Theoretical design of transition metal-doped oxo-triarylmethyl as a disposable platform for adsorption of ibuprofen.

Emerging environmental contaminants have become a crucial environmental issue because of the highly toxic effluents emitted by factories. Ibuprofen (IBP), as a typical anti-inflammatory drug, is frequently detected in water sources. Therefore, its removal using various adsorbents has drawn great interest. Herein, the structural, electronic, energetic, and optical properties of pristine oxo-triarylmethyl (oxTAM) and transition metal-doped oxo-triarylmethyl (TM@oxTAM, TM = Sc, Ti, V, Cr, and Mn) for adsorption of the IBU drug were investigated using density functional theory (DFT) calculations implemented in Gaussian and VASP codes. Frontier molecular orbital (FMO), density of states (DOS), and electronic band structure results demonstrated that transition metal-doped oxTAM causes a significant reduction in the energy band gap (Eg) value of pristine oxTAM, with the highest decrease (30.14 %) in the case of Mn@oxTAM. It was found that transition metal doping onto oxTAM leads to an increase in the adsorption energies (1.20-2.64 eV) and charge density between transition metal and IBU. Natural bond orbital (NBO) analysis revealed that charge was effectively transferred from the IBU towards the transition metal, which was further analyzed by charge decomposition analysis (CDA). Furthermore, quantum theory of atoms in molecules (QTAIM), interaction region indicator (IRI), electron localization function (ELF), and radial distribution function (RDF) analyses revealed that the IBU is adsorbed on the Sc@oxTAM surface via covalent interactions, while electrostatic with partially covalent interactions are dominated in other IBU/TM@oxTAM complexes. The results suggest that TM doping on the oxTAM provides a new insight for developing photocatalyst-based covalent organic frameworks (COFs) to remove emerging pollutants in wastewater.

Chitosan-based adsorptive membrane modified by carboxymethyl cellulose for heavy metal ion adsorption: Experimental and density functional theory investigations.

Low adsorption capacity and weak mechanical stability are the main drawbacks of chitosan (CS)-based adsorptive membranes for heavy metal ion removal. Polyvinyl alcohol (PVA) has been used to improve the mechanical stability of CS membranes, but adsorption capacity is disregarded. In the current study, the surface of the chitosan/polyvinyl alcohol (CP) membrane was modified using carboxymethyl cellulose (CMC) to increase its heavy metal ion adsorption capacity. Experimental and density functional theory (DFT) calculations were used to evaluate the heavy metal ion (As3+ and Cr3+) adsorption capabilities of CP and carboxymethyl cellulose-functionalized CP (CMC-CP) membranes. The batch adsorption process presented a higher heavy metal adsorption capacity of the CMC-CP membrane (As3+/CMC-CP = 234.78 mg/g and Cr3+/CMC-CP = 230.12 mg/g) compared to the CP membrane (As3+/CP = 89.02 mg/g and Cr3+/CP = 75.61 mg/g). The heavy metal/CMC-CP complexes confirmed higher adsorption energies (As3+/CMC-CP = -23.62 kcal/mol and Cr3+/CMC-CP = -23.21 kcal/mol) than the heavy metal/CP complexes (As3+/CP = -3.47 kcal/mol and Cr3+/CP = -2.92 kcal/mol). The electronic band structure was higher for CMC-CP (5.42 eV) compared to CP (4.43 eV). Experimental and theoretical findings were close, implying that the CMC-CP membrane has superior heavy metal adsorption capability than the CP membrane.

Chitin and derivative chitosan-based structures - Preparation strategies aided by deep eutectic solvents: A review.

The high molecular weight of chitin, as a biopolymer, challenges its extraction due to its insolubility in the solvents. Also, chitosan, as the N-deacetylated form of chitin, can be employed as a primary material for different industries. The low mechanical stability and poor plasticity of chitosan films, as a result of incompatible interaction between chitosan and the used solvent, have limited its industrialization. Deep eutectic solvents (DESs), as novel solvents, can solve the extraction difficulties of chitin, and the low mechanical stability and weak plasticity of chitosan films. Also, DESs can be considered for the different chitosan and chitin productions, including chitin nanocrystal and nanofiber, N,N,N-trimethyl-chitosan, chitosan-based imprinted structures, and DES-chitosan-based beads and monoliths. This review aims to focus on the preparation and characterization (chemistry and morphology) of DES-chitin-based and DES-chitosan-based structures to understand the influence of the incorporation of DESs into the chitin and chitosan structure.

Multivariate data-based optimization of membrane adsorption process for wastewater treatment: Multi-layer perceptron adaptive neural network versus adaptive neural fuzzy inference system.

Application of machine-learning methods to assess the batch adsorption of malachite green (MG) dye on chitosan/polyvinyl alcohol/zeolite imidazolate frameworks membrane adsorbents (CPZ) was investigated in this study. Our previous research results proved the suitability of the CPZ membranes for wastewater decoloring. In the current work, the residence time was combined with the other operational variables i.e., pH, initial dye concentration, and adsorbent dose (AD), to obtain the possible interactions involved in nonequilibrium adsorption. Two well-known soft-computing approaches, multi-layer perceptron adaptive neural network (MLP-ANN) and adaptive neural fuzzy inference system (ANFIS), were selected among different machine learning alternatives and then, comprehensively compared with each other considering reliability and accuracy for a 60 number of runs. The ANFIS structure with nine centers of clusters could predict the adsorption performance better than the ANN approach. Root mean square error (RMSE) and R-square were obtained 0.01822 and 0.9958 for the test data, respectively. The interpretability test resulted a linear trend predicted by the model and disclosed that the maximum value of the removal efficiency (99.5%) could be obtained when the amount of the inputs set to the upper limit. Lastly, the sensitivity analysis uncovered that the residence time has a decisive effect (relevancy factor > 80%) on the removal efficiency. According to the results, ANFIS is an effective and reliable tool to optimize and intensify the membrane adsorption process.

Nanofiltration of dye solution using chitosan/poly(vinyl alcohol)/ZIF-8 thin film composite adsorptive membranes with PVDF membrane beneath as support.

Nanobiocomposite adsorptive membranes were engineered by integrating metal-organic frameworks (ZIF-8), into the chitosan/poly(vinyl alcohol) blend and coating the blend on PVDF membrane support for an enhanced separation performance. The membranes were characterized by SEM, AFM, BET, XRD, ATR-FTIR and tensile stress analyses. The central composite design was utilized to optimize the water flux and dye rejection. Using CCD, the effect of the membrane thickness, PEG (pore-former), and chitosan content on the flux and rejection were studied. The optimal conditions were obtained as; 10 wt% PEG, 3 wt% chitosan, and 200 µm membrane thickness. The optimized flux and rejection were obtained 78.94 L m-2 h-1 and 90.3 %, respectively. The antifouling of the membranes was also examined by the filtration of BSA protein solution. The membranes showed comparable performance; however, extremely higher permeability (78.94 L m-2 h-1 bar -1) compared to similar TFC membranes that guarantee the economic favorability of the filtration process.