Composite Adsorbent Research Articles

Improvement of selenium adsorption performance at high temperature by CaO/ZSM-5 composite sorbents

ABSTRACT Selenium in flue gas from coal combustion, released into the atmosphere, will affect the environment and human health greatly. The adsorption method can achieve good control of selenium emission, by using CaO as adsorbent, but CaO is easy to sinter at high temperature, resulting in the decrease of adsorption capacity. Therefore, thermostability ZSM-5 molecular sieve was added to prepare composite adsorbent to improve the adsorption performance for selenium at high temperature. CaO/ZSM-5 composite adsorbent was prepared by impregnation method, and its adsorption performance and mechanism were studied. The results show that the composite adsorbent shows stronger adsorption capacity at high temperatures. The mixing ratio has a great influence on the microstructure of the composite adsorbent influencing the adsorption capacity. When the ratio is 1:1, the adsorption efficiency of the composite adsorbent shows a good performance. At 900°C, the adsorption efficiency of Z1C1(ZSM-5/CaO = 1:1 wt%) can still maintain 67%, which is 32% higher than that of CaO. Si and Al in the composite adsorbent have different effects on the improvement of microstructure. The existence of Si is conducive to maintaining the stable skeleton of the composite adsorbent, improving anti-sintering, while the addition of Al tends to improve the porosity, furtherly ameliorating the structure of the composite adsorbent for high-temperature adsorption.

Enhanced recovery of phosphate from wastewater using hollow hierarchical hydrotalcite/hydroxide composite microspheres adsorbent

The release of untreated phosphate into water systems is of great environmental concern, thus many adsorption methods have been developed to deal with this issue. In the present paper, we prepared magnesium/aluminum (Mg/Al)-based hydrotalcite/Al(OH)3 adsorbent with a hierarchical structure using a hydrothermal approach. Tests were conducted to assess variation in the Al/Mg mole ratio, interaction time, solution pH, competitive adsorption, and initial concentration of anions on the uptake of phosphate anions. The outcome revealed that 96.8 % of phosphate could be adsorbed within 2 h using the sample with an Al-to-Mg molar ratio of 1:3 (AM-3) with Langmuir theoretical maximum adsorption rate of 94.08 mg-P/g at 25 °C, which is 1.59 and 5.98 times higher than MgO (M) and Al2O3 (M) samples, respectively. The equilibrium experiment outcomes were fitted with the isotherm kinetic models and the results confirmed an adsorption mechanism involving surface adsorption that introduced phosphate ions into the layered structure of composite. The improved phosphate adsorption on AM-3 sample was attributed to the interaction of phosphate and hydroxyl ions during the adsorption. According to our experimental findings, the hydrotalcite prepared offers a great deal of promise for application as an adsorbent for the recovery of phosphate in environmental remediation.

Enhanced removal of Cu(II) ions from aqueous solution by in-situ synthesis of zeolitic imidazolate framework-67@wood aerogel composite adsorbent

ABSTRACT Zeolitic imidazolate frameworks (ZIFs) were considered to be one of the most promising emerging nanoporous adsorbents capable of efficiently removing a variety of heavy metals ions from wastewater. However, due to the powdered crystalline state, easy aggregation and instability of ZIFs materials, their actual large-scale applications in water matrices are significantly hindered. Compounding ZIFs with self-supporting porous wood aerogel (WA) to obtain advanced composites is excepted to further enhance their adsorption performance with higher practicability. Herein, a novel Zeolitic Imidazolate Framework-67 (ZIF-67)@wood aerogel (denoted as ZIF-67@WA) adsorbent for efficient capture of Cu(II) ions was successfully fabricated via in situ growth of Cobalt-based ZIF-67 particles onto the WA scaffold. Benefiting from the integration of unique three-dimensional porous structures and abundant accessible active sites, the obtained ZIF-67@WA hybrids exhibited fast adsorption kinetics and the maximum adsorption capacity towards Cu(II) calculated from the Langmuir model was 254.84 mg g−1. The adsorption kinetic and isotherm studies were consistent with pseudo-second-order model (R 2 = 0.991) and Langmuir model (R 2 = 0.973), indicating the adsorption of Cu(II) was a monolayer chemisorption process. This work proposed a new route for designing and constructing functionalized MOF@biomass hybrid materials for heavy metal wastewater treatment.

Novel Concepts for Graphene-Based Nanomaterials Synthesis for Phenol Removal from Palm Oil Mill Effluent (POME).

In recent years, the global population has increased significantly, resulting in elevated levels of pollution in waterways. Organic pollutants are a major source of water pollution in various parts of the world, with phenolic compounds being the most common hazardous pollutant. These compounds are released from industrial effluents, such as palm oil milling effluent (POME), and cause several environmental issues. Adsorption is known to be an efficient method for mitigating water contaminants, with the ability to eliminate phenolic contaminants even at low concentrations. Carbon-based materials have been reported to be effective composite adsorbents for phenol removal due to their excellent surface features and impressive sorption capability. However, the development of novel sorbents with higher specific sorption capabilities and faster contaminant removal rates is necessary. Graphene possesses exceptionally attractive chemical, thermal, mechanical, and optical properties, including higher chemical stability, thermal conductivity, current density, optical transmittance, and surface area. The unique features of graphene and its derivatives have gained significant attention in the application of sorbents for water decontamination. Recently, the emergence of graphene-based adsorbents with large surface areas and active surfaces has been proposed as a potential alternative to conventional sorbents. The aim of this article is to discuss novel synthesis approaches for producing graphene-based nanomaterials for the adsorptive uptake of organic pollutants from water, with a special focus on phenols associated with POME. Furthermore, this article explores adsorptive properties, experimental parameters for nanomaterial synthesis, isotherms and kinetic models, mechanisms of nanomaterial formation, and the ability of graphene-based materials as adsorbents of specific contaminants.

Preparation of ZnMgAl-Layered Double Hydroxide and Rice Husk Biochar Composites for Cu(II) and Pb(II) Ions Removal from Synthetic Wastewater

The efficiency of a new composite material of the layered double hydroxide (LDH) of ZnMgAl and rice husk biochar (RHB) for the removal of Cu(II) and Pb(II) ions from synthetic wastewater was investigated in this study. The images of the scanning electron microscope showed extremely fine crystalline LDH particles decorated on the rough surface of the RHB, while the successful formation of the composite adsorbent (LDH/RHB) was confirmed by the corresponding energy dispersive X-ray and the Fourier-transform infrared spectroscopy. An equilibrium contact time of 30 and 15 min for Cu2+ and Pb2+, respectively, was proposed for the optimum performance of the batch adsorption process. The dose of the LDH/RHB adsorbent was optimized at 0.4 g L−1 yielding maximum adsorption capacities of 117 and 124 mg g−1 for Cu2+ and Pb2+, respectively, with corresponding maximum removal efficiencies of nearly 94% and 99%. A solution pH of 6.0 yielded optimum results with an increasing trend in adsorption capacities and percentage removal by changing the solution pH from 2.0 to 7.0. Based on the best fit of the pseudo-second-order kinetic model to the experimental data, chemisorption was suggested to be the controlling mechanism of adsorption. The fitting of the Langmuir model suggested a monolayer sorption of Cu2+ and Pb2+, and the application of the Dubinin–Radushkevich isotherm proposed physical adsorption.

Improving toxic dye removal and remediation using novel nanocomposite fibrous adsorbent

Materials with regulated nanoscale morphology provide capabilities to remove dangerous pollutants from wastewater, by adsorption. In this study, the chitosan-based composite fibrous adsorbent was fabricated and used as a novel and facile eliminator in the process of removing cationic methyl orange (MO) from the water medium. Different methods were applied to check the properties of the desired composite fibrous adsorbent. The removal value showed that the chitosan-embedded composite fibrous adsorbent has super characteristics and can be removed the organic dye from the water. The influence of pH, time, temperature, eliminator quantity, and MO content was explored. With increasing time and eliminator quantity, the adsorption efficiency increased. The composite fibrous adsorbent with the advantage of its high functionality and combined micro-nanomorphology features, has emerged as a very promising candidate for obtaining versatile and robust adsorbents. This work presents how the tunned synthesis of composite fibrous adsorbent tailored their nanoarchitecture giving rise to adsorption capacities toward cleaning aqueous samples polluted with MO dye. The composite fibrous adsorbent was prepared by the direct immobilization method, with normal aging temperature, in order to study the effect of synthesis conditions on the adsorption properties of MO dye. The solution acidity was exhibited as the key factor, and a suitable pH of 5.50 was selected based on the efficiency. The competing ions were not adversely affected in the dye adsorption as defined by the stable bonding mechanism. The adsorption data were highly fitted with the Langmuir adsorption model with monolayer coverage. The determined maximum adsorption was 175.45 mg/g, which was comparable with the other forms of materials. The adsorbed MO dye elution was evaluated using ethanol and then the composite fibrous adsorbent was ready to use for MO dye adsorption after washing with water without significant loss in its functionality. Therefore, we explored the tunned morphology of composite fibrous adsorbent for obtaining performant adsorbents for the elimination of refractory pollutants in wastewater.

Development of novel ionic liquid-based silica gel composite adsorbents for designing high-efficiency adsorption heat pumps

Adsorption Cooling Systems ADCS as a thermally-driven technology provide an environmentally benign solution to supply cooling needs and utilize low-temperature heat sources. Adsorbent materials are the key element in the cooling performance of the ADCS. Poor heat transfer and low packing density are the main drawbacks of the conventional adsorbents, such as silica gel, that hinder the ADCS performance. Consolidated composite adsorbents represent a great solution for this problem, in which the binder material plays a significant role in the composite adsorbent synthesis and performance. In this paper, composite adsorbent based on RD Silica Gel SG as parent material and amino acid-based Polymerized Ionic Liquid PIL as a binder material, is synthesized at different PIL percentages, namely 2%, 5%, and 10%. The thermal and adsorption characteristics of the developed composite adsorbents in addition to the theoretical cooling performance ADCS with water adsorbate have been investigated. The results show that the thermal diffusivity has been improved by a maximum value of 20% for Composite 3, while the average volumetric water uptake has been enhanced for Composite 1 by a maximum value of 20.6%, compared to the parent silica gel.

Preparation of CO2 responsive cellulose composite adsorbent and its application in protein separation

AbstractThe separation of the proteins is of great theoretical and practical importance for biotechnological application. Considering the requirement of non‐destructive separation, the stimulus–response method is an alternative to the separation of protein. In this work, a cellulose‐based composite with CO2 stimulus–response property is prepared by a simple coprecipitation of poly (N, Nˊ‐diethylamino ethyl methacrylate)‐co‐poly (hydroxyethyl methacrylate) (PDH) and cellulose mixture solution. Subsequently, these composites as the adsorption medium are used to separate the bovine serum albumin (BSA, as the model protein) from solution through stimulus–response course (by CO2/N2 alternation). The results indicate that the ratio of the copolymers/cellulose composite have an obvious effect on the separation of BSA. The average maximum adsorption capacity can get to 562.6 mg/g, and the composites exhibits good adsorption/desorption cycling characteristics. After the composite materials are cycled for three times, the adsorption capacity can still decrease to 300 mg/g. Due to its high adsorption capacity and low preparation cost, the composite is expected to be widely used in industry.

Novel cetyltrimethylammonium bromide modified mixed adsorbent for efficient treatment of dyeing and printing wastewater

The treatment of dyeing and printing wastewater is a formidable challenge due to its high chemical oxygen demand (COD) and chromaticity, which pose severe threats to both the environment and human health. In this study, a composite modified adsorption material was prepared based on the applicability and feasibility in practical engineering applications. A novel mixed modified adsorbent was developed by incorporating activated carbon and activated clay as the foundation materials, followed by the addition of cetyltrimethylammonium bromide (CTAB) for modification. The performance of the composite adsorbent was evaluated via adsorption experiments of bromophenol blue (BPB) solution and dyeing and printing wastewater. The results demonstrated that the mixed modified adsorbent achieved a remarkable removal rate of 99% for BPB and 99.3% for chromaticity, under the optimal adsorption conditions. Furthermore, the regeneration performance of the mixed modified adsorbent was found to be exceptional. The adsorption process of BPB by the composite adsorbent was governed by the quasi-second-order kinetic model and Freundlich isotherm model, as evidenced by adsorption kinetics and isotherm analyses. The straightforward preparation method, coupled with the superior adsorption performance, underlines the promising potential of the proposed composite adsorbent for practical applications.

Performance and mechanism of phosphorus adsorption removal from wastewater by a Ce-Zr-Al composite adsorbent.

With the increasingly serious eutrophication of global water bodies and the strict discharge standards of tail water in wastewater treatment plants (WWTPs), there is an urgent technology need for efficient deep phosphorus removal from wastewater. A composite cerium-based adsorbent (Ce-Zr-Al) was synthesized by coprecipitation method for the adsorption of low concentration phosphorus in water. The performance of the Ce-Zr-Al composite adsorbent was explored, and the mechanism was also revealed through the analyses including SEM, BET, XPS, and FT-IR. The results showed that the composite adsorbent had excellent phosphorus removal performance. The phosphorus removal rate reached up to 92.6%, and the phosphorus concentration in effluent was less than 0.074 mg/L. The phosphate adsorption capacity of saturation was 73.51 mg/g. The adsorption process of phosphate was in accordance with pseudo-second-order kinetic model and Langmuir model. In addition, the composite adsorbent had a high zero potential point (pH PZC= 8) and a wide range of pH application. After the repeated desorption for 10 times in NaOH solution, the composite adsorbent still maintained good adsorbability (adsorption rate > 94%). The ligand exchange and electrostatic adsorption played the main role for the phosphorus removal from water using the composite adsorbent.

Comparative Study of the U(VI) Adsorption by Hybrid Silica-Hyperbranched Poly(ethylene imine) Nanoparticles and Xerogels.

Two different silica conformations (xerogels and nanoparticles), both formed by the mediation of dendritic poly (ethylene imine), were tested at low pHs for problematic uranyl cation sorption. The effect of crucial factors, i.e., temperature, electrostatic forces, adsorbent composition, accessibility of the pollutant to the dendritic cavities, and MW of the organic matrix, was investigated to determine the optimum formulation for water purification under these conditions. This was attained with the aid of UV-visible and FTIR spectroscopy, dynamic light scattering (DLS), ζ-potential, liquid nitrogen (LN2) porosimetry, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Results highlighted that both adsorbents have extraordinary sorption capacities. Xerogels are cost-effective since they approximate the performance of nanoparticles with much less organic content. Both adsorbents could be used in the form of dispersions. The xerogels, though, are more practicable materials since they may penetrate the pores of a metal or ceramic solid substrate in the form of a precursor gel-forming solution, producing composite purification devices.

NiCo bimetallic and the corresponding monometallic organic frameworks loaded CMC aerogels for adsorbing Cu2+: Adsorption behavior and mechanism

In this study, three-dimensional (3D) carboxymethylcellulose sodium (CMC) aerogel was decorated with NiCo bimetallic and the corresponding monometallic organic frameworks to prepare MOFs-CMC composite adsorbents for the removal of Cu2+. The obtained MOFs-CMC composite including Ni/Co-MOF-CMC, Ni-MOF-CMC, and Co-MOF-CMC were characterized by SEM, FT-IR, XRD, XPS analysis, and zeta potential. The adsorption behavior of MOFs-CMC composite for Cu2+ was explored by batch adsorption test, adsorption kinetics and adsorption isotherms. The experimental data satisfied the pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacities followed the sequence of Ni/Co-MOF-CMC (233.99 mg/g) > Ni-MOF-CMC (216.95 mg/g) > Co-MOF-CMC (214.38 mg/g), indicating that there was a synergistic effect between Ni and Co to promote the adsorption of Cu2+. Combining characterization analysis and density functional theory (DFT) calculation, it is clarified that the adsorption mechanism of MOFs-CMC for Cu2+ includes ion exchange, electrostatic interactions, and complexation.

Zirconium/lanthanum-modified chitosan/polyvinyl alcohol composite adsorbent for rapid removal of fluoride

A novel and easily separable adsorbent in the shape of a membrane for the rapid removal of fluoride from water was prepared after testing Zr, La and LaZr to modify a chitosan/polyvinyl alcohol composite adsorbent (CS/PVA-Zr, CS/PVA-La, CS/PVA-LA-Zr). The CS/PVA-La-Zr composite adsorbent can remove a large amount of fluoride within 1 min of contact time, and the adsorption equilibrium can be reached within 15 min. The fluoride adsorption behavior of the CS/PVA-La-Zr composite can be described by pseudo-second-order kinetics and Langmuir isotherms models. The morphology and structure of the adsorbents were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The adsorption mechanism was studied using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and which showed that ion exchange occurred mainly with hydroxide and fluoride ions. This study showed that an easily operable, low-cost and environmentally friendly CS/PVA-La-Zr has the potential to remove fluoride effectively from drinking water in a short time.

Moving adsorption belt system for continuous bioproduct recovery utilizing composite fibrous adsorbents.

A continuous protein recovery and purification system based on the true moving bed concept is presented. A novel adsorbent material, in the form of an elastic and robust woven fabric, served as a moving belt following the general designs observed in known belt conveyors. The composite fibrous material that forms the said woven fabric showed high protein binding capacity, reaching a static binding capacity equal to 107.3mg/g, as determined via isotherm experiments. Moreover, testing the same cation exchange fibrous material in a packed bed format resulted in excellent dynamic binding capacity values (54.5mg/g) even when operating at high flow rates (480cm/h). In a subsequent step, a benchtop prototype was designed, constructed, and tested. Results indicated that the moving belt system could recover a model protein (hen egg white lysozyme) with a productivity up to 0.5mg/cm2/h. Likewise, a monoclonal antibody was directly recovered from unclarified CHO_K1 cell line culture with high purity, as judged by SDS-PAGE, high purification factor (5.8), and in a single step, confirming the suitability and selectivity of the purification procedure.

Effect of Magnetic Field and Electrospray Combination on the Orientation of Carbon Nanotubes in Alginate Core-Shell Composite Adsorbent and Methylene Blue Adsorption

Effect of Magnetic Field and Electrospray Combination on the Orientation of Carbon Nanotubes in Alginate Core-Shell Composite Adsorbent and Methylene Blue Adsorption

A study on vermiculite-based salt mixture composite materials for low-grade thermochemical adsorption heat storage

High-performance renewable energy technologies are desired to meet the enormous demand during the clean energy transition. Thermal energy storage can help balance the mismatch between renewable energy supplies and end-user's demands. Thermochemical adsorption heat storage (TAHS) has attracted widespread attention for its ability to efficiently utilise low-grade renewables and waste heat. Composite adsorbent materials have been gaining increased research interest, which combine hygroscopic salts and host matrix via impregnating salts in the matrix. This paper reviews recent progress in composite materials for TAHS and provides material characterisation analysis on different vermiculite-based composites. The composites use vermiculite as the host matrix with impregnation of different binary and ternary salt mixtures (i.e., MgSO4–CaCl2, MgCl2–LiNO3, MgSO4–LiCl and MgSO4–LiNO3–MgCl2). Vermiculite impregnated with a binary mixture of MgSO4–CaCl2 demonstrated a high energy storage density of 1213 kJ/kg, with fast desorption kinetics in the temperature range of low-grade heat. It shows good suitability for domestic TAHS applications, particularly for space heating, with stable cyclic performance over 20 charging-discharging cycles, maintaining approximately 91.3% of its initial energy storage density. The findings of this study contribute to the growing body of research on composite materials and demonstrate the potential of vermiculite-based composites impregnated with binary salt mixtures for low-grade TAHS.

Sonocrystallization of a novel ZIF/zeolite composite adsorbent with high chemical stability for removal of the pharmaceutical pollutant azithromycin from contaminated water

Water pollution management, reduction, and elimination are critical challenges of the current era that threaten millions of lives. By spreading the coronavirus in December 2019, the use of antibiotics, such as azithromycin increased. This drug was not metabolized, and entered the surface waters. ZIF-8/Zeolit composite was made by the sonochemical method. Furthermore, the effect of pH, the regeneration of adsorbents, kinetics, isotherms, and thermodynamics were attended. The adsorption capacity of zeolite, ZIF-8, and the composite ZIF-8/Zeolite were 22.37, 235.3, and 131 mg/g, respectively. The adsorbent reaches the equilibrium in 60 min, and at pH = 8. The adsorption process was spontaneous, endothermic associated with increased entropy. The results of the experiment were analyzed using Langmuir isotherms and pseudo-second order kinetic models with a R2 of 0.99, and successfully removing the composite by 85% in 10 cycles. It indicated that the maximum amount of drug could be removed with a small amount of composite.

Strategies of stable thermal output and humidity dual control for a packed-bed adsorption thermal battery

Water-based adsorption thermal battery (ATB) could provide huge possibility in widespread applications; especially for space heating, leading to appreciable energy saving and low-grade heat energy utilization. A proof-of-concept prototype based on composite adsorbents has been constructed to investigate the thermal performances of a packed-bed ATB. A possible strategy of tunning airflow rate for performance regulation is proposed and studied to realize stable thermal output. Additional experimental results indicated that the output temperature and heating power can be synchronously stabilized through progressive tunability of loop airflow rate in the loop-cycle ATB system. The output RH spans 40–60% along the effective discharging process, enabling a controllable humidity management in the application of direct space heating considering human thermal comfort. A three-dimensional computational model for predicting the overall thermal output performances of a packed-bed adsorption thermal battery is further developed and established. The simulation results reveal that an effective heating time of 8.6 h with a discharging threshold temperature of 24 °C, and an average power density of 19.3 kW m−3 can be achieved with a maximum heat discharging efficiency of 63.4%. It is, therefore, apparent that the ATB is capable of achieving stable thermal outputs for space heating applications.

Improvement the Quality of Fish Oil from Waste Flouring Using Adsorbent Zeolit H5-NZA

Flouring process produces fish oil fractions colored dark brown and has a free fatty acid levels are high. This causes the oil fraction can be easily damaged and rancid. This problem can be overcome by purification by means of degumming first and then the fish oil the gross adsorbed using adsorbents natural zeolite (NZ) and H5-NZA with the composition of the adsorbent 10%, 15%, 20%, and 25% (w / w fish oil ) on the adsorption process temperature of 50 ° C, 70 ° C, 90 ° C. Adsorbent characterization results indicate that an increase in acidity and Si / Al ratio of zeolites that have been activated are H5-NZA. Increased acidity of 0.291 mmol / gram to 3,570 mmol / gram, while increasing the ratio of Si / Al of 4.373 into 6.398. The quality of fish oil before and after the adsorbed adsorbed using adsorbents also increased. H5-NZA adsorbent provides enhanced quality greater than the natural zeolite adsorbent. Improved quality is shown with increasing adsorbent composition. Adsorbent composition that provides improved quality of most good is a composition of 25%, while the adsorption process temperature optimum at 70 ° C

Development and performance evaluation of novel silica gel-coated heat exchanger with high durability and conductivity to improve adsorption water treatment

Adsorption water treatment (AWT) has received considerable attention because it can be used to produce freshwater using low-grade heat sources. Furthermore, owing to its nearly consistent desalination performance and high-water recovery rate (>80 %), it has a high potential for use as a minimal liquid discharge process. However, a low freshwater production yield per unit volume of the AWT system is observed because the AWT system uses an adsorbent-packed heat exchanger (APHE), which has a high thermal resistance. In this study, the development and performance evaluation of a novel adsorbent-coated heat exchanger (ACHE) with high durability and conductivity is presented to enhance the heat and mass transfer rates during the adsorption and desorption processes. Binders and spray coating methods are utilized to achieve a uniform coating thickness and highly durable ACHE, and the adhesion strength is investigated using a pull-off test. The physical properties of the composite adsorbent are then examined using argon and water vapor adsorption isotherms, and the thermal conductivity is determined using the transient plane source method. Finally, the performance of the AWT process is evaluated considering the hot-water temperature and cycle time and achieves a significant superiority in the ACHE compared with the APHE.