Chemical and Materials Sciences: Research Findings Vol. 7

Effect of Rhizoclonium grande-derived Saturated Fatty Acid Ethyl Esters on the Properties of Jatropha curcas Biodiesel Blends

J. M. Kahindo, C. Sumesh, R. Musau, J. O. Odalo, T. Thoruwa — Tue, 14 Apr 2026 00:00:00 +0000

Background: Although algal biodiesel has gained increasing attention as a renewable alternative, the role of algal-derived saturated fatty acid ethyl esters, especially from underexplored species such as Rhizoclonium grande in modifying the properties of commonly accepted biodiesel blends, remains less understood.

Aims: The effect of Rhizoclonium grande saturated fatty acid ethyl esters on physicochemical and fuel properties of Jatropha curcas biofuel was assessed.

Methodology: The study was conducted at the Technical University of Mombasa, Jomo Kenyatta University of Agriculture and Technology, Government Chemist, and Kenya Pipeline Laboratories in Mombasa, Kenya. A randomised block design with three blocks was employed, using Rhizoclonium grande and Jatropha curcas oils, their ethyl esters, and various blends. Probability and purposeful sampling methods were used to select samples, and each sample from a block was subjected to several treatments with three replications per treatment. Algae were collected from Shimoni in Kwale, Shelly beach, Jamvi la Wageni in Likoni and English Point in Mombasa to obtain algae oil. J. curcas seeds were collected from Shimba Hills, Kwale. Transesterification of J. curcas and Rhizoclonium grande oil was carried out separately, followed by GC-MS characterisation of the ethyl esters. Ethyl esters from J. curcas oils (JOFAEE) were blended with algae oil FAEE (5-25%) to obtain JAB1-JAB5. Physicochemical and fuel properties of JAB were assessed. Statistical analysis was done using STATA/SE 13.0 at 95% confidence level (P<0.05), two-tailed.

Results: Rhizoclonium grande produced 6.72 - 10.46 % v/w oil. From GC-MS analysis, the algae oil fatty acid esters contained pentadecanoic acid ethyl ester, dodecanoic acid ethyl ester, tetradecanoic acid ethyl ester and hexadecanoic acid ethyl ester. There was an observed significant difference in calorific value (P=0.03), kinematic viscosity (P=0.001), pour point (P=0.001) and cloud point (P=0.001) between JO FAEE and JAB samples, attributed to the presence of algae oil saturated FAEE. The JAB showed no significant difference in fuel properties with standard biodiesel B100 (P>0.05).

Conclusion: From the findings, the physicochemical and fuel properties of biofuel from J. curcas can be improved by the use of saturated FAEE from R. grande. This additive enables reliable engine performance and efficient combustion without any modification. Unlike common synthetic additives, R. grande esters are sustainable, renewable and quite compatible with infrastructure in existence. The approach is environmentally friendly, cost-effective, and reduces the need for other stabilisers, which simplifies storage and handling. Generally, this blend provides a scalable, practical strategy leveraging sustainable energy production for the advancement of biodiesel performance.

Membrane Protein Biomolecular Interactions Characterised by Microscale Thermophoresis

Tue, 14 Apr 2026 00:00:00 +0000

Microscale thermophoresis (MST) is a powerful immobilisation-free biophysical technique that is very useful for measuring biomolecular interactions with membrane proteins. MST is based on the physical phenomenon that particles move within temperature gradients, which is affected by their size, charge, hydration shell and conformation. This study aims to present an updated overview and practical application of MST as a biophysical technique for characterising membrane protein interactions. A fluorescent target molecule must be included in the sample to observe the movement of particles by MST. The intrinsic aromatic residues of membrane proteins can be used as the fluorophore for MST (label-free MST), or membrane proteins can be labelled with a range of fluorescent dyes or conjugated with fluorescent proteins (labelled MST). In the MST experiment, the membrane protein can be titrated with an unlabelled binding partner (e.g. other proteins, peptides, small molecules, ions) for quantifying interactions. MST is highly sensitive, using relatively small amounts of sample, and it has no limitations on the size of the target biomolecule, on the affinity of the interaction or on the composition of the buffer and other sample components. Membrane proteins can be characterised by MST in cell lysates, native membranes, solubilised in detergents, and reconstituted in lipids or other membrane mimetics. Different types of membrane proteins have had biomolecular interactions characterised by MST, including SARS-CoV-2 spike protein, GPCRs and other receptors, sensor kinases, ion channels, aquaporins and transport proteins. MST has great future potential in the drug discovery pipeline for medium- to high-throughput compound screening with membrane protein drug targets. This will be accelerated by technical developments in MST that enhance throughput, increase sensitivity and minimise interference.

Development and Validation of Micelle-Enhanced Spectrofluorimetric Method for Determination of Serotonin in Human Urine

Tue, 14 Apr 2026 00:00:00 +0000

Micelle-enhanced spectrofluorimetry has been successfully applied to detect various pharmaceutical and biological compounds. The present study describes the development and validation of a micelle-enhanced spectrofluorimetric method for the direct determination of serotonin in aqueous solutions and human urine. A micelle-enhanced spectrofluorimetric method was developed and validated for the direct determination of serotonin (5-hydroxytryptamine, 5-HT) in aqueous solutions and human urine. The effects of micellar media, pH, and surfactant concentration on fluorescence intensity were systematically investigated. Brij 700 (nonionic) and SDS (anionic) micelles significantly increased the fluorescence signal by providing a hydrophobic microenvironment that reduces solvent quenching and stabilises the excited state of 5-HT. The method exhibited excellent linearity over the 0.1–300 ng mL⁻¹ range, with low limits of detection (1.7–4.1 ng mL⁻¹) and quantification (3.3–13.5 ng mL⁻¹), high precision (RSD < 1.5 %), and reliable recoveries (89–101 %). The analytical performance was unaffected by endogenous urinary components, confirming good selectivity and robustness. Application to human urine samples using liquid–liquid or solid-phase extraction demonstrated accurate and reproducible quantification without the need for chromatographic separation. This approach provides a rapid, sensitive, and cost-effective alternative to conventional methods such as HPLC, highlighting the potential of micelle-enhanced spectrofluorimetry for clinical and bioanalytical monitoring of serotonin in complex biological matrices.

Effects of Solvent Polarity and Microenvironment on the Excited-State Dynamics and UV Photodegradation of Serotonin (5-Hydroxytryptamine)

Tue, 14 Apr 2026 00:00:00 +0000

Serotonin, like many small organic molecules, can undergo photochemical transformations under UV irradiation. Photodegradation of pharmaceuticals and biologically active compounds is an active research field due to concerns about drug stability under light exposure and the environmental fate of pharmaceutical residues in water systems. This study investigates the photophysical and photochemical behaviour of serotonin (5-HT) in various environments, including aqueous, organic, and micellar media. Using UV–vis absorption and fluorescence spectroscopy, key parameters such as dipole moments, Stokes shifts, and fluorescence lifetimes were determined. Solvatochromic analysis was performed with Lippert-Mataga, Bakhshiev, and related models, revealing significant intramolecular charge redistribution upon excitation (dipole moment increase to ~7.8 D). Photolysis kinetics were studied under controlled conditions, showing first- and second-order behaviours depending on the medium. Half-lives ranged from 24 s in aqueous pH 7 solutions to over 1900 s in micellar systems, illustrating enhanced photostability in hydrophobic microenvironments. The localisation of serotonin at the micelle–water interface was identified as a key factor governing its photochemical response. Quantitative data are summarised in tables for spectroscopic parameters, dipole moments, and kinetic constants, providing clarity and reproducibility. The findings offer insights into the influence of solvent polarity, pH, and micellar structures on serotonin’s stability and reactivity, with implications for neurochemistry, pharmacology, and photobiology. Overall, this comprehensive study demonstrates the utility of spectrofluorimetric methods in evaluating biomolecular photostability and provides a framework for designing safer drug formulations sensitive to light.

Expanded Perlite for Cadmium and Lead Removal from Synthetic Rainwater: Adsorption Performance and Fixed-Bed Column Design

Lola Domnina Pestaño, Eira Datul, Jinessa Mary Surot, Joshanne Mae Toledo — Tue, 14 Apr 2026 00:00:00 +0000

Utilising the abundant rainfall in the Philippines as an alternative source of clean water is possible due to the low concentration of contaminants in rainwater (RW). However, the presence of heavy metals such as lead and cadmium may pose serious health risks to the users. To address this issue, various low-cost adsorbents have been studied and applied for the removal of heavy metals from water. In this study, the performance of a low-cost natural mineral adsorbent called expanded perlite (EP) in removing heavy metals was investigated. EP properties such as morphological structure and surface functional groups present were determined using Scanning Electron Microscope (SEM) and Fourier Transform Infrared spectroscopy (FTIR), respectively. Batch adsorption studies of cadmium and lead were conducted under different EP dosages and contact times. Synthetic RW was prepared by diluting heavy metal stock solutions to 1 mg/L per metal. Analysis of results was done by developing Langmuir, Freundlich and Dubinin-Radushkevich (DR) isotherm models, and Lagergren’s pseudo-first order and Ho’s pseudo-second order kinetic models. A fixed-bed column was designed for the adsorption of Cd (II) and Pb (II) from rainwater. Analysis showed the adsorption of heavy metals fit better with the Freundlich and DR isotherm model than the Langmuir, suggesting the adsorption is multilayer and physisorption, and the pseudo-second order kinetic model. The removal efficiency of EP for Cd (II) and Pb (II) were 85.8042% and 50.843%, respectively. The adsorption capacity of Cd (II) and Pb (II) was 19.4630 mg/g and 2.9818 mg/g, respectively. The study indicated that EP is significantly effective in the adsorption of cadmium and lead ions in RW. An adsorption column was designed using the breakthrough curve evaluation of the Thomas Model and by using batch data gathered from the experiments. A fixed bed column was designed for the adsorption of Cd (II) and Pb (II) with a height of adsorbent medium of 16.75 m. Using EP, heavy metals such as cadmium and lead can be efficiently removed from rainwater, supporting safe water use at the household and community levels.

Characterisation of Oued Tfal Clay from the Region of Gafsa, Tunisia: Progressive Elimination of Carbonates

M. Mhamdi, N. Gasmi, E. Elaloui, N. Kbir-Ariguib, M. Trabelsi -Ayadi — Tue, 14 Apr 2026 00:00:00 +0000

Elimination of impurities from raw clay is a very important step. Purified clay has the highest adsorption capacity compared to other forms of raw clay. Purified clay is a versatile absorbent material that can be used in various applications to remove contaminants and impurities from liquids and gases. The major element (like silicon, aluminium, iron and sodium) compositions of OT raw and OTNa purified clay were determined by atomic absorption (spectrometry, Specta-SpanIII). The mineralogy was characterised by X-ray diffraction (Philips goniometer, PW1730/10, using the CuKa, 40KV, 40mA). The infrared spectra, obtained after using KBr pellets, were recorded with a Perkin Elmer 783 dispersive spectrometer from 4000 to 400 cm^-1.

The existence of calcium carbonate in raw clay is considered an impurity. In this paper, we have developed a new method for eliminating this impurity without affecting the structure of the clay. This work shows the results of various analyses on a representative clay sample from the southern west of Tunisia, particularly from Oued Tfal near the town of Gafsa.

Some carbonate, quartz, chlorite, and anorthite can be found in the raw smectite. The chemical composition and physical characteristics of the carbonate clay changed when it was attacked by a hydrochloric acid solution. These changes depend on several factors, including acid concentration, clay nature, and the acid-to-clay ratio. Although treatment to 0.5 M represents a total removal of carbonates, there are probably altered layers of the clay fraction. The result shows that for a treatment with acid solutions of concentrations below 0.5 M, there is a gradual removal of carbonate without protonation of the clay layers. The characterisation of the clay fraction shows that the sodium clay purified (OTNa) consists of a sodium montmorillonite smectite. The cation exchange capacity and the specific surface of OTNa measured using the method of methylene blue are equal to 82 meq/100g and 667 m²/g, respectively. The findings of this research have practical implications in various industries or sectors such as construction, ceramics, and environmental remediation, making the research very important for the scientific community.

Adsorption of Safranin Dye on Adsorbent Prepared from Desert Date Seed Coats

Buhari Magaji, Muhammad Mukhtar Sani — Tue, 14 Apr 2026 00:00:00 +0000

Desert date (Balanites aegyptiaca) is a plant species that is widely distributed in dry land areas of Africa and South Asia. Despite the increasing interest in low-cost adsorbents for wastewater treatment, there is limited information on the use of Balanites aegyptiaca seed coat–derived activated carbon for the removal of synthetic dyes such as safranin from aqueous solutions. This study evaluated activated carbon derived from Balanites aegyptiaca seed coats (BAAC) as a potential adsorbent for the removal of safranin dye from aqueous solutions. The research involved physico-chemical characterisation, as well as adsorption kinetics and isotherm studies. Seed coat samples were collected from Gombe Main Market, Gombe State, Nigeria. The prepared BAAC exhibited a percentage yield of 50%, pH of 6.1, moisture content of 16.3%, ash content of 10%, iodine number of 203.2 mg/g, and a surface area of 695 m²/g, indicating good adsorption potential. The FTIR spectroscopy revealed O-H, N-H, C-H, C=C, and C-O-H stretching vibrations. The influences of agitation time, initial dye concentration and adsorbent dose were studied in batch experiments at room temperature. The adsorptions were rapid in the first 15 minutes of agitation, with the uptake of 2.746 mg/kg. The adsorption equilibrium was achieved at 90 minutes of agitation. Kinetic studies showed a good correlation coefficient for both pseudo-first order and pseudo-second-order kinetics model but fitted well into pseudo-second order kinetic model. The adsorption data fitted well into the Langmuir isotherm with a correlation coefficient (R²) very close to unity and a Langmuir maximum adsorption constant, q_m> 1.00. Thus, the fitting into Langmuir indicates monolayer coverage on the adsorbents. Overall, the results demonstrate that BAAC is an effective and low-cost adsorbent with strong potential for application in the remediation of dye-contaminated wastewater. Future studies should investigate the performance of BAAC in continuous flow systems, its regeneration and reusability, and its efficiency in treating real industrial wastewater containing multiple contaminants.

Porous Organic Polymers in Environmental and Biomedical Applications: Toxicological Concerns and Sustainable Perspective

Varsha Rawat — Tue, 14 Apr 2026 00:00:00 +0000

Porous organic polymers (POPs) have gained significant attention as advanced functional materials due to their high surface area, tunable porosity, and remarkable chemical stability. These properties enable their extensive application in adsorption, catalysis, gas storage, environmental remediation, and emerging biomedical fields such as drug delivery and bioimaging. Despite their technological advantages, concerns regarding their environmental persistence, degradation behaviour, and potential toxicological impacts remain insufficiently explored. This chapter provides a comprehensive overview of the structural characteristics, synthesis strategies, and multifunctional applications of POPs, with a particular focus on their environmental and health-related implications. The degradation mechanisms of POPs, including hydrolytic, oxidative, and photolytic pathways, are critically discussed in relation to the formation of toxic byproducts and their ecological consequences, such as bioaccumulation and long-term exposure risks. Furthermore, the role of functionalization and structural diversity in influencing toxicity profiles is highlighted. Sustainable approaches, including green synthesis methods, biodegradable polymer frameworks, and recyclable systems, are emphasised as key strategies to reduce environmental burden. Also, the need for robust regulatory frameworks and standardised toxicity assessment models is addressed. This chapter aims to provide a balanced perspective to support the safe and sustainable development of POP-based technologies.