Van-Han Dang

Transforming agricultural residues into high-value engineering carbon aerogels provides a sustainable strategy for mitigating the environmental burden arising from improper disposal of these wastes. A viable strategy for producing adsorbent materials for wastewater treatment is directly converting biomass into carbon aerogel. This study has successfully produced three-dimensional carbon aerogel (CA-900) from durian rind using a hydrothermal and pyrolysis procedure followed by CO ₂ activation at 900 °C. In addition, the ACA-900 exhibited a remarkable adsorption for methylene blue dye (pH 6.88 at 30 °C) and followed a pseudo-second-order model (k ₂ = 0.766 g mg ⁻¹ min ⁻¹ following the chemisorption mechanism. At the same initial concentration (25 ppm), the ACA-900 adsorbs methylene blue rapidly at an equilibrium adsorption capacity of 24.84 mg g ⁻¹ in only 15 minutes, while it takes the CA-900 more than 120 minutes to reach equilibrium at 17.18 mg g ⁻¹ . The results indicate a viable, sustainable pathway to valorize abundant biowaste into a multifunctional adsorbent material via a nontoxic, environmentally benign fabrication process.

Urea production plays a crucial part in the worldwide agricultural economy, providing a primary supply of nitrogen for fertilizers. For storage and transport, urea is synthesized in granular form, and the prilling technology is frequently employed. In this technique, the hot liquid feed passes through an atomizer to produce small droplets, which then fall along the high tower. During the falling process, the liquid droplets gradually become solid because the internal energy is removed by the cooling air, which flows upward from the bottom. Typically, three consecutive thermal phases are analyzed for the solidification process: the liquid droplet cooling, solidification when the surface reaches freezing point, and the solid particle cooling. In this paper, the temperature distribution across the radius of the urea particles was analyzed using a heat transfer equation, which is considered a two-phase Stefan problem. The system of partial differential equations is solved numerically using the finite difference method and the enthalpy method. The temperature of the cooling air at various heights of the tower and the degree of solidification of different particle sizes were estimated and compared with data obtained from the urea factory to assess their reliability. The validation demonstrated a strong correlation between the model estimates and the real plant observations.

The Soxhlet extraction of β-carotene from the fruit peel of Momordica cochinchinensis was modeled, yielding valuable insights into the kinetic parameters for operation and optimization.

Dye pollutants, mainly discharged from the textile industry, have caused severe risks to human health and the ecosystem because of their toxicity, non-biodegradability, and carcinogenicity. This study investigated the use of commercial biochar derived from melaleuca wood as an adsorbent for the removal of methylene blue (MB) using a packed-bed column. The selected biochar was characterized by nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy, and scanning electron microscopy. The experiments were performed to determine breakthrough curves (BTCs) with varying pH (3–9), inflow rate (5–20 mL min–1), bed height (16–65 cm), and initial MB concentration (0.75–9 mg L–1). The biochar (particle size of 1–2 mm) exhibited a low adsorption capacity for MB (~21 mg kg–1), resulting in a short breakthrough time. The Thomas, Bohart-Adams, Yoon-Nelson, and Bed Depth Service Time models were quite suitable for describing the experimental BTCs, with R2-values ranging from 0.92 to 0.98. The obtained BTCs were not in the typical S-shape, which characterizes diffusion-controlled adsorption. Therefore, a serial logistic-exponential model, which accounts for both the mass transfer and interaction contributions, was proposed. The experimental data effectively fit this proposed model, as indicated by high R2-values (>0.998). The dominant influence of mass transfer compared to interaction in controlling the adsorption rate of MB was highlighted.