Effectiveness of biochar as an adsorbent for pesticides: Systematic review and meta-analysis.

The use of pesticides is intense in agriculture and has caused contamination in water, air and soil. This fact led to the need to study strategies that can minimize the effects that these pesticides have caused to the environment. In this context, biochar appears, as a type of material that has the ability to remove chemical substances, and because they can be activated with different chemical agents, they are extremely effective in the adsorption of toxic substances. Therefore, the aim of the study was to evaluate the use of biochar as a bioadsorbent for pesticides. This is a systematic review with meta-analysis and meta-regression, as the PRISMA protocol recommendations. Studies from the last 20 years were included, with at least the abstract available and considering preferentially experimental studies. Qualitative studies or studies with high risk of bias, other reviews and duplicates were excluded. The variables analyzed were the presence of factors that prove the effectiveness or not of pesticide adsorption. Studies with a superficial approach or those that do not show positivity or negativity in relation to the outcome were excluded. The search was conducted on the sources: Scopus, Web of Science electronic databases, PubMed (of the US National Library of Medicine, National Institutes of Health) and ScienceDirect (Elsevier). For better investigative determination, the data were searched separately. The descriptors used for the search were the following: Agrochemicals AND Activated Carbon AND Adsorption. Initially, 2431 references were found, from which 14 were selected to compose the meta-analysis review. With the joint analysis of the data, it was possible to verify using the random model (since the studies assess different contexts) that there is a proportion of effectiveness of the intervention of 81% (with a 95% confidence interval), ranging from 75 to 88%, which is represented by the meta-analysis diamond that is the final result of the statistical analysis. Biochar is effective in removing impurities, even including features such as low cost. There is a considerable lack of studies on the topic of pesticide adsorption with the use of biochar. The studies approach a very heterogeneous perspective on the subject, exposing different contexts.

Adsorption of phosphate in aqueous solution by ash from the fruit peel of Caryocar coriaceum Wittm: adsorption characteristics and behavior.

High phosphate concentrations in natural waters are associated with eutrophication problems that negatively affect the fauna and flora of ecosystems. As an alternative solution to this problem, we evaluated the adsorptive capacity of the fruit peel ash (PPA) of Caryocar coriaceum Wittm and its efficiency in removing phosphate (PO43-) from aqueous solutions. PPA was produced under an oxidative atmosphere and calcinated at 500 °C. The XRF and EDS analyses of PPA after contact with an aqueous PO43- solution showed an increase in its PO43- content, thus confirming the adsorption of PO43-. The Elovich and Langmuir models are the ones fitting the kinetics and the equilibrium state of the process, respectively. The highest PO43- adsorption capacity was approximately 79.50 mg g-1 at 10 °C. PO43- adsorption by PPA is a spontaneous, favorable, and endothermic process involving structural changes. The highest removal efficiency was 97.08% using a 100 mg.L-1 PO43- solution. In sight of this, PPA has shown potential as an excellent natural bioadsorbent.

Impacts of the Residual Trace Metals of Aquaculture in Net Cages on the Quality of Sediment.

Anthropogenic pollution by trace metals in aquatic environments in semiarid zones is a critical area of investigation. The objective of this study was to investigate the concentration and spatial distribution of trace metals in surface sediments in the Rosário reservoir, which is affected by the intensive aquaculture of Tilápia-do-Nilo (Oreochromis niloticus). Sediment samples were collected in three different areas, postculture (PCTV), cultivation (CTV) and control (CTRL) in the dry season in 2019. The granulometric composition, organic matter and concentrations of Fe, Mn, Zn, Cu, Cr, Cd, Pb and Ni metals were determined. Multivariate statistics were used. Geochemical and ecotoxicological indices and a comparison with sediment quality guidelines (SQG) were used. The sediment was characterized by silty clay loam with an average organic matter of 18.76 ± 4.27. The analytical merit figures demonstrated accuracy (metal recoveries in certified standards) between 89 to 99% and high precision (RSD < 5%). The concentration ranges for the metals were Fe: 0.11-0.85 (%), Mn: 14.46-86.91, Zn: 2.6-220.56, Cu: 26.89-98.75, Cr: 60.18-76.06, Cd: 0.38-0.59, Pb: 18.13-43.13, and Ni: 34.4-46.75, all in (mg/kg-1). The highest concentration values were found in the CTV areas (Fe: 40 ± 0.22, Mn: 66.48 ± 19.11, Zn: 114.83 ± 59.75 and Cr: 70.85 ± 2.62) and PCTV (Cd: 0.53 ± 0.04, Cu: 71.83 ± 21.20, Pb: 33.71 ± 4.34 and Ni: 44.60 ± 1.79). Pearson's correlation, hierarchical cluster analysis and principal component analysis confirmed the influence of fish farming on metals. Only Ni presented concentration values higher than the reference value established in the SQG. Thus, considering the probable geochemical and ecotoxicological effects, they comprise the two lowest levels of impact.

Spectrofluorimetric analyzes of thiamine and riboflavin in monofloral honey varieties of africanized bees (Apis mellifera).

This research aimed to study the validation of a viable and low-cost spectrofluorimetric method, capable of detecting and quantifying B vitamins in floral varieties of bee honey. The analyzes were performed using chemical and operational methods of pre-defined solutions and standards, performed in triplicate and the results expressed as mean ± standard deviation. The data were recorded in a Microsoft Office Excel spreadsheet (version 2013) and studied using the statistical program Bioestatic version 3.0. The calibration curves of the vitamins showed the linearity and precision of the method. Subsequently, a descriptive analysis of the data was performed, being considered normal in the Lilliefors normality tests. Finally, the data were subjected to Pearson's correlation test, showing positive and strong correlations, with r (Pearson) ranging from 0.7619 to 1. Honey had positive results regarding the detection and quantification of vitamins B1 and B2 through the spectrofluorimetric method.