Low-cost Adsorbent Research Articles

Efficient cadmium immobilization by organic loaded Na-montmorillonite in a contaminated soil

Clay minerals are effective sorbents for toxic metal immobilization in contaminated soils and waters. However, their Cd immobilization efficiency is unclear when they are loaded with organics. In this study, sodium montmorillonite (Na-M) was successfully loaded with potassium humate, chitosan, and glycine to adsorb Cd(II) in solution. Potassium humate loaded Na-M (Na-M-HA), which had the highest specific surface area and cation exchange capacity (CEC), showed the highest Cd(II) adsorption capacity (73.7 mg g−1), 22.5 % and 81.8 % higher than that of chitosan loaded Na-M (Na-M-CTS) and glycine loaded Na-M (Na-M-G), respectively. The pseudo-second-order kinetic model best described (R2 > 0.98) the adsorption kinetics of Cd(II) on the three Na-Ms, indicating that the adsorption processes were of chemisorption nature. The adsorption isotherm of Cd(II) on Na-M-HA was of the Freundlich type, suggesting multilayer adsorption. In contrast, the isothermal adsorption of Cd(II) on Na-M-CTS (R2 = 0.99) and Na-M-G (R2 = 0.89) was better described by the Langmuir model, suggesting the dominance of monolayer adsorption in the adsorption process. High temperature, high pH, low background ionic strength, and low valence competing cations favored Cd(II) adsorption on Na-M-HA. The underlying mechanisms of Cd(II) sorption on Na-M-HA were electrostatic attraction, ion exchange and complexation. Na-M-HA was applied to a Cd polluted soil planted with lettuce (Lactuca sativa L.). in a pot experiment. Compared to the control with no adsorbent application, Na-M-HA application at 2 % effectively reduced the available Cd content in soil and Cd accumulation in plant by 36.0 % and 56.8 %, respectively. This work demonstrated that Na-M-HA is a green, low-cost and excellent adsorbent for Cd stabilization, and that its application in Cd-polluted soils can efficiently reduce Cd bioavailability and thereby Cd transfer along the food chain and eventually reduce the threat of Cd pollution to human health.

Brief insights of various adsorbents utilized for the sequestration of toxic pollutants from aqueous phase: a review

Adsorption is often considered to be the most competent and investigated treatment technique among wastewater technologies. The purpose of sequestration from wastewater is not validated through preferred utilization of costly starting material which pave way for the development of low-cost adsorbents. This review asserts the augmentation of both economically and environmentally sound sorbent material. The review encompasses gathering information from the literature insights dispersed over decades for the remediation of toxic pollutants especially dyes and heavy metals by various categories of adsorbents. Additionally, this review highlighted the adsorption of various emerging contaminants and pharmaceuticals. The review targeted to showcase various categories of adsorbent that can be refashioned and efficiently employed toward water treatment process. The review outlines and purposes the classification of diverse adsorbents involved in water treatment. Various Isotherm models and kinetic models employed in adsorption were also discussed. Mechanism of removal of pollutants was also outlined. The process of desorption gives the regeneration and recovery possibility of adsorbent providing opportunity of waste minimization, reusing it repeatedly was also reviewed here. Lastly, the significance of review and the future perspective for further adsorbent advancement were also detailed out. Hence, this review sufficiently authorizes the various adsorbent conceivability toward water treatment.

Remediation of Pb (II), Cd (II), and Zn (II) from aqueous solutions using porous (styrene-divinylbenzene)/Cu-Ni bimetallic nanocomposite microspheres: continuous fixed-bed column study.

Bimetallic nanoparticles (BNPs) have been used as a new line of defence against heavy metal contamination among several types of nanoparticles (NPs) due to their enhanced, synergistic activity. In this study, we investigated the adsorption behaviour of porous (styrene-divinylbenzene)/CuNi bimetallic nanocomposite (P(St-DVB)/CuNi BNC) in a continuous flow fixed-bed column and its ability to remove Pb (II), Cd (II), and Zn (II) ions from aqueous solutions. We examined how the initial metal concentration, flow rate, and bed height affected the adsorption characteristics. Experimental results confirmed that the adsorption capacity increased with increase in influent metal concentration and bed height and decreased with increase in flow rate. The breakthrough and the column kinetic parameters were successfully predicted with three mathematical models: Thomas, Yoon-Nelson, and Adams-Bohart models. Both Thomas and Yoon-Nelson models showed good agreement with the experimental results for all the operating conditions. Successful desorption of heavy metals from the P(St-DVB)/CuNi BNC was performed using 0.5 M NaOH solution, and it showed good reusability of the adsorbent during four adsorption-desorption cycles. The results show that P(St-DVB)/CuNi BNC are effective and low-cost adsorbents, and they can be used in real-time large-scale industrial water treatment processes for the removal of heavy metals.

Removal of Textile Wastewater Pollutants Using Zeolite Mineral as Adsorbent: Isotherm Studies

Heavy metals and organic pollutants may represent long-term hazards to the ecosystem and human health, thus it is important to discover a safe and efficient way to remove pollutants from the environment. Widely varied techniques, such as adsorption for color removal from industrial wastewater, have therefore been developed. Due to its ease of use, its simplicity, ecofriendly and reduced cost as compared to other conventional methods, the adsorption process has been widely used for wastewater treatment. In this study, natural Clinoptilolite zeolite (NCZ) was employed as a high-capacity and low cost adsorbent. Using natural Clinoptilolite zeolite to adsorb dyes is essential for determining how wastewater treatment facilities remove the dye. A series of laboratory adsorption experiments were conducted for equilibrium reactions to study the effect of essential parameters for dye removal, including the amount of zeolite adsorbent 0.03 to 1 g, the methylene blue (MB) and eosin yellow (EY) dye concentration (50 to 200 ppm), the pH value 3 to 11, and the contact time 30 to 120 minutes. The selected range of operating factors was designed using the response surface method to establish a mathematical model that describes the adsorption process .Results showed that the optimum values of these factors to remove methylene blue dye were: 1 g of adsorbent dose, 50 mg/l of MB dye during 80 min at pH of 11 with removal efficiency reached to 99.9 %. ,and the optimum values of these factors to remove eosin yellow dye were: 0.03 g of adsorbent dose, 200mg/l of EY dye during 120 min at pH of 3 with removal efficiency reached to 98 %,also two models (Langmuir and Freundlich) isotherms were studied, Freundlich was best fitted model with a correlation of 0.9737, which suggesting a multilayer adsorption.

Synthesis of novel magnetic pitch-based hypercrosslinked polymers as adsorbents for effective recovery of Ag+ with high selectivity

Silver is an important precious metal with superior ductility, electrical and thermal conductivity, photosensitivity, and antibacterial properties. However, without proper recycling and treatment, silver emissions may pose a threat to the human health and subsistence environment due to their toxicity. Therefore, it is environmentally and economically important to recover Ag from waste electronic equipment and anode slime. Herein, carboxyl functionalized modified magnetic nanoparticles (Fe3O4@3-phenylglutaricacid nanoparticles) were designed and prepared to obtain the low-cost magnetic pitch-based HCP adsorbents (MPHCP and P-MPHCP). The novelty of present work is that superior adsorption capacity and magnetic responsiveness of adsorbent can be obtained by a simple one-step Friedel-Crafts reaction with very low-cost raw material. The maximum Ag+ adsorption capacity of MPHCP and P-MPHCP were 321 and 353 mg/g, respectively. The adsorption was completed within a short duration of 15 min for MPHCP and P-MPHCP at an initial Ag+ concentration of 100 mg/L. Moreover, the most selective is P-MPHCP wherein Ag+ is α = 61 times more selective than Pb2+ at a concentration of 100 mg/L.The adsorption capacity of MPHCP and P-MPHCP towards Ag+ still maintains above 89% after ten cycles of adsorption-desorption. This study not only provides new guidance for the development of porous polymeric adsorbents but also provides technical feasibility for the field of recovery and reutilization of precious metals, which has a very extensive practical application prospect.

Novel adsorbent synthesized from red mud and acid mine drainage for enhanced contaminant removal: Industrial waste transformation, adsorbent performance and metal(loid) removal mechanisms

Antimony (Sb), arsenic (As), and lead (Pb) are toxic metal(loid)s that can cause serious environmental pollution. The above emphasizes the need for a development of efficient technologies for metal(loid) removal, especially from low-pH environments due to the increased mobility of the contaminants under acidic conditions. Herein, for the first time, removal of Sb(V/III), As(V/III), and Pb(II) from acidic waters is described, using low-cost adsorbents synthesized from red mud (RM; a solid waste from the alumina industry) under the catalysis by acid mine drainage (AMD; acidic effluents from mines). The reactions between RM and AMD were studied to describe Fe/S/Ca/Al/Si speciation transformations during the adsorbent formation. In addition, Sb/As/Pb adsorption behavior and the relationship between adsorbent properties and Sb/As/Pb removal efficiencies were investigated. The maximum removal capacities for Sb(V), Sb(III), As(V), As(III), and Pb(II) reaching 1,637.8, 80.2, 109.2, 16.4, and 518.7 mg/g, respectively. The primarily Ca2+ from the Ca-bearing compounds (determined in RA2, synthesized under SRM/LAMD 2:1) contributed to Sb(V) removal (via precipitation of CaSb2O5(OH)2 and formation of Sb-bearing precipitate, with silicate gel nanospheres securing high stability of the immobilized Sb). In the As immobilization process, Fe(III) (hydr)oxides (formed in RA4, synthesized under SRM/LAMD 4:1) such as goethite (α-FeOOH) and bernalite (Fe(OH)3) played a dominant role. Convertible sulfates (e.g., CaSO4 and Al2(SO4)3) in RA10 (synthesized under SRM/LAMD 10:1) ensured a high removal capacity for Pb(II) across a wide pH range (2 to 7) via PbSO4 precipitation. In contrast, the formation of PbCO3 and Pb3(CO3)2(OH)2 was the main mechanism for Pb(II) removal by unamended RM at pH 5.0, while no contaminant removal capacity was observed at pH 2.0.

Chemically modified jackfruit leaves as a low-cost agro-waste adsorbent for Pb(II) removal from synthetic wastewater

There is an emerging need to develop an economical, efficient and agro-waste-based adsorbent for the removal of toxic heavy metal ions from various aqueous media. In the present investigation, jackfruit leaves (Artocarpus heterophyllus) have been chosen as a suitable agro-waste-based material for the efficient removal of Pb(II) from wastewater. The surface modification of jackfruit leaf powder (JLP) has been done by chemical modification with 20% isopropyl alcohol followed by treatment with (i) alkali-sodium hydroxide (AIJLP) and (ii) tartaric acid (TIJLP). In comparison to JLP depicting BET surface area of 29 m2/g, the chemical modification resulted in about a 1.5-fold increase and 2.5-fold increase in the surface area of TIJLP (50 m2/g) and AIJLP (72 m2/g), respectively. Therefore, batch experiments were performed for Pb(II) adsorption using AIJLP for the optimization of equilibrium conditions viz., Pb(II) concentration, pH and contact time. Under optimized conditions, AIJLP showed a loading capacity of 87.7 mg/g from the Langmuir model at pH 5.0. Kinetic data were best fitted with a pseudo-second-order model. The characterizations of the adsorbents have been performed by FESEM with EDX, FTIR, TGA, XPS and surface area analyzer (BET). The pore size and pore volume have been analyzed by the BJH method to understand the adsorption mechanism. Reusability studies reveal that AIJLP could efficiently remove more than 95% of Pb(II) in up to five cycles. All these results recommend the AIJLP as a promising adsorbent for the remediation of Pb(II) from wastewater.

Exploration of Reactive Black 5 Dye Desorption from Composite Hydrogel Beads—Adsorbent Reusability, Kinetic and Equilibrium Isotherms

A low-cost adsorbent was prepared by using cherry stones powder and chitosan and used to retain Reactive Black 5 dye from aqueous solution. Then, the spent material was submitted to a regeneration process. Five different eluents (water, sodium hydroxide, hydrochloric acid, sodium chloride and ethanol) were tested. Among them, sodium hydroxide was selected for an advanced investigation. Values of three working conditions, namely the eluent volume, its concentration and the desorption temperature, were optimized by Response Surface Methodology-Box-Behnken Design. In the established settings (NaOH volume: 30 mL, NaOH concentration: 1.5 M, working temperature: 40 °C), three successive cycles of adsorption/desorption were conducted. The analysis performed by Scanning Electron Microscopy and by Fourier Transform Infrared Spectroscopy revealed the evolution of the adsorbent throughout the dye elution from the material. Pseudo-second-order kinetic model and Freundlich equilibrium isotherm were able to accurately describe the desorption process. Based on the acquired results, our outcomes sustain the suitability of the synthesized material as dye adsorbent and the possibility of efficaciously recycling and reusing it.

PEG-templated synthesis of ultramicroporous n-ZIF-67 nanoparticles with high selectivity for the adsorption and uptake of CO2 over CH4 and N2

Challenges remain concerning the development of rapid and low-cost adsorbents that combine good separation performance with high adsorption capacity, especially for CO2. Herein, we report for the first time a new polyethylene glycol templated synthesis method to obtain a nanocrystalline zeolitic imidazolate framework (n-ZIF-67) at room temperature in 5 min. The n-ZIF-67 nanoparticles were characterized using X-ray powder diffraction with Rietveld refinement (space group = I-43 m, a = 17.0545(4) Å), Fourier-transform infrared, transmission electron microscopy, thermogravimetric analysis, and N2 adsorption (Brunauer-Emmett-Teller) measurements and exhibited excellent properties, including a total pore volume of 0.86 cm3/g, a high surface area equal to 1891 m2/g, and 0.64 nm size ultramicropores.). The highly porous ZIF-67 nanoparticles were explored for the adsorption and desorption of CH4, CO2, and N2 gases at pressures up to 40 bar and isotherm temperatures of 273, 298, 323, and 353 K. The adsorption isotherms revealed a high capacity for CO2 of 681 mg/g at 298 K and an adsorption enthalpy of 29.19 to 34.44 KJ/mol, in part linked to the ultramicroporous structure. The n-ZIF-67 particles exhibited gas uptake values for CH4 and N2 of 241 mg/g and 219 mg/g, respectively. As far as the authors are concerned, these are the highest capacities ever reported for zeolitic framework metal organic frameworks such as ZIF-67 and ZIF-8. The Langmuir adsorption isotherm was employed to obtain the maximum adsorption capacity, qm, and adsorption equilibrium constant, KL. The isosteric heat of adsorption data sheds light on a CO2 physisorption process. The n-ZIF-67 also exhibited high CO2/N2 and CO2/CH4 mixed gases selectivity, with the preferential adsorption of CO2 over N2 or CH4 confirmed by breakthrough experiments. The n-ZIF-67 with ultramicropores is therefore an effective new adsorbent for greenhouse gas capture with high CO2 gas selectivity over competing gases. Zeolitic framework MOFs merit further development as low-cost and easy-to-synthesize adsorbents to help address the pressing need to mitigate CO2 emissions.

Removal of Ammonia Nitrogen from Aqueous Media with Low-cost Adsorbents: a Review

Removal of Ammonia Nitrogen from Aqueous Media with Low-cost Adsorbents: a Review

Treatment of textile dyeing wastewater using a low-cost adsorbent

A cost-effective adsorbent was synthesized from Eichhornia Crassipes using phosphoric acid as an activating agent and it was applied for the decolourization of the Textile dyeing industry’s effluent (TDE). Physical, chemical and morphologic characteristics were investigated using characterization studies, BET and XRD techniques. Batch experiments were performed to determine the optimum dosage, temperature, time and pH. The ideal conditions for treating TDE were found to be 30 °C, 1 g/L dose, 90 min, and pH 7. Maximum decolourization of 92%, reduction of COD and BOD were found to be 66.77% and 83.94% respectively with 50 T TDE. As a result, the aquatic weed Eichhornia crassipes can be employed as an efficient adsorbent to remove dye from wastewater.

Robust Metal–Organic Frameworks with High Industrial Applicability in Efficient Recovery of C3H8 and C2H6 from Natural Gas Upgrading

Developing efficient adsorbents with high uptake and selectivity for separation and recovery of C 2 H 6 and C 3 H 8 from natural gas is an important but challenging task. In this work, we demonstrate that high surface polarity and suitable pore diameter are two key factors that can synergistically enhance the separation performance, exemplified by metal–organic framework (MOF)-303 and MIL-160 (MIL: Matériaux de l’Institut Lavoisier), both possessing one-dimensional (1D) open channels with high density of heteroatoms and desired pore size (5∼7 Å). Significantly, the uptake of MOF-303 for C 3 H 8 is up to 3.38 mmol g −1 at 298 K and 5 kPa with a record-high C 3 H 8 /CH 4 (5:85, v/v) ideal adsorbed solution theory (IAST) selectivity of 5114 among all reported MOFs. In addition, MOF-303 also displays high C 2 H 6 uptake capacity (at 10 kPa) and C 2 H 6 /CH 4 (10:85, v/v) selectivity, reaching 1.59 mmol g −1 and 26, respectively. Owing to the larger pore diameter and lower density of heteroatoms within its 1D channels, MIL-160 shows apparently lower uptake and selectivity compared to those of MOF-303, though the values exceed those of majority of reported MOFs. Density functional theory (DFT) calculations verify that the high surface polarity and the suitable pore diameter synergistically enhance the affinity of the frameworks toward C 3 H 8 and C 2 H 6 , giving rise to the high loading capacity and selectivity for C 3 H 8 and C 2 H 6 . Both MOFs feature remarkable moisture stability without structural change upon exposure to 95% relative humidity (RH) for a month. In addition, synthesis of both compounds can be readily scaled up through one-pot reactions to afford about 5 g samples with high crystallinity. Finally, the substantial potential of MOF-303 and MIL-160 as advanced adsorbents for efficient separation of C 3 H 8 /C 2 H 6 /CH 4 has been demonstrated by ternary breakthrough experiments, regeneration tests, and cyclic evaluation. The excellent separation performance, high stability, low cost, and good scalability endow both MOFs promising adsorbents for natural gas purification and recovery of C 2 H 6 and C 3 H 8 .

Adsorptive Removal of Potentially Toxic Elements From Wastewater Using Peanut Shells Biochar

This study aimed to investigate the efficiency of the peanut shell biochar that prepared by physical activation using pyrolysis process at 550°C as a low cost adsorbent for metal ions removal from wastewater. The biochar surface morphology, chemical functional groups and the porous structure were investigated by SEM, FTIR and BET method respectively. Different parameters that affect the metal ions adsorption were taken in consideration during adsorption experiments. These parameters included pH value (3 – 8), initial metal concentration (5 – 100mg/l), biochar dose (0.5 – 4g), contact time (5 – 240 min) and temperature (25 – 60°C). The results showed that the optimum metal ions adsorption conditions were pH 6, metal concentration 20mg/l, biochar dose 2.5g, 60min of contact time and 60°C of solution temperature. The adsorbent removal efficiency for the studied metal ions exceeded 80% from the total metal concentration. The obtained results confirmed the efficiency of the biochar from peanut shell as an active adsorbent for metal ions removal from aqueous solutions.

Low-cost adsorbents prepared from brewer’s spent grain for pollutants removal

Low-cost adsorbents prepared from brewer’s spent grain for pollutants removal

Marble waste derived hydroxyapatite: Low-cost adsorbent for the defluoridation of drinking water

Synthesis of hydroxyapatite (Hap) powder using waste marble powder resource was conducted in a pilot plant scale setup for its application in the defluoridation of drinking water. During synthesis, process parameters such as temperature, process time and pH were optimized so as to obtain good quality hydroxyapatite (MA-Hap LR) products. MA-Hap LR powder was characterised using FTIR, XRD which confirmed formation of purer form of Hap when synthesized at 72 °C having a crystallite size of 43.87 nm and surface area of 24.66 m2/g. SEM and TEM studies of MA-Hap LR indicated rod like morphology similar to pure Hap. The powder was pelletized via the extrusion-spheronization technique in a pelletizer using Polyvinyl alcohol as the binder. Pellets of varying size ranges (2–3 mm) were studied for their fluoride adsorption capacity. Continuous column experiments were conducted to optimize column operational parameters like inlet flow rate, input fluoride concentrations, pellet size, and bed height for maximum fluoride removal. The column fluoride adsorption capacity was obtained at 1.21 mg/g for 10 mg/L input fluoride concentration, bed height 25 cm, 1 LPH flow rate, and processed 28.5-bed volumes at a maximum adsorbent exhaustion rate of 7.4 g/L. Adsorbent regeneration studies indicated that MA-Hap LR72 pellets could be reused for three cycles. The eluent concentration required for the regeneration of exhausted pellets was optimized at 1 M NaOH, confirmed by FTIR and SEM studies of the pellets. The treated water quality was within the acceptable limits for parameters such as pH, alkalinity, hardness and TDS according to WHO and BIS regulations which describe the utility of hydroxyapatite prepared from waste marble powder as a good defluoridation agent for practical drinking water treatment applications.

Kinetic and Isotherm Studies of Methyl Violet Adsorption onto Carbonized Waterlily (Nymphaea lotus) Leaves Powder

In this study, the adsorption of methyl violet from an aqueous solution using carbonised water lily (CWL) leaves powder as a low-cost, efficient and eco-friendly adsorbent was investigated using a batch system under controlled conditions. The adsorbent's moisture, organic matter, ash, bulk density, pore volume, and pH were determined. The adsorbents were characterised by scanning electron microscopy (SEM) and Fourier Transform Infrared (FT-IR) techniques which confirm the adsorption of the methyl violet onto the CWL adsorbents. The effect of adsorption parameters such as contact time, dosage, initial concentration, pH and temperature were studied for optimisation. It was confirmed that contact time, dosage, concentration, pH and temperature positively affected the adsorption process. The kinetic data were best described by pseudo-second order under all experimental temperatures. The adsorption isotherms were estimated and established to fit nicely into the D-R model compared to other models generated and tested. Thermodynamic studies of the sorption process indicate that the process was feasible, spontaneous, and exothermic and decrease in the randomness of the adsorption process during the transfer of molecules between the adsorbent and adsorbates with entropy (∆S) of 23.77 J/mol.K. due to negative values of Gibb’s free energy observed. This study confirmed that CWL could be employed as a low-cost, eco-friendly adsorbent for removing toxic dyes such as methyl violet from an aqueous solution.

Utilization of date pits derived Bio-adsorbent for heavy metals in wastewater treatment: Review

This article provides an overview of the role of raw and burnt date pits as bio-waste for heavy metal removal. In recent years, many studies on the adsorption properties of various low-cost adsorbents, such as agricultural waste and activated carbons based on agricultural waste, have been published. This review summarizes recent research demonstrating the utility of raw and modified date pits biomass-based adsorbents in the removal of heavy metal pollutants from wastewater. Additionally, the chemical compositions, the derived activated carbon, and the proposed mechanism of heavy metal ions were discussed. It thoroughly showed how essential variables including pH, adsorbent dosage, initial metal ion concentration, physical and chemical properties, and temperature affect the adsorption of heavy metals. The significant application of date pits as a bio-adsorbent of heavy metal ions was demonstrated. According to the literature, date pit-based adsorbents are the most promising adsorbents for removing toxic materials because they adsorb heavy metals from aqueous solutions with high capacity in a short period.

Agricultural Byproducts Used as Low-Cost Adsorbents for Removal of Potentially Toxic Elements from Wastewater: A Comprehensive Review

Potentially toxic elements (PTEs) are ubiquitous chemical compounds in the environment due to contamination of air, water, or soil. They are primarily sourced from fossil fuel combustion, mining and smelting, electroplating, dyes and pigments, agricultural treatments, and plastic and metallic industries. These chemical contaminants can produce various adverse effects when they enter the human body and can also affect crops and aquatic ecosystems. To address these issues, researchers are developing various techniques, including ion exchange, membrane filtration, photocatalysis, electrochemical methods, bioadsorption, and combinations of these processes, to reduce the levels of these contaminants, especially from wastewater. Among these methods, bioadsorption has gained much attention due to its high efficiency, low cost, and abundance of adsorbent materials. Agricultural byproducts used as biosorbents include rice husk and bran, citrus peel, banana peel, coconut husk, sugarcane bagasse, soybean hulls, walnut and almond shells, coconut fiber, barley straws, and many others. Biosorption capacity can be described using adsorption kinetic models such as Elovich, Ritchie’s, and pseudo-second-order models, as well as different adsorption isotherm models such as Freundlich, Langmuir, Temkin isotherm, and BET models. Both conventional processes and adsorption models are influenced by parameters such as pH, agitation speed, contact time, particle size, concentration of the adsorbent material, initial concentration of the contaminant, and the type of modifying agent used. This review paper aims to examine the low-cost adsorbents and their removal efficiency and bioadsorption capacity for different PTEs present in wastewater, and their potential as decontamination methods.

Adsorption of textile dyes from aqueous solutions onto clay: Kinetic modelling and equilibrium isotherm analysis.

The commercial activated carbon commonly uses to reduce of dye amount in the textile industry effluents. In this study has focused on the use of a natural clay sample as low cost but potential adsorbent. For this purpose the adsorption of commercial textile dyes, Astrazon Red FBL and Astrazon Blue FGRL, onto clay was investigated. The physicochemical and topographic characteristics of natural clay sample were determined by scanning electron microscopy (SEM), X-Ray fluorescence spectrometry (XRF), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and cation exchange capacity measurements. It was determined that the major clay mineral was smectite with partial impurities. The effects of several operational parameters such as contact time, initial dye concentration, temperature, and adsorbent dosage on the adsorption process were evaluated. The adsorption kinetics was interpreted with pseudo-first order, pseudo-second order, and intra-particle diffusion models. The equilibrium adsorption data were analyzed using Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherm models. It was determined that the adsorption equilibrium was reached in the first 60min for each dye. The amount of adsorbed dyes onto clay decreased with increasing temperature, similarly, it decreased with increasing sorbent dosage. The kinetic data were well described by pseudo-second order kinetic model, and adsorption equilibrium data was followed both Langmuir and Redlich-Peterson models for each dyes. The adsorption enthalpy and entropy values were calculated as -10.7kJ.mol-1 and -13.21J.mol-1.K-1 for astrazon red and those for astrazon blue -11.65kJ.mol-1 and 37.4J.mol-1.K-1, respectively. The experimental results support that the physical interactions between clay particles and dye molecules have an important role for the spontaneous adsorption of textile dyes onto the clay. This study revealed that clay could effectively be used as an alternative adsorbent with high removal percentages of astrazon red and astrazon blue.

Assessment of physically treated banana leaves as a low-cost and eco-friendly adsorbent for removal of a textile azo dye

Assessment of physically treated banana leaves as a low-cost and eco-friendly adsorbent for removal of a textile azo dye