Adsorption Technology Research Articles

Efficient Purification of 2′-Fucosyllactose by Membrane Filtration and Activated Carbon Adsorption

With the rapid development of synthetic biology, the production of 2′-fucosyllactose by biological fermentation gradually has the basis for industrialization. However, the lack of efficient downstream technology of biological fermentation, especially purification technology, has become the main factor limiting its commercialization. In this study, based on the general E. coli biosynthesis of 2′-fucosyllactose fermentation broth, most of the impurities were removed and concentrated using membrane filtration technology after simple flocculation. The target 2′-fucosyllactose was eluted in a targeted manner using activated carbon adsorption and ethanol gradient elution technology. The 2′-fucosyllactose product with 90% or even higher purity could be prepared efficiently. This study explored a new direction for the industrial production of 2′-fucosyllactose.

Dynamic Adsorption of H2S onto a Goethite-Based Material.

The use of adsorption technology to remove H2S from synthetic gas (H2S and N2) using a goethite-based adsorbent was investigated. The influence of the H2S feed concentration (150-600 mg), the adsorbent dosage (1-4 g), and the gas flow rate (210-540 cm3/min) on the breakthrough curves and H2S adsorption on the adsorbent at the breakthrough point was investigated. Dynamic column experiments were performed to provide data for the theoretical models and to verify the performance of the system in the adsorption process. The theoretical models used in the present work were found to predict the adsorption breakthrough performance reasonably well.

Rapid adsorption of sulfamethazine on mesoporous graphene produced from plastic waste: optimization, mechanism, isotherms, kinetics, and thermodynamics

Sulfonamide antibiotics like sulfamethazine (SMZ) can threaten aquatic and terrestrial life even in small concentrations (≤ 1 mg/L); hence, their removal from wastewater is indispensable. However, the need to explore new promising adsorbents that are cheap, effective, and reusable also remains crucial to developing adsorption technology. This work presents a one-pot solvent-free conversion of the current most ubiquitous anthropogenic bio-resistant solid waste (plastics) into valuable carbon materials to remove SMZ from aqueous solution. High-density polyethylene waste was pyrolyzed at 500–1000 °C in an enclosed stainless-steel reactor to produce mesoporous graphene. The graphene products were characterized via microscopic and spectroscopic analyses. The effect of temperature on the graphene yield and properties was investigated. The optimum sulfamethazine (SMZ) adsorption was achieved with 600 °C carbon product (CP-600) due to its high porosity and aromatic structure. The adsorption parameters (pH, catalyst dose, and SMZ concentration) were optimized by response surface methodology (RSM) with a central composite design. 99.99% SMZ removal was achieved at 0.9 g/L adsorbent dose, 12.4 mg/L SMZ concentration, and pH 3 at 25 °C. FTIR analysis revealed that the SMZ adsorption occurred mainly via π–π/π+–π electron interactions between the aromatic and pyrimidine rings of SMZ and the benzene ring of graphitic CP-600. The SMZ adsorption followed the pseudo-second-order kinetics, Langmuir, and Freundlich isotherm models. The adsorption was controlled by film and intraparticle diffusion and was spontaneous and endothermic. The carbon synthesized in this work is reusable and can rapidly remove more SMZ than other SMZ adsorbents.

Construction of novel super microporous silica adsorbents using pluronic triblock copolymer as template towards desulfurization from fuel

As an efficient fuel purification technique, adsorption desulphurization has attracted wide attention. Silicon oxide has been verified as a promising candidate for adsorption desulfurization reagent due to the advantages of stable structure, inexpensiveness and accessibility. However, its adsorption desulfurization performance is always weakened by the limited pore channel size leading to pore diffusion resistance over the traditional microporous silicon oxide, and it suffers from the poor shape selectivity of mesoporous silicon oxide as well. In this work, we successfully prepared a novel super microporous silica material (SMS) with a unique bimodal micro-mesoporous pore size distribution mainly around 1.2 nm, 1.6 nm and 1.8 ∼ 3.5 nm, using a pluronic triblock copolymer with approximately an average molecular weight of 3858 as template by hydrothermal synthesis. The SMS possessed the characteristics of Ia3d cubic phase and super microporous as well as mesoporous silica structure, according to the X-ray diffraction characterization as well as nitrogen adsorption isotherms. The SMS could effectively reduce the diffusion resistance and exhibit improved shape selectivity compared to microporous or mesoporous silicon oxide, respectively, by virtue of its bimodal micro-mesoporous pore size distribution. Under an optimized crystallization temperature of 100 °C for 24 h, the as-synthesized SMS displayed a notable desulfurization performance with a breakthrough capacity of 0.122 mmol S/g benzothiophene, which was significantly superior to that of traditional mesoporous silica KIT-6 (0.04 mmol S/g). Furthermore, the desulfurization performance of SMS adsorbent was not significantly reduced after three cycles of regeneration. The SMS exhibited high desulfurization capacity, easy regeneration and satisfactory regeneration performance, and it could be applied in adsorptive desulfurization technology.

Development of a magnetic calcium-alginate hydrogel-sphere encapsulated with Fe–Mn–Zr ternary metal composite for heavy metal adsorption

Heavy metal contamination has become one of the greatest global environmental problems. In this study, a magnetic calcium-alginate hydrogel-sphere encapsulated with Fe–Mn–Zr ternary-metal composite (MCHETC) was prepared through a combined co-precipitation and extrusion approach and used for the adsorption of heavy metals in aqueous solutions. The active sites were dispersed in the MCHETC, which can be separated by the magnetic force for the ease in operation. Above 80% of ultimate adsorption was completed at a contact time of 5 h. The copper uptake history was well described by the intraparticle surface diffusion model, suggesting a multi-step process for the adsorption. The optimum pH for adsorption was 4; the maximum adsorption capacity was 103.1 mg-Cu/g. The adsorption capability well remained after the 5 adsorption–desorption cycles and the copper could be recovered. Furthermore, the adsorbent performed well in the nature water spiked with copper ions. The mechanism studies illustrated that the adsorption was mainly controlled by the ion-exchange reaction. This study demonstrated that the MCHETC adsorption technology may be used for heavy metal removal and recovery with higher efficacy.

Solar-radiation-induced adsorption/desorption system for carbon dioxide capture

Solid-adsorbent-based temperature swing adsorption (TSA) technology is intriguing in CO2 capture, and the predominant energy consumption lies in the temperature swing process. Inspired by the self-regulation of lizards, here, we design a solar-radiation-induced adsorption/desorption system, avoiding additional energy supply for the temperature swing process. In this system, adsorbents filled in a reversible quartz device are covered by radiative cooling coating. With the demand of adsorption and desorption, the temperature of adsorbents can be regulated by radiative cooling and solar heating, respectively. Adsorption tests for over 1 year using the metal-organic framework HKUST-1 as an adsorbent demonstrate that the CO2 working capacity of our system is higher than most industrial TSA with various adsorbents. Furthermore, our system can save more than 80% of the energy input for industrial TSA technologies.

Rational Design of Carbon-Based Porous Aerogels with Nitrogen Defects and Dedicated Interfacial Structures toward Highly Efficient CO2 Greenhouse Gas Capture and Separation.

CO2 capture from flowing flue gases through adsorption technology is essential to reduce the emission of CO2 to the atmosphere. The rational design of highly efficient carbon-based absorbents with interfacial structures containing interconnected porous structures and abundant adsorption sites might be one of the promising strategies. Here, we report the synthesis of nitrogen-doped carbon aerogels (NCAs) via prepolymerized phenol-melamine-formaldehyde organic aerogels (PMF) by controlling the addition amount of ZnCl2 and the precursor M/P ratio. It has been revealed that NCAs with a higher specific surface area and interconnected porous structures contain a large amount of pyridinic nitrogen and pyrrolic nitrogen. These would act as the intrinsic adsorption sites for highly effective CO2 capture and further improve the CO2/N2 separation efficiencies. Among the prepared samples, NCA-1-2 with a high micropore surface area and high nitrogen content exhibits a high CO2 adsorption capacity (4.30 mmol g-1 at 0 °C and 1 bar) and CO2/N2 selectivity (36.5 at 25 °C, IAST). Under typical flue gas conditions (25 °C and 1.01 bar), equilibrium gas adsorption analysis and dynamic breakthrough measurement associated with a high adsorption capacity of 2.65 mmol g-1 at 25 °C and 1.01 bar and 0.81 mmol g-1 at 25 °C and 0.15 bar. This rationally designed N-doped carbon aerogel with specific interfacial structures and high CO2 adsorption capacity, high selectivity, and adsorption performance remained pretty stable after multiple uses.

Boosting Ethane/Ethylene Separation by MOFs through the Amino‐Functionalization of Pores

Adsorption technology based on ethane-selective materials is a promising alternative to energy-intensive cryogenic distillation for separating ethane (C2 H6 ) and ethylene (C2 H4 ). We employed a pore engineering strategy to tune the pore environment of a metal-organic framework (MOF) through organic functional groups and boosted the C2 H6 /C2 H4 separation of the MOF. Introduction of amino (-NH2 ) groups into Tb-MOF-76 not only decreased pore sizes but also facilitated multiple guest-host interactions in confined pores. The NH2 -functionalized Tb-MOF-76(NH2 ) has increased C2 H6 and C2 H4 uptakes and C2 H6 /C2 H4 selectivity. The results of experimental and simulated transient breakthroughs reveal that Tb-MOF-76(NH2 ) has significantly improved one-step separation performance for C2 H6 /C2 H4 mixtures with a high C2 H4 (>99.95 %) productivity of 17.66 L kg-1 compared to 7.53 L kg-1 by Tb-MOF-76, resulting from the suitable pore confinement and accessible -NH2 groups on pore surfaces.

Zeolites in Adsorption Processes: State of the Art and Future Prospects.

Zeolites have been widely used as catalysts, ion exchangers, and adsorbents since their industrial breakthrough in the 1950s and continue to be state-of the-art adsorbents in many separation processes. Furthermore, their properties make them materials of choice for developing and emerging separation applications. The aim of this review is to put into context the relevance of zeolites and their use and prospects in adsorption technology. It has been divided into three different sections, i.e., zeolites, adsorption on nanoporous materials, and chemical separations by zeolites. In the first section, zeolites are explained in terms of their structure, composition, preparation, and properties, and a brief review of their applications is given. In the second section, the fundamentals of adsorption science are presented, with special attention to its industrial application and our case of interest, which is adsorption on zeolites. Finally, the state-of-the-art relevant separations related to chemical and energy production, in which zeolites have a practical or potential applicability, are presented. The replacement of some of the current separation methods by optimized adsorption processes using zeolites could mean an improvement in terms of sustainability and energy savings. Different separation mechanisms and the underlying adsorption properties that make zeolites interesting for these applications are discussed.

A critical review on adsorption and recovery of fluoride from wastewater by metal-based adsorbents

Rapid industrialization is deteriorating water quality, and fluoride pollution in water is one of the most serious environmental pollution problems. Adsorption technology is an efficient and selective process for removing fluoride from aqueous solutions using adsorbents. Metal-based adsorbents synergize the advantages of fast adsorption, high adsorption capacity, and excellent selectivity to effectively remove fluoride from water bodies, promising to satisfy environmental sustainability requirements. This paper reviews the metal-based adsorbents: iron-based, aluminum-based, lanthanum-based, cerium-based, titanium-based, zirconium-based, and multi-metal composite adsorbents, primarily focusing on the adsorption conditions and fluoride removal capacities and discusses prospects and challenges in the synthesis and application of metal-based adsorbents. This paper aims to stimulate new thinking and innovation in developing the next generation of sustainable adsorbents.

Removal of Dye (Methylene Blue) from Wastewater Using Bio-Char Derived from Agricultural Residues in Palestine: Performance and Isotherm Analysis

The main aim of this study was to perform a parametric study for treating a model dye containing wastewater (i.e., methylene blue, MB) using locally available biomass wastes in Palestine as the adsorbent. Eight different types of biomasses were investigated in batch adsorption tests, including coffee grains, almond shells, pistachio shells, date pits, jute sticks, sunflower shells, peanut shells, and grapevine sticks. The experiments were conducted on three different phases of processing for these materials: as natural adsorbents, biochar, and activated carbon. The biochar was prepared by pyrolysis, while ZnCl2 was used to chemically activate the materials for obtaining activated carbon. The influences of pH, initial MB concentration, and adsorbent dosage on the adsorption capacity and kinetics were investigated for activated carbon obtained from sunflower shells. The results indicate that the adsorption efficiency of natural adsorbents and biochar is highly dependent on the biomass type. As a natural adsorbent, peanut hulls demonstrated the maximum efficiency (>95%) for removing MB, whereas date pits showed the lowest efficiency (20%). In terms of biochar, jute sticks provide the highest removal efficiency. After activation with ZnCl2, a considerable increase in their adsorption efficiency (>95%) was obtained for most of the adsorbents, with sunflower shells being the most efficient adsorbent. The results confirm the technical feasibility of the adsorption technology to treat dye containing wastewater using locally available biomass wastes.

Novel oxymagnesite/green rust nanohybrids for selective removal and slow release of phosphate in water

The new paradigm in wastewater treatment demands to change traditional pollutants removal into resource recovery, especially for non-renewable P resources, effectively recovering phosphate from wastewater and reutilizing it as a nutrient is crucial to P sustainable utilization and P-related pollution control. The nanomaterial-based adsorption technology for P recovery from wastewater is becoming a research hotspot due to its high efficiency and selectivity. Herein, to recover aqueous phosphate, we developed novel oxymagnesite/green rust (OMGR) nanohybrids by a one-pot hydrothermal method. Green rust nanoparticles dispersed on the highly reactive oxymagnesite (MgO2MgCO3) nanosheets could achieve efficient recovery and reuse of P. The volume ratio of water to ethylene glycol played an important role in the preparation of OMGR. The OMGR possessed an excellent selectivity of phosphate removal in the presence of multi-anions and wide pH adaptability in 4.0–10.0. The formation of MgP nanocrystals and the inner-sphere FeOP complexes via ligand exchange contributed to the selective removal of P by OMGR, and the removal capacity reached 141 mg P.g−1. The process of phosphate removal by OMGR was spontaneously endothermic and controlled by the intraparticle and boundary layer diffusion. Most importantly, the high bioavailable P (127 mg.g−1) of P-loaded OMGR had a persistent release behavior regulated by dissolution and diffusion, indicating that the P-loaded OMGR can act as a slow-release P-fertilizer. The findings provide a green and eco-friendly approach to realizing P resource recovery and reuse for phosphate-containing wastewaters.

Removing forever chemicals via amphiphilic functionalized membranes

Per- and poly-fluoroalkyl species (PFAS) remain ever-present drinking water contaminants. While some physical adsorption technologies for PFAS removal have been implemented on a large scale, they are limited by high cost and low effectiveness. In this work, an amphiphilic coating was developed and used to functionalize an aluminum oxide hydroxide membrane. Dynamic filtration of challenge water containing eighteen PFAS demonstrated >99% removal of eleven of eighteen PFAS as defined in EPA 537.1. Comparable performance was observed under gravity filtration conditions with >90% removal of fifteen of the eighteen PFAS. A comparison of breakthrough rates using amphiphilic silanes versus granular activated carbon (GAC), the commonly used filtration technology, was performed. Filters with the new amphiphilic coating outperformed GAC under dynamic filtration conditions by more than an order of magnitude for the perfluorooctanoic acid adsorption capacity and even greater for perfluorooctane sulfonic acid. Molecular dynamics simulations were used to compute the free energy, enthalpy, and entropy of interactions between coatings and six PFAS contaminants. Computed interaction free-energy (FE) values agree with experimental filtration performance across contaminants. The ability to use simulated FE values to predict filtration efficiency presents an opportunity for future in-silico rational design with overall reduced cost and development time.

Facile and template-free fabrication of hollow spherical AlOOH and Al2O3 from the waste aluminum residue: Growth mechanism and fast removal of Congo red

Organic dye pollution has attracted considerable concern, and the adsorption technology using inorganic nanostructures has become prevalent. In this work, hollow spherical AlOOH (HSHA) was successfully fabricated via an one-pot and template-free hydrothermal method. After calcination at 550 ​°C for 1 ​h, hollow spherical Al2O3 (HSAO) with the same morphology was obtained. The hollow spherical structures comprised of plenty of uniform nanoflakes possessed the high specific surface areas and total pore volumes. HSHA and HSAO exhibit excellent adsorption performance for Congo red (CR) with the maximal adsorption capacities of 277.00 and 478.47 ​mg ​g−1, respectively. The adsorption almost reached the equilibrium within 10 ​min. The pseudo-second-order model fitted the adsorption process well. The adsorption was spontaneous. Both the Langmuir and Freundlich models fitted the adsorption well, but the Freundlich model was slightly better. HSHA and HSAO are the potential and qualified candidates for the dye removal.

Experimental tests of cadmium and trace metals adsorption on natural clays and activated carbon from wet phosphoric acid

Cadmium and trace metals elements present a significant challenge to the fertilizer industry, considering the increasingly strict regulation on their contents in fertilizers. Consequently, a specific need to develop efficient and cost-effective technologies for their removal has appeared within the last few years. This research article focuses on the adsorption technology already proved for water treatment as a promising and emerging technology for removing cadmium and trace metals from wet phosphoric (WPA), given its ease of use and low cost. Literature highlights a lack of adsorption applications for treating WPA in industrial conditions in terms of P2O5 content and temperature. In this scope, effective natural and activated clays, Montmorillonite (M), Illite (I), and Attapulgite (A), as well as sulfur-impregnated activated carbon, were prepared, characterized, and used for the adsorption of cadmium and trace metals from WPA with 25 % (w/w) P2O5 at 80 °C. For clay adsorbents, different quantities of 1, 2, 3, and 4 % (w/w) were tested with a contact time of 30 min. As a result, it was found that lead was removed in total while there was no significant adsorption of cadmium and nickel. Slight adsorption efficiency of 20 % was registered for chromium and arsenic, equivalent to an adsorption capacities of 2.5 mg/g and 0.2 mg/g, respectively. The latter effect could be attributed to their multiple oxidation states. The chemical activation of clays to pH 1 by using a 5 M NaOH solution increased chromium and arsenic adsorption efficiencies to 46 % and 19 %, equivalent to an adsorption capacities of 0.2 mg/g and 3.7 mg/g, respectively. Adsorption could not be reached for sulfur-impregnated activated carbon despite its large specific surface (528 m2/g) and its sulfur impregnation (10 % w/w). This latter was supposed to activate the chemisorption of cadmium and other trace metals like arsenic, copper, and zinc by forming covalent bonds due to their chemical affinity to sulfur. However, research on the carbon structure showed that sulfur was inactive as it forms a covalent bond with carbon in the mineral structure of activated carbon.

Arsenic removal technologies for middle- and low-income countries to achieve the SDG-3 and SDG-6 targets: A review

• Over 230 million population are suffering from ‘As’ laced drinking water and its associated health hazards worldwide. • To achieve SDG- 3 (Good health and well-being’) and SDG-6 (Safe and clean water and sanitation) ‘As’ problem needs to be managed. • Low and middle income countries have a challenge to implement highly efficient As removal technologies. • Chemical and biological technologies, adsorption, and hybrid technologies with running cost <1 US$/m 3 can be applied in low/middle income countries. • Regular monitoring of As, community participation, research on cost effective As-removal models coupled with policy level intervention is most needed. Contamination of arsenic (As) in groundwater has increased across the world with prominence in the middle- and low-income countries. The United Nations ‘Sustainable Development Goals’ (SDG's)- ‘good health and well-being’ (SDG 3) and ‘safe and clean water and sanitation for all’ (SDG 6), cannot be achieved without monitoring and remediating ‘As’ pollution in groundwater. Over 230 million people worldwide are affected due to arsenic-contaminated drinking water. More than 200 articles discussing the ‘As’ contamination, toxicity and cost effective technology were reviewed in this study focusing on economic status of the affected nation as per World bank report. Cost budget analysis suggested that chemical oxidation followed by precipitation (0. 043-0. 076 US$/m 3 ), low cost adsorbent (0. 1 US$/m 3 ), hybrid treatment technologies (0. 15-0. 17 US$/m 3 ) and biological oxidation (0. 2 US$/m 3 ) can be applied in low income countries through community based models to mitigate the health problem related to As contamination in order to achieve SDG 3 and SDG 6 targets. This study recommends further research on budget friendly ‘As’ remediation systems and policy level interventions in the affected nations to cater safe drinking water to all.

CO2 Capture in the natural gas processing at Pre-salt typical conditions via Fixed bed reactor adsorption technology

CO2 Capture in the natural gas processing at Pre-salt typical conditions via Fixed bed reactor adsorption technology

Insights on perovskite-type proton conductive membranes for hydrogen permeation

Hydrogen has received widespread attention because as its diverse delivery methods and no GHG emissions. The use of membrane separation can effectively replace the costly low-temperature distillation and pressure swing adsorption technology to achieve the purpose of low-cost hydrogen enrichment. As a promising hydrogen separation material, perovskite-type proton conductor hydrogen permeable membrane has been practically applied in hydrogen separation and purification process. In this paper, the principle of hydrogen permeability of perovskite-type proton conductor hydrogen permeable membrane is expounded, and its preparation method and application are summarized, and the development trend of the material is discussed.

Microwave-assisted industrial wastes of fly ash and carbide slag as adsorbents for simultaneous desulfurization and denitrification

In this paper, an efficient and low-cost desulfurization and denitrification adsorption technology was proposed by utilizing microwave-assisted fly ash and carbide slag as adsorbent with active coke (AC) as the catalytic adsorption media. The effect of different parameters on the removal of SO2 and NO using the prepared adsorbent was investigated. The optimal preparation and adsorption conditions were as follows: amount of AC 10 wt%, microwave-assisted power and time of 1000 W and 10 min, adsorption temperature of 150 °C. Under these conditions, the removal rates of T90% for SO2 and T80% for NO were 86 min and 30 min, respectively, whereas the maximum adsorption capacities of SO2 and NO were 0.57 mg/g and 0.07 mg/g, respectively. The reaction mechanism indicates that AC and oxygen would contribute to improving the adsorption activity and further facilitating the conversion of N2+ to N4+, and N5+, and S4+ to S6+. However, the generated sulfate and nitrate will poison the active sites of the adsorbent, which led to a decline in the adsorption capability of the proposed adsorbent.

Tandem production of high-purity sodium glycolate via the dual purification technology of crystallization and active carbon adsorption

High-purity glycolic acid (GA) are highly required for the production of biodegradable polymers, pharmaceuticals, and fine chemicals. For production of bio-polyester, GA purity has emerged as a bottleneck. In this paper, we innovatively propose crystallization to dispose of purity problem and investigated the repurification of sodium glycolate crystals. Compared to traditional chemical techniques, resting cell catalysis with bio-oxidation of ethylene glycol (EG) is a promising method for the green industrial production of GA. Gluconobacter oxydans is one of the most promising strains because of its ability to ferment high GA titer from EG. However, the GA directly from fermentation broth does not meet the high purity requirements for biodegradable materials. Therefore, a tandem process was designed and experimentally verified by combining crystallization and active carbon (AC) adsorption. Sodium glycolate (SG) formation was adopted due to low-cost operation in the biological step and easy electrodialysis of GA. According to the dissociation constants (Kɑ) of glycolate, the fermentation broth was adjusted to pH 9.50 and SG saturates at 60 ℃ for SG crystallization. The macroscopic yellow plate-like crystals 91.1 g of SG with 94 % purity were produced at room temperature (25℃). In the tandem process, AC rapidly removed most pigment-like contaminants in the fermentation broth but adsorbed only a little SG (1 %), indicating selective and effective adsorption. Over 97 % of the color was removed by adding 8 % AC to a saturated solution (188 g/L). Finally, 79.2 g SG with 99 % purity was obtained at the yield of 87 % from 104 g/L SG broth. This tandem process could provide an economically-feasible approach for the industrial bioproduction of high-purity SG and GA derived from EG.