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More aggressive reservoir conditions, such as higher concentrations of CO2 corrosive gases, have a massive effect on corrosion. Moreover, additional aqueous species, such as organic acids, have complicated the conditions and enhanced corrosion to the maximum rate. This study investigates and screens three commercial corrosion inhibitors on their performance in mitigating corrosion at welded areas of carbon steel in high CO2 conditions with the presence of organic acids. These investigations were conducted via chemical elucidations to study the functional groups present in the compounds that affect the inhibition performance and the electrochemical measurements to evaluate the inhibition activities and efficiency of these commercial inhibitors under extreme conditions of high CO2 and organic acids. The results indicated that only CT5727 and CT17906 gave a high inhibition efficiency of 90% in the absence and presence of organic acid, with CT5727 giving the lowest corrosion rate of 0.038 mmpy in the absence of organic acid, while CT17906 gave the lowest corrosion rate of 1.00 mmpy in organic acid condition. On the other hand, D4305 gave the worst inhibition performance under both conditions. The elucidation of these inhibitors also found that specific functional groups such as hydroxy, carboxylic acid, alkyl and alkene presence in the structure were believed to affect the inhibition performance of these commercial inhibitors in mitigating corrosion. These could be used as a future reference for the new development of corrosion inhibitors in similar conditions.

A high surface area adsorbent, such as MOFs, is an attractive option to evacuate heavy metals from wastewater. However, due to the possibility of the MOF structure collapsing when exposed to water, the stability and selectivity of MOFs for wastewater treatment remain a debatable task. Depending on the application, it has been shown that the consolidation of IL into MOF could improve the stability and reusability of pure MOF; nevertheless, research on the molecular interactions between the MOF framework and IL is still lacking. The stability, compatibility, and selectivity of this hybrid material are significantly influenced by the fundamental interactions between the MOFs and ILs moieties (cation and anion molecules), particularly the sorts of interactions. In this work, we focused on the topological properties of ILs and utilization of molecular docking calculations to assess the binding energy (ΔGbind) and binding affinity between UIO66 with TFSI-imidazole and TFSI-pyridinium ILs studied. The properties of ILs such as aromaticity of the structures, bond critical point (BCP), and electrostatic potential map surface were carried out using the Gaussian and Multiwfn software while the binding energies were computed using the AutoDock software to identify particular binding sites for IL toward MOF. The Autodock software's default setting was used to prepare all of the structures. To determine the binding locations of MOF, the IL was successively incorporated into the MOF pores inside the grid box of 90 x 90 x 90 Å (x, y, and z) dimensions. The results showed that both ILs; TFSI-imidazole, and TFSI-pyridinium IL, interacted favorably with the MOFs, having binding energies varying from -4.12 to -8.60 kcal mol-1. The stability of UIO66-ILs system increases with the addition of anion and cation. According to docking molecular structures, both cation and anion tend to bind in the corner of the MOF pore, which is in line with the previous work.

In this study, a series of mesoporous silica nanoparticle (MSN) was successfully synthesized using different ionic liquids (ILs) as a template. Five ILs and a surfactant with different alkyl side chains and types of anion namely 1-dodecyl-3-methylimidazolium iodide ([C12mim][I]), 3-diethylamino propanol vanillate (DV), 2-butylamino ethanol salicylate (BS), 3-diethylamino propanol salicylate (DS), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([bmim][NTf2]) and hexadecyltrimethylammonium bromide (CTAB) were used. All MSNs produced have broad peaks, indicating mesoporous silica in amorphous form as observed by XRD while the morphology of MSN showed the agglomeration of particles and due to parallel arrangement pores size in both for FESEM and HRTEM. The MSNs are amorphous and displayed Type IV BET isotherm with H2 hysteresis loops which is a typical isotherm for mesoporous materials and the highest surface area obtained was 638 m2/g. The study on uptake and release of ibuprofen and quercetin were carried out, where ibuprofen showed higher drug uptake compared to quercetin due to better interaction of MSN with drug molecules. The drug release conducted at 48 h indicates 33.1% of ibuprofen and 38.4% quercetin released. It can be indicated that MSN-BS is the best for drug loading and release. Drugs release kinetics study indicated that the release process follows the Korsmeyer peppes model. The best efficiency of drug loading for MSN-BS/IBU and MSN-BS/QUE was at 48 h and 25 °C with 250 rpm stirring rate for both IBU and QUE, respectively.

Lignin, a readily available form of biomass with a potential source of aromatic chemical compounds, has not been fully utilized due to its complex structure. Hence, this study aims to elaborate and optimize the effects of parametric microwave conditions for the catalytic degradation of lignin model compounds. In addition to that, 41 types of imidazolium-based Ionic liquids were employed for the conversion of lignin model compounds such as guaiacol and benzyl phenyl ether. The microwave-assisted conversion of lignin model compounds in imidazolium-based ionic liquids was performed at optimum applied microwave power 700 W and 30-min irradiation time. The percentages conversion and yield were quantified using high-performance liquid chromatography (HPLC) analysis. Results revealed that the chloride anion-based ionic liquids exhibited better nucleophilic behavior and catalyzed the cleavage of ether-based compounds efficiently under microwave irradiation. Among the imidazolium-based ionic liquids, 1H-methylimidazolium chloride ([1H-MIM][Cl]) exhibited better performance with guaiacol conversion and catechol yield of 99% and 81%, respectively. Therefore, the microwave-assisted technique was found to be more promising than conventional methods for the ionic liquid-based catalytic degradation of lignin model compounds.

Solvation free energy of six choline based ILs were computed under molecular dynamics (MD) simulation using Bennet Acceptance Ratio (BAR) method. H2S removal from the natural gas can be accomplished by absorption process using a solvent. Degree elimination of gases in liquid can be estimated by excess chemical potential (μex), Henry’s law constant (kH), enthalpy (hex), and entropy (sex). The Optimised Potential Liquids Simulation (OPLS) force fields used for ILs were validated against experimental density in order to get valid results of solvation free energy. The percentage error of the predicted density of six choline based ILs were below than 2.0% which is a good agreement with the previous study. The highest value of kH was 109.23 atm gained by choline thiocyanate [Chl][tcy] and the lowest value of kH was 23.25 atm obtained by choline acetate [Chl][act]. There are many features that influence the solubility of H2S for example length of alkyl chain, free volume effect, molar density, type of anions and hydrogen bonding interaction. In order to understand the behaviour of H2S molecules in ILs system, the radial distribution function (RDF) of H2S-ILs and RDF for specific atom were analysed. Basically, the shorter the alkyl chain, increase in molar density of ILs, reduce the free volume thus provide less space for H2S to occupy and decrease insolubility.

A compatibility and stability of Isoreticular Metal Organic Framework (IRMOF-1) impregnated with choline based ionic liquids (ILs) are studied by molecular dynamic simulation. Among three proposed IL/IRMOF-1 hybrid composites, cholinium formate, ([Chl][Fm]) is nominated as the best IL to be incorporated with IRMOF-1 since it shows the lowest RMSD value (0.502 nm, 0.637 nm, 0.923 nm) at three IL/IRMOF-1 w/w ratio (0.4%, 0.8% and 1.2%) respectively and become representative to all three ILs. Oxygen atom in the bridging carboxyl group shows the most flexible atom through RMSF analysis since it shows the highest fluctuation (1.001 nm) at WIL/IRMOF-1 = 0.4%. The RDF shows that the interaction between [Chl]+ and [Fm]− is higher in composite phase compare to bulky phase due to confinement effect of IRMOF-1. Both [Chl]+ and [Fm]− seem to be preferred to locate around carboxylate group inside the IRMOF-1 whereby [Fm]− shows the dominant interaction and strongly interacts with IRMOF-1 compared to [Chl]+. In terms of mobility, the cation shows high mobility with SDF value of 0.0419 nm2 in which mobility is expected to be increased with increasing of ILs ratio (0.4%, 0.8% and 1.2%) respectively. Intensity of the ions population around IRMOF-1 is interpreted by density map which is in agreement with the RDF analysis. Finally, the stability of the IRMOF-1 is confirmed by the radius of gyration (Rg) analysis in which 0.4% ILs shows the most stable conformation with the lowest Rg value = 1.667 nm that is in consistent with the RMSD analysis. Overall, the structural stability of IRMOF-1 is well interpreted and impregnation of ILs literally increase the stability of framework at lower IL/IRMOF-1 w/w ratio.

Searching for a suitable electrolyte in a lithium-ion battery is a challenging task. The electrolyte must not only be chemically and mechanically stable, but also be able to transport lithium ions efficiently. Ionic liquid incorporated into a metal–organic framework (IL@MOF) has currently emerged as an interesting class of hybrid material that could offer excellent electrochemical properties. However, the understanding of the mechanism and factors that govern its fast ionic conduction is crucial as well. In this review, the characteristics and potential use of IL@MOF as an electrolyte in a lithium-ion battery are highlighted. The importance of computational methods is emphasized as a comprehensive tool to investigate the atomistic behavior of IL@MOF and its interaction in electrochemical environments.

The purpose of this study is to assess water–polymer interaction in synthesized starch-derived superabsorbent polymer (S-SAP) for the treatment of solid waste sludge. While S-SAP for solid waste sludge treatment is still rare, it offers a lower cost for the safe disposal of sludge into the environment and recycling of treated solid as crop fertilizer. For that to be possible, the water–polymer interaction on S-SAP must first be fully comprehended. In this study, the S-SAP was prepared through graft polymerization of poly (methacrylic acid-co-sodium methacrylate) on the starch backbone. By analyzing the amylose unit, it was possible to avoid the complexity of polymer networks when considering S-SAP using molecular dynamics (MD) simulations and density functional theory (DFT). Through the simulations, formation of hydrogen bonding between starch and water on the H06 of amylose was assessed for its flexibility and less steric hindrance. Meanwhile, water penetration into S-SAP was recorded by the specific radial distribution function (RDF) of atom–molecule interaction in the amylose. The experimental evaluation of S-SAP correlated with high water capacity by measuring up to 500% of distilled water within 80 min and more than 195% of the water from solid waste sludge for 7 days. In addition, the S-SAP swelling showed a notable performance of a 77 g/g swelling ratio within 160 min, while a water retention test showed that S-SAP was capable of retaining more than 50% of the absorbed water within 5 h of heating at 60 °C. The water retention of S-SAP adheres to pseudo-second-order kinetics for chemisorption reactions. Therefore, the prepared S-SAP might have potential applications as a natural superabsorbent, especially for the development of sludge water removal technology.

A plasticized solid polymer electrolyte system is prepared using polymer blend of methyl cellulose–potato starch with lithium perchlorate (LiClO4) as dopant salt and glycerol as plasticizer. Transport properties of the electrolytes are investigated using electrical impedance spectroscopy (EIS). By applying a method proposed by Arof et al. which was found to be suitable for both Arrhenius and Vogel–Tammann–Fulcher (VTF) type of electrolytes, the number density (n), diffusion coefficient (D), and mobility (μ) of ions are found to be influenced by the concentration of glycerol. From ion and electron transference number analysis, it is verified that ions are the main charge carriers. Linear sweep voltammetry (LSV) verifies the suitability of the most conductive electrolyte to be employed in the carbon-based symmetric electrical double-layer capacitor (EDLC) fabrication. The EDLC has been tested using the galvanostatic charge–discharge and cyclic voltammetry (CV) techniques. The specific capacitance (Csp) of the electrode using CV at a sweep rate of 2 mV s−1 is found to be 61.58 F g−1. The EDLC has been tested for 1000 charge–discharge cycles with the highest Csp value of 28.04 F g−1.

One way to reconcile an issue associating with the harvesting of microalgal biomass is via the application of attached growth cultivation mode, whereby the mature microalgal biomass can be facilely harvested from the support material. Accordingly, the objectives of present works were to model the attached growth of Chlorella vulgaris onto polyurethane foam support material in a fluidized bed bioreactor while simultaneously bioremediating real nutrients-rich wastewater and biofixing CO2 for biodiesel production. The mathematical models accounting the impact of various interactions between light intensities and CO2 concentrations in culture medium on growing attached microalgal biomass were initially improved. The successful practicality of models was confirmed from the analysis of statistical accuracy while predicting the growth of attached microalgal biomass in real nutrients-rich wastewater. When the microalgal growth reached the stationary growth phase, all the nutrients (nitrogen and phosphorous sources of compounds) were completed impoverished, accentuating the bioremediation potentiality in satisfying the effluent discharged requirements. Subsequently, the modeling of microalgal CO2 biofixation also unveiled that the highest CO2 biofixation rate was transpiring in parallel with the growth rate of attached microalgal biomass during the exponential growth phase. Upon the harvesting, the neutral lipid from mature attached microalgal biomass was found to contain 97.7% (by wt. of lipid) of fatty acid methyl esters (FAMEs) mixture, heralding the biodiesel purity. Assessment of biodiesel quality showed a balance composition among the saturated, monounsaturated and polyunsaturated FAMEs mixture with high in C16 and C18 FAME species for the materialization of efficient combustion.

Active pharmaceutical ingredients (APIs) in the form of crystalline solid are commonly produced in drug manufacturing industries. However, crystalline solid APIs have a low solubility and the ability to cause polymorphism transformation. In order to overcome these problems, a modification of APIs in the form of protic ionic liquids (PILs) has been proposed. In the present study, a series of five ferulate-based PILs were successfully synthesised and characterised by appropriate spectral analysis. The antioxidant activity of synthesised PILs was determined through the 2,2‑diphenyl‑1‑picrylhydrazyl (DPPH) free radical scavenging assays. The spectroscopy analysis confirmed the formation of PILs supported by the Density Function Theory (DFT) calculation. The synthesised ferulate-based PILs exhibited low EC50 ranging from 12.93 ± 0.05 to 17.40 ± 0.04 μM indicating a strong antioxidant activity compared to parent acid (EC50 of 21.40 ± 0.05 μM). Prediction of antioxidant activity of the PILs and their ionic interactions at the molecular level were studied by applying DFT calculation at B3-LYP/6-311G*** level and COSMO-RS. Based on the optimised geometry, the ion-pair of PILs formed a strong directional intermolecular hydrogen bond between the –NH group of the cation with the –COOH group of the anion with interaction energy of −111 to −120 kcal mol−1. Predicted antioxidant activity indicated that the PILs's cation has a weak interaction with an anion as observed from the σ-potential analysis.

Mixed oxides catalyst has become a recent focus for production of biodiesel from the third-generation biomass. In this study, ZrO2 was synthesized by using sol–gel method with hydrothermal assisted. Mixed oxides catalysts were then prepared via incipient wetness impregnation of Bi2O3 (5, 15 and 30 wt%) on the synthesized ZrO2. Physicochemical properties of the catalysts were evaluated using different characterization techniques and their performances were investigated in the transesterification of marine microalgae of Nannochloropsis oculata to biodiesel. XRD diffractograms showed the presence of monoclinic (m) and tetragonal (t) phases of ZrO2 in all synthesized catalysts. It was found that the composition of the ZrO2 phases depend strongly on the Bi2O3 content. BET analyses showed that the total surface area of ZrO2 decreased with increased Bi2O3 content due to the pore filling effect. CO2-TPD and NH3-TPD analyses indicated that all the catalysts possessed both acidic and basic properties with different intensities. The highest FAME yield was obtained using 5Bi2O3/ZrO2 when the test was conducted at optimum reaction conditions of 20 wt% of catalyst loading and methanol to biomass ratio of 90:1 (mL/g) at 80 °C for 6 h. The synthesized biodiesel met the specifications of biodiesel standard for cetane number and iodine value except for the oxidative stability.

The black soldier fly larvae (BSFL) have been widely extolled for the application in managing various solid organic wastes. Owing to the saprophagous nature of BSFL, a rapid valorization of solid organic wastes can be accomplished with the simultaneous production of valuable biochemical compounds derived from larval biomass. In the present works, the mixed waste coconut endosperm (w-CE) and soybean curd residue (SC-r) substrates with increasing protein nutritional constituent were administered to BSFL. The correlations between protein from larval feed substrates and nutritional profiles of BSFL biomasses were ultimately unveiled. The protein from larval feed substrates could be increased by increasing of SC-r portion against w-CE. At the w-CE:SC-r ratio of 3:2, the highest larval total weight gained and growth rate were attained; indicating an optimum protein nutritional constituent in mixed organics (12.4%) that could enhance the BSFL palatability. Further increment of protein nutritional constituent in mixed organics was found acidifying the residual larval feed substrate progressively, undermining the growth of BSFL. By feeding the BSFL with optimum mixed organics, the maximum accumulations of larval lipid and protein could be achieved. Transesterification of extracted lipid had demonstrated high in monounsaturated fatty acids (73%) which was suitable for biodiesel. The BSFL palatability was finally confirmed from the bioconversion viewpoint of mixed organic wastes. Again, achieving the highest bioconversion efficiency of 14% into larval biomass after accounting the metabolic loss of 54%. Therefore, a total of 68% of mixed w-CE and SC-r could be successfully bioconverted.

The valorization of sewage sludge by black soldier fly larvae (BSFL) has gained attentions for sewage sludge management since the sludge can be reduced securely as well as larval biomass can be used for biorefineries application. Nevertheless, the BSFL growth was impeded while assimilating nutrition from sewage sludge due to the presence of extracellular polymeric substances (EPS) that had entrapped the essential nutrients inside. Accordingly, the pre-treatment of sewage sludge via anaerobic digestion at different pH was employed in this work to rupture the EPS structure and release more nutrients for larval growth. The results showed that larvae fed with raw sewage sludge had attained the lowest final larval weight (2.05 ± 0.38 mg/larva) as opposed to batches fed with pre-treated sewage sludges. This was because the soluble carbohydrate (more than 6.81 ± 1.31 mg of glucose/g sewage sludge) in EPS was released after anaerobic pre-treatment, facilitating larval assimilation for growth. Furthermore, it was observed that further increasing of pH for sewage sludge pre-treatment had led to lower final larval weight gained due to the inhibitory effect stemming from ammonia production at higher pH. The anaerobic pre-treatment of sewage sludge being executed at pH 3 for 8 days had achieved the highest final larval weight at 7.34 ± 0.97 mg/larva. The still low quality of sewage sludges after the pre-treatment also offered benefit, where high sewage sludge reduction and waste reduction index were recorded due to the necessity of BSFL to consume more sewage sludge in compensating the nutrients destitution in sludge. Lastly, the possibility of predicting final larval weight was successfully materialized via a statistical model derived from the multiple linear regression method. The derived model incorporated the interactive parameters of anaerobic pre-treated pH and durations at various combinations could predict the final larval weight.

In recent years, numerous research work has been conducted in order to find the most practical and cost-effective solution for corrosion issues in the oil and gas industry. Several studies have revealed that fatty hydrazide derivatives are the most suitable corrosion inhibitor for the application in the said industry. These compounds can also act as effective corrosion inhibitors in acidic medium with inhibition efficiency greater than 95%. This review summarizes and discusses the recent corrosion inhibitor development in acidic media from 2017 until 2021, focusing on fatty hydrazide derivatives. The significant findings and mechanisms of inhibition have been elucidated. In addition, intake on the computer simulation studies of fatty hydrazide inhibition properties is also included in this review. Finally, some suggestions for future research on corrosion inhibitors have been recommended.

This study investigates the removal and prediction of metolachlor from aqueous medium using advanced prediction technique and porous adsorbent material (metal-organic framework (MOF)). The powdered X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and Brunauer, Emmett and Teller (BET) were used to characterize the synthesized MOF. High removal efficiency (97.75%) was recorded within short time (30 min) using only 10 mg of the MOF. The variation in the pH and concentration were also studied to understand the adsorption. The experimental data set for the training and validation were designed and predicted using the model of artificial neural network (ANN). The ANN model gave accurate prediction for training (R2 = 0.998; R2adj = 0.991 and RMSE = 0.311) and validation (R2 = 0.996; R2adj = 0.991 and RMSE = 0.441) at node five. The porous nature of the adsorbent (1104 m2 g−1), fast equilibration time, % removal and accurate ANN prediction makes this MOF an effective material for remediating recalcitrant pollutants.

An aluminium-based metal–organic framework ((MOF), MIL-53(Al)), was hydrothermally synthesized, characterized and applied for the remediation of the herbicides dicamba (3,6-dichloro-2-methoxy benzoic acid) and 4-chloro-2-methylphenoxyacetic acid (MCPA) in aqueous medium. Response surface methodology (RSM) and artificial neural network (ANN) were used to design, optimize and predict the non-linear relationships between the independent and dependent variables. The shared interaction of the effects of key response parameters on the adsorption capacity were assessed using the central composite design-RSM and ANN optimization models. The optimum adsorption capacities for dicamba and MCPA are 228.5 and 231.9 mg g−1, respectively. The RSM ANOVA results showed significant p-values, with coefficients of determination (R2) = 0.988 and 0.987 and R2 adjusted = 0.974 and 0.976 for dicamba and MCPA, respectively. The ANN prediction model gave R2 = 0.999 and 0.999, R2 adjusted = 0.997 and 0.995 and root mean square errors (RMSEs) of 0.001 and 0.004 for dicamba and MCPA, respectively. In each set of experimental conditions used for the study, the ANN gave better prediction than the RSM, with high accuracy and minimal error. The rapid removal (∼25 min), reusability (5 times) and good agreement between the experimental findings and simulation results suggest the great potential of MIL-53(Al) for the remediation of dicamba and MCPA from water matrices.

The behavior of the inclusion behavior of guanosine (GU) with beta-cyclodextrin (β-CD) in the liquid, solid and virtual state were investigated. The absorption and fluorescence spectral were used to determine the inclusion behavior in liquid state. FT-IR, NMR, TGA, DSC, PXRD and FESEM techniques were used to investigate the inclusion behavior in solid-state, meanwhile the virtual state studies are done by molecular docking. The solid inclusion complex (GU: β-CD) was prepared by using the co-precipitation method. The binding constant (K) of (GU: β-CD) was calculated by using Benesi-Hildebrand. Besides that, the 1:1 stoichiometric ratio of inclusion complex was confirmed by using the Benesi-Hildebrand plot and Job's plot of continuous variation method. The most preferable model of GU: β-CD that suggested via molecular docking studies was in good agreement with experimental results. The inclusion complex of GU: β-CD exerted its toxicity effects towards HepG2 cell lines based on the reduced number of cell viability and lowest IC50 value compared to the GU and β-CD viability.

Three adsorbents based on the metal–organic frameworks (MOFs), viz.; MIL-88(Fe), NH2-MIL-88(Fe), and mixed-MIL-88(Fe) were synthesized using a microwave-assisted solvothermal technique. The as-synthesized MOFs were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The MOFs were shown to possess highly crystalline and porous structures with specific surface areas of 1240, 941, and 1025 m2 g−1 and pore volumes of 0.7, 0.6 and 0.6 m3 g−1 for MIL-88(Fe), NH2-MIL-88(Fe) and mixed-MIL-88(Fe), respectively. Faster removal of a model polycyclic aromatic hydrocarbon, anthracene (ANT) within 25 minutes, was achieved when these MOFs were used as adsorbents in water. The removal efficiency was 98.3, 92.4 and 95.8% for MIL-88(Fe), NH2-MIL-88(Fe) and mixed-MIL-88(Fe), respectively. The kinetics and isotherms of the process were best statistically described by pseudo-second-order and Langmuir models, respectively, while the thermodynamic studies revealed the exothermic and spontaneous nature of the process. Docking simulations were found to be consistent with the experimental results with MIL-88(Fe) showing the best binding capacity with the ANT molecule.

The compatibility and performance of an Isoreticular Metal-Organic Frameworks (IRMOF-1) impregnated with choline-based ionic liquids (ILs) for selective adsorption of H

Here in, we present a review on the adsorption of dyes and pharmaceuticals from water onto UiO (Universitetet i Oslo) metal–organic frameworks (MOFs). The MOFs possessed distinctive and promising properties, uncommon to other conventional adsorbents, such as ultra-porosity and remarkable stability, worthy of being super adsorbents for pollutants adsorption from water. They have shown prodigious performance towards the adsorption of both dyes and pharmaceuticals from the aqueous medium at both lower and higher concentrations. The vast adsorption efficiency of the MOFs is heavily attributed to their high Brunauer-Emmett-Teller (BET) surface areas and pore volume, providing abundant adsorption sites for the pollutants. The binding affinity of the MOFs for the dyes and pharmaceuticals adsorption has been elucidated by the different interactions such as electrostatic, hydrogen bonding and π-π stacking, often dictated by the surface charged of the target pollutant and the zeta potential on the MOF’s surface. The MOFs have shown higher efficiency even in multi-component systems. The ease for the regeneration of the MOFs using common organic solvents and the impressive performance for repeated cycles has been outstanding. The MOFs were thus regarded as superior over conventional porous adsorbents and commendable for large scale applications.

Molecular dynamics (MD) simulations were performed to study the structures and properties of a deep eutectic solvent (DES) synthesised from tetrabutylammonium bromide (TBAB) paired with ethylene glycol (EG). Measurements were performed at different mol ratios of TBAB:EG (1:2 to 1:6) and temperatures (303 to 333 K). Upon validation, MD simulations of DES’s density confirmed results to be in good agreement with previously validated experimental density (Maximum Deviation = 3.91%). The effects of different ratios and temperatures on radial distribution function (RDF), spatial distribution function (SDF), hydrogen bonding, mean square displacement (MSD) and self-diffusion coefficient of the TBAB:EG system were investigated. From RDF analysis, it was observed that Br− moved further away from TBA+ and formed a hydrogen bond with the hydroxyl group (OH) on EG at the closest distance of 0.270 nm. The self-diffusion coefficient of TBA+, Br− and EG increased proportionately to EG. High numbers of hydrogen bonds were observed at a high EG ratio as more intermolecular bondings between EG-Br were established. Hence, the introduction of EG molecules significantly affected ionic interaction within the resulting DES and changed its properties. Experimental data from infrared (IR) spectra and NMR were used to show a correlation between the formation of hydrogen-bonded EG-Br as observed in RDF. Increasing temperatures also altered the RDF, MSD and hydrogen bonding properties of the DES. Meanwhile, the main factor determining ionic movement was found to be the presence of TBA, as the ability of its cation’s long alkyl side chain to form clustering ions dictated the behaviour of the liquid. Therefore, the changes in ratios and temperatures in DESs are essential in predicting their properties and subsequently, in ascertaining the industrial applicability of a particular DES. The presented results showed that the studied DES can be used for many applications and suit the requirement for DNA technology, especially for DNA solvating medium.

Adsorptive removal of naphthalene (NAP) and phenanthrene (PHE) was reported using NH2-UiO-66(Zr) metal-organic frameworks. The process was optimized by response surface methodology (RSM) using central composite design (CCD). The fitting of the model was described by the analysis of variance (ANOVA) with significant Fischer test (F-value) of 85.46 and 30.56 for NAP and PHE, respectively. Validation of the adsorption process was performed by artificial neural network (ANN), achieving good prediction performance at node 6 for both NAP and PHE with good agreement between the actual and predicted ANN adsorption efficiencies. The good reusability of the MOF was discovered for 7 consecutive cycles and achieving adsorption efficiency of 89.1 and 87.2% for the NAP and PHE, respectively. The performance of the MOF in a binary adsorption system was also analyzed and the adsorption efficiency achieved was 97.7 and 96.9% for the NAP and PHE, respectively.

Three adsorbents based on the metal-organic frameworks (MOFs)

Oily wastewater from the oil and gas industry negatively affects the environment. Oily wastewater typically exists in the form of an oil-in-water emulsion. Conventional methods to treat oily wastewater have low separation efficiency and long separation time and use large equipment. Therefore, a simple but effective method must be developed to separate oil-in-water emulsions with high separation efficiency and short separation times. Magnetite–reduced graphene oxide (M–RGO) nanocomposites were used as a demulsifier in this work. Magnetite nanoparticles (Fe3O4) were coated on reduced graphene oxide (rGO) nanosheets via an in situ chemical synthesis method. The synthesized M–RGO nanocomposites are environmentally friendly and can be recovered after demulsification by an external magnetic field. M–RGO characterization was performed using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning microscopy, Raman spectroscopy, and vibrating sample magnetometry. Demulsification performance was evaluated in terms of M–RGO dosage, effects of pH, and brine concentration. The demulsification capability of M–RGO was determined based on the residual oil content of the emulsion, which was measured with a UV-vis spectrometer. The response surface method was used to determine the optimum conditions of the input variables. The optimum demulsification efficiency achieved at pH 4 and M–RGO dosage of 29 g L−1 was approximately 96%. This finding demonstrates that M–RGO nanocomposites are potential magnetic demulsifiers for oily wastewater that contains oil-in-water emulsions. Also, the recyclability of this nanocomposite has been tested and the results shown that it is a good recyclable demulsifier.

Bifunctional heterogeneous catalysts have a great potential to overcome the shortcomings of homogeneous and enzymatic catalysts and simplify the biodiesel production processes using low-grade, high-free-fatty-acid feedstock. In this study, we developed ZrO2-based bifunctional heterogeneous catalysts for simultaneous esterification and transesterification of microalgae to biodiesel. To avoid the disadvantage of the low surface area of ZrO2, the catalysts were prepared via a surfactant-assisted sol-gel method, followed by hydrothermal treatments. The response surface methodology central composite design was employed to investigate various factors, like the surfactant/Zr molar ratio, pH, aging time, and temperature on the ZrO2 surface area. The data were statistically analyzed to predict the optimal combination of factors, and further experiments were conducted for verification. Bi2O3 was supported on ZrO2 via the incipient wetness impregnation method. The catalysts were characterized by a variety of techniques, which disclosed that the surfactant-assisted ZrO2 nanoparticles possess higher surface area, better acid–base properties, and well-formed pore structures than bare ZrO2. The highest yield of fatty acid methyl esters (73.21%) was achieved using Bi2O3/ZrO2(CTAB), and the catalytic activity of the developed catalysts was linearly correlated with the total densities of the acidic and basic sites. The mechanism of the simultaneous reactions was also discussed.

The binding characteristics of DNA in deep eutectic solvents (DESs), particularly the binding energy and interaction mechanism, are not widely known. In this study, the binding of tetrabutylammonium bromide (TBABr) based DES of different hydrogen bond donors (HBD), including ethylene glycol (EG), glycerol (Gly), 1,3-propanediol (1,3-PD) and 1,5-pentanediol (1,5-PD), to calf thymus DNA was investigated using fluorescence spectroscopy. It was found that the shorter the alkyl chain length (2 carbons) and higher EG ratios of TBABr:EG (1:5) increased the binding constant (Kb) between DES and DNA up to 5.75 × 105 kJ mol−1 and decreased the binding of Gibbs energy (ΔGo) to 32.86 kJ mol−1. Through displacement studies, all synthesised DESs have been shown to displace DAPI (4′,6-diamidino-2-phenylindole) and were able to bind on the minor groove of Adenine-Thymine (AT)-rich DNA. A higher number of hydroxyl (OH) groups caused the TBABr:Gly to form more hydrogen bonds with DNA bases and had the highest ability to quench DAPI from DNA, with Stern-Volmer constants (Ksv) of 115.16 M−1. This study demonstrated that the synthesised DESs were strongly bound to DNA through a combination of electrostatic, hydrophobic, and groove binding. Hence, DES has the potential to solvate and stabilise nucleic acid structures.

The experimental adsorption of Anthracene (ANT), a model polycyclic aromatic hydrocarbon (PAHs) was optimized using central composite design (CCD) of response surface methodology (RSM). MIL-88(Fe) and NH2-MIL-88(Fe) Metal-organic frameworks (MOFs) were employed as the potential adsorbents. The model was described as the significant according to the analysis of variance (ANOVA) for the statistical fittings of R2 (0.991 and 0.992), and adequate precision (43.55 and 47.82) with the lack of fit F-values (2.15 and 1.59) for the MIL-88(Fe) and NH2-MIL-88(Fe) respectively. The highest adsorption efficiency achieved were 99.55 and 95.67% for the MIL-88(Fe) and NH2-MIL-88(Fe) respectively based on the RSM optimized conditions. The pseudo-second-order kinetic model has been described as the best mechanism for the adsorption process.

The properties of DNA in ionic liquids (ILs) have been well studied. However, it is not widely known about the quantitative analysis of ILs such as the binding profile, which could offer a detailed insight of their binding characteristic. In this study, the binding energy of alkylimidazolium-based ILs ([Cnbim]Br where n = 2, 4 and 6) to calf thymus DNA was determined using fluorescence spectroscopy. It was found that the binding constant increased while the values of binding Gibbs energy decreased linearly with increase of alkyl chain length of the ILs. Based on these data, the contribution of each methylene group in the tail of ILs in IL-DNA complex was determined. Moreover, low quenching constant was observed from the competitive displacement of intercalation of ethidium bromide to DNA, hence confirming that ILs are not intercalator. The length of alkyl chain contributed to the increase in the thermal stability of DNA as observed from UV–visible spectra while the CD results indicated that DNA retained its B-form without significant change in the conformation of its base pairs. The findings show that although the stability of DNA is mainly due to the electrostatic attraction between cationic head charge group of imidazolium cation and the DNA phosphate groups, the contribution from the length of alkyl chains also plays a significant role in IL-DNA complex.

Recently, pharmaceutical pollutants in water have emerged as a global concern as they give threat to human health and the environment. In this study, graphene nanoplatelets (GNPs) were used to efficiently remove antibiotics sulfamethoxazole (SMX) and analgesic acetaminophen (ACM) as pharmaceutical pollutants from water by an adsorption process. GNPs; C750, C300, M15 and M5 were characterized by high-resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction and Brunauer–Emmett–Teller. The effects of several parameters viz. solution pH, adsorbent amount, initial concentration and contact time were studied. The parameters were optimized by a batch adsorption process and the maximum removal efficiency for both pharmaceuticals was 99%. The adsorption kinetics and isotherms models were employed, and the experimental data were best analysed with pseudo-second kinetic and Langmuir isotherm with maximum adsorption capacity (Q m ) of 210.08 mg g −1 for SMX and 56.21 mg g −1 for ACM. A regeneration study was applied using different eluents; 5% ethanol-deionized water 0.005 M NaOH and HCl. GNP C300 was able to remove most of both pollutants from environmental water samples. Molecular docking was used to simulate the adsorption mechanism of GNP C300 towards SMX and ACM with a free binding energy of −7.54 kcal mol −1 and −5.29 kcal mol −1 , respectively, which revealed adsorption occurred spontaneously.

Optimization studies was conducted for the pyrene (PYR) adsorption onto Zr-based metal organic frameworks (MOFs), UiO-66(Zr) and NH2-UiO-66(Zr) in aqueous medium. Central composite design (CCD) model has shown good fittings of the coefficient of determination (R2) with non-significant lack of fit for both UiO-66(Zr) and NH2-UiO-66(Zr) MOFs. The optimized adsorption efficiency achieved by the UiO-66(Zr) and NH2-UiO-66(Zr) were 99.22 and 95.67% respectively. Artificial neural network (ANN) model was able to predict the experimental findings with high precision at topographic node of 5-4-2 structural layer. The kinetics and isotherms of the process was best described by pseudo-second-order Langmuir models respectively. The process was exothermic and spontaneous with the good reusability of the MOFs.

The compatibility and performance of an Isoreticular Metal-Organic Frameworks (IRMOF-1) impregnated with choline-based ionic liquids (ILs) for selective adsorption of H2S/CO2, were studied by molecular dynamics (MD) simulation. Cholinium alanate ([Chl][Ala]) was nominated as the suitable IL for impregnation into IRMOF-1, consistent with the low RMSD values (0.546 nm, 0.670 nm, 0.776 nm) at three IL/IRMOF-1 w/w ratios (WIL/IRMOF-1 = 0.4, 0.8, and 1.2). The [Chl]+ and [Ala]- ion pair was located preferentially around the carboxylate group within the IRMOF-1 framework, with the latter interacting strongly with the host than the [Chl]+. Results of radius of gyration (Rg) and root mean square displacement (RMSD) revealed that a ratio of 0.4 w/w of IL/IRMOF-1 (Rg = 1.405 nm; RMSD = 0.546 nm) gave the best conformation to afford an exceptionally stable IL/IRMOF-1 composite. It was discovered that the IL/IRMOF-1 composite was more effective in capturing H2S and CO2 compared to pristine IRMOF-1. The gases adsorbed in higher quantities in the IL/IRMOF-1 composite phase compared to the bulk phase, with a preferential adsorption for H2S, as shown by the uppermost values of adsorption ( [Formula: see text] = 17.954 mol L-1 bar-1) and an adsorption selectivity ( [Formula: see text] = 43.159) at 35 IL loading.

Polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds had been widely recognized as priority organic pollutants in wastewater with toxic effects on both plants and animals. Thus, the remediation of these pollutants has been an active area of research in the field of environmental science and engineering. This review highlighted the advantage of adsorption technology in the removal of PAHs and phenols in wastewater. The literature presented on the applications of various porous carbon materials such as biochar, activated carbon (AC), carbon nanotubes (CNTs), and graphene as potential adsorbents for these pollutants has been critically reviewed and analyzed. Under similar conditions, the use of porous polymers such as Chitosan and molecularly imprinted polymers (MIPs) have been well presented. The high adsorption capacities of advanced porous materials such as mesoporous silica and metal-organic frameworks have been considered and evaluated. The preference of these materials, higher adsorption efficiencies, mechanism of adsorptions, and possible challenges have been discussed. Recommendations have been proposed for commercialization, pilot, and industrial-scale applications of the studied adsorbents towards persistent organic pollutants (POPs) removal from wastewater.

Metal-organic frameworks (MOFs), MIL-88(Fe) and NH2-MIL-88(Fe) were synthesized using microwave-assisted solvothermal technique. BET analysis has shown the porous nature of the MOFs, possessing surface areas with corresponding pore volumes of 1240 m2g−1 and 0.7 m3 g−1, 941 m2 g−1 and 0.6 m3 g−1 for MIL-88(Fe) and NH2-MIL-88(Fe), respectively. Other characterizations were also conducted using scanning electron microscopy (SEM), powdered X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy. The MOFs were evaluated for application as adsorbents for the removal of pyrene (PYR) in aqueous solution. The removal efficiency achieved by MIL-88(Fe) was 99.7% while for NH2-MIL-88(Fe) was 96.0% within 40 minutes. Both MOFs has shown good removal of the PYR even after 5 consecutive uses. The adsorption isotherm was studied and favoured more by the Langmuir model, while the kinetics was found to follow pseudo-second-order model. The process was thermodynamically exothermic and spontaneous. Thus, the MOFs studied exhibited favourable features as potential adsorbents for the removal of PYR in wastewater.

This work compared the effect of soaking and roasting Phoenix dactylifera L. seeds pretreatment methods on oil yield. The conversion of the Phoenix dactylifera L. seed oil to fatty acid methyl ester (FAME) was conducted via transesterification reaction using Ce-Zr/Al-MCM-41 monometallic and bimetallic catalysts. The reaction conditions were optimized using response surface methodology based on the central composite design (RSM-CCD). The result shows a quadratic model fitting with an R2 value of ~0.98% from the analysis of variance. In addition, the optimum FAME yield of 93.83% was obtained at a reaction temperature of 60.5 &deg, C, a reaction time of 3.8 h, a catalyst concentration of 4 wt.%, and a methanol to oil molar ratio of 6.2:1 mol/mol. The effect of the regenerated catalyst was significantly maintained for five cycles. The fuel properties of the produced FAME lie within the values reported in studies, ASTM D6751, and EN14214 standards.

Metal-organic frameworks UiO-66(Zr) and NH2-UiO-66(Zr) were characterized by x-ray diffraction (XRD), fourier transformed infrared spectroscopy (FTIR), field emission scanning electron microscopy (SEM), thermogravimetry (TG) and N2 adsorption–desorption measurements. The porous nature of the materials was revealed by the higher Brunauer-Emmett-Teller (BET) surface area of 1420 m2 g−1, 985 m2 g−1 and particles size of 7.56 nm, 3.56 nm for UiO-66(Zr) and NH2-UiO-66(Zr) respectively. Enhanced adsorption capacity and recyclability of the MOFs towards anthracene (ANT) and chrysene (CRY) removal in aqueous medium was achieved. 98.6 and 96.4% of ANT was removed within 25 mins, while 97.9 and 95.7% of CRY was removed within 30 mins for the UiO-66(Zr) and NH2-UiO-66(Zr) respectively. Molecular docking was employed to model the surface interactions of the synthesized MOFs with the pollutants and the simulated binding energies were in good agreement with the experimental results.