A floating biosorbent of polylactide and carboxylated cellulose from biomass for effective removal of methylene blue from water.

A floating adsorbent bead was prepared from polylactide (PLA) and maleic anhydride (MAH)-modified cellulose in a one-pot process (OP bead). Cellulose was extracted from waste lemongrass leaf (LGL) and modified with MAH in the presence of dimethylacetamide (DMAc). PLA was then added directly into the system to form sorbent beads by a phase separation process that reused unreacted MAH and DMAc as a pore former and a solvent, respectively. The chemical modification converted cellulose macrofibres (55.1 ± 31.5 µm) to microfibers (8.8 ± 1.5 µm) without the need for grinding. The OP beads exhibited more and larger surface pores and greater thermal stability than beads prepared conventionally. The OP beads also removed methylene blue (MB) more effectively, with a maximum adsorption capacity of 86.19 mg⋅g-1. The adsorption of MB on the OP bead fitted the pseudo-second order and the Langmuir isotherm models. The OP bead was reusable over five adsorption cycles, retaining 88 % of MB adsorption. In a mixed solution of MB and methyl orange (MO), the OP bead adsorbed 96 % of the cationic dye MB while repelling the anionic dye MO. The proposed method not only reduced time, energy and chemical consumption, but also enabled the fabrication of a green, effective and easy-to-use biosorbent.

Selective separation of dyes by green composite membrane based on polylactide with carboxylated cellulose microfiber from empty fruit bunch.

A bio-based membrane was prepared by a non-solvent induced phase separation process. A polylactide (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) polymer blend was mixed with functionalized cellulose microfiber from empty fruit bunch (EFB) modified with maleic anhydride (MEFB). MEFB reduced the water contact angle and increased the porosity of the membrane. In a batch adsorption process, the pseudo-second order and Langmuir isotherm models best described the adsorption of the cationic dye methylene blue (MB) on PLA/PBAT and PLA/PBAT-MEFB membranes. In a dynamic adsorption process, pure water flux was higher through the PLA/PBAT-MEFB membrane (1214 L m-2 h-1) than the PLA/PBAT membrane (371 L m-2 h-1). The PLA/PBAT-MEFB membrane removed 97.2 % of MB while the PLA/PBAT membrane removed only 58.7 %. The hydrophilicity of the membrane and its adsorption efficiency toward MB were improved by the abundant carboxyl groups in MEFB. A filtration test using a mixed dye solution of anionic methyl orange (MO) and MB showed that the PLA/PBAT-MEFB membrane rapidly adsorbed MB while permitting MO to pass through. Moreover, this membrane could be easily regenerated and maintained a satisfactory separation performance over several cycles. Based on the membrane performance and its economical preparation, the proposed biocomposite membrane could be used for selective filtration and wastewater treatment.

Novel cellulose-based biosorbent from lemongrass leaf combined with cellulose acetate for adsorption of crystal violet.

A novel biosorbent from lemongrass leaf fibers incorporated with cellulose acetate (TLGL-CA) was prepared and its properties and adsorption capacity toward crystal violet (CV) were investigated. The good adhesion between TLGL and CA in TLGL-CA sheet was revealed by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), and tensile properties. The potential of the biosorbent for CV adsorption was indicated by its high swelling capacity and the presence of functional groups of lignocellulose. Adsorption results obtained at different contact times and initial CV concentrations fitted well with the pseudo-second order model. The adsorption data at equilibrium were well described by the Langmuir isotherm model and the maximum monolayer adsorption capacity was 36.10 mg g-1 at 25 °C. In the desorption study, five adsorption-desorption cycles of CV were successfully repeated with TLGL-CA sheet, using acetic acid as the desorbing agent. Based on the study results, it was concluded that the developed biosorbent is effective, inexpensive, and convenient to use for the removal of cationic dye in wastewater.