Construction of efficient Ni-FeLDH@MWCNT@Cellulose acetate floatable microbeads for Cr(VI) removal: Performance and mechanism.

Water pollution is an aggravating dilemma that is extending around the world, threatening human survival. Strikingly, the notorious heavy metals like hexavalent chromium ions (Cr6+) cause environmental problems raising awareness of the essentials for finding feasible solutions. For this purpose, the self-floating Ni-FeLDH@MWCNT@CA microbeads were prepared for removing Cr6+. The morphological, thermal, and composition characteristics of Ni-FeLDH@MWCNT@CA microbeads were analyzed using XRD, FTIR, TGA, SEM, XPS, and zeta potential. Notably, the adsorption aptitude of Cr6+ was enhanced by raising the MWCNTs proportion to 5 wt% in microbeads. The Cr6+ adsorption onto Ni-FeLDH@MWCNT@CA fitted Langmuir and Freundlich isotherm models with qm of 384.62 mg/g at pH 3 and 298 K. The adsorption process was described kinetically by the pseudo-2nd order model. More importantly, the adsorption of Cr6+ onto Ni-FeLDH@MWCNT@CA occurred via electrostatic interactions, inner/outer sphere complexations, ion exchange, and reduction mechanisms. Besides, the cycling test showed the remarkable reusability of Ni-FeLDH@MWCNT@CA floatable microbeads for five subsequent cycles. The self-floating Ni-FeLDH@MWCNT@CA microbeads in this work provide essential support for the potential applications for the remediation of heavy metals-containing wastewater.

Carboxymethyl cellulose/carboxylated graphene oxide composite microbeads for efficient adsorption of cationic methylene blue dye.

An efficient composite adsorbent was fabricated based on carboxymethyl cellulose (CMC) microbeads incorporated carboxylated graphene oxide (GOCOOH) for the adsorptive removal of cationic methylene blue dye (MB). The developed CMC/GOCOOH composite microbeads were characterized by means of FTIR, TGA, SEM, XPS, BET and zeta potential analysis tools. Various parameters affecting the removal of MB dye such as the amount of GOCOOH, initial MB concentration, adsorbent dosage, pH and medium temperature were optimized using a series of batch adsorption experiments. The experimental data of the adsorption process were more fitted to Langmuir isotherm (R2 = 0.998) with a maximum adsorption capacity of 180.32 mg/g and followed the pseudo-second order kinetic model. Moreover, the adsorption of MB dye onto CMC/GOCOOH composite microbeads was an exothermic process with a maximum capacity at pH 10. Besides, the fabricated adsorbent exposed also better reusability for nine repetitive cycles with highly adsorption properties. The gained results imply that the CMC/GOCOOH microbeads could be potentially applied as an effective and reusable adsorbent for MB dye removal from aqueous solutions.

Fabrication of novel iminodiacetic acid-functionalized carboxymethyl cellulose microbeads for efficient removal of cationic crystal violet dye from aqueous solutions.

Novel anionic adsorbent microbeads were fabricated based on surface functionalization of p-benzoquinone-carboxymethyl cellulose (CMC-PBQ) activated microbeads with iminodiacetic acid (IDA). The developed IDA@CMC-PBQ microbeads were characterized by FT-IR, TGA, SEM, XPS and zeta potential analysis tools. Ion exchange capacity measurements proved the successful generation of extra carboxylic groups on the surface of IDA@CMC-PBQ microbeads with a maximum value reached 3.984 meq/g compared to 1.32 meq/g for neat CMC microbeads. The fabricated microbeads were tested for the removal of cationic crystal violet (CV) dye from aqueous solutions under various adsorption conditions. The results clarified that the removal percent of CV dye was augmented and reached a maximum value of 91.56% with increasing IDA concentration up to 0.15 M. Moreover, the experimental data were well-fitted both Langmuir and Freundlich isotherms with a maximum adsorption capacity of 107.52 mg/g. while the adsorption process was obeyed the pseudo-second order kinetic model. The developed adsorbent displayed respectable reusability after five sequential cycles and exhibited higher adsorption ability towards cationic CV dye compared to cationic methylene blue (MB) and anionic methyl orange (MO) dyes. Therefore, IDA@CMC-PBQ adsorbent could be effectually used as a convenient and reusable adsorbent for removing cationic dyes from their aqueous solutions.