst named SG750. As the photocatalysts with mixed anatase and rutile phases, P25 and SG750, showed greater activity than those of pure phase, an in-depth study was undertaken of these two catalysts in the adsorption and degradation of DMP. The degradation results were fitted with a high degree of correlation to the Langmuir-Hinshelwood model and those for adsorption to the Freundlich model. The Freundlich constants showed good correlation with FTIR observations of the DMP-P25 and DMP-SG750 interactions. These two photocatalysts were additionally modified by photodeposition with Pt and Au (0.5–1.5wt%) to study the effect of these metals on degradation and mineralization kinetics.

The performance of mesoporous magnetite zeolite nanocomposite in removing dimethyl phthalate from aquatic environments

In this study, magnetic zeolite nanocomposite with an average diameter of 90–100nm was synthesized through a chemical co-precipitation method, and used for the adsorption of dimethyl phthalate (DMP) from aqueous solution. The surface morphology of the adsorbent was characterized by scanning electron microscope, transmission electron microscopy, energy dispersive X-ray, vibrating sample magnetometer, dynamic light scattering, Brunauer, Emmett, Teller, and X-ray diffraction techniques. Batch system was followed to optimize the conditions for the removal of DMP. The adsorption experiments were carried out in terms of pH, contact time, various concentrations of DMP as well as nanocomposite, and temperature. The results showed that with increase in adsorbent dosage and contact time increased the adsorption efficiency. However, the efficiency decreased by increasing pH and initial DMP concentration. Experimental data were found to fit well with Langmuir isotherm (R2 > 0.981) in all the studied temperatures. Adsorption kinetics also showed that the adsorption behavior follows the pseudo-second-order kinetic model (R2 > 0.996). Besides, thermodynamic analysis demonstrated that the adsorption process occurs spontaneously and is inherently endothermic. The DMP adsorption efficiency did not change after 10 batch sorption–desorption reactions, indicating the potential application prospect of the synthesized adsorbent in real water treatment.

Preparation of a sludge-based adsorbent and adsorption of dimethyl phthalate from aqueous solution

AbstractIn this paper, a sludge-based adsorbent (SBA) was prepared from biochemical sludge from a wastewater treatment plant by chemical activation using 3.0 M ZnCl2 followed by pyrolysis at 700°C for 1 h in an anoxic atmosphere. The physical and chemical properties of the SBA were characterized by N2 adsorption, scanning electron microscopy (SEM), Fourier Transform infrared red (FT-IR) spectroscopy, X-ray diffraction (XRD), and Boehm titrations. The adsorption behavior of dimethyl phthalate (DMP) on the SBA was studied in batch reactors by investigating a range of variables including pH, DMP concentration, and adsorption time. The optimal pH for DMP adsorption was found out to be around 6, as this gave the best surface charge interactions. Adsorption equilibrium isotherms and the kinetics models of DMP adsorption on the SBA were also investigated. Experimental data indicated that the Freundlich model was most applicable to the adsorption process to show the SBA’s heterogeneous surface supporting sites of...

Electrochemically assisted coagulation for the adsorptive removal of dimethyl phthalate from aqueous solutions using iron hydroxides

In this study, the adsorptive removal of dimethyl phthalate (DMP) from aqueous solutions by electrochemically generated iron hydroxides was investigated in batch mode. Four electrode pairs were used to characterize the performance of electro-coagulation (EC) for the DMP removal efficiency. Experimental results indicated that a Fe/Al electrode pair was the optimum choice out of four different electrode pair combinations. In addition, the effects of varying current density and solution temperature on DMP adsorption characteristics were evaluated. The findings indicated that complete DMP removal could be achieved within reasonable removal efficiency and with relatively low electrical energy consumption. The optimum current density and temperature were found to be 20 mA/cm2 and 298 K, respectively. Thermodynamic parameters, including the Gibbs free energy, enthalpy, and entropy, indicated that the DMP adsorption of aqueous solutions on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288–318 K. The experimental data were fitted with several adsorption isotherm models to describe the EC process. The adsorption of DMP preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules.

Environmental application of graphene-based CoFe2O4 as an activator of peroxymonosulfate for the degradation of a plasticizer

The application of graphene-based CoFe2O4 (G-CoFe2O4) as an activator of peroxymonosulfate (PMS) to degrade a plasticizer, dimethyl phthalate (DMP), has been investigated systematically, including the catalytic performance, beneficial effects, and the reaction mechanisms. In general, G-CoFe2O4 was found more efficient than CoFe2O4 to activate PMS. Several operational parameters were examined (e.g. the graphene content, reagent dosage, solution pH). Results showed that the optimum graphene content was determined to be 22%, and higher content could lead to excessive adsorption and incomplete degradation of DMP. A wide pH range of 4.0–8.35 was determined to be applicable for G-CoFe2O4. Furthermore, the role of graphene in the hybrid catalyst was found to serve as a matrix rather than a catalyst, and the adsorption of DMP molecules induced by the presence of graphene could be desorbed again by the participation of PMS ions. Finally, the degradation mechanisms were investigated, where both OH and SO4- were verified to be the active radicals in the G-CoFe2O4/PMS process. The DMP degradation was found mainly through the radical attack (OH and SO4-) of the aromatic ring and the oxidation of the aliphatic chain. The latter was also responsible for the TOC removal in the process.

Catalytic ozonation of organic compounds in water over the catalyst of RuO2/ZrO2-CeO2

This research investigates the performances of RuO2/ZrO2-CeO2 in catalytic ozonation for water treatment. The results show that RuO2/ZrO2-CeO2 was active for the catalytic ozonation of oxalic acid and possessed higher stability than RuO2/Al2O3 and Ru/AC. In the catalytic ozonation of dimethyl phthalate (DMP), RuO2/ZrO2-CeO2 did not enhance the DMP degradation rate but significantly improved the total organic carbon (TOC) removal rate. The TOC removal in catalytic ozonation was 56% more than that in noncatalytic ozonation. However this does not mean the catalyst was very active because the contribution of catalysis to the overall TOC removal was only 30%. The adsorption of the intermediates on RuO2/ZrO2-CeO2 played an important role on the overall TOC removal while the adsorption of DMP on it was negligible. This adsorption difference was due to their different ozonation rates. In the catalytic ozonation of disinfection byproduct precursors with RuO2/ZrO2-CeO2, the reductions of the haloacetic acid and trihalomethane formation potentials (HAAFPs and THMFPs) for the natural water samples were 38%–57% and 50%–64%, respectively. The catalyst significantly promoted the reduction of HAAFPs but insignificantly improved the reduction of THMFPs as ozone reacts fast with the THMs precursors. These results illustrate the good promise of RuO2/ZrO2-CeO2 in catalytic ozonation for water treatment.

Synthesis and characterization of L-tryptophan containing microbeads for removal of dimethyl phthalate from aqueous phase

Poly(ethylene glycol dimethacrylate-N-methacryloyl-L-tryptophan methyl ester) [poly(EGDMA-MATrp)] beads (average diameter=106–300μm) were synthesized by copolymerizing of N-methacryloyl-L-tryptophan methyl ester (MATrp) with ethylene glycol dimethacrylate (EGDMA). The usability of newly synthesized material for the removal of dimethyl phthalate (DMP) from aqueous phase was investigated. The poly (EGDMA-MATrp) beads were characterized by N2 adsorption/desorption isotherms (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and swelling studies. Initial concentration, pH, contact time and temperature effects on the adsorption of DMP from aqueous solutions were analyzed. An optimum adsorption capacity of 237.3mgg−1 for DMP was obtained at 25°C. The present adsorption process obeyed pseudo-second-order kinetic model. All the isotherm data can be fitted with both the Langmuir, and the Dubinin–Radushkevich isotherm models with high correlation coefficients. Thermodynamic parameters ΔH=2.398kJmol−1, ΔS=65.76JK−1mol−1, and ΔG=−17.20kJmol−1 to −18.57kJmol−1 with the rise in temperature from 25°C to 45°C indicated the adsorption process was endothermic and spontaneous. The DMP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the beads in applications.

Effect of pH and Temperature on Adsorption of Dimethyl Phthalate on Carbon Nanotubes in Aqueous Phase

Adsorptions of dimethyl phthalate (DMP) on carbon nanotubes (CNTs) in aqueous phase at various pH and temperatures were studied. The increase in pH results in the increase in adsorption coefficient. The adsorption is governed by the π-π electron interaction which is affected by the changes in pH of the medium. The outer diameter of the CNTs greatly influences the adsorption behavior of CNT for DMP. Under the same working temperature, the adsorption capacity of CNTs for DMP is inversely related to the average outer diameter of the CNT: single-walled SWCNT (1.4 nm)>multi-walled MWCNT10 (9.4 nm)>MWCNT30 (27.8 nm)>MWCNT40 (42.7 nm). The larger surface area of CNTs provides many active sites for adsorption of DMP molecules. The Freundlich model can describe well the adsorption isotherms of DMP on CNTs. The thermodynamic parameters of standard free energy, standard enthalpy (ΔH), and standard entropy changes are determined, showing that the adsorption of DMP on CNTs is an endothermic and spontaneous reaction. The ΔH value of 27.8 nm-sized MWCNT (22.69 kJ/mol) is higher than 1.4 nm-sized SWCNT (6.05 kJ/mol), inferring that the adsorption process becomes more endothermic with the increase in the outer diameter of CNTs.

Adsorption and desorption of dimethyl phthalate on carbon nanotubes in aqueous copper(II) solution

The adsorption and desorption of dimethyl phthalate (DMP) on five types of carbon nanotubes (CNTs) were studied in the absence and presence of 50mg/L copper(II) (Cu2+) ion. The adsorption and desorption data are well described by the Freundlich model and the first-order two-compartment model, respectively. The adsorption capacity of CNTs for DMP is inversely related to the average outer diameter of the CNTs. The surface acidic functional groups of CNTs increases in the order of lactones < hydroxyl < carboxyl functionalities and decreases with the increase in the outer diameter. The adsorption of DMP on CNTs increases in the presence of Cu2+ ions. The adsorption coefficient increases in pH 3–6 and is nearly the same at pH > 6 for all CNTs. The presence of Cu2+ ions decreases the amounts of desorbed DMP from CNTs, inferring that Cu2+ ions could suppress the DMP desorption from CNTs and reduce DMP toxicity to our environment.

Assesment of dimethyl phthalate removal from aqueous phase using barium hexaferrite containing magnetic beads

The barium hexaferrite (BaFe12O19) containing magnetic poly (ethylene glycol dimethacrylate-vinyl pyridine; mag-poly [EGDMA–VP]) beads (average diameter=53–212μm) were synthesized and characterized. Their use as an adsorbent in the removal of dimethyl phthalate (DMP) from an aqueous solution was investigated. The mag-poly (EGDMA–VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly (EGDMA–VP) beads were characterized by N2 adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM), and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DMP from aqueous solutions such as pH, initial concentration, contact time, and temperature were analyzed. The maximum DMP adsorption capacity of the mag-poly (EGDMA–VP) beads was determined as 96.2mg/g at pH 3.0, 25°C. All the isotherm data can be fitted with both the Langmuir and the Dubinin–Radushkevich isotherm models. The pseudo-first-order, pseudo-second-order, Ritch-second-order, and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DMP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.