Renowned for its versatility in environmental applications, biochar exhibits substantial potential to enhance anaerobic digestion, facilitate carbon sequestration, and improve water treatment through its highly efficient adsorption mechanisms. This study focuses on biochar derived from pineapple crown biomass, produced through slow pyrolysis, and its efficiency in removing organic dyes from contaminated water. The structural, morphological, and surface properties of both biochar and chemically activated biochar samples were comprehensively characterized using a range of techniques, including XRD, FTIR, XPS, BET surface area analysis, and SEM microscopy. The adsorption performance was evaluated using methylene blue (MB), rhodamine B (RhB), and malachite green (MG) dyes as model contaminants, with particular emphasis on the contact time on dye removal efficiency. Initial results showed removal rates of 10.8%, 37.5%, and 88.4% for RhB, MB, and MG, respectively. Notably, chemical activation significantly enhanced the adsorption efficiency, achieving complete (100%) removal of all tested dyes. Complete adsorption of MB and MG occurred within 9 min, indicating rapid adsorption kinetics. Adsorption data fit well with pseudo-second-order kinetics (R² = 0.9748–0.9999), and the Langmuir isotherm (R² = 0.9770–0.9998) suggested monolayer adsorption with chemical interactions between dyes and biochar. The intraparticle diffusion model further clarified the adsorption mechanisms. These findings demonstrate the efficacy of activated biochar for dye removal and highlight the potential of pineapple crown biomass in environmental remediation.

Banana is the most cultivated fruit plant in the world. It is produced in Latin America, Asia and Africa. India and China are the world’s largest banana producers, with almost 41% of the world’s production. This fruit reaches a total world production of 158.3 million tons per year. However, during their production cycle, the banana agroindustry produces large volumes of solid waste derived from overripe fruit. It contributes between 8–20 percent of the waste (around 100 kg of banana waste for every ton of banana produced). Therefore, the use of overripe banana waste represents a huge opportunity for bioenergy production. This work demonstrates that banana waste can be further used for power generation using a microbial fuel cell (MFC) coupled with anaerobic digestion (AD). First, the maximum methane production (MMP), methane production rate (MPR) and biochemical methane potential (BMP) were measured using an anaerobic batch bioreactor for 64 days of monitoring. Finally, the digestate generated from AD was used in the MFC to determine the polarization curve, maximum voltage, maximum power density (MPD), resistance and current. As a result, the AD generated an MMP of 320.3 mL, BMP of 373.3 mLCH₄/gVS and MPR of 18.6 mLCH₄/Lb⋅day. The MFC generated 286 mV (maximum voltage), 41.3 mW/m² (MPD), 580.99 Ω (resistance) and 0.0002867 A (current). Both processes together produced a total bioenergy of 13.38 kJ/gVS. This coupled system showed a suitable and promising use of banana waste for ecofriendly bioenergy generation. Therefore, this feedstock could be taken advantage of for generating sustainable processes and developing a circular economy in the banana agroindustry.

The transition toward sustainable synthesis routes plays a crucial role in advancing scalable and environmentally responsible photocatalytic materials. In this study, a green combustion synthesis of bismuth vanadate (BiVO₄) was developed, using orange peel powder (OPP) as both a renewable fuel and a multifunctional complexing agent. The incorporation of OPP eliminated the need for hazardous reagents and promoted waste valorization, aligning with the principles of green chemistry and the circular economy. Comprehensive structural, morphological, and optical characterizations were performed using XRD, Raman, XPS, FTIR, SEM/TEM, and UV–Vis spectroscopy. An increasing OPP content induced a phase transition from a mixed tetragonal-monoclinic system to a predominantly monoclinic BiVO₄ structure, which correlated with improved photocatalytic performance. Although the residual organic components of OPP were not explicitly identified, the data indicated enhanced crystallinity and the formation of oxygen vacancies. These vacancies contributed to bandgap narrowing (2.21 eV), improved charge separation, and reduced electron–hole recombination. The optimized BiVO₄ sample (N3-350) exhibited remarkable photocatalytic activity, achieving over 95% degradation of methylene blue and malachite green, and 80% of acid blue 113 under visible-light irradiation. Electrochemical measurements revealed an increase in charge carrier density and favorable band edge alignment, supporting efficient photocatalytic hydrogen evolution (163 μmol H₂ g⁻¹ h⁻¹) and CO₂ photoreduction to formic acid (46.9 μmol h⁻¹), all without the need for noble metal cocatalysts. This green synthesis approach for BiVO₄ demonstrates the effectiveness of biomass-derived materials in photocatalytic and environmental applications and provides a viable pathway for sustainable materials design.