Surface Area Adsorption Research Articles

Sulfide- and UV-induced aging differentially affect contaminant-binding properties of microplastics derived from commercial plastic products

Microplastics in the environments can undergo various aging processes that alter their physicochemical properties and consequently their affinities for environmental contaminants. Here, we compare the effects of sulfide-induced aging (a common process in anoxic environments) and UV-induced aging on contaminant binding of polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET) microplastics derived from commercial plastic products. The two aging processes differentially affect adsorption of pyrene (a model nonionic, nonpolar organic) and ciprofloxacin (CIP, a zwitterion under the conditions tested) by modulating the hydrophobicity, surface charges and polarity of the microplastics to different extents. The effects of the two treatments on Cd(II) adsorption correlate well with their modulation on ζ potential and surface (O + S)/C ratio of the microplastics. For all three microplastics sulfide treatment results in stronger adsorption of Cr(VI) and its subsequent conversion to Cr(III) than does UV treatment, as the thiol groups formed during sulfide treatment strongly regulate the complexation and reduction of Cr(VI). Notably, both sulfide and UV treatments result in the flattening of the PET microplastics, significantly enhancing the adsorption of all four contaminants, by increasing surface area for adsorption. The findings of this study further underline the importance of understanding environmental aging/weathering processes of microplastics, particularly, those readily occur in anoxic environments but were previously not well studied.

Iron-rich coal fly ash-polydopamine-silver nanocomposite (IRCFA-PDA-Ag NPs): tailored material for remediation of methylene blue dye from aqueous solution.

Water pollution has become one of the most acute environmental problems. One of the pollutants coming to water bodies from industries are dyes, which are harmful to human health, living organisms, and the esthetic appearance of water. Most dyes are toxic, carcinogenic, rarely biodegradable, and highly soluble in water. Therefore, industrial wastewater treatment has become important. Adsorption technique of removal of dyes from water is simple, efficient, and inexpensive as compared to other techniques. Adsorption efficiency depends on the type and surface area of adsorbents. Iron-rich coal fly ash (IRCFA)-Polydopamine (PDA)@ Silver (Ag) nanocomposite was prepared by separating the iron-rich part (IRCFA) from coal fly ash and coated with polydopamine. IRCFA was mixed with 10mM tris buffer solution containing 1g dopamine. The prepared IRCFA-PDA was added to an aqueous solution of silver nitrate, heated at 60°C, and then 30mL of flower waste extract was added to this solution. Solid IRCFA-PDA@Ag was obtained, and the prepared nanocomposite was used for the removal of methylene blue (MB) dye from water. The nanocomposite used was prepared by a cost-effective method and has high reusability, separability, and fast regeneration ability. The mechanism of removal of MB dye has been discussed in detail.

Performance of Adsorbent from Calcium Carbide Residue to Reduce Exhaust Emissions of Two-wheeler

The performance of calcium carbide residue in reducing two-wheel exhaust emissions has been studied. To perform this experiment, the carbide residue was first converted into adsorbent and then mounted in the exhaust gas line. Two-wheeler used are vehicles commonly used among Indonesian motorcyclists. The test was carried out by varying the adsorbent dimensions and engine transmission. Engine emission tests and adsorbent performance investigations were performed both before and after the exhaust emissions made contact with the adsorbent. The results showed that upon direct contact with the carbide adsorbent, the emission of two-wheeled engines decreased. Carbon-based emissions were reduced significantly in the early stages of the experiment. Moreover, emissions reduction benefits are seen in all adsorbent and transmission engine configurations. The greater the adsorbent's surface area, the better the emission reduction. A significant emissions reduction is also achieved when the first engine transmission condition is applied compared to the neutral transmission. However, the adsorption efficacy declined over time in all research variations. The presence of channels and pores in the adsorbent, and the high temperature attained by the adsorbent, keep improving the adsorbent's adsorption capabilities. However, as saturation increases, the adsorbent's adsorption, and oxidation capability decline.

Aligned silver nanoparticles anchored on pyrrolic and pyridinic-nitrogen induced carbon nanotubes for enhanced oxygen reduction reaction

Comprehension of the metal-nanostructure arrays is of great significance for the rational design of the cathode catalyst for the oxygen reduction reaction (ORR). Therefore, we fabricated a cathode catalyst consisting of the small-size, aligned silver nanoparticles (Ag NPs) embedded into the pyrrolic and pyridinic-Nitrogen functionalized carbon nanotubes. The N-defected structure was prepared by acidification of carbon nanotubes (CNTs) to avoid inherited stacking of its layers followed by the introduction of 2,7 diaminophenazine (DPA) using a hydrothermal process, while small-size Ag NPs were aligned through electrodeposition onto the N-defected carbon nanotube (CNT-DPA-Ag). The individual role of pyrrolic and pyridinic -N in the electrocatalytic ORR performance, synthesis of small size, and distribution behavior of Ag NPs were evaluated. To maximize the ORR performance of the catalyst, the advantage was taken from the presence of carbon atoms next to the pyridinic-N which is a Lewis base and acts as an adsorption and protonation site for the oxygen (O2) molecule and eventually ensures a direct 4e− transfer route for the electrochemical conversion of O2 into water (H2O). Transmission electron microscopy (TEM) analysis of CNT-DPA-Ag revealed a small size, aligned Ag NPs (average size 2 nm) resulting in a large surface area and rich electroactive sites for adsorption of O2. The CNT-DPA-Ag showed a remarkable ORR performance in terms of positive onset potential (-0.052 V), high diffusion-limiting current density (-5.54 mAcm−2), and noteworthy methanol tolerance, and long-term durability in comparison to the commercial 20 wt% Pt/C.

Effect of Particle Size on Chromium (III) and Manganese (IV) Removal from Tannery Wastewater

The removal of Cr (III) and Mn (IV) from a tannery wastewater was evaluated using atomic absorption spectrophotometer (AAS). Activated carbon prepared from sorghum (bicolor) chaff was used to remove Cr (III) and Mn (IV). The evaluated physicochemical properties of the activated carbon were pH (6.30), bulk density (0.33 g/cm3), moisture content (4.40%), Iodine Adsorption Ratio (0.28 mol/g), porosity (13.00), attrition factor (11.00%), and surface area (797.4 m2/g). Optimum percentage adsorption and equilibrium adsorption capacity for the effect of pH, inlet flow rate, bed height, inlet concentration and particle size gave, (89.796, 90.116, 93.046) % and (2.245, 2.253, 2.326) mg/g, (74.720, 84.990, 91.346) % and (2.277, 2.275, 2.284) mg/g, (88.192, 89.994, 90.190) % and (2.205, 2.249, 2.255) mg/g, (88.934, 90.002, 90.634) % and (2.223, 2.250, 1.266) mg/g, (91.346, 89.964, 88.936) % and (2.284, 2.249, 2.223) mg/g for Cr (III) and (84.630, 87.830, 82.507) % and (1.269, 1.317, 1.238) mg/g, (47.770, 74.425,83.790) % and (0.239, 0.744, 1.257) mg/g, (85.590, 84.023, 83.167) % and (1.284, 1.260, 1.248) mg/g, (82.473, 83.790, 85.230 ) % and (1.237, 1.257, 1.278) mg/g, (88.497, 87.220, 84.420) % and (1.327, 1.308, 1.266) mg/g for Mn (1V) respectively. The results therefore, shows that percentage adsorption increases with the effects mentioned and the kinetic data fitted well to the model for the effect of particle size.

The influencing factors of gas adsorption behaviors in shale gas reservoirs

The adsorption state is one of the main states for shale gas occurrence, and the gas adsorption behavior in shale directly affects shale gas content under reservoir conditions. This paper provides a comprehensive literature review on shale gas adsorption behavior and its affecting factors that have been developed in recent years. Influence factors of gas adsorption behavior are examined, including total organic carbon content (TOC), organic matter type, organic matter maturity, minerals and clay minerals, moisture content, pore characteristics and other characteristics of the shale itself. The characteristics of gas adsorption behavior under high temperature and pressure conditions showed that adsorption behaviors were difficult to describe by the Langmuir equation. This review indicates that shale contains higher organic matter content and organic matter maturity and has a higher adsorption capacity. The adsorption capacity with type III kerogen is higher than that for type II or type I. Clay minerals can provide free space for gas adsorption and promote adsorption. Normally, as the moisture content increased, adsorption capacity decreased. Micro pores provided a larger specific surface area for gas adsorption. As the temperature increased, the adsorption capacity decreased. As the pressure increased, shale adsorption characteristics showed two different behaviors as follows: one obeyed the Langmuir equation, and the other presented an inverted, U-shaped, single-peak distribution. However, there are some controversies surrounding adsorption, especially regarding the aspects of clay minerals, water content, pore characteristics, etc. The key is that the mechanism of adsorption in shale is unclear. There will be many new challenges in the field of shale gas adsorption research. Such challenges include studying the organic matter chemical structure, understanding the interaction between organic matter and clay minerals and how they affect adsorption, clarifying gas adsorption behavior changes, predicting favorable areas of adsorbed gas with the coupling of reservoir temperature and pressure, and building a better theory and model of shale gas adsorption.

Application of natural zeolite clinoptilolite for the removal of ammonia in wastewater

This work intends the characterization of the natural zeolite clinoptilolite and its capability in removing the ammonia in wastewater. The natural zeolite clinoptilolite was characterized using transmittance electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, X-ray fluorescence (XRF) and zeta potential prior to the adsorption process. The results showed that the natural zeolite clinoptilolite possessed the lamellar and needle-like structure thus giving the highest surface area for effective adsorption. The main constituent of the element consisted of natural zeolite clinoptilolite is known to have a high affinity towards ammonia. Additionally, the zeta potential analysis has shown that natural zeolite clinoptilolite is negatively charged in all media pH with the highest negative potential of −30 mV recorded at pH 7 thus, contributing to the highly effective electrostatic interaction with the contaminants’ cations. Consequently, the excellent performance in removing ammonia of up to 82.97 % has revealed that the natural zeolite clinoptilolite has a great potential to be developed as a synergized adsorptive ceramic membrane that is combining the adsorption and the filtration of water simultaneously.

Adsorption Characteristics and Electrochemical Behaviors of Methyl Blue onto Magnetic MgxCoyZn(1-x-y)Fe2O4 Nanoparticles

Magnetic MgxCoyZn(1-x-y)Fe2O4 nanoparticles were successfully prepared by the rapid combustion approach, and SEM, XRD, VSM, EDX, and FTIR techniques were applied for their characterization. The influence of the element ratios (Mg2+, Co2+, and Zn2+) in magnetic MgxCoyZn(1-x-y)Fe2O4 nanoparticles on their properties was explored. To acquire a larger specific surface area for better adsorption of methyl blue (MB), magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles calcined at 400°C for 2 h with 25 mL anhydrous ethanol were selected, and their average particle size and the saturation magnetization were about 81.3 nm and 13.5 emu·g-1, respectively. Adsorption kinetics models and adsorption isotherm models were applied to research the adsorption characteristics of MB onto magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles. The pseudo-second-order kinetics model ([Formula: see text]) and Temkin isotherm model ([Formula: see text]) were the most consistent with the data, indicating that the adsorption was the chemical multilayer adsorption mechanism, and the process was an exothermic reaction. The E of the Dubinin-Radushkevich (D-R) isotherm model was 0.2347 KJ·mol-1, indicating the adsorption involved physical adsorption besides chemical adsorption. The [Formula: see text] and [Formula: see text] ([Formula: see text] KJ·mol-1) of the adsorption process of MB adsorbed onto magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles measured through the thermodynamic experiment were both less than 0, which proved that the process was a spontaneous exothermic reaction. The adsorption capacity of MB onto magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles increased with the pH of MB solution increasing from 2 to 4 at room temperature, and it had no significant change when the pH of MB solution was 4-12, while the relative removal rate was 98.75% of the first one after 2 cycles. The electrochemical impedance spectroscopy (EIS) and the cyclic voltammetry (CV) data further demonstrated that MB was adsorbed onto magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles.

Tuning humidity sensing properties via grafting fluorine and nitrogen-containing species on single-walled carbon nanotubes.

The effect of humidity on the electrical conductivity of single-walled carbon nanotube (SWCNT) films depends on both the conductivity of individual nanotubes and the electrical contacts between them. Here, we study these factors by comparing the sensor response of nanotubes with fluorine- and nitrogen-containing groups attached to the sidewalls. Experiments carried out in a wide range of relative humidity (RH) at room and elevated temperatures showed that the conductivity of non-functionalized SWCNTs and contacts between them decreases upon the adsorption of water molecules. Covalent fluorination reduces the conductivity of SWCNTs and significantly increases the sensitivity of the film to low concentrations of water vapor. The response at high RH decreases due to the large number of water molecules adsorbed on the conductive regions of the nanotubes. As a result of substitutional reactions of fluorinated SWCNTs with dimethylformamide and ethylenediamine, nitrogen-containing groups are added, the amount of which, however, is much less than the amount of fluorine. This modification of the SWCNTs improves intertube contacts in the film and increases the surface area for water adsorption. Our results show that an increase in the number of functional groups on the SWCNT surface enhances the sensitivity of the sensor to low water concentrations and worsens the response at high RH. SWCNTs modified with ethylenediamine have the highest sensitivity over the entire range of RH.

Natural calcium phosphates from circular economy as adsorbent phases for the remediation of textile industry waste-waters

Adsorption is one of the most important techniques for the remediation of textile industry wastewaters containing high concentrations of toxic dyes. Calcium phosphates (CaPs) have been advocated among the most promising adsorbent phases in virtue of their high dye adsorption potential, low production cost, and possible recovery from circular economy sources. In this paper, we investigated the application of synthetic CaPs (CaP–S) and two CaPs extracted from food by-products, namely from bone meal (CaP-BM) and fish bones (CaP-FM) for the removal of a model dye, copper phthalocyanine tri-sulfonic acid, also known as acid blue 185 (AB-185). All the materials were characterized from the physical-chemical point of view and used for the study of adsorption kinetic and isothermal adsorption of AB-185 at neutral, acidic and basic pH values. The best adsorption capacity was obtained for CaP–S, followed by CaP-BM and CaP-FM. Nonetheless, results showed that all the materials can be employed for removing AB-185 from wastewaters of textile industry, and we correlated dye removal efficiency to the adsorbent phase specific surface area (SSA) and ζ-potential, as well as to dye concentration and pH of wastewaters. Finally, as the process used to produce the studied CaPs affects their main final physical-chemical parameters and performance in terms of dyes removal, it is important to consider the variables of CaPs production process (e.g., temperature, time of treatment, grinding etc.), especially when CaPs are recovered from circular economy sources by thermal treatments of food-byproducts.

Copper-doped perylene diimide supramolecules combined with TiO2 for efficient photoactivity

Designing organic-inorganic hybrid semiconductors is an effective strategy for improving the performance of the photocatalyst under visible light irradiation. In this experiment, we firstly introduced Cu into perylenediimide supramolecules (PDIsm) to prepare the novel Cu-dopped PDIsm (CuPDIsm) with one-dimensional structure and then incorporated CuPDIsm with TiO2 to improve the photocatalytic performance. The introduction of Cu in PDIsm increases both the visible light adsorption and specific surface areas. Cu2+ coordination link between adjacent perylenediimide (PDI) moleculars and H-type π-π stacking of the aromatic core greatly accelerate the electron transfer in CuPDIsm system. Moreover, the photo-induced electrons generated by CuPDIsm migrate to TiO2 nanoparticles through hydrogen bond and electronic coupling at the TiO2/CuPDIsm heterojunction, which further accelerates the electron transfer and the separation efficiency of the charge carriers. So, the TiO2/CuPDIsm composites exhibit excellent photodegradation activity under visible light irradiation, reaching the maximum values of 89.87 and 97.26% toward tetracycline and methylene blue, respectively. This study provides new prospects for the development of metal-dopping organic systems and the construction of inorganic-organic heterojunctions, which can effectively enhance the electron transfer and improve the photocatalytic performance.

Adsorbent Precoating by Lyophilization: A Novel Green Solvent Technique to Enhance Cinnarizine Release from Solid Self-Nanoemulsifying Drug Delivery Systems (S-SNEDDS).

Solidification by high surface area adsorbents has been associated with major obstacles in drug release. Accordingly, new approaches are highly demanded to solve these limitations. The current study proposes to improve the drug release of solidified self-nanoemulsifying drug delivery systems (SNEDDS) to present dual enhancement of drug solubilization and formulation stabilization, using cinnarizine (CN) as a model drug. The solidification process involved the precoating of adsorbent by lyophilization of the aqueous dispersion of polymer-adsorbent mixture using water as a green solvent. Then, the precoated adsorbent was mixed with drug-loaded liquid SNEDDS to prepare solid SNEDDS. The solid-state characterization of developed cured S-SNEDDS was done using X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC). In vitro dissolution studies were conducted to investigate CN SNEDDS performance at pH 1.2 and 6.8. The solidified formulations were characterized by Brunauer-Emmett-Teller (BET), powder flow properties, scanning electron microscopy, and droplet size analysis. In addition, the optimized formulations were evaluated through in vitro lipolysis and stability studies. The cured solid SNEDDS formula by PVP k30 showed acceptable self-emulsification and powder flow properties. XRD and DSC revealed that CN was successfully amorphized into drug-loaded S-SNEDDS. The uncured solid SNEDDS experienced negligible drug release (only 5% drug release after 2 h), while the cured S-SNEDDS showed up to 12-fold enhancement of total drug release (at 2 h) compared to the uncured counterpart. However, the cured S- SNEDDS showed considerable CN degradation and decrease in drug release upon storage in accelerated conditions. The implemented solidification approach offers a promising technique to minimize the adverse effect of adsorbent on drug release and accomplish improved drug release from solidified SNEDDS.

A review of biomaterial as an adsorbent: From the bibliometric literature review, the definition of dyes and adsorbent, the adsorption phenomena and isotherm models, factors affecting the adsorption process, to the use of typha species waste as adsorbent

This paper presents a review of adsorption isotherms of some dyes from aqueous solutions by biomaterial. In this paper, we reported Typha waste as a model of biomaterial classified as a low-cost adsorbent. The paper also briefly discusses about the literature information from the definition of dyes and adsorbents, bibliometric analysis, adsorption phenomena, adsorption isotherm models, and factors affecting the adsorption, to the use of Typha species waste as a low-cost adsorbent. The operational parameters factors are explained in terms of pH, adsorbent dosage, contact time, and initial dye concentration that will affect the process of removing textile dye. The solution of pH turns out to be the most important condition in the adsorption process for anionic dye, a low pH value are preferable in contrast to cationic dye where the suitable pH value is high. For the adsorbent dose, the adsorption capacity increase along with the increment of adsorbent dosage due to the increase of theavailable amount of adsorption site. The contact time between the adsorbent and dye affects the efficiency of dye removal where a strong attraction force will shorten the time. As for the effect of dye initial concentration, increasing the initial concentration enhances the increment of adsorbent surface area to adsorb dyes. Several isotherm models are described. The Langmuir model is frequently used to evaluate the adsorption capacity of the Typha species waste as adsorbents. This review paper suggested that the accuracy level obtained from adsorption processes is greatly dependent on the successful modeling of adsorption isotherms. Typha biomaterial wastes can be considered as the new useful low-cost natural adsorbents for dye clean-up operations in aquatic systems.

Effects of Clay Mineral Content and Types on Pore-Throat Structure and Interface Properties of the Conglomerate Reservoir: A Case Study of Baikouquan Formation in the Junggar Basin

Many factors need to be considered in the evaluation of tight conglomerate reservoirs, including the microscopic pore-throat structure, pore connectivity, lithology, porosity, permeability, and clay mineral content. The contents and types of clay minerals reflect the mineral evolution process during the deposition of the reservoir and can reflect the reservoir’s physical properties to a certain extent. In this study, cores from the Baikouquan Formation in Mahu were used to comprehensively analyze the effects of the clay mineral content on the physical properties of a tight conglomerate reservoir, including field emission scanning electron microscopy (FE-SEM), casting thin section observations, X-ray diffraction (XRD), interface property testing, high-pressure mercury injection, low temperature N2 adsorption, and nuclear magnetic resonance (NMR)-movable fluid saturation testing. The results revealed that differences in different lithologies lead to differences in clay mineral content and pore structure, which in turn lead to differences in porosity and permeability. The interface electrification, adsorption, and specific surface area of the reservoir are positively correlated with the clay mineral content, which is mainly affected by the smectite content. As the clay mineral content increases, the proportion of nanoscale pore throats increases, and the core becomes denser. The saturation of the movable fluid controlled by the >50 nm pore throats in the tight conglomerate ranges from 8.7% to 33.72%, with an average of 20.24%. The clay mineral content, especially the I/S (mixed layer of Illite and montmorillonite) content, is negatively correlated with the movable fluid. In general, the research results clarified the relationship between the lithology and physical properties of clay minerals and the microscopic pore structure of the tight conglomerate reservoirs in the Baikouquan Formation in the Mahu area.

Reduced Graphene Oxide Functionalized Magnetic Nanocomposites for Environmental Pollutant Removal

Nowadays, the excessive and uncontrolled discharge of chemicals are imposing major health threats. The demands for clean and safe water amplifies the need to develop improved technologies for environmental contaminant removal. Considering the limitations of conventional methods for contaminants removal, we have prepared magnetic iron oxide nanoparticles functionalised with reduced graphene oxide as a potential material for environmental pollutants removal. The magnetic properties in potential adsorbent materials are highly desirable due to several advantages. Among which are their large adsorptive surface area, low diffusion resistance, high adsorption capacity and fast separation in large volumes of solution. The surface functionalised magnetic iron oxide nanoparticles (MNP) were fabricated using a one-pot hydrothermal method by adding reduced graphene oxide (rGO) into the reaction system. The graphene oxide were reduced prior to the addition in the hydrothemal decomposition step. The resultant rGO-MNP nanocomposites were characterised using FT-IR, SEM and VSM to investigate the functional groups, morphology and magnetic properties, resepectively. We also demonstrated the potential of the hybridised magnetic material with hydrophobic reduced graphene oxide for environmental pollutant removal.

Dye adsorption performance of nanocellulose beads with different carboxyl group content

The problems caused by water pollution are increasingly serious, wastewater contains a lot of heavy metal ions, textile dyes, medicines, etc. However, most adsorption materials usually face problems such as inefficient recycling, high cost, and secondary pollution. As a natural polymer, cellulose has low cost, degradability and good biocompatibility. In this work, by changing the addition amount of sodium hypochlorite during 2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation, nanocellulose with different carboxyl content could be prepared, which is expected to be a good high-efficiency cationic adsorbent due to its rich in hydroxyl groups on the surface and negatively charged. Then the calcium chloride solution was used as the cross-linking agent to prepare TEMPO-oxidized cellulose nanofibril beads (TOCNB) by the dropping solidification method. As the content of carboxyl groups increases, the Zeta potential value of the nanocellulose dispersion became increasingly negative. The nanocellulose beads all presented a good three-dimensional network porous structure. With the increase of carboxyl group content, the specific surface area increases from 173 to 367 m2 g−1, and the adsorption capacity for methylene blue (MB) also gradually strengthened. The saturated adsorption capacity of TOCNB on MB was calculated as high as 925.93 mg g−1. The nanocellulose bead was a cationic adsorbent with highly efficient adsorption and adjustable specific surface area, and the preparation method was simple, fast, efficient and green.

Removal of natural organic matter fractions by adsorptive asymmetric ceramic membrane functionalized with in situ phytogenic nanoscale zero valent iron: Performance and Fenton cleaning strategy

AbstractExtant literature has demonstrated that conventional water treatment processes especially in developing countries struggle in completely removing detrimental organic loads. Emerging research delineates nanomaterials such as nanoscale zero valent iron (nZVI) to have excellent performance in organic matter removal from aqueous media. In this work, nZVI particles were prepared from the liquor of commercially available green tea and supported on kaolin (K‐nZVI) and investigated as an adsorbent for natural organic matter (NOM) sequestration from aquatic media. Further, the asymmetric ceramic membrane was prepared by incorporating the developed adsorbent on a concrete support for the removal of NOM. A Fenton cleaning strategy was developed to mitigate fouling. The Brunauer–Emmett–Teller (BET) results revealed the developed adsorbent surface area was greater compared to raw kaolin (27.07 and 11.64 m3 g−1, respectively). The scanning electron microscopy (SEM) imagery of the developed adsorbent showed the particle staking was presented as paper slices of varying sizes, an indication of dispersed particles with characteristic plate‐like fragments. The synthesized membrane exhibited a pHZPC value of 4.79 ± 0.03. This meant at pH above 4.79 ± 0.03, the membrane would be negatively charged, and conversely at pH below the pHZPC value. Membrane fouling due to bovine serum albumin (BSA) deposition showed a 50% flux decline in the first 60 min, coinciding with the rapid adsorption capacity within the same time frame. The optimal cleaning parameters of pH (4.5) and H2O2 (5 mM) gave the best flux recovery rates. This work demonstrated an efficient Fenton cleaning strategy to regenerate the developed membrane.

A fluorescent turn on/off probe for glucose detection based on a boronic acid-capped 1,1′-ferrocenedicarboxylic acid functional graphene oxide

The accurate determination of glucose in the human body is highly desired because excessive ingestion of glucose may lead to obesity, diabetes and other diseases. This work demonstrates a fluorescent probe for sugar detection using the unique affinity of boronates for cis -diols. The fluorescent sensing system is composed of two components: 1) Aminated graphene oxide (GON) decorated with phenylboronic acid (BPA) and 1,1'-ferrocenedicarboxylic acid (FCA) as a fluorescence quencher (FCA–GON–BPA); and 2) fluorophores of a cis -diol modified tetraphenylethylene derivative (TPBD) with aggregation-induced emission (AIE) characteristics as the luminescence. FCA–GON–BPA can selectively bind cis -diol-containing fluorogens, such as TPBD, resulting in fluorescence quenching of the probe system. Upon addition of glucose, a new cyclic boronate ester is formed, resulting in the cis -diol-containing fluorogen dissociating from the quenched system, and TPBD fluorescence is recovered. The probe has an obvious response to the presence of glucose and a low limit of detection (LOD, 4.36 mg/mL). • The fluorophore has the characteristics of aggregation-induced emission. • The reaction platform is graphene oxide with high adsorption surface area. • Glucose preempts binding of fluorophore and quencher to release fluorescence.

Nanomaterials as a cutting edge in the removal of toxic contaminants from water

In the past several decades, the development of industries and agricultural techniques have contributed majorly to the contamination of water. A drastic increase of heavy metals, dyes, inorganic, organic, and bio-contaminants in surface, ground, and seawater has become a severe concern among the environmentalists and scientific community for the health and safety of living beings. According to the latest survey of WHO, by the year 2025, 50% of freshwater in the world will become contaminated due to its high demand in every industrial sector. So, in order to remove these toxic contaminants, scientists are emphasizing on the development of modern, sustainable, and technologically advanced techniques for the treatment of contaminated water. The use of nanomaterials for this purpose is one such promising application due to their high surface area, high surface capacity, electrical, magnetic, physiochemical, and catalytic features, ease of functionalization, and cost-effectiveness. As a result, nanomaterials are being exploited in multidisciplinary research like adsorption, photocatalytic degradation, and membrane filtration for the removal of heavy metals, organic/inorganic dyes, oil spills, etc. Recently, various studies have been focusing on these nanomaterials as a potential alternative for the treatment of pollutants from wastewater. This review compiles the studies of different nanomaterials along with their synthesis processes, applications, and effect of modification and functionalization of nanomaterials on certain key properties such as adsorption capacity, surface area, and pH range. Effects of various factors such as ionic strength affecting metal ions, adsorbent dosage, contact time, temperature, initial ion concentration, and pH are also explained in this review.

CO2 Adsorption Performance on Surface-Functionalized Activated Carbon Impregnated with Pyrrolidinium-Based Ionic Liquid

The serious environmental issues associated with CO2 emissions have triggered the search for energy efficient processes and CO2 capture technologies to control the amount of gas released into the atmosphere. One of the suitable techniques is CO2 adsorption using functionalized sorbents. In this study, a functionalized activated carbon (AC) material was developed via the wet impregnation technique. The AC was synthesized from a rubber seed shell (RSS) precursor using chemical activation and was later impregnated with different ratios of [bmpy][Tf2N] ionic liquid (IL). The AC was successfully functionalized with IL as confirmed by FTIR and Raman spectroscopy analyses. Incorporation of IL resulted in a reduction in the surface area and total pore volume of the parent adsorbent. Bare AC showed the largest SBET value of 683 m2/g, while AC functionalized with the maximum amount of IL showed 14 m2/g. A comparative analysis of CO2 adsorption data revealed that CO2 adsorption performance of AC is majorly affected by surface area and a pore-clogging effect. Temperature has a positive impact on the CO2 adsorption capacity of functionalized AC due to better dispersion of IL at higher temperatures. The CO2 adsorption capacity of AC (30) increased from 1.124 mmol/g at 25 °C to 1.714 mmol/g at 40 °C.