Vol. 3 No. 2 (2025): July

This paper provides a detailed review of nanoparticle biosynthesis, highlighting biological synthesis methods in comparison to physical and chemical approach. It addresses the shortcomings of existing techniques and explores potential advancements in this field. And, the applications of the nanoparticles prepared in a biological in the medical field, as well as studying its advantages and disadvantages, were highlighted. The paper review also provides a brief overview of nanoparticle applications, linking them to both the desired and achieved sizes through various synthesis methods.

Azo dyes are synthetic organic pollutants widely used in the textile, food, leather, and cosmetic industries. Effluents containing these dyes are often discharged into the aquatic environment without adequate treatment, causing serious pollution that is toxic, carcinogenic, and resistant to biological degradation. Among various effluent treatment methods, adsorption stands out as an efficient, simple, and economical technique. Biochar a porous solid resulting from biomass pyrolysis has been of great interest as a potential adsorbent due to its superior physical-chemical properties and abundant raw material availability. This article reviews recent developments in the utilization of biochar, both natural and modified, for adsorption of azo dyes from wastewater. It discusses the mechanism of interaction between biochar and dye, operational factors that affect efficiency, and various biochar modification strategies such as chemical activation, metal addition, composite formation, and the use of nano-biochar. Data from various literatures show that the adsorption capacity of biochar towards Rhodamine B and Congo Red can reach more than 1000 mg/g, especially after advanced modifications. Nonetheless, technical and economic challenges in the widespread application of biochar still need to be overcome. This article provides an in-depth insight into the potential and future direction of biochar development as a sustainable solution in the treatment of wastewater polluted with azo dyes.

Recent studies on plasma generated at atmospheric pressure have become increasingly significant, with researchers intensifying their focus on its practical applications, particularly in industrial and medical fields. DBD plasma has been utilized in this study to examine the mechanical properties of compound materials (PMM/HA) synthesized in the laboratory. The compressive strength results indicate a gradual increase in stress and Young’s modulus with increasing time before and after the plasma treatment, also hardness levels were found to have improved, before and after the plasma treatment (63.3, 71.3, 73, and 74.3) respectively. Either the bending test result increased post-impact, with a notable enhancement corresponding to extended time periods. DBD plasma had a much bigger effect on bending strength. The polymer and hydroxyapatite showed a rise from 63.31 MPa before impact to 74.4 MPa after 90 seconds. This shows that the samples’ mechanical properties get better with longer plasma exposure. Method A base material made of PMMA polymer was added to with a nanomaterial made of hydroxyapatite (HA) to make a bioceramics compound. We conducted hardness, bending, and tensile tests to investigate the influence of DBD
on the mechanical properties of nanocomposite materials. Nanosized materials (PMMA/HA) showed a big improvement in their properties after plasma treatment for three different lengths of time (30, 60, and 90 seconds). This shows that the samples’ mechanical properties get better with longer plasma exposure.

Cadmium iodide bulk- and nano-crystals are grown and doping defect and quantum-confinement effects in IR-induced optical susceptibility in the nanocrystals are investigated. Bulk-sized and intrinsic crystals are also investigated as of reference. The nanomaterials with various crystal sizes are pumped with an IR laser beam. This pump-probe experiment probes the doubledfrequency IR-induced second harmonic optical beam. The expression for the second harmonic intensity is obtained from the electric polarization of the nanomaterial process subjected to high intensity illumination. The second–order susceptibility is calculated from the experimentally measured data. The results show that a significant enhancement in the optical susceptibility is achieved in nanomaterials with moderately doping. The maximum second–order optical susceptibility is found to 0.65 pm/V. However, bulk and intrinsic crystals show no considerable second harmonic effect. A nonlinear transmittance measurement for the determination of the second-order contribution in absorption supports the effect.

This study investigates the transformation of Eucheuma cottonii (EC) into a highly efficient adsorbent through hydrothermal carbonization at 200°C, resulting in hydrochar (HC-200). The FT-IR analysis reveals significant structural changes, including reduced intensity of oxygenated functional groups such as carbonyl and hydroxyl, alongside increased aromaticity, contributing to enhanced hydrophobicity and structural stability. These alterations render HC-200 well-suited for adsorption applications. BET analysis highlights a marked increase in the specific surface area and mesoporosity of HC-200 compared to EC, with hysteresis loops confirming enhanced adsorption capacity. SEM imaging shows substantial morphological changes, including rougher surfaces, increased porosity, and the presence of spheroidal structures, indicative of successful carbonization and improved diffusivity. Adsorption studies underline HC-200's superior performance in anionic dye removal, with a maximum adsorption capacity 37.894 mg/g. pHpzc analysis demonstrates more acidic surface characteristics, which favor adsorption in acidic conditions. Adsorption kinetics align predominantly with the pseudo-second-order model, indicating chemisorption as the dominant mechanism. The regeneration study shows HC-200's excellent reusability, maintaining significant adsorption efficiency over seven cycles, whereas EC experiences a steep decline in performance.