Mg Of Adsorbent Research Articles

Dinitrobutylphenol Removal from aqueous Environments by Synthesized magnetic particles from walnut hard-shell ash

<p>Dinitrobutylphenol is a toxic and resistant pollutant that pollutes the environment by producing toxins and chemical wastewater. Present paper aims to study the efficiency of the magnetic particles of walnut hard shell ash as a cheap and bi-compatible adsorbent for the removable of DNBP from aqueous environments. This study was conducted at laboratory scale and studied the most important parameters including contact time, pH, adsorbent dose, concentration of the pollutant and temperature on the efficiency of the process. Walnut hard shell ash was magnetized and its properties were studied using SEM, FTIR, XRD, and BET techniques. The fitness of the data was studied using Langmuir and Freundlich isotherms. Results showed that at pH=7, temperature 25°C , 700 mg of adsorbent, within 50 min, the removal efficiency of DNBP with the initial concentration of 20 mg reached 93%. The isotherm studies showed that this process with fitness coefficient of 99% conforms to Langmuir equation and it has higher conformity to maximum adsorption of 142.88 mg/g. Magnetic particles of walnut hard shell ashes as a natural bio-friendly and cheap adsorbent is able to efficiently remove DNBP as a toxic and persistent material from aqueous environments and industrial wastewaters.</p>

Design and preparation magnetic bio-surfactant rhamnolipid-layered double hydroxide nanocomposite as an efficient and recyclable adsorbent for the removal of Rifampin from aqueous solution

In this study, a magnetic core–shell rhamnolipid (MCSR) intercalated cobalt/aluminum layered double hydroxide (LDH) has been used for water remediation and rifampin (RIF) removal. Biosurfactants, including rhamnolipid (RL), exhibit advantages such as low toxicity and environmental compatibility. Moreover, rhamnolipid can promote the removal efficiency of the adsorbent. The effect of major factors on the adsorption process, including pH of the solution, initial RIF concentration, contact time, and adsorbent dosage were examined and optimized in detail. Accordingly, in acidic pH the adsorption efficiency was the highest because in this condition, OH functional groups of RIF molecules may be protonated leading to interacting with positively charged LDH layers. The results showed that the RIF removal efficiency is 96 %. According to the Langmuir model, the maximum adsorption capacity obtained for 0.67 g/L of adsorbent (20 mg of adsorbent in 30 mL of RIF solution) was 221.30 mg/g. In accordance with the modeling results, the Temkin isotherm better expresses the adsorption mechanism at the surface of MCSR-LDH. Furthermore, the kinetic data was better suited to the pseudo-first-order model, indicating that the solution reaches equilibrium between 20 and 30 min. Evaluation of thermodynamic parameters indicated the exothermic nature of adsorption process (ΔH° = −68362.70 J/mol). The magnetic property of MCSR-LDH leads to the easy recovery of the adsorbent by an external magnet at the end of the adsorption process, so that it can be regenerated for repeated cycles of at least four cycles without a significant decrease in efficiency.

Magnetic Beads of Zero Valent Iron Doped Polyethersolfun Developed for Removal of Arsenic from Apatite-Soil Treated Water.

The drop immerses calcium chloride aqueous solution was utilized to prepare the zero valent iron-doped polyethersulfone beads (PES/ZVI) for the efficient removal of arsenic from apatite-soil treated waters. The proposed beads can assist in promoting uptake efficiency by hindering ZVI agglomeration due to a high porosity and different active sites. The PES/ZVI beads were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetism (VSM). The main objective of this study was to investigate the function of new PES/ZVI beads with an increased removal efficiency for the remediation of arsenic ions from the apatite-soil treated waters. A maximum adsorption removal of 82.39% was achieved when the experiment was performed with 80 mg of adsorbent for a contact time of 180 min. Based on the results, a removal efficiency >90% was obtained after 300 min of shaking time with an arsenic concentration of 20 mg·L−1. The experimental process was fitted with the Langmuir model due to the high R2 (0.99) value compared to the Freundlich model (0.91) with an adsorption capacity of 41.32 mg·g−1. The adsorption process speed was limited by pseudo-second-order (R2 = 0.999) and the adsorption mechanism nature was endothermic and physical.

Preparation of sulfonic acid-functionalized polymeric ionic liquid-based magnetic adsorbent and its applications to diquat extraction

有效萃取复杂食品样品中的极性污染物是实现其准确测定的瓶颈,也是食品安全分析的难点。针对污染物的结构特点,设计和发展能与之产生特定作用的新型材料是高效萃取的关键。敌草快是一种广谱性除草剂,为碱性的阳离子有机化合物。该文以1-乙烯基咪唑和1,3-丙磺酸内酯为原料合成了磺酸功能化的离子液体,通过自由基聚合反应,将其固载至磁性纳米颗粒表面,得到磺酸功能化的聚(1-乙烯基-3-丙基磺酸基咪唑氯盐)修饰的磁性纳米颗粒(Poly([VPImi-SO3H][Cl])-MP)。采用红外光谱、扫描电镜、振动样品磁强计和热重分析等对其结构、形貌和磁性进行了表征。将其作为磁性固相萃取的吸附剂,萃取青菜中的敌草快。磺酸基的功能化使Poly([VPImi-SO3H][Cl])-MP的表面在一定pH下带有丰富的负电荷,与敌草快之间产生强的静电吸引作用,可实现对敌草快的有效萃取。对影响萃取效率的各种参数如溶液pH、吸附剂质量、吸附时间、解吸剂种类和体积等进行了优化。在优化条件下,结合磁性固相萃取和高效液相色谱技术,对方法的性能及适用性进行了考察。敌草快在0.2~20 μg/g内具有良好的线性(r=0.9981),检出限(S/N=3)和定量限(S/N=10)分别为0.09 μg/g和0.2 μg/g; 3个水平(0.5、1.0和2.5 μg/g)下的加标回收率为82.7%~97.5%,相对标准偏差为2.8%~5.0%(n=3)。结果表明,磺酸功能化的Poly([VPImi-SO3H][Cl])-MP能快速、有效地萃取敌草快,建立的方法能用于青菜中敌草快的准确测定。

A rapid removal of xylene from air based on nano-activated carbon in the dynamic and static systems and compared to commercial activated carbon before determination by gas chromatography

As main air pollutants, volatile organic compounds (VOCs) must be paid special attention. In this study, the removal efficiency of xylene from the air was investigated by nano-activated carbons (NACs) as an efficient adsorbent and compared to commercial activated carbons (ACs). In the chamber, the xylene vapor in pure air was generated, stored in the airbag (5 Li), and moved to adsorbents. Then, the xylene vapor was absorbed on the NAC/AC adsorbents and desorbed from it by a heat accessory. The efficiency of xylene removal with NACs and ACs was investigated in the dynamic and static systems based on 100-700 mg L-1 of xylene, flow rates of 100 ml min-1, and 100 mg of adsorbent at a humidity of 32% (25°C). Xylene concentrations were determined by gas chromatography equipped with a flame ionization detector (GC-FID). In the batch system, the maximum absorption capacity for NACs and ACs was obtained at 205.2 mg g-1 and 116.8 mg g-1, respectively. The mean adsorption efficiency for NACs and ACs adsorbents was obtained at 98.5% and 76.55%, respectively. The RSD% for NACs ranged between 1.1-2.5% in optimized conditions. The characterizations of the NACs adsorbent showed that the particle-size range was between 35-100 nm.

Effective removal of highly toxic Pb2+ and Cd2+ ions using reduced graphene oxide, polythiophene, and silica-based nanocomposite

The purpose of this study is to develop a highly capable reduced graphene oxide, polythiophene, and silica-based low-cost composite material and investigate its adsorption behavior. The synthesized composite was analyzed using various analytical methods and applied to eliminate highly toxic metallic pollutants from contaminated water. Different adsorption parameters were used to decontaminate the wastewater. The best conditions for removing Pb2+ and Cd2+ ions were obtained. The adsorption efficiency was determined to be 65.9 (±0.9) % and 61.5 (±1.4) % at contact time of 60 minutes, 75.9 (±0.7) % and 76.1 (±0.8) % at 105 mg of adsorbent, 98.7 (±0.7) % and 93.2 (±0.6) % at pH 6 for Pb2+ and Cd2+ ions. The adsorbent was re-utilized up to three times with good adsorption effectiveness. A thermodynamic study has indicated the spontaneity of the adsorption process. The pseudo second order rate constant were found to be 19.1 (±1.5) and 16.5 (±1.7) g/mg/min for Pb2+ and Cd2+ ions, respectively.

Evaluation of removal of acid dyes using PAM-FeSO4 hybrid polymer as flocculant

PurposeIn this study, the removal of a series of acid dyes by hybrid polymer adsorbent was investigated. Textile industry wastewater is mainly consisted of suspended solid particles and organic compounds with complex and nondecomposable structures. Treatment of such wastewaters has received much attention by researchers because of high water consumption and the presence of various chemical compounds, especially dyes. The use of polymers has recently attracted much attention for the treatment of textile wastewaters. According to the literature, hybrid polymers are highly capable of adsorbing dyes. In this research work, polyacrylamide/iron sulfate (PAM-FeSO4) hybrid polymer was successfully synthesized through solution polymerization of acrylamide with ammonium persulfate and sodium thiosulfate and gradual addition of iron sulfate. The hybrid polymeric adsorbent was then used for removing acidic dyes with different chemical structures.Design/methodology/approachThe effects of various experimental conditions and parameters, such as initial concentrations of dye and adsorbent, on the adsorption capacity of the adsorbent were investigated. The dye concentration was measured by an UV–vis spectrophotometer. The adsorption equilibrium was studied by plotting adsorption isotherms. The experimental data was fitted to Langmuir and Freundlich isotherms.FindingsThe adsorption experiments indicated that the PAM-FeSO4 hybrid polymer has a high adsorption capacity (117.64 mg g−1 for the Orange ІІ and 80.64 mg g−1 for the Sunset Yellow [SY]) when 80 mg of adsorbent was immersed in the dye solution (1 g L−1) with a pH of 11 at 25°C. The analysis of the equilibrium isotherms using the Langmuir and Freundlich isotherms indicated that the Langmuir model fit well to the experimental data.Originality/valueTo the best of the authors’ knowledge, this study is original. The removal of acid dyes such as Sunset Yellow and Methyl Orange using PAM-FeSO4 hybrid polymer as flocculant was done for the first time.

Magnetic solid-phase extraction of bisphenol A from water samples using nanostructured material based on graphene with few layers and cobalt ferrite

In this study, magnetic hybrid materials composed of cobalt ferrite, natural organic matter, and graphene (CoFe2O4/NOM/graphene) were synthesized and applied as adsorbents in the magnetic solid-phase extraction (MSPE) of bisphenol A (BPA) from aqueous matrices. To our knowledge, no studies have been previously conducted using this material for MSPE. Techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and transmission electron microscopy (TEM) were used to investigate the composition and morphology of the adsorbent. The MSPE method was optimized considering the main parameters influencing the process, with the best results obtained using 50.0 mg of adsorbent, agitation at 150 rpm, total extraction time of 7.5 min, 10 mL of methanol as extractant, and pH between 4 and 10. BPA analysis was performed using HPLC-DAD and HPLC-FL, with the latter showing better sensitivity. The developed method provided a wide linear range from 0.1 to 5000 μg L−1, with limits of detection (LOD) and quantification (LOQ) of 0.022 and 0.072 μg L−1, respectively. The extraction procedure presented reproducibility (RSD) of 2.13–2.21% and excellent recoveries in the range 99.3–104%. The developed MSPE method using CoFe2O4/NOM/graphene proved to be simple, fast, and efficient for the analysis of BPA in a variety of aqueous matrices.

Sustainable green functional nano aluminium fumarate-MOF decorated on 3D low-cost natural diatoms for the removal of Congo red dye and fabric whitening agent from wastewater: Batch & continuous adsorption process

Industrial contaminants such as dyes being released into water streams, making the water unfit for the domestic purposes. Treatment of such dye contaminants still remains as a challenge which transformed as leading issues in environment remediation. Some of the important limitations involved in the dye adsorption includes cumbersome synthetic routes, high cost adsorbents, more contact time, lack of efficiencies and usage of more adsorbents. To address these drawbacks, present work involves facile surface modification of 3D diatoms (DE) with 2D aluminium fumarate metal-organic framework (Al-MOF) as a sustainable approach to obtain hybrid materials for the removal of industrial important toxic dyes. It is significant to note that the surface area of diatoms increased dramatically from 16.6 to 1330.8 m2g−1 revealing that the surface modifications with Al-MOF played a significant role in tuning the surface properties of DE. The developed hybrid materials were investigated for batch adsorption studies for the removal of CR dye which displayed outstanding 98.13% removal efficiency for just 20 mg of adsorbent with rapid contact time of 15 min. Moreover, the maximum adsorption capacity (qm) was found to be 181.82 mg/g, which is of better significance. Further, hybrid materials were adapted as powder-based membranes a continuous flow adsorption studies where 100 mg of materials showed excellent 99.65% of rejection performances with flux rate of 1747.1 Lm−2h−1. To demonstrate their capability in real-time sample analysis, 100 mg of hybrid materials were used for the removal of fabric whitening agent through batch adsorption and continuous flow studies exhibited with effective 94% and 99.2% efficiencies respectively. Additionally, the reusability test of adsorbents showed it could be used up to 6 cycles where the adsorbents can be regenerated with facile methanol wash. The developed hybrid materials could be one of the potential candidates for the removal of hazardous textile dye from wastewater since the adsorbent displayed rapid adsorption, efficient removal, utilization of minimal adsorbents, better reusability and finally substantiated with real time sample analysis.

Mechanism adsorption analysis during the removal of Cd2+ and Cu2+ onto cedar sawdust via experiment coupled with theoretical calculation: Mono- and multicomponent systems

In this work, a deeper comprehension of the adsorption phenomena for Cd2+ and Cu2+ occurring in mono- and multicomponent systems on an adsorbent material obtained from cedar sawdust was accomplished by using spectroscopic characterization, and computational tools. The adsorbents were prepared by a simple calcination process at 300, 400, and 500 °C or pyrolysis at 300 °C. The experimental results showed that the adsorption capacity of the CS-C-400 adsorbent is higher for Cd2+ (36 mg g−1) than Cu2+ (15 mg g−1) ions in monocomponent systems (50 mg of adsorbent, 50 mL of solution, pH = 5, 25 °C, 200 rpm, and 72 h). In contrast, the trend for the adsorption capacity was Cu2+ > Cd2+ in most of the concentrations for multicomponent systems, due to that Cu2+ showed greater antagonism to Cd2+ during the competitive adsorption (qCd2+ was 96 % reduced). Computational results correlated well with the experimental ones and evidenced the occurrence of complexation interactions between metal ions and the surface oxygenated functional groups (hydroxyl, carboxyl, ester, and ether) onto the adsorbent surface, as was also proposed through spectroscopy results. Computational and experimental results indicate that Cd2+ and Cu2+ adsorption on the adsorbent surface is governed by the occurrence of complexation, and π-cation interaction for both ions, while ionic exchange plays a significant role in Cd2+ adsorption.

Functionalization of unzipped multi-walled carbon nanotube oxides with l-tyrosine for the adsorption of methylene blue

The present study was carried out to understand the ability of functionalized unzipped multi-walled carbon nanotube oxides for methylene blue dye adsorption. Parameters that influence the dye adsorption efficiency such as amount of adsorbent, adsorption time, stirring speed and pH of solution were optimized. Dye removal efficiency of 99.8% and maximum adsorption capacity of 420.14 mg/g were obtained with the optimum conditions such as 20 mg of adsorbent, pH 7–9 of the solution and stirring speed of 400 rpm for 15 min. The results from the kinetic study revealed that the adsorption of methylene blue dye on the prepared nano-adsorbent followed pseudo-second-order kinetic model. Langmuir isotherm was found to be best fit for the adsorption of methylene blue dye with functionalized nano-particles. Also, the reusability study showed a dye removal efficiency of 94% even after six cycles of adsorption–desorption. The nano-particles produced in the present study are found to be an effective adsorbent for the removal of methylene blue dye from waste water.

Scavenging of hexavalent chromium from aqueous solution by Macadamia nutshell biomass modified with diethylenetriamine and maleic anhydride

Based on the premise that aqueous anions of hexavalent chromium (Cr(VI)) are capable of electrostatic interaction with cationic and polar active sites, acid-washed Madacamia nutshell biomass was sequentially treated with diethylenetriamine (DETA) and maleic anhydride (MA) to graft poly(diethylenetriamine–co–maleic anhydride). By displaying a new peak at 1685 cm−1 ascribed to amide CO stretching vibrations, Fourier transform infrared spectroscopy highlighted the formation of amide groups through reaction of DETA with carboxyl groups on the biomass surface. Scanning electron microscopic images of the MA-modified biomass displayed polymeric growths attributed to copolymerization of DETA with MA. The polar and ionizable amide and amine groups of the grafted copolymer endowed the adsorbent with Cr(VI) removal capabilities over a wide pH range demonstrated by removal efficiencies between 70.9% and 81.7% in the pH 1.6 to pH 10.0 range for the treatment of 20 mL solutions containing 100 mg L−1 Cr(VI) with 200 mg of adsorbent. Conformity of the adsorption isotherm data to the Freundlich model revealed the heterogeneous nature of the adsorbent surface, which comprised a variety of functional groups capable of interaction with Cr(VI) species in solution. The Sips isotherm model provided the best fit to the equilibrium experimental data, and the adsorption capacity was 779.1 mg g−1 at pH 1.6, room temperature and an adsorbent dosage of 5.0 g L−1. The findings indicate that Cr(VI) adsorption onto diethylenetriamine and maleic anhydride modified Madacamia nutshell biomass is a promising option for Cr(VI) removal from aqueous solutions.

Functional metal–organic framework as high-performance adsorbent for selective enrichment of pharmaceutical contaminants in aqueous samples

Facile and sensitive analysis methods for pharmaceutical contaminants in aqueous environment are of vital importance for water safety, especially when large amounts of anti-viral drugs are being used, discharged and accumulated. In this work, we used functional metal–organic framework (MOF) as high-performance adsorbent for selective enrichment of such pharmaceutical contaminants in aqueous samples. The MOF was synthesized via a new synthesis method previously developed by our group and immobilized on paper membrane to be used in solid-phase extraction (SPE) device. Different metal ions were anchored by MOF to screen out the adsorbent with the best affinity. The targets were a potential anti-COVID-19 drug favipiravir, and its structural and functional analogues (ingredients or intermediates, other anti-viral drugs). To deeply understand the adsorption mechanisms, quantum calculation and computational fluid dynamics (CFD) simulation were both applied. The experimental and in-silico results together demonstrated that the as-prepared MOF adsorbent possessed high affinity and fast dynamics. The established SPE-based liquid chromatography (LC) method worked well in the range of 10–1000 ng/mL, with only 3 mg of adsorbent per device and 5 mL sample needed, and no mass spectrometer (MS) included, which was very efficient compared to commercial adsorbents. The results met the current detection needs in the application scenario, and inspirable for later design of well-behaved adsorbents.

Facile One Pot Synthesis of Thiocarbamoyl Chitosan for the Adsorptive Elimination of Hexavalent Cr (VI) Ions

The industrial effluents include heavy metals such as Cr, Pb, Hg,Cu, Ni etc. which are affecting ecosystem and have harmful effects on mankind. Biopolymers like chitosan have been extensively applied for waste water treatment. Use of thio urea and glutaraldehyde to make thiocarbamoyl chitosan was investigated for removal of chromium ion from aqueous solution. TC-CS was characterized by various spectrometric techniques such as FTIR, SEM, EDX, BET and pHzpc. It was observed that 94% of metal ions have been removed within the first 2 hrs after contact with bio-sorbent. The adsorption study indicates that the removal rate of Cr (VI) ions from aqueous solution by TC-CS sorbent was excellent and up to 1.06 mmol/gm (56.18 mg/gm). The removal efficiency was dependent on solution-pH, contact time, adsorbent dose and initial metal concentration. The highest adsorption was found at pH 6 at 100 mg of adsorbent. Adsorption kinetics data followed pseudo second order kinetic model with linear coefficient of 0.9997. The adsorption process could be described well by Langmuir isotherm (R2=0.9860) suggesting favourable adsorption through homogeneous monolayer adsorption.

Cellulose from Tamarix aphylla’s stem via acetocell for cadmium adsorption

This study emphasized the efficiency of unconventional delignification treatment “Acetocell” as a basic pretreatment to isolate cellulose fiber from Tamarix aphylla’s stem. Chemical proprieties of obtained cellulose were determined and its efficiency for cadmium ions adsorption was evaluated subsequently. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis, thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), fluorescence microscope and Morfi were used to analyze the thermochemical and morphological characteristics of the fibers before and after treatment. Cellulose was used as a biosorbent to remove cadmium ions from polluted water. The effects of many parameters on the efficiency removal of cadmium were investigated; the amount of cellulose, the contact time, pH and the initial concentration of cadmium ions. The optimum conditions were 45 mg of adsorbent, 45 mg L−1, 1200 min and pH 8 which provide best adsorption capacity equal to 44.21 mg g−1. The energy value E = 6.65 kJ mol−l which confirm the physical interaction between cellulose-cadmium ions. Then Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models were followed for modeling adsorption. Langmuir isotherm and the pseudo-second order model seems the most suitable which describe better the adsorption of cadmium ions with best R2 values which equal to 0.9937 and 0.9979, respectively.

In-tip solid-phase microextraction: a method for determination of sulphonamide residues in environmental water samples

ABSTRACT This study involved the development of an in-pipette tip solid-phase microextraction (SPME) method using activated charcoal as an adsorbent. Simultaneous determination of three sulphonamide antibiotic residues in environmental water was performed using this method, coupled with high-performance liquid chromatography-photodiode array (HPLC-PDA) detection. Seven extraction parameters were optimised by one-variable-at-a-time (OVAT) and response surface (RSM) methods. Optimum extraction efficiency was achieved when 10 mL of sample solution at a natural pH (pH 5–6) was loaded through a 1 mL pipette tip packed with 10 mg of adsorbent, washed with 1 mL of hexane and eluted with 500 µL of 1% ammonium in methanol solution. Under the optimised experimental condition, this method manifested good linearity (5–500 µg L−1) at the coefficient of determination, R2 of 0.9992 to 0.9993, high sensitivity (limit of detection, LOD: 0.38–1.14 µg L−1; limit of quantification, LOQ: 1.14–3.35 µg L−1), and satisfactory recoveries (82.8–108.7%) with acceptable reproducibility (RSD < 4.6%). Real sample analysis of five environmental water samples sourced from Universiti Malaya, Kuala Lumpur and Malacca showed that the samples contained either none or traces of the target sulphonamides (SAs) with their concentration lower than the LOQs. In contrast to other methods, the comparison outcomes depicted that this in-tip SPME method was beneficial in terms of its simple, reusable, cost-saving setup together with a significant reduction in chemical consumption.

Preparation of shrimp-based chitin blend with polyaniline for chromium (VI) removal from aqueous solution

Heavy metals are major constituent of environmental pollution. Among the heavy metals, chromium (Cr) has received widespread attention due to its constant presence in the water body beyond the permissible limit. Hence, the present work discusses about the preparation of shrimp-based chitin/polyaniline composite that synthesized via in-situ chemical oxidative polymerization. A higher % yield of 80.53 % was derived from shrimp shells. The prepared composite was characterized via Fourier transform infrared (FTIR) and ultraviolet–visible (UV–Vis) spectroscopic techniques. Then, shrimp-based chitin/polyaniline was optimized in terms of pH, contact time and amount of adsorbent in the removal % of Cr (VI) from aqueous solution. The results suggests that, pH = 1, 20 mins of contact time and 10 mg of adsorbent is the most optimum condition for Cr (VI) removal from aqueous solution.

Facile sol-gel synthesis of calcium oxide nanoparticles for effective removal of Ni(II) from aqueous solution

ABSTRACT In this study, nanoparticles of calcium oxide (CaO-NPs) were prepared via the sol-gel technique and introduced as a highly efficient adsorbent for removing Ni(II) from aqueous media. The prepared adsorbent was characterised via SEM, TEM, FTIR, XRD, and TGA. The pHzpc and surface area were also determined. XRD pattern exposed a polycrystalline nature of the adsorbent. SEM analysis showed that the adsorbent possesses enhanced surface porosity highlighting its potential capacity for adsorption. TEM analysis confirmed the crystallisation of adsorbent with a simple cubic structure. The FTIR spectrum displayed that the adsorbent surface comprises mostly (–OH and C=O) groups which are principally accountable for the adsorption of Ni(II). A series of batch adsorption experiments were done to study the effect of several parameters as pH, adsorbent dose, time of contact, initial concentration of adsorbate, temperature, ionic strength, and presence of interfering ions on the removal of Ni(II) ions from aqueous solutions using CaO-NPs. Maximum removal was obtained with 200 mg of adsorbent after 90 min contact time at pH 7 and 25°C as optimal conditions. The adsorption process was fitted well with Langmuir isotherm model and pseudo-second-order kinetic model, showing that the adsorption of Ni(II) ions on CaO-NPs was monolayer coverage with 166.67 mg/g capacity of adsorption. Thermodynamic studies revealed a spontaneous and endothermic adsorption process. The regeneration study using Na2EDTA indicated that the prepared adsorbent has a high renewal potential without notable loss in its performance. Moreover, the prepared adsorbent proved its good applicability and performance by successful application of the suggested procedure for the recovery of Ni(II) added to some real water samples. Accordingly, the obtained results showed that CaO-NPs can rapidly and efficiently remove Ni(II) from aqueous solutions. Also, CaO-NPs adsorbent is eco-friendly, easy to produce, cost-effective, non-toxic, and with good adsorption-desorption capacity. Therefore, this study will contribute to ecological cleaning and wastewater treatment.

Fabrication of MNPs/rGO/PMMA Composite for the Removal of Hazardous Cr(VI) from Tannery Wastewater through Batch and Continuous Mode Adsorption.

Herein, we report the synthesis of magnetic nanoparticle (MNP)-reduced graphene oxide (rGO) and polymethylmethacrylate (PMMA) composite (MNPs/rGO/PMMA) as adsorbent via an in situ fabrication strategy and, in turn, the application for adsorptive removal and recovery of Cr(VI) from tannery wastewater. The composite material was characterized via XRD, FTIR and SEM analyses. Under batch mode experiments, the composite achieved maximum adsorption of the Cr(VI) ion (99.53 ± 1.4%, i.e., 1636.49 mg of Cr(VI)/150 mg of adsorbent) at pH 2, adsorbent dose of 150 mg/10 mL of solution and 30 min of contact time. The adsorption process was endothermic, feasible and spontaneous and followed a pseudo-2nd order kinetic model. The Cr ions were completely desorbed (99.32 ± 2%) from the composite using 30 mL of NaOH solution (2M); hence, the composite exhibited high efficiency for five consecutive cycles without prominent loss in activity. The adsorbent was washed with distilled water and diluted HCl (0.1M), then dried under vacuum at 60 °C for reuse. The XRD analysis confirmed the synthesis and incorporation of magnetic iron oxide at 2θ of 30.38°, 35.5°, 43.22° and 57.36°, respectively, and graphene oxide (GO) at 25.5°. The FTIR analysids revealed that the composite retained the configurations of the individual components, whereas the SEM analysis indicated that the magnetic Fe3O4–NPs (MNPs) dispersed on the surface of the PMMA/rGO sheets. To anticipate the behavior of breakthrough, the Thomas and Yoon–Nelson models were applied to fixed-bed column data, which indicated good agreement with the experimental data. This study evaluates useful reference information for designing a cost-effective and easy-to-use adsorbent for the efficient removal of Cr(VI) from wastewater. Therefore, it can be envisioned as an alternative approach for a variety of unexplored industrial-level operations.

Electrosynthesis of metal-organic frameworks (MOFs) using 4,4′methylene dianiline polymer and metals (Al, Cu, and Fe) for imidacloprid pesticide adsorption in the aquatic environment

ABSTRACT Extensive use of imidacloprid in pest control and its unfavourable removal efficiency has resulted contamination of aquatic environments. Herein, 4,4ʹ-methylenedianiline nano-polymer (MDANP) as organic linkers and Cu, Fe, and Al as metal sources were used to synthesise several metal-organic frameworks (MOFs) nanomaterials. Three MOFs (MDANP/Cu, MDANP/Fe, and MDANP/Al) were synthesised by the electrochemical polymerisation method and used as a nano-adsorbent to remove imidacloprid from the aqueous environment. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), transient electron microscopy (TEM), and Field-scattering scanning electron microscopy (FE-SEM) techniques were used to analyse physicochemical characteristics of produced MDANP and MOFs. Kinetic data have been fitted with pseudo-second-order models; according to the obtained correlation coefficients (R2 = 0.9993). Adsorption isotherm models suggested that except imidacloprid adsorption on MDANP, which was best explained by the Freundlich model (R2 = 0.9018), pesticide adsorption from MOFs was well explained by the Langmuir model (R2 = 0.9473). The removal efficiency of imidacloprid onto MDANP and MOFs decreased from 65.28% to 40.25% and from 61.56% to 36.89%, respectively, as the initial concentration of imidacloprid increased from 25 to 400 mg/L. The results showed that the highest adsorption of imidacloprid happens within 120 min for 150 mg of adsorbent. Under optimum conditions, a maximum adsorption capacity of 97.4 mg/g occurred. Thus, MDANP and MOFs have medium potential for environmental implications and can be exploited as nano-adsorbents of imidacloprid pesticides in aquatic environments.