Sorption Capability Research Articles

Fabrication of plasma-treated superhydrophobic polydimethylsiloxane (PDMS) – Coatėd melamine sponge for enhanced adhesion capability and sustainable oil/water separation

A persistent global issue is the need for developing novel absorbent materials with high absorption efficacy and rapid absorption rates for effective oil–water separation. This work presents a novel, resilient, and recyclable material with exceptional sorption capabilities, achieved through a simple surface modification of melamine sponge (MS) using Argon plasma treatment followed by Polydimethylsiloxane (PDMS) polymer coating (Ar-PT/PDMS@MS). This study also delineates the choiceful impact of atmospheric and vacuum plasma over the surface modification of MS. The material's super hydrophobicity, demonstrated by a high-water contact angle of ∼165°, is enhanced using novel plasma treatment to homogenously coat PDMS polymer. This treatment also imparts sturdiness to withstand harsh environmental conditions. The modified 3D networked structure of melamine sponge with a porous core was able to selectively absorb the oil of various densities with the capacity range of 42–139.5 mg/g. The batch and continuous O/W separation studies revealed the efficiency of the modified MS to be able to selectively separate light nonaqueous phase liquids (LNAPL) and dense nonaqueous phase liquids (DNAPL) oil with more than 99% efficiency. The continuous studies showed that using diesel oil the separation efficiency was >99% for 35 L of oil for more than 5 h. It was also discovered that it outperformed and exceeded commercial absorbent materials in terms of absorption capacity. The recyclability studies highlighted the ability of the modified MS to be used for more than 10 cycles without compromising its separation efficiency. These findings may foreshadow Ar-PT/PDMS@MS's ability to be a promising antagonist for oil–water (O/W) separation in real-world oil-spill scenarios.

Fabrication of electrospun cellulose/ball-milled bone char membranes for fast, efficient and selective sorption of aquatic U(VI)

Powdered sorbents in aqueous solutions suffer from the deficiency in the solid/liquid separation even the sorption capacities were higher than their bulk or less-dispersed forms. The combination of powdered sorbents with membranes would be highly desired to balance the contradiction between high separation efficiency and sorption capability. In this study, cellulose/ball-milled bone char (CL/MB) membranes with sub-micrometer diameter (276.0–281.7 nm) and developed porosity (21.5–98.6 m2/g) were fabricated by electrospinning technique. Bone chars originated from the pyrolysis of bone residuals at 350 °C, 500 °C and 650 °C could well dispersed in the electrospinning solvent. CL/MB membranes could adsorb U(VI) with fast kinetics (180.0 min), efficient capacity (309.8 mg/g at pH 5.00 and T 298 K) and excellent selectivity against the interference of coexisting ions in simulated waters. With spectroscopic analysis, the formation of (Ca(UO2)2(PO4)2(H2O)3 precipitation was dominant for the selectivity. The surface complexation of O-/reductive N-groups with U(VI), the electrostatic attraction of deprotonated O- with positively charged U(VI) species, the cation exchange of U(VI) with Ca2+ components, and the cation-π coordination of U(VI) should also be considered. This study pave the way for the feasible utilization of electrospun CL/MB membranes as a promising sorbent to capture aquatic U(VI).

Comparative assessment of phosphate adsorption properties and mechanisms on Mg/Al-engineered sewage sludge biochar in aqueous solution

This study reported the development of Mg/Al-engineered sewage sludge biochars (SSBCs) with adjustable surface properties and enhanced phosphate PO43− (ad)sorption capacity. These biochars successfully addressed the traditional constraints of electric repulsion interactions with PO43− ions at various pH levels, leading to highly efficient and recyclable PO43− enrichment from aqueous solution. It was determined that a ratio of 1:2 of Mg/Al is the optimal concentration of Mg/Al SSBCs for maximum PO43− (ad)sorption capability. In this study, the pseudo-second-order kinetics and Redlich Peterson isotherm worked well for Mg-SSBC, however, the pseudo-first-order kinetics and Langmuir isotherm explained the Al-SSBC interaction with PO43− ions properly. Both Mg-SSBC and Al-SSBC showed strong adsorption specificity to PO43− ions, with all coexisting anions producing negative effects on the PO43− adsorption. The data demonstrate that the variation in adsorption mechanism viz., including electrostatic attraction, complex formation, cationic bridging, and chemical co-precipitation was observed in between Mg-SSBC and Al-SSBC. Comparison between Mg-SSBC and Al-SSBC showed that Mg-SSBC has a more extensive pH range for PO43− removal and greater stability with compound elimination power, i.e., Mg-SSBC is more effective for the elimination of phosphates from aqueous solution.

Radiation-Induced De Novo Defects in Metal-Organic Frameworks Boost CO2 Sorption.

Defects in metal-organic frameworks (MOFs) can significantly change their local microstructures, thus notably leading to an alteration-induced performance in sorption or catalysis. However, achieving de novo defect engineering in MOFs under ambient conditions without the scarification of their crystallinity remains a challenge. Herein, we successfully synthesize defective ZIF-7 through 60Co gamma ray radiation under ambient conditions. The obtained ZIF-7 is defect-rich but also has excellent crystallinity, enhanced BET surface area, and hierarchical pore structure. Moreover, the amount and structure of these defects within ZIF-7 were determined from the two-dimensional (2D) 13C-1H frequency-switched Lee-Goldburg heteronuclear correlation (FSLG-HETCOR) spectra, continuous rotation electron diffraction (cRED), and high-resolution transmission electron microscopy (HRTEM). Interestingly, the defects in ZIF-7 all strongly bind to CO2, leading to a remarkable enhancement of the CO2 sorption capability compared with that synthesized by the solvothermal method.

Metal organic framework doped amine-functionalized polymeric beads for selective removal of Uranium (VI) from alkaline leach liquor: Batch and column study

In this work, a diethylenetriamine (DETA) functionalized metal organic framework (ZIF-67) incorporated polyacrylonitrile (PAN) bead (MFB) was developed to capture U efficiently from simulated medium and alkaline leach liquor. The synthesized beads were characterized using suitable analytical methods. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to understand the U uptake mechanism. The process of adsorption was inherently heat-absorbing and spontaneous in nature. The Langmuir sorption capability (Qm) was 835 mg/g, at pH 7 and, 298 K. Surface- grafted abundant amine (–NH2) groups introduce significant coordinative interaction with the U species in aqueous medium. The adsorbent is reusable and structurally robust with >85 % U removal after five consecutive regeneration cycles. The performance of the continuous adsorption columns was simulated by a fundamental adsorption-diffusion model and the relevant transport parameters were evaluated. For real life alkaline leach liquor with U concentration 825 mg/L and 100 to 500 kg of adsorbent, the adsorption column had a breakthrough life of 46 to 108 days with constant flow rate of 500 L/day. This study showed that the synthesized MFB is an excellent adsorbent that is inexpensive, non-toxic, recyclable,environmentally compatible, and selective towards U removal from alkaline leach liquor.

Facile fabrication of organic superhydrophobic corn silk-derived cellulose acetate nanofiber for the effective sequestration of oil from oil-water mixture.

Oil spills and subsequent cleanup by oil-water separation remain a global concern. For the first time, corn silk-derived cellulose acetate (CSCA) and polyacrylonitrile (PAN) composite nanofiber are reported to create a superhydrophobic oil-water sequestration membrane. CA : PAN solutions with various PAN concentrations were evaluated for viscosity and conductivity. A CSCA nanofiber membrane was fabricated through electrospinning, which was superhydrophobic and oleophilic in water. Scanning electron microscope, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis/differential scanning calorimetry were used to analyze the membrane's morphological features. CSCA nanofibers formed a highly spherical bead with a maximum contact angle of 156° (>120°) in pure water solutions, demonstrating their superhydrophobicity. This study found that membranes can remove oil from oil-water mixtures and emulsions, as gravity is the only force required for propelling the system. Mineral oil had the highest oil sorption capability (908%), while toluene had the lowest (664%). For mineral oil-water mixtures, the CSCA membrane has the greatest separation flux at a maximum of 442 L/m2/h and the best separation efficiency at up to 99.67%. These findings provide strong support for using an as-prepared CSCA nanofiber membrane as a viable reusable oil sorbent in oil spill cleaning.

Fabrication and characterization of organometallic nanocomposite for efficient abatement of dye laden wastewater: CCD optimization, adsorption mechanism, co-existing ions, and cost analysis

Water pollution on account of textile industrial effluents represents a serious environmental problem which is increasing day by day. The rapid development of nano-technology has facilitates the development of new efficient composite materials which are extremely efficient in order to treat the textile industrial effluents. In this study, magnesium oxide/polyaniline nanocomposite (MgO/PANI-NC) was synthesized by a hybrid precipitation-oxidation process for the sequestration of Eriochrome Black-T (EBT) dye from aqua media. The characterization outcomes exposed that the synthesized nanocomposite contains nano size rods with appreciable specific surface area (78.208 m2/g). Furthermore, the influence of numerous parameters like solution pH, nanocomposite dose, dye initial concentration, and sonication time were explored and the optimum dye elimination efficacy (87.00 %) was achieved at solution pH 6.0. Kinetic and isotherm analysis of sorption of EBT dye onto MgO/PANI-NC exposed the suitability of pseudo-second-order model and Langmuir model was the utmost consistent isotherm model, respectively with highest sorption capability of 222.22 mg/g. Finally, the cost analysis of synthesized MgO/PANI-NC indicated that the preparation cost of MgO/PANI-NC was ∼ 98.00 $/kg. The EBT dye effectiveness decreases from 87.00 % to 69.25 % after five consecutive uses, showing good stability and reusable characteristics of MgO/PANI-NC.

Using walnut shells as low-cost adsorbent materials in an anaerobic filter medium of a De-centralized wastewater treatment system (DEWATS)

The flow of unprocessed sewage through municipal sewers is a great source of water contamination. This study aims to observe the pollutants removal efficiencies of walnut shells as an efficient low-cost adsorbent material compared to gravel materials as an anaerobic filter medium. Two models of the De-Centralized Wastewater Treatment System (DEWATS) were constructed. The wastewater flowing from toilets and handwashing places was connected to anaerobic filters filled with walnut shells and gravel. The efficiency of both filter media in the removal of biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), nitrate (NO3), and phosphate (PO43), pH and temperature were observed at the influent of the settler tank and then at the effluent of the collection tank (CT). Temperature and pH were within the acceptable limit of wastewater discharge. The results also indicated that the walnut shells filter media was more efficient at removing organic pollutants (TSS 94%, BOD5 88%, COD 85%, Nitrate 57%, phosphate 46%, and TDS 29%) than the gravel (TSS 81%, BOD5 82%, COD 84%, Nitrate 35%, phosphate 38%, and TDS 26%) at the successive stages. The average removal efficiency of the walnut shell was 88% while in the gravel case, it was 83%. The removal efficiency of walnut shell filters was extensively better over the complete experiment compared to gravel filters for the removal of pollutants, representing the high sorption capability of the walnut shell material. The results of this study show that the walnut shells may be a very useful substitute for other conventional fillers for anaerobic treatment in the anaerobic filter of DEWATS.

MXene/Graphene modified cellulose aerogel for photo-electro-assisted all-weather cleanup of high-viscous crude oil from spill

The frequent occurrence of oil spills has led to serious environmental pollution and ecological issues. Given the high-viscosity of crude oil, it is essential to develop sorbents with efficient viscosity reduction and sorption capacity in various environmental conditions. Herein, a superhydrophobic carboxymethyl cellulose (CMC) aerogel co-modified by MXene and graphene jointly (M-Mxene/Gr CA) with aligned channels structure was prepared. The aligned channels structure can effectively improve the longitudinal thermal conductivity and reduce the sorption resistance. Through the modification of MXene and graphene, the aerogel realized efficient photo/electro-thermal conversion, thus ensuring its adaption to various working environments. The rapid heat generation can significantly reduce the viscosity of crude oil, achieving rapid recovery. Under one sun illumination (1.0 kW/m2), the surface temperature of M-Mxene/Gr CA can reach 72.6 °C and its sorption capability for high-viscous crude oil reaches 18 g/g. Combining photo-thermal and electro-thermal (0.5 kW/m2 and 23 V), the average sorption rate of crude oil can reach 1.3 × 107 g m−3 s−1. Finally, we present a continuous sorption system to recover offshore oil spills under the assistance of a pump. This work provides a new option for tackling high-viscous offshore oil spills due to its environmental friendliness and fast sorption capacity.

Enhanced Lewis basicity of ZIF-8 from metal incorporation (Mg, Cu, or Ce) for glycerol carboxylation using CO2 as a feedstock

Herein, Mg, Ce, and Cu were incorporated into ZIF-8 to improve its Lewis basicity for glycerol carboxylation. Upon metal incorporation, the Ce- and Cu-incorporated ZIF-8 remained structurally intact with slightly increased Lewis basicity, whereas the Mg-incorporated ZIF-8 exhibited a more perturbed structure containing additional exposed N atoms and metal sites (Zn and Mg). The improved Lewis basicity facilitated the increased glycerol conversion of the Mg-incorporated ZIF-8 and its yield of glycerol carbonate in the presence of CH3CN as a homogeneous dehydrating agent. Using NaHCO3 as the heterogeneous dehydrating agent, a much higher selectivity (90%) was obtained over Mg-incorporated ZIF-8 compared to that of CH3CN (∼60% higher), attributed to a high water sorption capability of NaHCO3 that inhibits side reactions. The heterogeneity of NaHCO3 enables efficient recycling (>3 cycles) for repeated catalytic glycerol carboxylation. The results suggested that metal incorporation is an effective and facile approach to improve ZIF-8 Lewis basicity, combined with heterogeneous NaHCO3 as the dehydrating agent, which is beneficial for glycerol carboxylation using CO2 as a feedstock.

Performance Evaluation of Extraction Coatings with Different Sorbent Particles and Binder Composition.

Binders are critical components used in the preparation of a range of extraction devices, including solid-phase microextraction (SPME) devices. While the main role of a binder is to affix the sorbent particles to the selected support, it is critical to select the optimal binder to ensure that it does not negatively impact the coating's particle sorption capability. This work presents the first comprehensive investigation of the interactions between binders and solid sorbent particles as these interactions can significantly impact the performance of the coating. Specifically, the findings presented herein provide a better understanding of the extraction mechanisms of composite coatings and new rules for predicting the particle adhesion forces and binder distribution in the coating. The influence of binder chemistry on coating performance is investigated by examining a selection of the most used binders, namely, polydimethylsiloxane (PDMS), polyacrylonitrile (PAN), poly(vinylidene difluoride) (PVDF), polytetrafluoroethylene amorphous fluoroplastics (PTFE AF 2400), and polybenzimidazole (PBI). The solid particles (e.g., hydrophilic-lipophilic balanced (HLB) and C18) used in this work were selected for their ability to provide optimal extraction coverage for a broad range of analytes. The results show that PDMS does not change the properties of the solid particles and that the binder occupies a negligible volume due to shrinking after polymerization, resulting in the solid particles making up most of the coating volume. Hence, the coating sorption characteristics correspond closely to the properties of the selected solid particles. On the other hand, the results also showed that PTFE AF 2400 can interact with the active surface of the sorbent, leading to the deactivation of the sorbent particles. Therefore, the extraction performance and permeability coefficients decrease as the size of the penetrant increases, indicating a rigid porous structure. The results of this study can aid in the optimization of SPME devices as they provide reference values that can be used to determine the optimal binder and the sorbent affinity for the targeted compounds. Finally, the present work also provides the broader scientific community with a strategy for investigating the properties of sorbent particle/binder structures and defines the characteristics of a good coating/membrane by analyzing all parameters such as kinetics, thermodynamic equilibria, and morphology.

Biomass steam gasification for hydrogen-rich syngas production over fly ash-based catalyst pretreated by coupling of washing and calcination

Biomass gasification to produce syngas is promising, but the limited hydrogen content of the syngas restricts its potential applications. This study proposed an efficient thermochemical approach that used cost-effective fly ash pretreated with washing and calcination (WCFA) as a catalyst to enhance hydrogen-rich syngas production from biomass steam gasification. Catalyst characterizations indicated that washing removed most chloride salts in raw fly ash by dissolution, and subsequent calcination decomposed Ca-containing compounds into CaO, resulting in smaller catalyst grains, more developed pore structure, and greater capability and reaction rate of CO2 sorption. With WCFA, the H2 release during gasification was prolonged by ∼10 min and its release peak increased by over 1.5 times, compared to no catalyst. Consequently, the cold gas efficiency, syngas yield, and H2/CO ratio increased from 53%, 792 mL/gbiomass, and 0.39 for no catalyst to 72%, 1132 mL/gbiomass, and 1.05 for WCFA. The WCFA catalyst calcined at 800 °C for 60 min was optimal for H2 formation, due to its enriched CaO composition and improved porosity, which effectively catalyzed volatiles cracking/reforming and absorbed CO2 to lead the chemical equilibrium of water gas shift reaction move foward.

Preparation of cellulose gel extracted from rice straw and its application for metal ion removal from aqueous solutions

Rice straw waste was used to extract natural cellulose fibers, which was then chemically converted to cellulose gel. Both extracted cellulose and modified cellulose (gel) were characterized using different techniques and used for biosorption of b+arium, manganese, cobalt, nickel, copper, zinc, and cadmium. Both celluloses' chemical compositions were investigated. The FT-IR, XRD, TEM, and SEM results all support the success of the proposed chemical modification. Because of the increase in pore size within the gel composition, the metal sorption capability of the final chelating material (gel) was greater than that of extracted cellulose. The experimental data were fit to the sorption isotherm models of Langmuir, Freundlich, and Temkin. This new modified biopolymer's behaviour suggested that it could be used as a promising sorbent for cation removal from polluted dye baths and waste water. Furthermore, this modified cellulose was prepared as cheap material extracted from the rise waste which helping in protection of the environment and it was confirm excellent behaviour in the removal heavy metals from their aqueous solution compared to the previous materials reported before.

Modifications to sorption and sinking capability of microplastics after chlorination

Abstract Chlorination disinfection in water treatments may be highly destructive to microplastics (MPs). Herein, low- and high-dose (concentration–time values at 75 and 9,600 mg min L−1, respectively) chlorination processes were used to simulate short-term chlorination in drinking water treatment plants and long-term residual chlorine reaction in drinking water supply systems, respectively. Both chlorination processes induced modifications to polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), and polyvinyl chloride (PVC) MPs, varying in polymer types and sizes. Oxidized and chlorinated bonds were detected, and destructed surfaces with increased specific surface area and reduced hydrophobicity were observed. As a result, the sorption capacity of all MPs was weakened, e.g., low-dose chlorination (pH 7) depressed the sorption of ciprofloxacin by 6.5 μm PE (Kf from 0.140 to 0.128 L g−1). The sinking behavior of PET, PS, and PVC MPs was enhanced, e.g., the sinking ratio of 200 μm PET increased by ∼30% after low-dose chlorination (pH 7). By contrast, PE tended to float after high-dose chlorination. Furthermore, chlorination of MPs generated various products, which were the degraded fragments from the MP skeleton. In general, chlorination disinfection reduces the potential of MPs as transport vectors of organic contaminants.

Fabrication of biochar from jarul (Lagerstroemia speciosa) seed hull for ultrasound aided sequestration of ofloxacin from water: Phytotoxic assessments and cost analysis

Water pollution by pharmaceutical pollutants such as antibiotics are rising day by day and antibiotics are considered as emerging contaminants because of their eventual threats for both human health and aquatic ecology. Recently waste biomass derived biochar has drawn a lot of attention, especially as adsorbents, for antibiotics contaminated wastewater sequestration because of their high sorption capability, higher surface area, and microporosity. In this study, waste biomass (Lagerstroemia speciosa) seed coats were used to produce biochar (CLSHB) through a pyrolysis progression followed by chemical activation with NaOH for the effective removal of an antibiotic drug ofloxacin (OFL) from water. The surface area, and pore volume of CLSHB were assessed to be 82.192 m2/g, and 0.189 cm3/g, consecutively. The optimum removal percentage of OFL was obtained to be 91.43 % at solution pH 5.0, adsorbent dose of 1.0 g/L, OFL concentration of 20 mg/L, and sonication time of 90 min. The OFL adsorption data were well-fitted by the Langmuir isotherm model with uptake capacity of 34.60 mg/g, which depicts the monolayer adsorption of OFL onto the CLSHB surface. OFL adsorption kinetics results fit to the pseudo-second-order model, indicating that chemical sorption might be the main mechanism by which the pharmaceutical adhered to the CLSHB surface. The phytotoxicity assessment demonstrated that the treated OFL solution obtained in this process was deemed suitable for seed germination and the total synthesis cost of CLSHB was found to be only 8.7 $/kg. The OFL elimination efficacy with CLSHB decreases from 91.43 % to 73.26 % after fifth cycle of consecutive use, demonstrating the strong stability and reusability of CLSHB.

Strontium-Induced Gelation of Sodium Alginate in the Presence of Carbon Nanotubes: Elemental Analysis and Gel Structure

The elemental composition and structural features of the junction zones of a strontium–alginate hydrogel and their alteration under the intercalation of multi-walled carbon nanotubes into the hydrogel structure were studied. It was shown that the crosslinking with Sr2+ cations due to electrostatic interactions leads to the association of polymer chains into junction zones with incompletely filled cells. It was found that in strontium alginate, the average cell occupation number of Sr2+ cations is less than 1 and approximately equal to 0.64. In nanocomposite hydrogels including multi-walled carbon nanotubes, its increase to 0.81 indicates the appearance of a more ordered structure of alginate chains in junction zones. The information about the most preferred types of egg-box cells for binding with Sr2+ cations was analyzed. The existence of Sr2+ cations in nonequivalent positions was established. The possibility of separating the contributions of chemical adsorption due to ionic bonds with alginate chains and physical adsorption due to the appearance of local energy minima near alginate chains, leading to the appearance of ordered secondary structures, was demonstrated. It has been shown that the addition of carbon nanotubes to a hydrogel changes their sorption capability, leading, first of all, to an increase in the possible sites of physical adsorption.

Removal of Fluoride from Geothermal Water by Waste-Synthesized Al(OH)3-HAP@ZMS Composite Adsorbent: Sorption Capability and Mechanism

Removal of Fluoride from Geothermal Water by Waste-Synthesized Al(OH)3-HAP@ZMS Composite Adsorbent: Sorption Capability and Mechanism

Influence of co-milling oxide physical properties on the structural changes of natural clinoptilolite zeolites

Zeolites are a family of open-framework aluminosilicate minerals used in many diverse fields, including building materials, agriculture, water treatment, and catalysis. In this study, natural zeolites were mechano-chemically treated by co-milling with corundum and cristobalite. The idea behind the study was that co-milling with high-hardness oxides would cause natural zeolite to undergo more structural distortion, potentially increasing its reactivity and sorption capabilities. Corundum has a density of 3.95 g/cm3 and a hardness of 9, while cristobalite has a density of 2.27 g/cm3 and a hardness of 6-7, according to the Mohs hardness scale. In a planetary ball mill, the zeolites and 20 wt.% of various oxides were co-ground for 30 min. The grinding media used were hardened steel balls with a weight ratio of 20:1 between the balls and the minerals. Raw minerals and milled products were evaluated using X-ray diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy. It revealed that co-milling with different hardness oxides had a minor effect on the structural distortion of raw zeolite. Crystallite size reduction and amorphization were observed in high hardness oxides rather than in zeolite particles. After milling, the amorphization of natural zeolite milled alone was 30.4%, while no significant amorphization was observed when co-milled with corundum and cristobalite. Preliminary results of Cr(VI) adsorption tests on raw and milled zeolites indicate that co-milling with high-hardness oxides is not the preferred method to enhance the activity of natural zeolite.

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.

Redistribution of perfluorooctanoic acid in sludge after thermal hydrolysis: Location of protein plays a major role

Perfluorinated compounds (PFCs) are a group of bio-recalcitrant pollutants that remain in waste activated sludge and may subsequently be transferred with sludge to thermal hydrolysis pretreatment (THP) process. Instead of reduction, it is observed previously that the concentration of free PFCs elevated after THP. By employing perfluorooctanoic acid (PFOA) as a representative, this study developed a hierarchical scheme to pinpoint the key factors that contribute to free PFOA elevation from the complex sludge transformations. According to the results, the relative abundance of PFOA in the liquid phase increased by 11.7 – 22.9% during THP. In the solid phase, the amide groups reduction and the spatial structure change of proteins weakened the sorption capability of solids for PFOA. In the liquid phase, the increase of proteins, which could bind and form static hindrance to regulate the behavior of PFOA, was the main factor to retain PFOA in liquid. In contrast, other sludge transformations including changes in pH, zeta potential, ionic condition and specific surface area, displayed insignificant impact on the redistribution process. The study presents a detailed picture on how sludge transformations would regulate PFCs distribution that ultimately direct the selection of further treatment processes.