Fine Chemical Engineering

Adsorption of Methyl Red Using Agricultural Waste-Derived Adsorbents: A Case Study with Argan Nut Shells

2025-10-10T17:41:25+08:00

The effluents from textile and tannery industries contain high levels of synthetic dyes such as Methyl Red (MR), which represent a serious threat to aquatic ecosystems and human health due to their toxicity and persistence. To search for cost-effective and sustainable adsorbents derived from agricultural residues is therefore an urgent environmental priority. In this study, Argan Nut Shells (ANS), an abundant byproduct of argan oil production, were investigated as a low-cost adsorbent for MR removal. Adsorption performance was evaluated under different conditions, and results showed that 80 mg of ANS removed 53.5% of MR from 20 mL of solution. Although this efficiency appears modest, it remains competitive when compared with other natural adsorbents such as rice husk and coconut shells, particularly considering the economic and ecological value of valorizing argan residues. Kinetic modeling demonstrated that the adsorption process followed a pseudo-second-order model, with intraparticle diffusion not being the sole rate-limiting step, while equilibrium was reached after 80 minutes of contact. The Freundlich model, indicating a heterogeneous adsorption surface, best described the adsorption isotherms. Thermodynamic parameters revealed that the adsorption of methyl red onto ANS was spontaneous (ΔG° < 0) and exothermic (ΔH° < 0). The point of zero charge (pH_PZC) value was determined to be 3.68. Fourier-Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-Ray Spectroscopy (EDS) analyses confirmed surface modification after MR adsorption and provided insights into the interaction mechanism.

Drug Quantification by Simultaneous HPLC Analysis

2025-10-15T10:31:58+08:00

High-Performance Liquid Chromatography (HPLC) analysis has been commonly used to monitor (separate, identify, and quantify) potentially toxic compounds in the environment. In this context, a large amount of research has investigated the so-called Emerging Contaminants (ECs), which are new pollutants that, until a few years ago, were not detected or were considered to pose a low risk to the environment and were not regulated. In this work, in particular, the technique was employed for the simultaneous determination of three emerging pollutants: Paracetamol (PAR), Salicylic Acid (SA), and Acetylsalicylic Acid (ASA) in the sample matrix. To study the effect of a set of factors on the responses, a factorial design was used. The responses (chromatographic parameters) considered in the experimental design took into account asymmetry, tailing factor, and resolution. The following factors were investigated: buffer solution pH, mobile phase flow rate, and the proportion of buffer in this mobile phase. The results indicated that optimized control of mobile phase pH, facilitated by judicious use of buffer solutions, forms the basis for achieving optimal HPLC separations. In addition, tests were performed to assess the interference from the matrix in the analysis.

Crystallographic Structure and Density Functional Theory (DFT) Study of a Novel Crystalline Molecule, Diisopropylammonium Hydrogen Maleate

2025-10-10T15:11:02+08:00

Maleates are present in large amounts in foods and medicines. These are important pharmacophores in modern medicines because they can improve the physical and chemical properties of drugs, including their water solubility. Enhancing the physicochemical properties of new maleate-based compounds and enriching the literature largely depend on the synthesis method of multicomponent solid forms. In this research, we analyzed the synthesis, theoretical vibrational spectra, and geometric parameters of the diisopropylammonium hydrogen maleate molecule (iPr₂NH₂·OC-C₂H₂-CO₂H) using both experimental and theoretical methods. Parallel zigzag chains are formed through O-H···O and N-H···O hydrogen bonds between cations and the interconnected acidic anions HO₂C-C₂H₂-CO₂, as demonstrated by the crystallographic analysis of this compound. An experimental study was conducted to investigate the characteristics of a new crystal, assessing the applicability of various Density Functional Theory (DFT) methods and adjustments to describe its structural and spectroscopic properties. Using the DFT/M06-2X and DFT/B3LYP methods with the basis sets 6-31+G(d,p), 6-311G(d,p), 6-311++G(d,p), and 6-311++G(d), theoretical vibrational frequencies and geometric parameters (bond lengths and bond angles) were calculated for the first time. The calculated frequency values were corrected using an appropriate scaling factor to obtain Infrared (IR) spectra consistent with IR data from the literature. A good agreement was observed when the optimized geometric parameters were compared with the corresponding experimental data. The dipole moment, as well as the energies of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO), were also determined.

Efficient Removal of Florasulam, Metalaxyl, and Thiamethoxam Pesticides from Water Using Carboxymethyl Cellulose-Functionalized Magnetic Graphene Oxide Nanoparticles

2025-10-14T17:56:55+08:00

Magnetic Graphene Oxide Nanoparticles (MGO-NPs) and a series of Carboxymethyl Cellulose-functionalized Magnetic Graphene Oxide Nanoparticles (CMC-MGO-NPs) were prepared for application as adsorbents in pesticide removal. Three distinct CMC-MGO-NPs were prepared by varying the weight ratios of CMC to MGO-NPs (1 : 1, 3 : 1, and 5 : 1, w/w). The nanocomposites were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and zeta potential analysis, which confirmed their successful preparation. In addition, specific surface area and porosity were determined. These products were then evaluated for their efficiency in removing florasulam, metalaxyl, and thiamethoxam pesticides from aqueous solutions. Key operational parameters were optimized using a Plackett-Burman factorial design, which identified pesticide concentration, adsorbent dosage, temperature, pH, agitation time, and ionic strength as the most statistically significant factors affecting removal efficiency. Significantly, the CMC-MGO-NPs-2 demonstrated high maximum removal efficiencies of 93.82% for florasulam and 88.10% for metalaxyl, highlighting their strong affinity for these pesticides. However, a lower efficiency of 28.46% was observed for thiamethoxam, indicating selectivity in the adsorption process. In addition, the adsorption of pesticides onto CMC-MGO-NPs-2 was evaluated using various kinetic and isotherm models. These results underscore the potential of CMC-MGO-NPs-2 as a highly effective, low-cost, and magnetically separable adsorbent for the remediation of specific pesticides from wastewater.

Production of Automotive Primer Using Nano/Microparticles Obtained from Expanded Polystyrene Packaging Waste

2025-10-30T14:13:07+08:00

Polystyrene nano/microparticles obtained from post-consumer expanded polystyrene waste (WPS) were dissolved in toluene and incorporated into a commercial-grade automotive primer. The use of WPS situates the developed product within current sustainability and circular economy concepts. The main objective of this study was to develop an automotive primer containing 2 and 4 wt.% of nano/microparticles. For this purpose, WPS particles were dissolved in toluene and added to the primer, which was formulated with various compatibilizers and plasticizers. The resulting P03 primer exhibited chemical, rheological, mechanical, and morphological properties comparable to those of standard commercial primers, demonstrating that the addition of WPS-derived nano/microparticles does not compromise performance. This approach provides a promising recycling route for WPS, avoids secondary waste generation, and aligns with the principles of sustainable development and the circular economy.

A Simple and Scalable One-Pot Chemical Reduction and Functionalization of Reduced Graphene Oxide Films for Flexible Supercapacitor Applications

2025-09-29T15:42:08+08:00

This study presents a one-pot, low-cost, and scalable method for preparing chemically Reduced Graphene Oxide Films (RGOFs) doped with iodine groups for supercapacitor applications. The Graphene Oxide Film (GOF) was first fabricated via a simple solution-casting technique, followed by chemical reduction using Hydriodic acid (HI) as the reducing agent. The as-prepared GOF and RGOF were thoroughly characterized in terms of their electrical, mechanical, morphological, and structural properties using appropriate analytical techniques. Results indicate that GOF was successfully reduced and functionalized with iodine groups. When tested as supercapacitor electrodes, the films demonstrated nearly ideal capacitive characteristics, delivering a high specific capacitance of ~ 380 F·g^-1. Furthermore, they maintained good cyclic stability, preserving nearly 98% of their initial capacitance after 4,000 charge/discharge cycles. These promising results highlight the potential of these films as cost-effective and scalable candidates for next-generation high-performance flexible supercapacitors.