SOUTHERN JOURNAL OF SCIENCES

Background: This study explores the potential use of biomass residues from soybean pressing via static pyrolysis to produce carbonaceous materials for pesticide adsorption. It emphasizes concerns regarding the environmental impact of agroindustrial waste and the persistent nature of pesticides in soil and water systems. Aims: To investigate the efficacy of biochar obtained from soybean waste in adsorbing pesticides. Specifically, to analyze the gas products generated during pyrolysis and characterize the obtained carbonaceous material for its adsorption capabilities. Methods: Soybean residue underwent static pyrolysis at various temperatures and durations. Gas analysis utilizing FTIR spectroscopy identified the gaseous products generated during the pyrolysis process. The obtained biochar underwent successive washes and characterization through FTIR spectra comparison with commercial activated carbon. Through absorption assays, using UV-VIS spectroscopy, investigations were conducted on the solid biocarbon fractions to evaluate their capacity for absorbing pesticides. Results: Gas Analysis: The study revealed the production of volatile organic compounds (VOCs) and highlighted the prevalence of mono-carbon compounds with increased temperature and pyrolysis time. The analysis demonstrated consistent carbon mass percentages across different reaction conditions. Characterization of Biochar: Comparison with activated carbon indicated structural similarities with heightened intensity in certain bands, suggesting the presence of incomplete cellulose cracking in the obtained biochar. Regarding the Chlorothalonil, Atrazine and DIcamba remotion, notably, the concentration of Chlorothalonil in a 7:3 water: acetonitrile solution decreases by 77 % through adsorption on the carbons. Discussion: The investigation examined the adsorption efficiency of the biochar for Chlorothalonil, Atrazine, and Dicamba from aqueous solutions. Chlorothalonil exhibited substantial retention by the biochar, while Atrazine showed comparatively lower adsorption effectiveness. Remarkably, Dicamba did not demonstrate retention by either the biochar or activated carbon. Conclusion: The study underscores the potential of pyrolyzed soybean waste for pesticide adsorption, particularly highlighting Chlorothalonil's strong affinity with the carbonaceous structure. Further research is needed to optimize adsorption properties and explores potential enhancements of these materials through additional treatment methods, offering promising avenues for environmental remediation.

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.

Background: MQ-series gas sensors belong to the metal oxide semiconductor (MOS) family of sensors that can sense the presence of many gases. These sensors find their application in gas alarm systems as key components. While necessary sensor circuit output voltage value for alarm point in a stand-alone gas alarm system is desirable, but what exact combination of the sensor circuit parameters is required? Hitherto, the determination of these circuit parameters has not been given much attention in the research community. Aim: the purpose of this work is to explore a structured graphical approach of determination of MQ series gas sensor circuit parameters for a stand-alone gas alarm system that yields desired sensor circuit output voltage value for the alarm point; the main objective of the study was to develop mathematical model equations that relate the: (i) sensor resistance (RS) with the gas concentration (x) and the sensor resistance at standard calibration concentration of the sensor base gas in the clean air (Ro) and (ii) sensor circuit output voltage (VRL), load resistance (RL) and sensor resistance (RS). It is expected from the model equations developed that graphical correlations of the sensor circuits parameters will be generated. Using these graphs for a particular case of an MQ-4 gas sensor under the influence of LPG, the parameters that yield desired sensor circuit output voltage of 2V for 1000 ppm of LPG alarm point will be determined. Methods: Model equations were developed for the sensor dynamics, and based on these model equations, graphs for the determination of required sensor parameters were plotted for a case of MQ-4 gas sensor response to LPG. Results and Discussion: The results yielded optimal values for R_O,R_S and R_L of 20 kΩ, 30 kΩ and 20 kΩ respectively, for alarm settings of 1000 ppm and a desired sensor circuit output voltage of 2 V. Based on determined parameters, the calibration equation for determination of best concentration value for a given value of emulated LPG concentration was developed. Using the method proposed in this study makes the process of determining the MQ-series gas sensor circuit parameters less cumbersome as their value can easily be obtained from the resulting graphs. Conclusions: a structured graphical approach for determination of MQ-series gas sensor circuit parameters for alarm points in a stand-alone gas alarm system showed that using MQ-4 gas sensor and LPG as the target gas, and for a sensor circuit output voltage of 2 V for alarm point at 1000 ppm of LPG, the corresponding value of R_O, R_S and R_L obtained were 20 kΩ, 30 kΩ, and 20 kΩ respectively. Hence, a structured graphical approach is suitable for determining MQ series gas sensor circuit parameters for a stand-alone gas alarm system under the influence of its associated gases.