The behavior of composite beads of Zea mays rachis and sodium alginate (AL) for Pb (II) adsorption was studied. The Zea mays rachis–sodium alginate was prepared and characterized. The IR spectra showed interactions of the functional groups and the metal ions after adsorption. The kinetic data were fitted to the pseudo-first- and pseudo-second-order models, the maximum adsorption capacity was 60 mg/g for Pb (II), and the isotherm data were best adjusted to the Freundlich model, indicating that the adsorbent is heterogeneous. The thermodynamic study shows that the process is physisorption. The service time of columns increases as the height of columns increases, and this behavior was attributed to the active sites available in the columns. The initial concentration of Pb (II) had a significant effect on the breakthrough curves. As the concentration increases, the saturation time decreases. The material was regenerated four times (adsorption–desorption cycles), without a significant change in the removal efficiencies.

Acid hydrolysis was performed to produce reducing sugars from pineapple crown (PC), corn cob (CC), and rose stem (RS); the holocellulose contents of PC, CC, and RS were 69.36%, 70.17%, and 63.89%, respectively. The highest production of reducing sugars was obtained at 150 °C and 1.5 M sulfuric acid (H₂SO₄) for PC (46.04 g/100 g) and 2.0 M (H₂SO₄) (41.61 and 15.96 g/100g respectively) for CC and RS with a reaction time of 150 min. The Saeman equation adequately described the hydrolysis kinetics. The production of reduced sugars was the predominant reaction (k₁> k₂, k_r> 1) instead of decomposition for PC and CC, and that of RS was dominated by the decomposition. The E_a obtained from the Arrhenius equation showed that PC and CC (3.676 kJ/mol mean value from all concentrations used) are more easily hydrolyzable materials than RS (E_a=10.95 kJ/mol mean value). The trends in the thermodynamic parameters, ΔH, and ΔG, showed that hydrolysis is an endothermic and non-spontaneous process. The temperature had a greater influence on the production and decomposition of reducing sugars than did the concentration of H₂SO₄ for PC and CC.

The adsorption behaviour of Cu(II) was investigated in the presence of a new material. This material was obtained from chitosan (Ch) and polyvinyl alcohol (PVA) at different weight percentages (35/65, 50/50 and 65/35), dripping this mixture in a NaOH solution, and then subjecting to crosslinking reaction under nitrogen atmosphere at 353 K with ethylene glycol diglycidyl ether to improve its resistance to acids and alkalis. Adsorption test were conducted to evaluate the optimal Ch/PVA ratio, 35/65 ratio presented the best adsorption capacity. The interaction between Cu(II) and functional groups of Ch/PVA was determined by Fourier transformed infrared spectroscopy. Kinetics and isotherm experiments were performed to evaluate the adsorption behaviour of Cu(II). The kinetic experimental data were best fitted to pseudo-second-order model and equilibrium data to the Langmuir model. Thermodynamics parameters such as free Gibbs energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated. These parameters indicated spontaneous and endothermic adsorption process.

An experimental study of hydrodynamic and mass transfer processes was carried out in an absorption column of 0.252 m diameter and 3.5 m of packed bed height developed by Mexican National Institute of Nuclear Research (ININby its acronym in Spanish) of stainless steel gauze corrugated sheet packing by means of SO₂-air-water systems. The experiments results include pressure drop, flows capacity, liquid hold-up, SO₂composition, and global mass transfer coefficient and mass transfer unit height by mass transfer generalized performance model in order to know the relationship between two-phase countercurrent flow and the geometry of packed bed. Experimental results at loading regimen are reported as well as model predictions. The average deviation between the measured values and the predicted values is±5% of 48-data-point absorption test. The development of structured packing has allowed greater efficiency of absorption and lower pressure drop to reduce energy consumption. In practice, the designs of equipment containing structured packings are based on approximations of manufacturer recommendations.