Polymerization of graphene oxide with polystyrene: Non-linear isotherms and kinetics studies of anionic dyes

Preparation and Application of Responsive Nanocellulose Composites

Cellulose nanofibrils/poly(N-Isopropylacrylamide) semi-interpenetrating networks (MMCNF-PNAs) were synthesized using an in situ fabrication (semi-IPN). The polymerization of N-isopropylacrylamide (NIPAM) (free radical) was conducted in the presence of magnetic modified cellulose nanofibrils (MMCNFs). The adsorption behaviors and surface morphology of the synthesized adsorbents were investigated systematically. The adsorption behaviors of the as-prepared MMCNF-PNA towards methylene blue (MB, as the model contaminant) dye was studied, and the optimal adsorption conditions were also studied. The adsorption processes could be well fitted using pseudo-second-order and Elovich kinetic models. Meanwhile, Langmuir and Freundlich isotherm models were used to fit the adsorption which occurred at 25, 37 and 65 °C. The corresponding results showed that the Freundlich isotherm model fitted the adsorption process better, indicating that the dye's adsorption happened via heterogeneous adsorptive energies on the prepared MMCNF-PNAs. Their desorption and reusability were also studied to verify magnetic responsivity. To sum up, MMCNF-PNAs are promising magnetic and thermal stimuli-responsive adsorbents, showing a controlled adsorption/desorption process.

Investigation on the Controllable Synthesis of Colorized and Magnetic Polystyrene Beads With Millimeter Size via In Situ Suspension Polymerization

A series of colorized and magnetic polystyrene/Fe₃O₄ (PS/Fe₃O₄) composite beads with millimeter size are successfully synthesized by introducing hydrophobic Fe₃O₄via in situ suspension polymerization of styrene for the first time. Effects of the hydrophobic Fe₃O₄ content, stirring speed, and surfactant dosage on the macromorphology and particle size of PS/Fe₃O₄ beads are systematically investigated to realize the controllable synthesis. Moreover, three kinds of hydrophobic pigments are also employed to synthesize colorized polystyrene, which demonstrates the versatility, simplicity, and wide applicability of the proposed method. Scanning electron microscopy (SEM) and element mapping (EM) images demonstrated that the hydrophobic Fe₃O₄ is well dispersed in the polystyrene matrix. Thermogravimetric analysis (TGA) shows that the resultant PS/Fe₃O₄ beads possess a better thermal stability than neat PS. PS/Fe₃O₄ beads have a promising application in the fields of colorized extruded PS board, colorized expanded PS foam particle, and board.

Using of magnetized and non-magnetized tomato industrial processing solid waste in remediation of Reactive Blue 19 dye aqueous solution

In this study, the removal performance of the Reactive Blue 19 (RB19) dye of the magnetized and non-magnetized industrial tomato solid waste (TW) from the aqueous medium was investigated. The properties of the prepared TW and magnetically modified TW (MTW) bio-sorbents were illuminated using XRD, BET, SEM, VSM, FT-IR and Boehm titration analysis techniques. The optimal conditions for sorption of RB19 by both sorbents were identified. The kinetics and equilibrium data of RB19 sorption by both sorbents were found to match the pseudo-second-order kinetic and Langmuir isotherm models, respectively, with high correlation coefficients. The maximum RB19 sorption capacity under the optimum conditions determined by TW and MTW was determined as 38.76 and 58.14 mg/g, respectively. Thermodynamic parameters calculated for RB19 sorption by both sorbents showed that the processes were spontaneous and exothermic.

Adsorption Performance for Reactive Blue 221 Dye of β-Chitosan/Polyamine Functionalized Graphene Oxide Hybrid Adsorbent with High Acid-Alkali Resistance Stability in Different Acid-Alkaline Environments

A hybrid material obtained by blending β-chitosan (CS) with triethylenetetramine-functionalized graphene oxide (TFGO) (CSGO), was used as an adsorbent for a reactive dye (C.I. Reactive Blue 221 Dye, RB221), and the adsorption and removal performances of unmodified CS and mix-modified CSGO were investigated and compared systematically at different pH values (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12). The adsorption capacities of CS and CSGO were 45.5 and 56.1 mg/g, respectively, at a pH of 2 and 5.4 and 37.2 mg/g, respectively, at a pH of 12. This indicates that TFGO was successfully introduced into CSGO, enabling π-π interactions and electrostatic attraction with the dye molecules. Additionally, benzene ring-shaped GO exhibited a high surface chemical stability, which was conducive to maintaining the stability of the acid and alkali resistance of the CSGO adsorbent. The RB221 adsorption performance of CS and CSGO at acidic condition (pH 3) and alkaline condition (pH 12) and different temperatures was investigated by calculating the adsorption kinetics and isotherms of adsorbents. Overall, the adsorption efficiency of CSGO was superior to that of CS; thus, CSGO is promising for the treatment of dye effluents in a wide pH range.

Thermal and pH dual-responsive cellulose microfilament spheres for dye removal in single and binary systems

Cellulose microfilaments/poly(N-Isopropylacrylamide-co-acrylic acid) spheres (MPNAA) were prepared via the in-situ synthesis of semi-interpenetrating networks (semi-IPN). The free radical copolymerization of acrylic acid (AA) (for pH-sensitive chain segments) and N-isopropylacrylamide (NIPAM) (for temperature-sensitive chain segments) was conducted in a microwave-reactor in the presence of porous cellulose/microfilament composite spherical beads pre-prepared. The surface morphology and adsorption properties of the as-prepared spheres were systematically characterized. The adsorption behaviors of resulting MPNAA towards dyes, methylene blue (MB) and methyl violet (MV), were pH sensitive; and the optimal adsorption occurred at pH 9. The dynamic adsorption processes could be well fitted with pseudo-second-order kinetic, Elovich and simplified intraparticle diffusion models. Meanwhile, Langmuir, Temkin, Freundlich, and Dubinin-Raduskevich models were used to fit the adsorption isotherms at 25, 40, and 55 °C, respectively. The results indicated that the adsorption capacities of MPNAA towards MB and MV could reach as high as 497.5 and 840.3 mg g^-1, respectively, in single systems; and high adsorption capacity was maintain in binary systems with the favorable adsorption of MV. Overall, the semi-IPN MPNAA spheres are promising as novel pH- and temperature-responsive adsorbents, facilitating the controllable adsorption/desorption processes.