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In this study, municipal solid waste bottom ash (MSW-BA) and fly ash (MSW-FA) were used as a source of aluminosilicate to prepare geopolymer (GEO) adsorbents (GEO-MSWBA and GEO-MSWFA) for the removal of methylene blue (MB) from water. The effects of temperature, pH, and initial concentration on the MB adsorption onto GEO-MSWBA and GEO-MSWFA were evaluated. The adsorption isotherms parameters and thermodynamics were also determined. Detailed physical and chemical characterizations of the prepared adsorbents were carried out to further understand their impact on MB adsorption. The results from the scanning electron microscopy revealed a uniform granule-sphere like structure on both prepared geopolymers, which would facilitate the MB adsorption onto the adsorbents. The X-ray diffraction allowed observation of the microstructural transformations that occur after the alkaline activation. The surface areas of the GEO-MSWBA and the GEO-MSWFA were recorded as 32.78 m 2 /g and 4.5 m 2 /g, respectively. From the Fourier transform infrared, a stretching vibration of the aluminosilicate tetrahedral was observed, which indicated the success of geopolymerization. The prepared geopolymers showed a high capability of MB adsorption from an aqueous solution. The adsorption process was best suited and explained using the Langmuir isotherm model with a maximum adsorption capacity of 666.7 mg/g for the GEO-MSWBA (at 25°C) and 769.2 mg/g for the GEO-MSWFA (at 35°C). The positive value of the enthalpy (ΔH o ) for the GEO-MSWBA suggested the reaction favored endothermic reaction while the negative value of entropy (Δ S o ) indicated a solid/liquid random interaction. On the other hand, the negative ΔH o value for the GEO-MSWFA indicated the reaction followed an exothermic reaction causing energy to be released, the positive Δ S o value indicated a good affinity at the solid-liquid surface. The overall negative value for Gibbs free energy (Δ G o ) for both adsorbents suggested the adsorption was spontaneous and feasible. It was also inferred that n - π interaction, direct and indirect hydrogen bond, and electrostatic interaction between the MB and the prepared geopolymers facilitated the adsorption process. The current study shows that the GEO-MSWBA and the GEO-MSWFA have a great potential of removing MB as a cationic dye from water without performing any sort of laborious pretreatments.

In this paper, novel composite materials from modified roasted date pits using ferrocyanides were developed and investigated for the recovery of lithium ions (Li + ) from seawater reverse osmosis (RO) brine. Two composite materials were prepared from roasted date pits (RDP) as supporting material, namely potassium copper hexacyanoferrate-date pits composite (RDP-FC-Cu), and potassium nickel hexacyanoferrate-date pits composite (RDP-FC-Ni). The physiochemical characterization of the RO brine revealed that it contained a variety of metals and salts such as strontium, zinc, lithium, and sodium chlorides. RDP-FC-Cu and RDP-FC-Ni exhibited enhanced chemical and physical characteristics than RDP. The optimum pH, which attained the highest adsorption removal (%) for all adsorbents, was at pH 6. In addition, the highest adsorption capacities for the adsorbents were observed at the initial lithium concentration of 100 mg/L. The BET surface area analysis confirmed the increase in the total surface area of the prepared composites from 2.518 m 2 /g for RDP to 4.758 m 2 /g for RDP-FC-Cu and 5.262 m 2 /g for RDP-FC-Ni. A strong sharp infrared peak appeared for the RDP-FC-Cu and RDP-FC-Ni at 2078 cm −1 . This peak corresponds to the C≡N bond, which indicates the presence of potassium hexacyanoferrate, K 4 [Fe(CN) 6 ]. The adsorption removal of lithium at a variety of pH ranges was the highest for RDP-FC-Cu followed by RDP-FC-Ni and RDP. The continuous increase in the adsorption capacity for lithium with increasing initial lithium concentrations was also observed. This could be mainly attributed to enhance and increased lithium mass transfer onto the available adsorption active sites on the adsorbents’ surface. The differences in the adsorption in terms of percent adsorption removal were clear and significant between the three adsorbents ( P value < 0.05). All adsorbents in the study showed a high lithium desorption percentage as high as 99%. Both composites achieved full recoveries of lithium from the RO brine sample despite the presence of various other competing ions.

Addressing the critical issue of water pollution, this review article emphasizes the need to remove hazardous dyes and phenolic compounds from wastewater. These pollutants pose severe risks due to their toxic, mutagenic, and carcinogenic properties. The study explores various techniques for the remediation of organic contaminants from wastewater, including an enzymatic approach. A significant challenge in enzymatic wastewater treatment is the loss of enzyme activity and difficulty in recovery post-treatment. To mitigate these issues, this review examines the strategy of immobilizing enzymes on newly developed nanostructured materials like graphene, carbon nanotubes (CNTs), and metal–organic frameworks (MOFs). These materials offer high surface areas, excellent porosity, and ample anchoring sites for effective enzyme immobilization. The review evaluates recent research on enzyme immobilization on these supports and their applications in biocatalytic nanoparticles. It also analyzes the impact of operational factors (e.g., time, pH, and temperature) on dye and phenolic compound removal from wastewater using these enzymes. Despite promising outcomes, this review acknowledges the challenges for large-scale implementation and offers recommendations for future research to tackle these obstacles. This review concludes by suggesting that enzyme immobilization on these emerging materials could present a sustainable, environmentally friendly solution to the escalating water pollution crisis.

Incineration has emerged as one of the acceptable ways to treat municipal solid waste (MSW) due to its potential in reducing the mass and volume of the waste. However, it produces two major by-product residues, namely MSW-bottom ash (MSW-BA) and MSW-fly ash (MSW-FA). These residues have gained great attention to their hazardous nature and potential to be reused and recycled. In this paper, the physicochemical characterizations of the MSW-BA and the MSW-FA were performed, followed by a systematic investigation of metals extraction from MSW-BA and MSW-FA. Various extracting agents were used to investigate the possibility to extract 21 metals including cadmium (Cd), vanadium (V), chromium (Cr), and lead (Pb). It was revealed that some metals were present in a high amount in the MSW-BA while other metals were higher in the MSW-FA. Moreover, the energy-dispersive X-ray spectroscopy results revealed that the MSW-BA was dominated by oxygen (O) 55.4 ±0.6 wt%, silicon (Si) 22.5 ±0.3 wt%, and calcium (Ca) 18.5 ±0.2 wt%. On the other hand, the MSW-FA was enriched with Ca 45.2 ±0.5 wt%, and O 40.3 ±0.4 wt%. From the scanning electron microscopy, the MSW-BA was observed as flaky with an irregular surface that consisted of large pores, while, the MSW-FA was present as agglomerated particles and had a bimodal distribution. Moreover, Fourier transform infrared spectroscopy revealed that Al-Fe-OH, Al-Al-OH, Si-O, C-O, and C-H were some of the major functional groups present in the ashes. The F-tests concluded that the metal extraction from the MSW-BA and MSW-FA were significantly affected by the acid type. it is concluded that nitric acid and phosphoric acid were the best-suited acid for the MSW-BA while sulfuric acid and phosphoric acid for the MSW-FA. More than 11 wt% of Cd and 9 wt% of Cu were extracted from MSW-BA while 6 wt% of Pb and 4.5 wt% of V were extracted from the MSW-FA. The present methodology is an interesting development in metal extraction from the MSW-BA and the MSW-FA, which can develop in a cost-effective and sustainable option to utilize MSW.

Gas operations generate large volumes of wastewater, necessitating efficient water management schemes. This study evaluates a forward osmosis (FO) pilot plant for volumes reduction of gas industry process water (PW). The osmotic pressure difference between seawater (40 g/L Total Dissolved Solids (TDS)) and low salinity (2 g/L TDS) PW is used for the osmotic concentration (OC). In the OC, PW volumes get reduced, while diluted draw solution (DS) is directly discharged, obviating the high-energy DS recovery step. A thin-film composite hollow fiber (HF) FO membrane was tested under FO mode using synthetic solutions to assess the performance on the OC unit. Subsequently, the pilot unit was subjected to PW feed for 48 h of continuous operation, primarily to evaluate water flux, reverse solute flux (RSF), and membrane fouling. The cleaning requirement to remove contaminants from the membrane surface was examined. The membrane achieved a water flux and RSF between 11.5 to 6.43 LMH and 38.57 to 9.45 mmol h −1  m −2 , respectively at feed recovery rates between 60 and 90%. The membrane achieved a water flux of 10 LMH, which slightly decreased to 9.6 after 48 h of operation, mainly due to inorganic scaling. Lastly, cleaning with citric acid succeeded in recovering the initial water flux.

The aim of this research was to investigate the potential of raw and iron oxide impregnated carbon nanotubes (CNTs) as adsorbents for the removal of selenium (Se) ions from wastewater. The original and modified CNTs with different loadings of Fe2O3 nanoparticles were characterized using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffractometer (XRD), Brunauer, Emmett, and Teller (BET) surface area analyzer, thermogravimetric analysis (TGA), zeta potential, and energy dispersive X-ray spectroscopy (EDS). The adsorption parameters of the selenium ions from water using raw CNTs and iron oxide impregnated carbon nanotubes (CNT-Fe2O3) were optimized. Total removal of 1 ppm Se ions from water was achieved when 25 mg of CNTs impregnated with 20 wt.% of iron oxide nanoparticles is used. Freundlich and Langmuir isotherm models were used to study the nature of the adsorption process. Pseudo-first and pseudo-second-order models were employed to study the kinetics of selenium ions adsorption onto the surface of iron oxide impregnated CNTs. Maximum adsorption capacity of the Fe2O3 impregnated CNTs, predicted by Langmuir isotherm model, was found to be 111 mg/g. This new finding might revolutionize the adsorption treatment process and application by introducing a new type of nanoadsorbent that has super adsorption capacity towards Se ions.

This brief review explores the synthesis, functionalization, and deployment of biochar as an electrode material for electrochemical energy storage, particularly in relation to supercapacitors and lithium‐ion batteries (LIBs). Biochar, generated via the pyrolysis of diverse biomass feedstocks, offers tunable porosity, surface chemistry, and conductivity; however, electrochemical performance is limited by structural heterogeneity and insufficient activity. In order to mitigate these issues, the review analyzes significant functionalization techniques—including chemical activation (e.g., KOH), heteroatom doping (nitrogen [N], sulfur [S], and phosphorus [P]), metal impregnation, and plasma‐assisted modification—that improve surface area, redox activity, and charge transport. Characterization techniques such as scanning electron microscopy (SEM), X‐ray diffraction (XRD), Raman spectroscopy, and electrochemical evaluations (cyclic voltammetry [CV], galvanostatic charge–discharge [GCD], electrochemical impedance spectroscopy [EIS]) are investigated to establish relationships between structure and performance. Functionalized biochar has exhibited specific capacitance values surpassing 377 F/g and energy densities reaching 54 Wh/kg in supercapacitors, while biochar‐based battery anodes have attained capacities up to 1483 mAh/g with significant coulombic efficiency. The review concludes by delineating prospective research trajectories, including biochar/MXene hybrids, integration of flexible devices, and environmentally sustainable synthesis methods, as promising avenues to enhance scalable, high‐performance energy storage technologies that align with principles of a circular economy.

Drilling fluids are the core of drilling operations, and they are responsible for many roles, such as lubricating drill string, cooling down drilling equipment, maintaining wellbore integrity, and transporting cuttings to the surface. High-energy demands have caused the oil and gas production rates to increase by orders of magnitude, which is accompanied by increased usage of different drilling fluids, including oil-based muds (OBM) and water-based muds (WBM). Large amounts of fluids used without caution can cause severe consequences to the environment if not well monitored. Therefore, the field has been exploring the utilization of biodegradable and environmentally friendly additives (green). These green formulations can promote a safer alternative to the currently available commercial additives, meet sophisticated drilling requirements, and ensure resource sustainability. A comprehensive overview of the literature has been conducted in this review, starting with a background on oil and gas reservoir types and cuttings transportation mechanisms, followed by a discussion on various recent green fluids or additives emerging in the field. In addition, an economic comparison has been conducted to assess the feasibility of the reviewed green formulations. Finally, the review ends with a summary and future prospective on the topic. In conclusion, this review suggests the development of multifunctional drilling fluids with good hole-cleaning properties, utilizing additives studied for different functions (e.g., filtration). Enhancement of rheological properties achieved through the addition of these additives indicates their suitability for hole-cleaning applications, which must be confirmed through additional studies. Consequently, filling the existing gap in the literature is by triggering research topics in this area.

Spherical ZnO nanoparticles doped by samarium ions were successfully synthesized via a simple sol–gel method. The structures, morphologies, optical properties and surface areas were investigated for all samples using specific characterization methods. The hexagonal wurtzite structure of ZnO and samarium-doped ZnO nanoparticles were determined. The results obtained showed that the sizes of samarium-doped ZnO nanoparticles decreased with increasing samarium ion concentration. It was noticed that in the presence of samarium ions, the band gap slightly changed from the 3.198 eV of ZnO to 3.288 eV for samarium-doped ZnO with enhanced absorption in the UV region. This can be attributed to the transition of electrons from the conduction band to the acceptor energy level of samarium. The XPS results of samarium-doped ZnO, showed that only one oxidation state of samarium, with good incorporation into the ZnO matrix, was presented, with no peak of samarium oxide. The surface areas analyses showed that higher surface areas were obtained for samarium-doped ZnO, which is attributed to the smaller size of the particles. The photocatalytic degradation of 2-chlorophenol was investigated under sunlight in presence of ZnO and samarium-doped ZnO nanoparticles. A higher performance of samarium-doped ZnO for photocatalytic degradation of 2-chlorophenol at 0.50 wt.% was observed, compared to pure ZnO nanoparticles under the same experimental conditions. Graphical abstract

The calcium carbonate (CaCO3) scale is one of the most common oilfield scales and oil and gas production bane. CaCO3 scale can lead to a sudden halt in production or, worst-case scenario, accidents; therefore, CaCO3 scale formation prevention is essential for the oil and gas industry. Scale inhibitors are chemicals that can mitigate this problem. We used two popular theoretical techniques in this study: Density Functional Theory (DFT) and Ab Initio Molecular Dynamics (AIMD). The objective was to investigate the inhibitory abilities of mixed oligomers, specifically acrylamide functionalized silica (AM-Silica). DFT studies indicate that Ca2+ does not bind readily to acryl acid and acrylamide; however, it has a good binding affinity with PAM and Silica functionalized PAM. The highest binding affinity occurs in the silica region and not the –CONH functional groups. AIMD calculations corroborate the DFT studies, as observed from the MD trajectory that Ca2+ binds to PAM-Silica by forming bonds with silicon; however, Ca2+ initially forms a bond with silicon in the presence of water molecules. This bonding does not last long, and it subsequently bonds with the oxygen atoms present in the water molecule. PAM-Silica is a suitable calcium scale inhibitor because of its high binding affinity with Ca2+. Theoretical studies (DFT and AIMD) have provided atomic insights on how AM-Silica could be used as an efficient scale inhibitor.