In this study, material and energy losses were systematically assessed, together with a comprehensive economic and environmental evaluation, for an industrial expanded polystyrene (EPS) recycling process implemented under a circular economy framework at a company located in Medellín, Colombia. The system boundaries were clearly defined, and detailed mass and energy balances were performed using operational data collected over a six-month period. The process achieved a yield of 78.09 percent in the production of densified polystyrene from post-consumer EPS, with the main material losses attributed to solid residues and water losses during processing. The total energy consumption was 7350.34 kWh, of which 55.46 percent corresponded to energy losses, predominantly thermal losses associated with the EPS melting stage. Techno-economic evaluation indicated that the process is financially viable over a twelve-year operational horizon. Furthermore, the environmental assessment demonstrated a 68.44 percent reduction in carbon footprint, underscoring the strong potential of this recycling route as a sustainable and effective alternative for the management of recyclable solid waste.

In this study, graphene production via liquid-phase exfoliation assisted by sonication was evaluated using deionized water as a solvent and two graphite sources: one recovered from spent lithium-ion batteries (LIBs) and a commercial counterpart. A 750 W, 20 kHz ultrasonic processor was used, with sonication amplitudes ranging from 50% to 80% for two hours while maintaining a constant temperature of 45 °C. The resulting dispersions were left undisturbed for 24 h at ambient temperature to allow natural phase separation between decanted and dispersed fractions. These fractions were subsequently dried and weighed to determine exfoliation yield. High-quality graphene was successfully obtained via direct liquid-phase exfoliation of graphite recovered from LIBs, assisted by sonication in deionized water. Graphene formation was confirmed in both suspended and decanted fractions after two hours of sonication at 80% amplitude through complementary characterization techniques, including UV-Vis, Raman spectroscopy, HRTEM, and XRD. Comparative experiments using thermally pretreated battery graphite and commercial graphite revealed that graphene dispersions derived from untreated LIB-derived graphite exhibited greater long-term stability than those obtained from commercial or thermally pretreated battery graphite before sonication.

Benzaldehyde is a key intermediate in the fine chemical, pharmaceutical, fragrance, and agrochemical industries, and the development of efficient and sustainable synthetic routes remains a major research priority. This review critically examines the principal catalytic pathways reported for benzaldehyde production, with particular emphasis on the oxidation of benzyl alcohol and the partial oxidation of toluene. Reaction conditions, catalytic systems, and performance descriptors such as conversion and selectivity are systematically analyzed, highlighting the strengths and limitations of each approach. Special attention is given to the choice of oxidants, reaction phase, and operating temperature, as these factors strongly influence process efficiency and product distribution. From a sustainability perspective, conventional routes are compared with greener alternatives based on molecular oxygen or air, aiming to reduce energy consumption and the generation of hazardous by-products. The review further discusses current challenges associated with catalyst stability, overoxidation, and process scalability. It identifies the principal scientific gaps limiting the industrial implementation of heterogeneous catalytic systems and critically examines how catalyst design, synthesis methodologies, sustainable feedstocks, waste-derived materials, and techno-economic considerations can collectively contribute to scalable and environmentally responsible benzaldehyde production. Finally, future research directions are proposed to guide the development of highly selective, economically viable, and sustainable catalytic processes.

Se estudió la valoración integral de cáscara de naranja bajo un esquema de biorrefinería donde se obtiene aceite de naranja (con hidrolato como subproducto y valorización del aceite mediante la extracción de limoneno en etapas posteriores), pectina y harina para uso como suplemento en alimentación animal. El proceso consistió en cuatro etapas generales: i) extracción y obtención de aceite e hidrolato de naranja mediante el proceso de arrastre de vapor, ii) obtención de limoneno iii) extracción de pectina por medio de hidrólisis ácida, y iv) obtención de pienso a partir de procesos de centrifugado y secado. Los experimentos y caracterizaciones se realizaron a escala laboratorio, donde a partir de 700 g de cáscara (húmeda) se obtuvieron 3.34 mL de aceite (80-85% %), alrededor de 500 mL de hidrolato y cerca de 260 g de residuos sólidos (secos). De estos últimos, a partir de lotes de 50 g de material seco se obtuvo 9 g de pectina y alrededor de 40.3 g harina para suplemento en alimentación animal. Según el análisis técnico-económico para la escala de producción utilizada y para el contexto nacional colombiano, se logran indicadores positivos como el valor presente neto (7,215 USD) y la tasa interna de retorno (5.27%), que muestran la alternativa de inversión interesante como para ser considerada una opción de valoración de residuos por pequeños y medianos productores de cítricos en el país.

Se estudió la remoción de metales pesados (Zn, Ni, Fe, Cu y Cr) en aguas residuales no domésticas (ARnD) reales de la industria de galvanoplastia (Medellín, Colombia) en un sistema discontinuo usando biomasa de cáscara (BCB) y pseudotallo de banano (BPT) obtenidos mediante procesos físicos simples. Los resultados fueron comparados con un carbón activado comercial (CAC). Los adsorbentes fueron caracterizados a través de FTIR, BET, Punto isoeléctrico, Boehm y DRX, mostrando poca variación hacia los materiales BCB y BPT en términos de composición química, morfología y estructura. También se determinaron las propiedades fisicoquímicas del ARnD previamente al tratamiento de adsorción encontrando una concentración inicial de 18,73 mg/L, 10,1 mg/L, 11,2 mg/L, 36,7 mg/L y 0,44 mg/L por espectrofotometría de absorción atómica para el Zn, Ni, Fe, Cu y Cr, respectivamente. Estos valores se compararon con la normatividad Colombiana la Resolución 0631 de 2015, donde se evidenció que sobrepasan los límites máximos permisibles establecidos. Las pruebas de adsorción se llevaron a cabo a temperatura ambiente, pH de 3,65 y 200 rpm variando la cantidad de adsorbente (1 - 5 mg) para un tiempo de 2 h. Los porcentajes máximos de remoción fueron de 42,69 %, 83,10 %, 95,17 %, 81,90 % y 99,82 % para Fe, Ni, Fe, Cu, Zn y Cr, respectivamente. Se observa que los valores alcanzados con los bioadsorbentes son similares al carbón comercial, lo que sugiere que los residuos de banano podrían ser una alternativa de bajo costo para el tratamiento de este tipo de efluentes.

Spent lithium-ion battery (LIB) cathodes were investigated as a multimetallic resource for catalyst precursor synthesis. Cathode material was leached under ultrasound using citric or sulfuric acid, with and without H₂O₂, to compare metal recovery, stability, and thermal transformation. Sulfuric acid with H₂O₂ achieved the highest extraction efficiencies, with 93.10% Co and 97.15% Mn, while Li extraction exceeded 95%. Maximum sulfuric concentrations were 12,822 mg L⁻¹ Co, 4588 mg L⁻¹ Mn, 185 mg L⁻¹ Ni, and 659 mg L⁻¹ Li. Initial citrate solution without H₂O₂ contained 25,870.90 mg L⁻¹ Co, 15,121.95 mg L⁻¹ Mn, 4118.14 mg L⁻¹ Li, 965.79 mg L⁻¹ Al, 162.74 mg L⁻¹ Cu, and 12.69 mg L⁻¹ Ni. Both liquors precipitated. The citrate system exhibited metal–citrate coordination, whereas the sulfuric system retained hydrated sulfate and aquo/sulfate species. After drying, the citrate precursor formed a carbon- and oxygen-rich matrix, while the sulfate precursor retained sulfur and oxygen at 400 °C. Citrate decomposition occurred at 200–400 °C, while sulfate transformation extended to approximately 612 °C. Reduction occurred at 400–900 °C for citrate and predominantly at 800–900 °C for sulfate. Both routes provide complementary precursor platforms for catalyst preparation; however, catalytic performance was not evaluated in this study and remains to be demonstrated.