The present work investigates the use of Agave americana fibers (AGF) as a precursor for activated carbon (AC) preparation via chemical activation using phosphoric acid (H₃PO₄), and the study of the influence of the preparation conditions on the adsorption capacity of the prepared AC toward Alpacide Yellow (AY). The preparation experiments have been conducted at different impregnation ratios: acid/AGF (20 g/1 g, 30 g/1 g, and 40 g/1 g) with varied impregnation times (2 h, 4 h, and 6 h) and at different carbonization temperatures (200 °C, 400 °C, and 600 °C). The impregnation ratio of 40 g/1 g, the impregnation time of 6 h, and the carbonization temperature of 400 °C were selected as the optimal conditions for the preparation of AC with enhanced properties. Despite its low specific surface area (25 m²/g), the prepared AC showed a higher adsorption capacity toward AY (5.71 mg/g) as compared with that of the commercial activated carbon (CC) (5.27 mg/g) which showed a higher specific surface area (825 m²/g). This could be due to the existence of pores and functional groups on the surface of AC, as evidenced by the analysis results of FTIR, DSC, and SEM. The adsorption process was found fast and fractal since it followed the kinetic model of the Brouers-Sotolongo fractal (BSf) (R² = 0.999), while the mathematical modeling of the adsorption isotherm of AY on the synthesized AC was stochastic since it followed the General Brouers-Sotolongo (GBS) (R² = 0.999).

Air pollutant concentration of Trivandrum, the capital of Kerala, exceeded the limits of National Ambient Air Quality (NAAQ) standards, according to a study conducted in 2015 by NATPAC. These polluted corridors harbour vegetation on roadsides and traffic islands, planted solely for aesthetic appeal. Analysis of air pollution tolerance levels of existing plants can act as a scientific basis for efficient planning of the urban landscape. Sixty-seven species, including flowering, fruit-bearing, ornamental, shade-providing and timber-yielding species, were screened for their relative resistance to air pollution. Based on leaf pH, relative water content, chlorophyll and ascorbic acid levels, the Air Pollution Tolerance Indices (APTI) of each species were formulated and they were grouped into the following: tolerant, moderately tolerant, intermediate and sensitive groups. Agave americana (18.40), Cassia roxburghii (17.63), Anacardium occidentale (11.97), Cassia fistula (11.60), Mangifera indica (11.59) and Saraca asoca (10.88) may be considered for planting near green spaces like roundabouts and near pollution prone industrial areas, as they belong to tolerant category. Comparison of APTI during summer and monsoon also revealed the stability of Agave americana, Saraca asoca, Ficus benghalensis, Peltophorum pterocarpum, Ficus elastica, Ixora finlaysoniana, Mangifera indica, Canna indica and Delonix regia in maintaining pollution tolerance even during water disparity. Agave americana, Anacardium occidentale, Ficus elastica, Mangifera indica, Syzygium cumini, Ficus benghalensis, Nerium oleander and Ficus benjamina were found to be suited for mass planting, as was evident from their Anticipated Performance Indices (API).

The main objective of the present study is to introduce a new and ecologically safe method for managing the rice weevil, Sitophilus oryzae. Therefore, the Agave americana leaf extract’s phytochemical profile, and its insecticidal activity against the adults of S. oryzae were evaluated. The A. americana leaf extract was screened for the following phytochemicals: total phenolics (14.70 ± 0.31 mg GAE/g FW), total flavonoids (5.15 ± 0.18 mg RE/g FW) and saponins (10.32 ± 0.20 mg OAE/g FW). The HPLC-ESI/TOF-MS analysis results revealed that flavonoid glycosides (kaempferol, quercetin, and isorhamnetin derivates) were the major phenolic compounds of the A. americana leaf extract. In addition, the GC-MS analysis identified n-alkanes (77.77%) as significant compounds of the lipophilic fraction from the leaf extract. Moreover, the insecticidal potential was assessed through contact and repellent bioassays towards the rice weevil adults. The LD₅₀, LC₅₀, and RC₅₀ values were 10.55 μg/insect, 8.99 μg/cm², and 0.055 μg/cm² for topical application method, treated filter-paper method, and repellent bioassay, respectively. Furthermore, the A. americana leaf extract inhibited digestive enzyme activities, and median inhibition concentrations IC₅₀ were evaluated to be 146.06 ± 1.74 and 86.18 ± 1.08 μg/mL for α-amylase and protease, respectively. Overall, our results highlighted the promising potential of the leaf extract against S. oryzae adults, allowing us to recommend the extract under investigation as an ecofriendly alternative to synthetic insecticides.