The occurrence of organic micropollutants such as pharmaceutical drugs and hormones in environmental matrices reflects the inefficiency of traditional wastewater treatment technologies. Biosorption is a promising alternative from a technical-economic point of view, yet understanding the mechanisms of adsorption in new biosorbents is vital for application and process optimization. Within this context, this study aims to evaluate the mechanisms of adsorption and removal of synthetic and natural hormones in Pinus elliotti bark biosorbent (PS) compared to commercial granular activated carbon (GAC) through kinetic models, isotherm models, and thermodynamic models. The adsorbents were also characterized by morphology, chemical composition, functional groups, and point of zero charges. Characterization of the adsorbents highlights the heterogeneous and fibrous morphology and broader range of functional groups found for PS. Kinetic adjustments showed high accuracy for pseudo-second-order, Elovich, and intraparticle diffusion models, presenting multilinearity and evidencing multi-stage adsorption. PS's isotherms followed high-affinity models, predominating chemosorption, while GAC's followed Langmuir model, where physisorption predominates. These mechanisms were confirmed by thermodynamic models, which also indicated a higher dependence on temperature in the adsorption. In the fortified water removal test, PS showed removal values higher than GAC, highlighting the advantages attributed to the characteristics of this adsorbent.

Allelopathic effect of Azadirachta indica fresh leaves on the germination of native plants in the Seasonally Dry Tropical ForestEfeito alelopático das folhas frescas de Azadirachta indica na germinação de plantas nativas de floresta tropical sazonalmente seca

We tested the hypothesis that of the species studied in the Brazilian Semiarid, the ones most functionally similar to tree Azadirachta indicawould be more affected by this exotic species during germination and early development. At first, we produced a crude extract of A. indica fresh leaves in six different dilutions. We placed 25 seeds of four native species ( Cenostigma pyramidale, Libidibia ferrea, Mimosa caesalpiniifolia, and Amburana cearensis) to germinate in Petri dishes for each dilution, with four replicates for each species. We assessed: radicle length, emergence percentage, emergence speed index, and mean emergence time. We conducted an experiment in a greenhouse to assess how the exotic plant affected the development of individual plants of the studied species. We planted five seeds of each native species alone and five in interaction with the exotic species using ten 20-l buckets. The experiment lasted four months, and the functional attributes of the individuals were collected. Among the native species analyzed, according to the cluster analysis using the functional attributes of the species planted alone, M. caesalpiniifolia, C. pyramidaleand L. ferreawere functionally more similar to the exotic species. In the germination experiment, the extract affected only root length, regardless of the functional similarity. We noticed that only M. caesalpiniifoliahad its early development strongly inhibited when planted in interaction with the exotic species. Although the functional similarity between the exotic and the native species did not influence germination, it negatively affected the development.

A disponibilidade de recursos como nutrientes e água desempenha um papel importante no desenvolvimento e sobrevivência de plantas jovens, principalmente na recuperação de áreas degradadas. As características do solo e as condições climáticas do semiárido brasileiro evidenciam a necessidade de irrigação constante para contrapor a dificuldade de armazenamento de água. Nesse sentido, o hidrogel é capaz de armazenar água e liberá-la aos poucos, podendo facilitar a recuperação de uma área sob processo de degradação. Diante disso, o objetivo deste trabalho foi avaliar a frequência de irrigação e o efeito do hidrogel no crescimento de plantas jovens na recuperação de área degradada no semiárido cearense. Para isso, 180 mudas de 8 espécies nativas da Caatinga foram distribuídas em nove parcelas e submetidas a aplicação de hidrogel com irrigação diária (T1), hidrogel com irrigação 3 vezes por semana (T2) e sem hidrogel com irrigação diária (T3), durante seis meses, com monitoramento contínuo quanto ao crescimento vertical, horizontal e à sobrevivência. A aplicação de hidrogel beneficiou o crescimento em altura e diâmetro, assim como área basal. Além disso, a taxa de sobrevivência de T1 e T2 foi maior, sendo as espécies pioneiras as mais beneficiadas. Dessa forma, a aplicação do hidrogel pode ser considerada uma estratégia eficiente quando se busca o desenvolvimento de espécies em áreas com limitações hídricas como a região semiárida; principalmente na recuperação de áreas, por proporcionar o crescimento e sobrevivência de espécies pioneiras e nativas, que irão proteger o solo de erosões e darão suporte para o desenvolvimento de outras de crescimento lento.