SOUTHERN JOURNAL OF SCIENCES

Background: Industrial wastewater contains pollutants that are detrimental to human health in varied proportions. Among the pollutants are heavy metals, including Zn2+, Pb2+, and Cu2+ found in a characterized pharmaceutical wastewater. Several techniques have been proposed for the heavy metal sequester. However, they are with attendant challenges. The adsorption techniques using clay-metal oxide modified adsorbent/composite such as silver-clay adsorbent is considered suitable for an effective sequestering process. Aims: To develop and characterize Ag/clay adsorbent for pharmaceutical wastewater treatment. Methods: The Ag nanoparticles were synthesized using Parkia biglobossa aqueous leaves extract in an optimization study. The raw clay was beneficiated and doped with silver nanoparticles via the wet impregnation method. The silver-clay adsorbent was characterized using FTIR, XRD, SEM, and EDS characterization tools. The developed adsorbent was used for the batch adsorption process of the heavy metal ion removal from the wastewater. Results and Discussion: The phytochemical analysis and FTIR results of the P. biglobosa showed that the leaf contains phenol, tannin, and flavonoids which acts as reducing, capping, and stabilizing agent required for synthesizing the silver nanoparticles. The prepared silver nanoparticles modified clay adsorbent Ag/clay, have evenly distributed stacks of pseudo-hexagonal plates, are rich in silica, possess silver nanoparticles in the frameworks, and contain functional groups suitable for binding heavy metals. The adsorptions of Zn2+, Pb2+, and Cu2+ from pharmaceutical wastewater onto the silver-modified clay were studied as a function of adsorbent dosage and contact time. The percentage removal results obtained showed that the adsorbent had up to 99.96%, 99.5%, and 99.44% removal efficiency for Zn2+, Pb2+, and Cu2+, respectively, which are better compared with previous studies. The adsorption process was feasible, spontaneous, and exothermic, with Langmuir and Pseudo-second-order models as best fits for the process. Conclusions: The adsorption of selected heavy metal ions onto the green synthesized silver-modified clay adsorbent (Ag/clay) was feasible, spontaneous, and exothermic in the order Zn2+>Pb2+>Cu2+ with Langmuir and Pseudo-second-order model best fitted for the process. These show that the synthesized silver oxide nanoparticles supported on local clay can be used as a potentially low-cost adsorbent to remove heavy metal ions from industrial wastewater.

Biomass is the term attributed to any renewable resource derived from organic matter that can be used in energy production. Agricultural production generates residues that are of great importance for their energy use, of which sugar cane, eucalyptus, and rice. Various residues are generated from rice cultivation, among which the rice husk and rice straw are the most important. Several thermal conversion technologies have been developed for the use of biomass in industry. Pyrolysis has been notable for its ability to produce biofuels at different stages of aggregation. The slow pyrolysis of biomass has been proposed as a pretreatment method to improve the physical-chemical characteristics of rice straw. In this process is produced, mainly, a solid called biochar, which has a higher energy content when compared to the biomass of origin. This study investigated the slow pyrolysis of rice straw at 300 - 700°C for the purpose of obtaining biochar, bio-oil, and gases for energy purposes. The experimental results show that pyrolysis temperature has important roles in yield product. The highest biochar yield was observed at a temperature of 300°C with 49.91 wt%. This represents 47% more when compared to yield at 700°C (33.87 wt.%). This behavior is linked to the proximate analysis results for fixed carbon 26.01 wt.% at 300°C. The high pH of the biochar was attributed to the presence of alkali metals, according to XRF. Thermal decomposition of the biomass resulting in a gradual increase of bio-oil (16.81 - 34.70 wt.%) and gas (6.53 - 18.05 wt.%) on a wet basis. Thus, in the dry base parameter, the bio-oil increases from 19.22 - 30.6 wt.% and the gases at 9.42-20.19 wt.%. Drying of the raw material showed, by the results, a significant increase in the co-products.

Background: The Second Southern Science Conference (SSCON 2024) represents a significant milestone in international scientific collaboration, bringing together researchers from twelve nations across multiple continents. The conference, held in Mendoza, Argentina, and co-hosted by the University of Vassouras in Brazil, marked both the 64th anniversary of Universidad de Mendoza and the 20th anniversary of Periódico Tchê Química, demonstrating the growing importance of cross-border academic partnerships. Aim: This study aimed to document and analyze the outcomes and impact of the Second Southern Science Conference, focusing on participation metrics, collaborative patterns, and institutional contributions while highlighting the significance of the hybrid format in facilitating global scientific dialogue. Methods: The analysis involved quantitative assessment of conference participation metrics, including the number of approved papers, author distributions, and institutional representation. The study examined participation patterns across countries and institutions, analyzing collaboration trends through statistical data visualization and comparative analysis of submission rates. Results: The conference achieved significant participation metrics with 65 approved papers and 242 contributing authors, averaging 4 authors per paper. The Universidad Nacional de Córdoba emerged as the leading institution, showcasing its 4 centuries legacy of academic excellence. The analysis revealed strong representation from Latin American institutions, with Brazil and Argentina leading in submissions. Most papers involved 2-5 collaborators, indicating effective research collaboration patterns. Over 500 people participated in the event through both in-person and virtual attendance options. Discussion: The hybrid format successfully facilitated broader international participation and knowledge exchange, which is particularly beneficial for addressing contemporary global challenges. The strong showing from Latin American institutions highlights the region's growing influence in international scientific discourse. The conference's interdisciplinary nature fostered new collaborative initiatives and research partnerships. Conclusions: The conference demonstrated the effectiveness of hybrid international scientific events in fostering global collaboration and knowledge exchange. Areas for improvement were identified, including extended submission timelines and establishment of a permanent management committee. The success of this edition supports the planning of future iterations, with the next edition scheduled to be held in Vassouras, Rio de Janeiro.