Surface characterization and sorption efficacy of tire‐obtained carbon: experimental and semiempirical study of rhodamine B adsorption

This work focuses on the surface characterization and sorption activity of carbon derived from waste tires. The carbon was prepared by thermal treatment of waste rubber tires, followed by exposure to nitric acid and hydrogen peroxide. The tired‐obtained activated carbon (AC) was evaluated using a variety of techniques. Fourier transform infrared spectroscope and Raman spectra reveal existence of hydroxyl and carboxylic groups on AC surface. Scanning electron microscope and Brunauer–Emmett–Teller revealed the porosity of AC is well developed with mesopore structure (mesopore volume of 0.96 cm³/g). AC was tested for Rhodamine B sorption, and the adsorption kinetics well fitted using a pseudo second‐order kinetic model. The adsorption isotherm data could be well described by the Langmuir model. Semiempirical calculations using Austin Model 1 were performed to explain the adsorption at molecular level. Binding enthalpies in the range of 0.5–4 kcal/mol of four possible scenarios were computed. We believe the combination between experimental work and semiempirical calculations allows for a better understanding of Rhodamine B molecules adsorption on the AC surface. Copyright © 2015 John Wiley & Sons, Ltd.     

Surfaced-modified TiO2 Nanofibers with Enhanced Photodegradation Under Visible Light

Asynchronized surface modification method based on coaxial electrospinning was developed to fabricate high-efficiency photodegradative nanofiber for water purification. TiO₂ nanoparticles assembled uniformly on the surface of polycaprolactone(PCL) nanofibers to form composite nanofibers through one step process. The maximal content of Ti element was 25.6%(mass fraction) in the PCL/TiO₂ composite nanofibrous membrane, which exhibited hydrophilicity and excellent photodegradation under visible light in water. The Rhodamine B dye degraded 96.17% in 120 min under visible light by the PCL/TiO₂ composite membrane. The adsorption behavior fitted Langmuir model well and indicated chemical related adsorption. This PCL/TiO₂ composite nanofibrous membrane has super degradation properties and displays great application potential to environmental protection.     

Preparation and characterization of nanocomposite,silica aerogel,activated carbon and its adsorption properties for Cd (II) ions from aqueous solution

A novel composite adsorbent, silica aerogel activated carbon was synthesized by sol-gel process at ambient pressure drying method. The composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Nitrogen adsorption/desorption isotherms (BET).In the present study, the mentioned adsorbent was used moderately for the removal of cadmium ions from aqueous solutions and was compared with two other adsorbents of cadmium, activated carbon and silica aerogel. The experiments of Cd adsorption by adsorbents were performed at different initial ion concentrations, pH of the solution, adsorption temperature, adsorbent dosage and contact time. Moreover, the optimum pH for the adsorption was found to be 6.0 with the corresponding adsorbent dosage level of 0.1 g at 60 °C temperature. Subsequently, the equilibrium was achieved for Cd with 120 min of contact time.Consequently, the results show that using this composite adsorbent could remove more than 60% of Cd under optimum experimental conditions. Langmuir and Freundlich isotherm model was applied to analyze the data, in which the adsorption equilibrium data were correlated well with the Freundlich isotherm model and the equilibrium adsorption capacity (q_e) was found to be 0.384 mg/g in the 3 mg/L solution of cadmium.     

Activated carbon blended with grape stalks powder: Properties modification and its application in a dye adsorption

In this study, activated carbon was blended with grape stalks powder to adsorb methylene blue (MB) dye with various concentrations from a wastewater. For this purpose, five independent variables involving pH (2–13), contact time (5–270 min), grape stalks powder dosage (0.1–10 g/l), methylene blue initial concentration (20–300 mg/l), and activated carbon dosage (0.1–10 g/l) for methylene blue adsorption were studied. The Central Composite Design (CCD) under Response Surface Methodology (RSM) was applied to estimate the independent variables effects on the methylene blue adsorption. The pseudo- first order, pseudo-second order, Elovich and intraparticle diffusion models were employed to study the adsorption kinetics and isotherm. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models were applied to investigate the adsorption isotherm. It was concluded that the intraparticle diffusion isotherm and pseudo-second order kinetic models could show the best results. Furthermore, some data such as physical adsorption (by analyzing FTR and applying some standard equations) and mean free energy (E) were discovered in this research. Finally, activated carbon blended with grape stalks powder as an effective bio-adsorbent for the methylene blue reduction from a wastewater was introduced.     

Fabrication of SiO2/CuFe2O4/polyaniline composite: A highly efficient adsorbent for heavy metals removal from aquatic environment

A novel multifunctional of SiO₂/CuFe₂O₄/polyaniline composite was synthesized through the interaction between silica (SiO₂), copper iron oxide (CuFe₂O₄), and polyaniline (PANI) as starting materials. SiO₂/CuFe₂O₄/polyaniline composite was characterized for morphology, crystallinity, textural properties, and utilised for the removal of Fe(II), Mn(II), and Cu(II) from synthetic wastewater solutions. The roles of solution pH (2.0–6.0), interaction time (15–420 min), initial ion concentration (50–700 mg/L), and solution temperature (30–50 °C) in the adsorption process were investigated. The adsorption capacities of SiO₂/CuFe₂O₄/PANI for the tested metal ions were high compared to SiO₂, CuFe₂O_4, and polyaniline. Equilibrium studies indicated that Fe(II) and Mn(II) adsorption were compliant with the Langmuir model, while the Freundlich equation described the removal of Cu(II) ions. The maximum Langmuir capacities were up to 285.71, 416.67, and 454.55 mg/g for Cu(II), Fe(II), and Mn(II), respectively. The pseudo-first-order kinetic model fitted well the metal ions removal data. The rate-controlling step reflected the involvement of surface and inner pore diffusion (intraparticle) processes. Electrostatic attractions and chelation were mainly responsible for the binding of metals ions onto SiO₂/CuFe₂O₄/PANI. The selectivity of the studied ions was governed mainly by the hydrated ionic radii and the composite adsorption active sites. SiO₂/CuFe₂O₄/PANI can be easily reused with a slight decrease (around 2–3%) in metal removal efficiency after four successive regeneration cycles.     

Preconcentration and analysis of Rhodamine B in water and red wine samples by using magnesium hydroxide/carbon nanotube composites as a solid‐phase extractant

A convenient and accurate analysis approach that combined solid‐phase extraction and high‐performance liquid chromatography was developed to determine the amount of Rhodamine B in red wine and Xiang‐jiang river water samples. A novel composite, magnesium hydroxide/carbon nanotube composites, was synthesized and used as the solid‐phase extractant for the preconcentration/analysis of Rhodamine B. Magnesium hydroxide/carbon nanotube composites, which combined the merits of carbon nanotubes and magnesium hydroxide, exhibited acceptable adsorption and desorption efficiencies for Rhodamine B. The linear range of the proposed solid‐phase extraction with high‐performance liquid chromatography method for Rhodamine B was 0.05–20.0 mg/L, with a limit of detection of 3.6 μg/L. The precision and reproducibility of the developed solid‐phase extraction with high‐performance liquid chromatography method and the batch‐to‐batch reproducibility of the solid‐phase extractant were also validated at spiking levels of 0.5 and 2.0 mg/L. The recovery of Rhodamine B was 94.33–106.7%, and the recovery relative standard deviations of the intra‐ and interday precisions were ≤ 3.83 and ≤ 6.01%, respectively. The relative standard deviation of the batch‐to‐batch reproducibility was ≤ 7.98%.     

In situ self‐assembled reduced graphene oxide aerogel embedded with nickel oxide nanoparticles for the high‐efficiency separation of ovalbumin

A three‐dimensional reduced graphene oxide aerogel with embedded nickel oxide nanoparticles was prepared by a one‐step self‐assembly reaction in a short time. The nanoparticles could be captured into the interior of reduced graphene oxide network during the formation of the three‐dimensional architecture. The composite exhibited porosity, good biocompatibility, and abundant metal affinity binding sites. The aerogel was used to isolate ovalbumin selectively from egg white, and favorable adsorption was achieved at pH 3. An adsorption efficiency of 90.6% was obtained by using 1 mg of the composite for adsorbing 70 μg/mL of ovalbumin in 1.0 mL of sample solution, and afterwards a recovery of 90.7% was achieved by using an eluent of 1.0 mL Britton–Robinson buffer solution at pH 5. After the adsorption/desorption, ovalbumin showed no change in the conformation. The adsorption behavior of ovalbumin on the reduced graphene oxide composite well fitted to the Langmuir adsorption model, and a corresponding theoretical maximum adsorption capacity was 1695.2 mg/g. A sodium dodecyl sulfate polyacrylamide gel electrophoresis assay demonstrated that the aerogel could selectively isolate ovalbumin from chicken egg white.     

Kinetic and thermodynamic studies on the adsorption behavior of Rhodamine B dye on Duolite C-20 resin

The adsorption behavior of Rhodamine B dye from aqueous solutions was investigated onto the cation-exchange resin, Duolite C-20 (hydrogen form). The effects of various experimental factors; sorbent amount, contact time, dye concentration and temperature, were studied by using the batch technique. Lagergren pseudo-first-order equation shows good applicability with high correlation coefficients for all ranges of initial dye concentrations and at different temperatures. This equation was used to describe the kinetics of the dye adsorption process. The adsorption constants were evaluated by using both the Langmuir and Freundlich adsorption isotherm models. Thermodynamic parameters were obtained and it was found that the adsorption of Rhodamine B dye onto Duolite C-20 resin was an endothermic and spontaneous process at the temperatures under investigation.     

Chemical modification of activated carbon surface with iron functional groups for efficient separation of vanadium: batch and column study

In this study, iron functional groups-impregnated activated carbon (IIAC) composite was prepared as a novel adsorbent for vanadium separation. Adsorption experiments were performed in batch and column systems, and the effects of various operating parameters, such as solution pH, initial concentration, contact time, and temperature, were evaluated. The kinetic data confirmed the validity of the pseudo-second-order kinetic model for vanadium adsorption on IIAC. The sorption equilibrium data were analyzed using Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models. The results showed that IIAC has a vanadium ions adsorption capacity of 313 mg g^?1. The activation and thermodynamic parameters were determined using kinetics and equilibrium data. The experimental data of the column adsorption process were fitted by Thomas and BDST models. The results showed that Thomas model can well describe the breakthrough curves. The column experiments showed that IIAC composite has good adsorption performance for vanadium ions adsorption.

     

Surface Polymers on Multiwalled Carbon Nanotubes for Selective Extraction and Electrochemical Determination of Rhodamine B in Food Samples

In this study, we combine magnetic solid phase extraction (MSPE), with the screen-printed carbon electrode (SPCE) modified by a molecular imprinted polymer (MIP) for sensitive and selective extraction and electrochemical determination of Rhodamine B in food samples. A magnetic solid phase extraction (MSPE) was carried out using magnetic poly(styrene-co-divinylbenzene) (PS-DVB) and magnetic nanoparticles (MNPs) synthetized on the surface of multiwalled carbon nanotubes (MWCNTs). An MIP was prepared on the surface of MWCNTs in the presence of titanium oxide nanoparticles (TiO₂NPs) modifying the SPCE for the rapid electrochemical detection of Rhodamine B. The MIPs synthesis was optimized by varying the activated titanium oxide (TiO₂) and multiwalled carbon nanotubes (MWCNTs) amounts. The MSPE and electrochemical detection conditions were optimized as well. The present method exhibited good selectivity, high sensitivity, and good reproducibility towards the determination of Rhodamine B, making it a suitable method for the determination of Rhodamine B in food samples.     

Non-linear modelling of the adsorption of Indigo Carmine dye from wastewater onto characterized activated carbon/volcanic ash composite

Over the past couple of years, the resurgence of placing an effective and sustainable amendment to combat against the auxiliary industrial entities like Indigo Carmine (IC), remains a highly contested agenda from a global point. The birth of non-linear modelling for these auxiliary entities is also of significant interest in order to avoid loss of some useful information. With the renaissance of activated carbon (AC), the AC prepared from palm kernel shells (PKSAC) and composite prepared by combining the PKSAC and porous volcanic ash (BVA) from the foot of active volcanic mountain of Cameroon will be of significant contribution for ever increasing pollution problems. Non-linear modelling method was used to model the uptake capacity by adsorption process of IC onto PKSAC and PKSAC/BVA composite. Effects of contact time (0–60 min), adsorbent dose, pH of solution and initial dye concentration (10–20 ppm) were studied on the quantity removal of the hazardous IC dye from aqueous solution in a batch experiment. The prepared PKSAC and PKSAC/BVA composite were characterized using Nitrogen adsorption at 77 K (BET), Fourier transform Infrared spectroscopy (FTIR), Sacanning electron microscopy with energy dispersive X Ray (SEM-EDX), and particle size. The optimum IC uptake was 11.025 and 12.642 mg/g for PKSAC and PKSAC/BVA composites adsorbent respectively. Four Isotherms and kinetic non-linear regression models each were used to model the adsorption data. It results that for the isotherm models, the Langmuir and Freundlich isotherm models best fitted the adsorption phenomenon while pseudo-first and pseudo-second order kinetic models well described the adsorption mechanism. Furthermore, the adsorption speed constant (α) of the Elovich kinetic model being higher than the desorption coefficient (β) implies chemisorption was the dominant mechanism in the adsorption process. The composite shows 14.67% higher in retention capacity of the IC dye than the pristine carbon. Conclusively, the expanding of activated carbon/volcanic ash composite represents a potentially viable and powerful tool, leading to the plausible improvement of environmental preservation.     

Effect of micro-arc oxidation treatment on laser joint microstructures of Ti-6Al-4V alloy/CFRP

Resin-based carbon fibre reinforced composite (CFRP) with excellent properties has been widely applied in aerospace industry. In this study, polyether ether ketone enforced composite (PEEK-CFRP) and Ti-6V-4V titanium alloy had been joined by laser welding process. Micro-arc oxidation (MAO) process was conducted on the surface of titanium alloy to improve the joint property. Fractures and mechanical properties of joints were analysed. Interfacial microstructures of the joints had been investigated, and the formation mechanism of joint had been figured out. The results showed that after MAO treatment, the joint strength had been greatly improved and the shear strength reached to 42.3 MPa compared with pretreated sample. The wettability of CFRP on titanium alloy was rising with the contact angle of 68.8°. Fracture showed that cohesive failure contributed to the main fracture mode. As joints were formed by both mechanical bonding and chemical bonding, ‘anchor-shaped’ structures were found in the joint to enhance the mechanical bonding effects due to the flowing of the melted resin. (−OH) bonds were identified at the surface of MAO-treated titanium alloy that provided conditions for hydrogen bond interaction. TiO₂, TiO and Ti–V–C phase were found at interface, whereas Ti–F and Ti–O–F bonds were generated during the welding process, which made great contribution to the chemical bonds between titanium alloy and CFRP.     

Adsorption of organochlorine pesticides on modified porous Al30/bentonite: Kinetic and thermodynamic studies

Adsorption of pesticides (heptachlor epoxide, dieldrin and endrin) onto modified bentonite by Keggin cation [Al₃₀O₈(OH)₅₆(H₂O)₂₄]¹⁸⁺ denoted Al₃₀ cation to form composite (Al₃₀/B), has been investigated as a possible alternative method for their removal from aqueous solutions. The study was aimed to use a low-cost material as a step towards cleaner environment. Interestingly, these chemical modifications altered the physicochemical characteristics of bentonite in term of morphology, surface area and functionality which has been confirmed by using nitrogen adsorption–desorption isotherm, scanning electronic microscopy (SEM) and X-ray diffraction (XRD). Gas chromatography coupled to mass spectrometry (GC–MS) was used to identify and analyze the pesticides. Different physicochemical parameters were analyzed: contact time, adsorbent dose, pH, and temperature. The results showed that the removal percentage of pesticides on Al₃₀/B was the highest at contact time of 5 h, adsorbent dosage of 25 mg, at pH 7.5, and at optimum temperature of 45 °C. Furthermore, the Kinetic study indicated that the adsorption of pesticides on Al₃₀/B was well adapted to the pseudo-first order kinetic with a correlation coefficient near unity. The results of adsorption were fitted to the Langmuir and Freundlich isotherms. The Freundlich model represented the adsorption process better than Langmuir model, with correlation coefficients (R²) values range from 0.986 to 0.989. The Thermodynamic study suggested that the adsorption of pesticides was chemisorption, spontaneous and endothermic process. Therefore, Al₃₀/B composite can be utilized effectively for removal of pesticides with efficiency up to 98%.     

Preparation of BiVO4/MIL‐125(Ti) composite with enhanced visible‐light photocatalytic activity for dye degradation

Because of their desired features, including very specific surface areas and designable framework architecture together with their possibility to be functionalized, Metal Framework (MOF) is a promising platform for supporting varied materials in respect of catalytic applications in water treatment. In this work, a novel visible‐light‐responsive photocatalyst that comprised BiVO₄ together with MIL‐125(Ti), was synthesized by a two‐step hydrothermal approach. The characterization of as‐obtained samples as performed by X‐ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscope, X‐ray photoelectron spectroscopy and ultraviolet‐visible diffuse reflection spectra. Rhodamine B was selected being a target for the evaluation of the photocatalytic function of as‐developed photocatalyst. The photocatalytic reaction parameters, for example, the content of BiVO₄ as well as initial concentration of Rhodamine B was researched. The composite photocatalyst possessing Bi:Ti molar ratio of 3:2 brought to light the fact that the greatest photocatalytic activity had the ability to degrade 92% of Rhodamine B in 180 min. In addition to that, the BiVO₄/MIL‐125(Ti) composite could keep its photocatalytic activity during the recycling test. The phenomenon of disintegration of the photo‐generated charges in the BiVO₄/MIL‐125(Ti) composite was brought to discussion as well.     

Thorium adsorption on graphene oxide nanoribbons/manganese dioxide composite material

A functional graphene oxide nanoribbons/manganese dioxide composite material (MnO₂-GONRs) was synthesized by hydrothermal method using graphene oxide nanoribbons (GONRs) as raw material which were formed by longitudinal unzipping of multi-walled carbon nanotubes with KMnO₄ and H₂SO₄. The microstructure of MnO₂-GONRs was characterized by SEM and FT-IR. The various factors affecting the adsorption of Th(IV) in aqueous solution such as pH, solid–liquid ratio, contact time, initial concentration and temperature were investigated by batch static adsorption experiments, and the adsorption mechanism is also discussed. The results showed that MnO₂-GONRs had a good adsorption effect on Th(IV) with a maximum adsorption of 166.11 mg/g.

     

部分还原氧化石墨烯-Fe3O4对水中Mn(Ⅱ)的快速去除

采用改进的Hummers法制备了氧化石墨烯(GO), 继而用一步共沉淀法制备了部分还原氧化石墨烯-四氧化三铁复合物(PRGO-Fe₃O₄). 采用X射线衍射(XRD)、 场发射扫描电子显微镜(FESEM)、 X射线能量色散光谱(EDX)、 高分辨透射电子显微镜(HRTEM)、 选区电子衍射(SAED)及傅里叶变换红外光谱(FTIR)等技术对其进行了分析表征; 考察了pH值、 接触时间、 吸附材料用量、 共存物质、 GO的还原、 循环使用次数等因素对Mn(Ⅱ)吸附行为的影响. 结果表明, PRGO-Fe₃O₄中Fe₃O₄颗粒分布均匀, 大小为15~20 nm, 剩磁和矫顽力均很小. 因Fe₃O₄颗粒的锚定作用, 石墨烯片层很薄, 使PRGO-Fe₃O₄对Mn(Ⅱ)表现出高效的吸附性能和良好的循环使用性能: 当pH=7、 PRGO-Fe₃O₄用量为500 mg/g时, 对201.3211 mg/L的Mn(Ⅱ)溶液仅3 min即达吸附平衡, 吸附率和吸附量分别为99.35%和404.49 mg/g, 磁分离仅需10 s, 经5次循环吸附后, 容量保持率为首次的78%. 机理与热力学研究结果表明, 吸附为吸热、 自发的单层化学吸附.     

Metal–organic framework MIL‐125(Ti) for efficient adsorptive removal of Rhodamine B from aqueous solution

A metal–organic framework material, MIL‐125(Ti), was solvothermally prepared and characterized using X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and surface area measurements. MIL‐125(Ti) was then used as an adsorbent for Rhodamine B (RhB) removal in aqueous solution. The adsorption kinetics, adsorption mechanism, adsorption isotherm, activation energy and various thermodynamic parameters were studied in detail. The maximum adsorption capacity of MIL‐125(Ti) for RhB was 59.92 mg g^?1. MIL‐125(Ti) appears to be a promising material for RhB adsorption from aqueous solutions. Copyright © 2014 John Wiley & Sons, Ltd.     

Glycine‐functionalized reduced graphene oxide for methylene blue removal

Glycine‐functionalized reduced graphene oxide (GRGO) was prepared through the reaction of glycine and chlorine‐functionalized reduced graphene oxide. The product was characterized by SEM, HRTEM, IR, Raman, and XPS. The nitrogen content (8.28%) was high in product, peak at 285.8 eV was assigned to the C–N bond, which implied that the chlorine residues in raw material were substituted by amine group of glycine. The intensity ratio of D and G peak was about 1.5, which also implied that more saturated carbon atoms were present in the product. Results of SEM, IR, and XPS confirmed that glycine molecules were attached to graphene sheets. Compared with reduced graphene oxide (61.5 mg/g) and active carbon (45.2 mg/g), GRGO had a good adsorption capacity (98.9 mg/g) for methylene blue. The adsorption process was fitted to three kinetic models and three adsorption isotherm models. The adsorption process complied with pseudo‐second order kinetic model and Langmuir model.     

Effective sequestration of Congo red dye with ZnO/cotton stalks biochar nanocomposite: MODELING,reusability and stability

Widespread application of dyes and disposal of their untreated effluents into water bodies adversely affect the ecosystem due to their complex aromatic structures and persistent nature. The present study aims to utilize the cotton stalks biochar (CSB) and its composite with zinc oxide nanoparticles (CSB/ZnONPs) to evaluate for the decontamination their batch scale potential of Congo red dye from wastewater. The characterization of CSB and CSB/ZnONPs was performed with Fourier-transform infra-red (FTIR) spectroscopy, scanning electron microscopy, energy-dispersive X-ray (EDX) and point of zero charge (PZC) to get insight of their potential for the decontamination of CR. The effects of initial CR concentration (25–500 mg/L), dosage of CSB and CSB/ZnONPs (0.5–2 g/L), solution pH (2–10) and contact time (0–180 min) were evaluated on CR removal at temperature (25 ± 1.5 °C). The results disclosed that CSB/ZnONPs showed excellent adsorption potential (556.6 mg/g) in comparison with CSB (250 mg/g) and most of the other adsorbents previously studies in the literature. The equilibrium experimental data were equally explained with Freundlich and Langmuir isotherm models (R² > 0.98) while kinetic data demonstrated the best fit with pseudo second order model. The CSB/ZnONPs composite exhibited excellent reusability (89.65%) after five adsorption/desorption cycles for the sequestration of CR from contaminated systems. The present study demonstrated that metallic nanocomposite of CSB (CSB/ZnONPs) is an excellent candidate for the cost effective and environment friendly decontamination of CR from industrial wastewater and is suggested to be considered for the decontamination of other pollutants from the wastewater.