Pseudo-second Order Reaction Research Articles

Characterization and Removal of Nickel (II) from Paint Industry Effluent by Rice Husk Adsorbent

Rice husk adsorbent was studied to assess its efficiency in adsorption of nickel from paint industry effluent and to derive vital parameters that would assist in making timely decisions in tertiary treatment of wastewater. Standard methods were used in conducting the experiments. Results showed that significant adsorption of 84.77% of nickel was removed by carbonized rice husk (CRH) in 10 minutes and 98.42% in 60 minutes, a difference of 13.65%. Optimum pH of 8 was observed as 98.91% of nickel was adsorbed. Slight change in the adsorption efficiencies was noticed between 0.2 g and 0.4 g doses of CRH adsorbent, but reasonable and insignificant change occurred between 0.4 g and 1.0 g doses. Langmuir isotherm plot showed that separation factor was 0.998 an indication of favorable adsorption and a good fit for the Langmuir isotherm model. Therefore, the adsorption process was better described by the Langmuir equilibrium isotherm model. Adsorption intensity of 2.02 was observed in the Freundlich model, a value greater than 1.0 an indication of unfavorable adsorption. Lagergren pseudo first- and second-order plots showed that R2 = 0.799 for pseudo first-order and R2 = 0.969 for pseudo second-order reactions, an indication that adsorption of nickel by CRH follow Lagergren second-order kinetic. FTIR spectra identified N-H, O-H, C=H, C=O, C=C-C, C-Cl, P-O-C, and cis-C-H out-of-plane bend stretching bands as the functional groups involved in nickel adsorption by CRH adsorbent. It was concluded that rice husk is a good adsorbent in tertiary treatment of wastewater.

Application of layered double hydroxide enriched with electron rich sulfide moieties (S2O42−) for efficient and selective removal of vanadium (V) from diverse aqueous medium

The preparation of an adsorbent with highest efficiency, selectivity and stability is usually a challenging task. Herein, we prepared a thio functionalized layered double hydroxide (LDH) denoted as S2O4 LDH by intercalating a strong reducing agent (S2O42−) in the interlayers of trimetallic LDH and was applied to capture vanadium (V(V)) oxyanions from aqueous medium of diverse conditions. The successful preparation of the adsorbent was first confirmed using XRD, FTIR, EDX and CHS analyses. The results revealed that the modified LDH showed excellent performance at a wider pH range which can avoid the tedious work of adjusting pH in actual industrial wastewater treatment. The adsorption capacity was increased with temperature and obtained 379.55 mg/g at 323 K comparing to 112.3 mg/g at 293 K. The adsorption isotherm was better fitted to Langmuir model which suggested monolayer adsorption behavior. At lower temperature (293 K), the sorption kinetics were fitted to a pseudo-first order reaction model which implied physisorption reaction while at higher temperatures (303 and 323 K), the reaction order fitted to pseudo-second order reaction model which highlighted the chemisorption reaction mechanism. As confirmed using XRD, FTIR, EDX and XPS instrumental techniques, the dominant removal mechanism of V(V) involved ion-exchange and partial reduction reactions to nontoxic and less soluble V(IV) and V(III) species due to the low valent sulfur group and followed adsorption in S2O4 LDH. The prepared adsorbent showed very good selectivity towards V(V) in the presence of different co-existing ions both in synthetic wastewater and spiked real water samples. This novel adsorbent also exhibited high recyclability and obtained >90.0% removal of V(V) after four consecutive adsorption–desorption cycles due to the unique memory effect of the LDH. We believe that this strategy provides a new direction to find highly efficient and selective materials for capturing vanadium ions from wastewater of diverse conditions.

Adsorption performance of the polystyrene/montmorillonite composites: Effect of plasma treatment

Polystyrene/montmorillonite (PS/MMT) composite films with high adsorption activity were prepared via solution intercalation technique followed by treatment of composite films in low-pressure air plasma. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used to investigate the impact of plasma on the elemental composition and morphology of the composite surface. It was revealed that plasma treatment of the PS/MMT composite led to an increase in wettability and adsorption performance. The removal kinetics of methylene blue dye from aqueous solutions was experimentally studied. It was determined that plasma processing of the composite resulted in a significant improvement of the MB adsorption process: the initial rate of the process increased by 4 times (from 1.2 × 10−8 to 4.8 × 10−8 mol/(g•min)). Adsorption kinetic curves are obeyed the pseudo-second order reaction equation.

Removal of Congo Red Dye From Aqueous Solution Using Eco-Friendly Adsorbent of Nanosilica

The development of a new, cheap, efficient, and ecofriendly adsorbents has become an important demand for the treatment of waste water, so nano silica is considered a good choice. A sample of nanosilica (NS) was prepared from sodium silicate as precursor and the nonionic surfactant Tween 20 as a template. The prepared sample was characterized using various characterization techniques such as FT-IR, AFM, SEM and EDX analysis. The spectrum of FTIR confirms the presence of silica in the sample, while SEM analysis of sample shows nanostructures with pore ranging (2-100nm).The adsorptive properties of this sample were studied by removing Congo red dye (CR) from aqueous solution. Batch experimental methods were carried out at room temperature (25⁰C) to study the different variables which affect the adsorption process like: NS amount, initial concentration of CR, and contact time. The results were 0.2 g of NS/50 ml of dye solution and 60 min contact time to reach equilibrium. The experimental results at equilibrium were analyzed using Langmuir and Freundlich adsorption isotherms and showed the best fitted with Freundlich model which reveal heterogeneity of the surface of NS adsorbent. Kinetics aspects were also investigated by evaluating parameters from pseudo- first and pseudo-second order reaction equations on adsorption rate which show good fitting with both kinetics equations, but pseudo-second order equation was the best to describe the kinetics parameters. The adsorptive properties of this sample were studied by removing Congo red dye (CR) from aqueous solution. Batch Experimental methods were carried out at room temperature (25⁰C) to study the different variables which affect the adsorption process like: NS amount, initial concentration of CR, and contact time. The experimental results at equilibrium were analyzed using Langmuir and Freundlich adsorption isotherms and show best fitted with Freundlich model which reveal heterogeneity of the surface of NS adsorbent. Kinetics aspects was also investigated by evaluating parameters from pseudo- first and pseudo-second order reaction equations on adsorption rate which show good fitting with both kinetics equations, but pseudo-second order equation was the best to describe the kinetics parameters.

Study on Adsorption Performance of MgO/Calcium Alginate Composite for Congo Red in Wastewater

This research prepared a poly-functional material which has outstanding adsorption performance and easily recyclable for Congo red dye removal. The multifunctional gel yarn composed of calcium alginate and nano-magnesium oxide was prepared by wet spinning. For the morphology and structure of MgO/CA composite, the compound product was characterized by Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). Then, the adsorption performance of MgO/CA aerogel for Congo red was studied, including the influence of four factors (adsorbent dosage, pH, initial concentration, contact time), adsorption isotherm, adsorption kinetics and adsorption thermodynamics. The results show that the adsorption properties of MgO/CA aerogel on Congo red largely depend on these factors. The best contact time for MgO/CA aerogel to remove Congo red is 24 h. Besides, the maximum adsorption capacity of the adsorbents is usually very high (312.5, 322.6 and 344.8 mg/g at 303, 313 and 323 K, respectively). The adsorption kinetics can be best described by a pseudo second-order reaction, and the adsorption data agree well with the Langmuir model. Thermodynamic parameters including the changes in entropy (ΔS0), free energy (ΔG0) and enthalpy (ΔH0), and stated that adsorption by the MgO/CA aerogel was endothermic and spontaneous.

Preparation and characterization of SiO2@C nanocomposites from rice husk for removal of heavy metals from aqueous solution

This study focused on preparation and characterization of two activated SiO2@C nanocomposites from rice-husk waste material through a controlled method. Both of them contain different percentages of silica and carbon. After chemical and thermal activations of the prepared composites, high energy ball milling was utilized to prepare nano powders. The percent of silica in the prepared nanocomposites was determined by HF method. Moreover, their chemical compositions were determined by XRF technique. The prepared materials were also examined by x-ray diffraction technique, FT-Infrared, scanning electron microscope, high resolution transmission electron microscope, Zeta Sizer, and Surface-Area-Analyzer. The prepared SiO2@C nanocomposite that contains higher silica percent was selected as adsorbent for removing of Cu, Zn and Pb from aqueous solutions. The effects of pH and contact time on the adsorption process were also studied. The results showed that SiO2@C nanocomposites with different percentages of silica and carbon were prepared successfully by the proposed method. The sample that contains higher silica, exhibited smaller particle size (20–50 nm), higher specific surface area (262.39 m2g-1) and higher negative zeta potential (−71 mV). On the other hand, the sample that contains lower silica exhibited higher particle size (20–70 nm), lower specific surface area (42.95 m2g-1), and lower zeta potential (-6 mV). The adsorption efficiencies of prepared SiO2@C nanocomposites at pH 6 for removing of Cu, Zn, and Pb from aqueous solutions were 96.5, 97, 9 and 88.66%, respectively. The kinetic study revealed that the adsorption process proceeded by pseudo-second order reaction.

Removal of methylthioninium chloride dye from aqueous solution using cogon grass as adsorbent

The aim of this study was to investigate the removal Methylthioninium Chloride dye using cogon grass to treat the effluent. The effects of various parameters such as adsorbent dosage, dye concentration and contact time were studied. Funtional group properties of cogon grass had been characterized using Fourier transform infrared spectroscopy (FTIR). The adsorption process attained equilibrium around 50 minutes. The maximum adsorption capacity was calculated to be 46.30 mg/g with optimized condition of adsorbent dosage 0.1 g at temperature 30 °C for 50 minutes. The adsorption kinetics of Methylthioninium Chloride with cogon grass suit into non-linear pseudo-second order reaction model that refers to the amount of adsorbate and amount of solute adsorbed on adsorbent surface at equilibrium. It was also found that the Langmuir isotherm fit better (R 2 = 0.9959) compare to the Freundlich isotherm (R 2 = 0.4093). The high levels of color removals were achieved with low contact times; and the cogon grass can be effectively used as adsorbent of methylthioninium chloride in aqueous solutions. These results prove that cogon grass is highly potential to be used as low-cost adsorbent for the dye removal from industrial wastewater.

Removal of E102 dye from aqueous solution by adsorption on the surface of polyaniline walnut husks nanocomposite.

Abstract Development of a new, cheap, efficient, and ecofriendly adsorbents become important demand for the treatment of waste water, so nano polyaniline walnut husks is considered a good choice. A sample of nanocomposite was prepared from polyaniline . The prepared sample was characterized using various characterization techniques such as FT-IR, SEM and XRD analysis. The SEM analysis of sample shows nanostructures with pore ranging (2-100nm(. The adsorptive properties of this sample were examined by eliminating E102 dye from aqueous solution. Amount Experimental methods were perform at room temperature (25⁰C) to study the different variables which affect the adsorption process like: nanocomposite amount, initial concentration of dye, and contact time. The experimental results at equilibrium were determined using Langmuir and Freundlich adsorption isotherms and show best fitted with langmuir model which reveal that the adsorption of E102 dye by the nanocomposite is monolayer adsorption. Kinetics aspects was also investigated by evaluating parameters from pseudo- first and pseudo-second order reaction equations on adsorption rate which show good fitting with both kinetics equations, but pseudo-second order equation was the best to describe the kinetics parameters.

Systematic study on the synthesis of novel ion-imprinted polymers based on rhodizonate for the highly selective removal of Pb(II)

The present work reports the successful synthesis of a novel Pb2+ ion-imprinted polymer (Pb-IIP) based on a rhodizonate-like selective ligand by precipitation. Three functional monomers, namely acid acrylic (ACRY), 2-acrylamido-2-methylpropane sulfonic acid (AMPSA) and allylamine (ALLY), were chosen by computer simulation using density functional theory (DFT). The materials obtained were applied for the selective removal of Pb2+ from aqueous solutions and were characterized by Fourier transform Infra-red (FTIR), scanning electronic microscopy (SEM) and flame atomic absorption spectrometry (FAAS). The results obtained from the adsorption experiments performed under optimal conditions were in good agreement with the computational design and showed that IIP-AMPSA exhibited a relatively higher adsorption capacity for Pb2+ (51.84 mg g−1) than IIP–ACRY (31.02 mg g−1) and IIP-ALLY (12.90 mg g−1). Kinetics studies showed that the adsorption process followed a pseudo second-order reaction rate, and equilibrium was reached after 10 min of reaction. The Temkin isotherm model was found to be the most appropriate for fitting the experimental data, indicating that the adsorption process occurred in the active centers with heterogeneous surface. Based on the application of IIP-AMPSA, the relative selectivity coefficients obtained for Pb2+ in the presence of Cu2+, Ni2+, Cd2+, Zn2+, Co2+, and Fe2+ were in the range of 89–128. The practical application of IIP-AMPSA showed that the recovery rate of Pb2+ from river samples was almost 100%; this can be attributed to the imprinted cavities and specific binding sites that were created, which, positioned in a predetermined orientation, formed a well-defined coordination geometry through the rhodizonate ligand.

Stable silver nanoparticle doped mesoporous biochar-based nanocomposite for efficient removal of toxic dyes

In this present study, biochar-based silver nanocomposite (Ag-nBC) has been synthesized by combining (i) AgNPs, synthesized biochemically using Shorea robusta leaf extract, and (ii) S. robusta leaf biochar, produced via mild thermal pyrolysis (300 °C) and tested for toxic dye removal efficiency. The Ag-nBC was characterized by FESEM-EDX, BET, XRD, XPS, TGA, and FTIR, found to be irregular, heterogeneous, and mesoporous, containing a significant amount of surface functional groups. The Ag-nBC showed > 90% removal for Congo red (CR) and Rhodamine B (RhB), where the dye removal experiments were found to be spontaneous exothermic, followed Freundlich isotherm and pseudo-second order reaction kinetic model. The adsorption mechanism of CR involved surface complexation through specific electrostatic attraction and H-bonding, while RhB exhibited only surface complexation. Notably, this heterogeneous Ag-nBC system showed excellent stability at wide ranges of pH and promising reusability, suggesting great potential for waste biomass minimization and dye effluent treatment.

Six fruit and vegetable peel beads for the simultaneous removal of heavy metals by biosorption

ABSTRACT In this study, a comparison between the biosorption performance of six fruit and vegetable peels, namely kiwifruit (KP), apple, banana, cucumber, orange and potato immobilized on sodium alginate beads has been made. Inductively coupled plasma coupled with mass spectroscopy was used for measuring the concentration of metal ions in solution before and after biosorption. A range of kinetic models were also applied to the biosorption batch data. The results showed that biosorption percentage of the ions were different on the various beads. For example, the decreasing order of biosorption by one KP bead at equilibrium was Cd > Cu > Hg > Ni > Pb > Cr > As, with approximately 92%, 84%, 80%, 75%, 67%, 34%, and 17% simultaneous removal of ions, respectively. The fastest biosorption was seen with Cd and Pb, as both reached equilibrium by 24 h. Equilibrium time of all other ions occurred by 48 h. While all beads in their unmodified form were suitable for the removal of divalent cations, KP bead showed significantly higher removal of the anion hexavalent Cr. Biosorption of Cd, Hg and Ni was limited by both pseudo-first order and pseudo-second order reaction rates. For Cr and Cu, the reaction was controlled by film diffusion and pseudo-first order rates. At a higher solution concentration, the preference of ions biosorbed as well as their percentage removed changed. Overall, the results indicated that KP beads show promise as a cost-effective method for removing toxic ions by biosorption, especially hexavalent chromium from drinking water.

Synthesis and characterization of magnetically separable and recyclable crumbled MgFe2O4/reduced graphene oxide nanoparticles for removal of methylene blue dye from aqueous solutions

Graphene oxide (GO) is an excellently conductive carbon material composed of versatile building blocks that can self-assemble a broad range of nanoparticles, and the features of GO can be tuned to accommodate various self-assembly approaches. Using the benefits of a simple self-assembly of two oppositely charged nanomaterials via electrostatic interactions, GO and MgFe2O4 can be self-assembled together, and the assembled composites are expected to possess special properties as catalysts in comparison to their individual counterparts. In this research, novel magnetic separable MgFe2O4/crumbled reduced GO (rGO) nanoparticles of surface area 35 m2/g and adsorption capacity 24.81 mg/g were synthesized to eliminate methylene blue (MB) dye as a primary cationic organic dye pollutant model. The physicochemical features were explored using field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and N2-adsorption/desorption isotherms. The rod-like structured of the as-synthesized nanoparticles with crystallite size of 11 nm were deposited homogeneously on the surface of wrinkles of rGO with a crumbled sheet structure. The microstructure analysis indicated the accumulation of MgFe2O4 on the wrinkles and the edges, rather than the basal planes, due to the distribution of the COOH groups on the GO. The influences of catalyst dose, dye concentration, pH, rate of agitation, and the change in temperature during the dye removal process were investigated. The elimination of MB followed a pseudo second-order reaction and was characterized by multi-layer formation on the solid surface. The values of enthalpy and entropy change were 61 and 0.219 kJ/mol, respectively, indicating a strong interaction between dye molecules and solid surface and the enhancement of the random arrangement of dye molecules on the adsorbent surface. The novel magnetic and easily separable nanoparticles retained 75% of their reactivity on dye removal after four consecutive cycles. The prepared magnetic rGO will allow the synthesis of highly effective and low-cost nanoparticles for dye removal from aqueous solution.

New insights into the efficient removal of emerging contaminants by biochars and hydrochars derived from olive oil wastes

The removal of emerging contaminants (ECs) for water source reclamation, minimizing energy and chemical use, is an environmental concern worldwide. In this study, we used the technologically cleaner pyrolysis and hydrothermal carbonization (HTC) processes to convert olive oil production wastes into chars in order to simultaneously remove triclosan (TCS), ibuprofen (IBP) and diclofenac (DCF) from water. The chars prepared from olive stone (S), olive tree pruning (P) and pitted and reprocessed wet olive mill waste (H), as well as commercial biochars and a commercial active carbon (CAC), were characterized using different techniques and assayed as adsorbents. Pyrolysis temperatures had only a slight effect on the adsorption capacity of chars. The pseudo second-order reaction kinetic and the Freundlich equation provided the best fit for experimental data. The pH values of char suspensions were negatively correlated with their maximum adsorption capacities. The hydrochars synthetized at the lowest temperatures (≤ 240 °C), which had an acidic pH and were rich in oxygenated functional groups, recorded the highest adsorption rates (64% for DCF, 43% for IBP) and especially for TCS, with a rate of 98%, despite of a low surface area of 7.5 m2/ g. This study demonstrates for the first time that unmodified hydrochars from pitted and reprocessed wet olive mill waste are inexpensive, sustainable and environmentally friendly adsorbents which can be used to remove ECs and other similar compounds in water treatments.

A Study on Adsorption of Heavy Metals with Zeolite and FeS Media

Objectives:Adsorption characteristics in aqueous solution were investigated to effectively remove heavy metals by the crystallization of FeS and reaction kinetics were analyzed to compare with heavy metal adsorption characteristics of zeolite.Methods:The adsorption characteristics of each media were analyzed using Langmuir adsorption isotherm, and the adsorption reaction kinetics of heavy metals (Pb, Cu, Zn) on zeolite and FeS media were analyzed by a pseudo-first or pseudo-second order reaction kinetics.Results and Discussion:The maximum adsorption capacity of zeolite was highest in Pb, and the adsorption preference was in the order of Pb>Cu>Zn. In the case of FeS media, Cu was found to have a higher adsorption capacity than Pb or Zn, and the adsorption preference was observed to be Cu>Pb>Zn. It was found that the adsorption mechanism is based on chemical adsorption (chemisorption) because adsorption of each heavy metal onto zeolite or FeS media is more suitable for pseudo-second order kinetics.Conclusions:It was found that the removal of heavy metals through FeS media has a different pattern from zeolite, and when comparing the adsorption capacity of each media, it was found that FeS media is more effective for Zn or Cu except Pb.

Alkali-cation-incorporated and functionalized iron oxide nanoparticles for methyl blue removal/decomposition

Enhancing the rate of decomposition or removal of organic dye by designing novel nanostructures is a subject of intensive research aimed at improving waste-water treatment in the textile and pharmaceutical industries. Despite radical progress in this challenging area using iron-based nanostructures, enhancing stability and dye adsorption performance is highly desirable. In the present manuscript alkali cations are incorporated into iron oxide nanoparticles (IONPs) to tailor their structural and magnetic properties and to magnify methyl blue (MB) removal/decomposition capability. The process automatically functionalizes the IONPs without any additional steps. The plausible mechanisms proposed for IONPs incubated in alkali chloride and hydroxide solutions are based on structural investigation and correlated with the removal/adsorption capabilities. The MB adsorption kinetics of the incubated IONPs is elucidated by the pseudo second-order reaction model. Not only are the functional groups of –OH and –Cl attached to the surface of the NPs, the present investigation also reveals that the presence of alkali cations significantly influences the MB adsorption kinetics and correlates with the cation content and atomic polarizability.

English

The discharged of lead and cadmium above maximum permissible limits into surface water and environment without any pre-treatment methods has caused severe heath challenges to humanity. In other to minimize the reoccurrence, this research aim to ascertain biosorption capacity of bamboo stem biomass to remove lead and cadmium from aqueous solution. Batch experiment and data evaluation under optimum removal conditions (such as pH, contact time, temperature, biosorbent dosage, initial heavy metal concentration) were determined. Maximum optimum removal was observed for both metal ions at pH 5, 90 min contact time, 298K temperature with 50 ppm of initial concentration for 95.92 and 80.98% removal for lead and cadmium. Lead revealed better results at all concentrations for bamboo stem biomass with increase in percentage removal as concentration of heavy metal increases. Kinetics and isotherms models were applied and this shows that kinetic models are described and fitted well with pseudo-second order reaction while adsorption isotherm model supported Freundlich model with high R2 values. Thermodynamically, biosorption of lead and cadmium was exothermic and lead was greater than cadmium in the order of spontaneity and entropy. From these results, it can be concluded that bamboo stem biomass has been shown to be productive in removal of heavy metals from aqueous solution. Key words: Biosorption, bamboo stem biomass, heavy metals, kinetics, isotherms, thermodynamics. &nbsp

Removal mechanisms of cadmium and lead ions in contaminated water by stainless steel slag obtained from scrap metal recycling

In this work, steel slag was shown to be a successful filter material for the removal of lead and cadmium from natural waters with a removal efficiency of >95 %, even under acidic conditions (pH 3.5). Overall, precipitation was found to be the main removal mechanism over adsorption with a tight relationship with the final matrix pH. Batch experiments showed fast removal kinetics with >98 % removal efficiency for lead and cadmium in 5 and 15 min, respectively. The removal kinetics followed a pseudo second-order reaction (R2 = 0.999), and the K2 was calculated to be 927 h−1 and 204 h−1 for lead and cadmium, respectively. A strong interference for the removal was observed with ethylenediaminetetraacetic acid (EDTA) but slightly with fulvic and humic acids, and non-significant with polymeric acid e.g. isosaccharinic acid. In addition, the column experiment showed spontaneous removal kinetics for lead and cadmium with a contact time of 3.6–36 seconds depending on loading flow-rates. Column experiments at similar liquid to solid ratios showed a high removal capacity with gradient over isocratic solution loading. The high removal efficiencies in combination with limited hazardous metals leaching led to the conclusion that slag is an appropriate filter material for treating contaminated waters. Moreover, the slag treated solutions with alkaline conditions showed reacted efficiently with CO2 in flue gas. Consequently, the pH of the treated solution is neutralized making it easier to waste and this reaction may contribute to reducing CO2 gas emissions.

Fluoride removal from water using ceramic based adsorbent prepared from spent mosquito repellent liquid vaporiser rods

ABSTRACT A new adsorbent has been tested which is prepared from the recycled material for the fluoride removal from water. The spent mosquito repellent liquid vaporiser rod/wick has been collected and carbonised to cleanse from any other substance already present on it. The need for low cost, easy maintenance and capacity to remove impurities even at low concentration inspired to use these recyclable ceramic rods. Fluoride adsorption characteristics were studied in the batch system. Effects of parameters like potential of H+, stirring speed, adsorbent dose, contact time and also initial F¯ ions concentration were tested. Optimum conditions for experimental data revealed that the adsorbent showed maximum F¯ ions removal of 80% at 5 mg/L F¯ concentration at pH 7. At stirring speed of 300 rpm, 8 g/L adsorbent dose and 180 minutes maximum F¯ ions removal was observed and remained constant even after increment in parameters. Langmuir and Freundlich isotherms were interpreted from the data for fluoride removal and maximum adsorption capacity of 16.69 mg/g was obtained from Langmuir isotherm. The adsorbent prepared has obeyed the Freundlich isotherm more than Langmuir. In addition to this, in kinetic studies it has been found that adsorption reaction followed pseudo-second order reaction kinetics. Several advantages of ceramics enhance adsorbent as effective medium i.e. granular structure, more surface area along with cost effective preparation from rods.

Simultaneous removal of lead(II), chromium(III), and copper(II) heavy metal ions through an adsorption process using C-phenylcalix[4]pyrogallolarene material

• C -phenylcalix[4]pyrogallolarene, is a good adsorbent material for lead(II), chromium(III), and copper(II) ions. • The kinetic of lead(II), chromium(III), copper(II), and nickel(II) ions adsorption follows pseudo-second order reaction. • The adsorption of lead(II), chromium(III), copper(II), and nickel(II) ions fits well with the Langmuir model. • Ion exchange is the main mechanism occurring in the heavy metal adsorption onto C-phenylcalix[4]pyrogallolarene material. Heavy metal ion removal remains a serious challenge to the sustainability of our environment. In this work, a simple adsorbent, i.e., C -phenylcalix[4]pyrogallolarene bearing 12 phenolic functional groups, has been successfully synthesized and evaluated for the simultaneous adsorption of heavy metal ions in acidic media. Results showed that C -phenylcalix[4]pyrogallolarene exhibited good adsorption percentages for heavy metal ions, i.e., lead(II), chromium(III), copper(II), and nickel(II). Given that the adsorption of all metal ions was driven by the ion exchange mechanism, the adsorption process depends on the pH value of the aqueous phase, yielding the optimum pH values of 5.0, 4.9, 5.2, and 7.9 for lead(II), chromium(III), copper(II), and nickel(II) ions, respectively. The kinetics of heavy metal ion adsorption was governed by the pseudo-second order model, whereas the adsorption isotherm behavior was governed by the Langmuir model. The results also showed that the adsorption capacities for lead(II), chromium(III), copper(II), and nickel(II) were 60.97, 14.31, 8.14, and 16.86 mg g −1 , respectively. The interaction between heavy metal ions and C -phenylcalix[4]pyrogallolarene was also investigated through UV–vis, FTIR, and 1 H-nuclear magnetic resonance (NMR) spectroscopic studies. The findings showed that C -phenylcalix[4]pyrogallolarene is a potential adsorbent material for the simultaneous removal of heavy metal ions.

Influence of microwave-assisted synthesis on the structural and textural properties of mesoporous MIL-101(Fe) and NH2-MIL-101(Fe) for enhanced tetracycline adsorption

In this paper, the effect of conventional solvothermal and a microwave-assisted method for the synthesis of MIL-101(Fe) and NH2-MIL-101(Fe) as adsorbents for the removal of tetracycline in wastewater is reported for the first time. The results had shown that the microwave treatment led to a significant reduction in the material synthesis time, which greatly saved the energy. It was also found that the microwave-assisted synthesized material exhibited small particle size, high specific surface area and better adsorption capacity. The introduction of amino group further enhanced the adsorption capacity of MIL-101(Fe). The adsorption capacity of MIL-101(Fe) and NH2-MIL-101(Fe) samples for tetracycline adsorption by microwave assisted synthesis method reached up to 332 mg/g and 378 mg/g, respectively. Moreover, the adsorption isotherm was well-fit with Freundlich model, indicating a multilayer adsorption. The kinetic studies indicated that the reaction followed pseudo second-order reaction kinetics with a best fit to the theoretical value. Due to the higher adsorption efficiency and lower energy consumption of the synthesis, the as-prepared microwave assisted materials could be used as potential adsorbents for different pollutants in wastewater.