Different Types Of Adsorbents Research Articles

From Sampling to Analysis: How to Achieve the Best Sample Throughput via Sampling Optimization and Relevant Compound Analysis Using Sum of Ranking Differences Method?

The determination of an optimal volatile sampling procedure is always a key question in analytical chemistry. In this paper, we introduce the application of a novel non-parametric statistical method, the sum of ranking differences (SRD), for the quick and efficient determination of optimal sampling procedures. Different types of adsorbents (Porapak Q, HayeSep Q, and Carbotrap) and sampling times (1, 2, 4, and 6 h) were used for volatile collections of lettuce (Lactuca sativa) samples. SRD identified 6 h samplings as the optimal procedure. However, 1 or 4 h sampling with HayeSep Q and 2 h sampling with Carbotrap are still efficient enough if the aim is to reduce sampling time. Based on our results, SRD provides a novel way to not only highlight an optimal sampling procedure but also decrease evaluation time.

Dynamic characteristics of a prestressed micro-diaphragm in a fluid subjected to distributed mass loading

This paper studies the vibrational behaviors of a distributive mass-loaded microscale circular diaphragm submerged in a fluid. The vibration of the diaphragm involving loadings simultaneously induced by an acoustic field and the adhesion of distributive mass has been investigated. Two different types of adsorbates, namely, in the form of discrete particles (mass only) and a uniform layer (mass and rigidity), are considered and compared. Moreover, the pre-existing stress in the diaphragm has also been taken into consideration. Based on Lamb's hypotheses of the fluid-loaded structure in conjunction with the Rayleigh–Ritz theorem, an analytical solution for the dynamic characteristics of the coupling system, including the resonant frequency, mode shape, and the quality factor, is developed. The results have been compared with those of the finite element simulations, and a good agreement has been obtained. The results reveal that the adsorbate properties contribute differently to the dynamic response of the micro-diaphragm in the fluid, and the contribution may be intervened by tuning the pre-stress. The theoretical model and novel analytical solution are of interest in the design of micro-diaphragm-based biosensing devices.

Investigation of human adipose-derived stem-cell behavior using a cell-instructive polydopamine-coated gelatin-alginate hydrogel.

Hydrogels can be fabricated and designed to exert direct control over stem cells' adhesion and differentiation. In this study, we have investigated the use of polydopamine (pDA)-treatment as a binding platform for bioactive compounds to create a versatile gelatin-alginate (Gel-Alg) hydrogel for tissue engineering applications. Precisely, pDA was used to modify the surface properties of the hydrogel and better control the adhesion and osteogenic differentiation of human adipose-derived stem cells (hASCs). pDA enabled the adsorption of different types of bioactive molecules, including a model osteoinductive drug (dexamethasone) as well as a model pro-angiogenic peptide (QK). The pDA treatment efficiently retained the drug and the peptide compared to the untreated hydrogel and proved to be effective in controlling the morphology, cell area, and osteogenic differentiation of hASCs. Overall, the findings of this study confirm the efficacy of pDA treatment as a valuable strategy to modulate the biological properties of biocompatible Gel-Alg hydrogels and further extend their value in regenerative medicine.

Adsorption of BS-18 Amphoterically Modified Bentonite to Tetracycline and Norfloxacin Combined Pollutants

Antibiotic pollution in the environment has become a hot topic. The amphoteric surfactant octadecyl dimethyl betaine (BS-18) was adopted to modify bentonite to investigate the effects and mechanisms of the composite adsorption of different types of antibiotics. Under the different modification ratios, temperatures, pH values, and ionic strength conditions, the adsorption of tetracycline (TC) and norfloxacin (NOR) by bentonite was studied under single and compound conditions, and the adsorption mechanism was analyzed and discussed in combination with the surface properties of amphoterically modified bentonite. The results showed that compared with those of CK, the CEC and specific surface area of the soil samples modified by BS-18 decreased, whereas the total carbon and total nitrogen contents increased. The adsorption order of BS-18 amphoterically modified bentonite to TC was CK > 100BS > 25BS > 50BS, which was in accordance with the Langmuir model; the adsorption order of NOR was 25BS > 50BS > CK > 100BS, which was consistent with the Henry model. The adsorption capacity of TC and NOR in the TC and NOR composite system was higher than that in the single system. With the increase in temperature, the adsorption of amphoterically modified bentonite to TC showed a positive warming effect, whereas the adsorption of NOR declined as the temperature increased. When the ionic strength increased from 0.001 mol·L-1 to 0.500 mol·L-1, the adsorption of TC and NOR on each soil sample was inhibited. The pH of the solution can affect the existing forms of TC and NOR, and the adsorption capacity showed different trends as the pH increased. The adsorption of TC by BS-18-modified bentonite was mainly caused by electric charge attraction, whereas the adsorption of NOR was mainly caused by the combination of electric charge attraction and the hydrophobic effect. The different values of the octanol/water partition coefficient and the difference in structure resulted in different adsorption modes. In the TC and NOR composite system, a TC+NOR mixture was formed to promote the adsorption of soil samples.

Molecular Determination of Organic Adsorption Sites on Smectite during Fe Redox Processes Using ToF-SIMS Analysis.

Turnover of soil organic carbon (SOC) is strongly affected by a balance between mineral protection and microbial degradation. However, the mechanisms controlling the heterogeneous and preferential adsorption of different types of SOC remain elusive. In this work, the heterogeneous adsorption of humic substances (HSs) and microbial carbon (MC) on a clay mineral (nontronite NAu-2) during microbial-mediated Fe redox cycling was determined using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results revealed that HSs pre-adsorbed on NAu-2 would partially inhibit structural modification of NAu-2 by microbial Fe(III) reduction, thus retarding the subsequent adsorption of MC. In contrast, NAu-2 without precoated HSs adsorbed a significant amount of MC from microbial polysaccharides as a result of Fe(III) reduction. This was attributed to the deposition of a thin Al-rich layer on the clay surface, which provided active sites for MC adsorption. This study provides direct and detailed molecular evidence for the first time to explain the preferential adsorption of MC over HSs on the surface of clay minerals in iron redox processes, which could be critical for the preservation of MC in soil. The results also indicate that ToF-SIMS is a unique tool for understanding complex organic-mineral-microbe interactions.

Application of EIS technique to investigate the adsorption of different types of depressants on pyrite

Application of EIS technique to investigate the adsorption of different types of depressants on pyrite

Multifunctional crosslinked chitosan/nitrogen-doped graphene quantum dot for wastewater treatment

The fabrication of multifunctional nanomaterial for the adsorption of different types of pollutants is a challenge and could be a solution for many problems associated with wastewater treatment. This current study propose the use of crosslinked chitosan/nitrogen doped-graphene quantum dot nanocomposites (CS/NGQD) synthesized via glutaraldehyde as cross-linker to remove various pollutants including bacteria, proteins, fluoride, dyes, and pharmaceuticals. This nanomaterial was characterized using different techniques (FT-IR, XRD, SEM, TEM, and Raman spectroscopy). This nanocomposite offered higher pollutants removal efficiencies compared to its component parts. Using CS/NGQD the removal reached 60% for proteins and 88% for the bacterial load. A significant removal enhancement was also obtained for pharmaceuticals (63% for chlorothiazide, 81% for carbamazepine, and 89% ranitidine), dyes (82% for Azo blue, 84% for methylene blue and 94% for orange G), and fluoride (42%). Interestingly, after 5 cycles of reuse, the nanocomposite remains efficient for the removal of pollutants from water.

Biocompatible MIP-202 Zr-MOF tunable sorbent for cost-effective decontamination of anionic and cationic pollutants from waste solutions

This reported work aims to fabricate an eco-friendly Zr bio-based MOF and assessment its adsorption efficiency towards the cationic and anionic dye pollutants including methylene blue (MB) and direct red 81 (DR-81), respectively. Also, its adsorption tendency for the highly toxic heavy metal of hexavalent chromium (Cr(VI)) was compared with dyes. The adsorption performance of bio-MOF showed that the maximum monolayer adsorption capacities were recorded as 79.799 mg/g for MB, 36.071 mg/g for DR-81, and 19.012 mg/g for Cr(VI). Meanwhile, the optimum dosage of as-synthesized MIP-202 bio-MOF was 0.5, 1, and 2 g L−1 for MB, DR-81, and Cr(VI), respectively. Thermodynamic analysis demonstrated the spontaneous, thermodynamically, and endothermic nature of the decontamination processes onto the fabricated Zr bio-based MOF. The adsorption data were fitted by Langmuir isotherm model compared with Freundlich and Temkin models for all studied water pollutants. Pseudo-second-order kinetic model was a fit model for description of the adsorption kinetics of the different cationic and anionic pollutants onto Zr bio-based MOF. These outcomes indicated that Zr bio-based MOF has potential application for adsorption of different types of industrial water pollutants including cationic and anionic dyes and heavy metals.

Synergistic Adsorbent Sequence for Dissolved Organic Nitrogen Fractional Removal from Biotreated Pharmaceutical Wastewater

Adsorption has demonstrated great promise for removing dissolved organic nitrogen (DON), but effective solutions to alleviate the competitive adsorption of different types of DON are lacking. Herei...

Using magneto-adsorbent for methylene Blue removal: A decision-making via analytical hierarchy process (AHP)

Uncontrolled release of dyes from industrial effluents have led to significant environment pollution. Thus, it is crucial to develop an effective strategy to remove dye molecules from water resources. Over the past few decades, researchers have been investigating the feasibility of using Fe3O4 nanoparticles, natural polymer beads, Fe3O4-encapsulated natural polymer beads and other types of magneto-adsorbents for dye adsorption. Most of the results demonstrated that the dye removal efficiency attained by these adsorbents is promising. However, problem arises when comes to the final decision to select the most suitable adsorbent for industrial implementation. In fact, there has been no systematic comparison performed among different types of adsorbents. Hence, this case study aims to analyse the most suitable type of magneto-adsorbent for methylene blue removal based on a structured analytical hierarchy process (AHP). First, an AHP model was developed via multi-level of objective. The criteria involved in the decision-making were the adsorption capacity, the ability to conduct Fenton degradation, the potential side effect, the adsorbent cost, the energy consumed, and the required downstream separation process. Our analysis implied that Fe3O4 is best to be used for methylene blue removal at its bare condition (i.e without any modification/encapsulation). Here, bare Fe3O4 was found to score higher global priority (0.303) than the modified/encapsulated counterparts owing to its excellent local weight in the dominant criteria.

Investigation of using egg shell powder for bleaching of soybean oil

Egg shell that accounts about 11% of egg weight is one of the industrial wastes that in this research has been used for soybean oil bleaching. The effects of using 1% and 2% of five different types of adsorbents; egg shell powder, egg shell ash, acid activated egg shell powder, acid activated egg shell ash and commercial bleaching earth have been investigated on the bleaching of neutralized soybean oil. The peroxide value, free fatty acid, chlorophyll, carotenoids, metals (copper and iron) and oil retention were determined. Egg shell structure was investigated. According to the results, the bulk of the egg shell consists of calcium and some other compounds such as magnesium, iron and manganese while silicate is the main composition of commercial bleaching earths. The results indicated that soybean oil bleaching with 2% egg shell powder reduced carotenoids and chlorophyll contents up to 82.56% and 46.33%, respectively. Also using of adsorbents based on egg shell reduced significantly (p < 0.05) the peroxide value, free fatty acid contents and oil retention as compared to commercial bleaching earth. It might be concluded that egg shell powder as an industrial waste can be employed as an adsorbent and regarded as a good alternative for bleaching of edible oils due to its high efficiency to remove undesirable components (pigments, iron, copper, oxidation products and free fatty acids) from neutralized oils and environmental protection against acid pollution.

Different types of adsorbents for selenium (Se) removal from water: A review

Development of adsorption materials based on metal oxides, silicon dioxide, carbon, biosorbents and adsorbents, obtained from natural waste, can be used to remove selenium from water. Research on some of these materials is at the laboratory level, while the others were tested in the pilot plants, and a few have found a commercial application. The high adsorption capacities show a possibility of their application for selenium removal from water. This paper presents a literature review of different types of adsorbents for the removal of selenium (Se) from water.

Ionic liquid-modified graphene oxide sponge for hexavalent chromium removal from water

Chromium pollution in groundwater is a major cause of concern due to significant health risks of hexavalent chromium (Cr(VI)) ions. Graphene oxide (GO) covalently modified with 1-aminopropyl-3-methylimidazolium bromide (mimNH2) and freeze-dried to give 1-aminopropyl-3-methylimidazolium bromide functionalized graphene oxide sponge (mimGO sponge). mimGO sponge effectively adsorbed hexavalent chromium (Cr(VI), toxic) by electrostatic interactions and reduced Cr(VI) to trivalent chromium (Cr(III), less toxic) by an indirect mechanism with the contribution of delocalized π-electrons on the six-membered aromatic ring of mimGO sponge. The change in contact time, adsorbent loading, initial Cr(VI) solution concentration, and different types of adsorbents were investigated. The experimental data were fitted to the pseudo-second order kinetic model, which showed hydro-chromate adsorption on mimGO sponge was surface adsorption with chemical interaction. The adsorption process was well-defined by the Langmuir isotherm model, and equilibrium adsorption capacity was 208.3 mg/g at 23 ℃ in an acidic environment. The electrostatic interaction between the chromate ions and mimGO sponge also caused a reduction of Cr(VI) to less benign Cr(III) on the adsorbent surface. Thus, mimGO sponge has a green adsorbent that showed the potential for Cr(VI) removal from water.

Adsorption of Methyl Chloride on Molecular Sieves, Silica Gels, and Activated Carbon

AbstractAdsorption of methyl chloride (CH3Cl or MeCl) on five different types of adsorbents was investigated experimentally at increasing pressures and room temperature. Prior to adsorption, all adsorbents were analyzed to assess their physical and chemical characteristics. The experimental data was then used to determine the adsorption isotherms, heats of adsorption, adsorption rates, and their respective theoretical models. The MeCl adsorption capacity was found to reasonably correlate with the adsorbent's surface area. The MeCl adsorption isotherm and adsorption rates were fitted for the first time to a Freundlich isotherm model and pseudo first‐/second‐order kinetic models, respectively. The range of heat of adsorption indicated a physisorption type of bonding; hence, the investigated adsorbents can potentially be regenerated for cyclic adsorption.

Nanoparticle Adsorption on Antifouling Polymer Brushes.

Polymer brushes have been widely used to functionalize surfaces and provide antifouling capabilities against proteins and cells. Many efforts have focused on methods for functionalization of antifouling polymer brush surfaces for interactions with specific cells, proteins, and bacteria, but none have focused on immobilizing nanoparticles (NPs) on these surfaces. This article demonstrates that both pristine NPs and protein-coated NPs can adsorb onto well-functioning antifouling polymer brush coatings formed from poly-l-lysine-graft-poly(ethylene glycol) (PLL-g-PEG) and methoxy PEG-thiol. The role of ionic strength in solution, substrate surface material, and NP surface charge in the interaction was investigated to explore the forces behind the interaction. The adsorption of different types of NPs onto the surface was studied, determining that polystyrene, gold, carbon black, and silica particles can adsorb onto PLL-g-PEG. We show that the approach can be applied in, and studied by, both surface plasmon resonance and fluorescence imaging and suggest its application as a means to study NP-protein interactions, such as the protein corona. NPs self-assembled at antifouling polymer brush surfaces provide a novel platform for both scientific studies and applications in biotechnology.

Treatment of fluoride-contaminated water. A review

Delivering the right amount of fluoride to drinking water protects the teeth from decay and reduces the risk of cavities. Nonetheless, fluorosis has been diagnosed as the result of excessive exposure of fluoride, which induces brain impairment, muscle disorders and hyperactivity. Fluoride ingestion during the formation of the tooth enamel is the main reason for fluo-rosis, which is characterized by hypomineralization. Dissolution of fluoride-containing rock minerals contributes to naturally occurring fluoride contamination in water. The intentional addition of fluoride to water in dental care is alarming in growing countries such as India. This article reviews the origin of fluoride, the analysis of fluoride derivatives and the technologies to remove fluoride from water. The manuscript presents adsorption techniques for fluoride removal, using different types of adsorbents. The adsorption capacities of adsorbents under various conditions, such as contaminant concentration, adsorbent dosage, time, pH and temperature, are presented. Adsorbent types include alumina, zeolites, organic waste, shell-based and carbon-based including graphite and carbon nanotubes. Defluoridation of water using clays and muds, modified activated alumina, chitosan derivatives and composites are also discussed.

Role of oxygen, nitrogen and sulfur functionalities on the surface of nanoporous carbons in CO2 adsorption: A critical review

Abstract In todays’ perspective, separation of CO2 from different gas streams is extremely important. Besides the key separation need of CO2 that lies with its isolation from N2 in flue gas, different other separation needs of CO2 includes natural gas separation, biogas upgrading, direct CO2 capture from air and purification other gas streams from the mixtures of CO2. The technical challenges of CO2 separation varies with the type of gas mixtures and CO2 concentration. Within different CO2 separation techniques, adsorptive separation of CO2 has gained attention owing to its low cost, regenerability and zero hazard. Among different types of adsorbents, nanoporous carbons are highly attractive because of their lowest cost, versatile synthesis protocol and efficient separation. In past several years, both computation and experimental results established that few selected heteroatoms, including oxygen, nitrogen and sulfur on the surface of porous carbon influences CO2 adsorption to a great extent compared to pristine carbons. This critical review summed up the synthesis procedure, characterization protocol and surface characteristics of oxygen, nitrogen and sulfur functionalized porous carbons, specific type of functionalities in each type of heteroatom that particularly influences CO2 adsorption and computational results as well as experimental findings that corroborated the positive role of heteroatoms in CO2 separation. At the end, few sets of critical comments and recommendations have been provided on the need of accurate analysis, exact interpretation of the role of heteroatoms in CO2 separation and future direction of research that might benefit the CO2 separation by heteroatom doped carbons in real-world.

Comparative analyses of carbon dioxide capture from power plant flue gas surrogate by micro and mesoporous adsorbents

Pressure swing adsorption (PSA) performances using 5 different types of adsorbents were compared to observe their usefulness in achieving the balance between purity and recovery of the captured carbon dioxide (CO2). Three of the adsorbents were mesoporous (pore size of greater than 2 nm), whereas the other two adsorbents were microporous (pore size of smaller or equal to 2 nm) in nature. Among the 5 adsorbents being tested, microporous palm kernel shell (PKS) reinforced with cerium and silica species was found to yield the maximum CO2 purity of 85.42% from the initial 15.00% CO2 purity in the feed (˜5 fold increase in the purity) with CO2 recovery of 54.62% in the first cycle of PSA operation. The PKS was found to perform better CO2 capture than its more expensive inorganic micro-porous ZIF-8 counterpart and the other mesoporous organic adsorbents, possibly due to the high affinity of Ce species that was present in the sample. The energy saving gained from PSA operated with the equalization mode using PKS reached 75.15% over 5 cycles of operation with further increase in CO2 recovery to 75.20% (37.70% increase) in the fifth cycle.

Adsorbate-enhanced field-emission from single-walled carbon nanotubes: a comparative first-principles study

We report a comparative ab initio study of different types of adsorbates and their adsorption mechanism on the field-emission performance of single-walled carbon nanotubes by analyzing electrical properties and transport characteristics and considering the thermal stability of the adsorbed structure. Adsorbates were found to reduce the work function by up to 1.3 eV, enhance tunneling near the carbon nanotube tip, and increase the field-emission current by as much as two orders of magnitude. A significant localization of the electron cloud was also observed near the adsorbates under a high applied electric field.

Carbon Nanomaterials for the Adsorptive Desulfurization of Fuels

The increasing demand for cleaner fuels and the recent stringent regulations of commercial fuel specifications have driven the research of alternative methods to upgrade the current industrial desulfurization technology. Adsorptive desulfurization, the removal of refractory sulfur compounds using appropriate selective tailor-made adsorbents, has shown up as a promising alternative in the recent years. Carbon nanomaterials, namely, graphene, graphene oxide, carbon nanotubes and carbon nanofibers, show a significant potential as desulfurization adsorbents. Their surface area and porosity, their ability of easy functionalization, and their suitability to serve as a support of different types of adsorbents have rendered them attractive candidates for this purpose. In this review, after a presentation of the current industrial desulfurization practice and its limitations, the structure and properties of the carbon nanomaterials of interest will be described, followed by a detailed account of their applications in adsorptive desulfurization. The major literature findings and conclusions will be presented and discussed as a road map for future research in the field.