Mohd Shaiful Sajab

Citric acid modified kenaf core fibres for removal of methylene blue from aqueous solution.

Chemically modified kenaf core fibres were prepared via esterification in the presence of citric acid (CA). The adsorption kinetics and isotherm studies were carried out under different conditions to examine the adsorption efficiency of CA-treated kenaf core fibres towards methylene blue (MB). The adsorption capacity of the kenaf core fibres increased significantly after the citric acid treatment. The values of the correlation coefficients indicated that the Langmuir isotherm fitted the experimental data better than the Freundlich isotherm. The maximum adsorption capacity of the CA-treated kenaf core fibres was found to be 131.6mg/g at 60°C. Kinetic models, pseudo-first-order, pseudo-second-order and intraparticle diffusion, were employed to describe the adsorption mechanism. The kinetic data were found to fit pseudo-second-order model equation as compared to pseudo-first-order model. The adsorption of MB onto the CA-treated kenaf core fibres was spontaneous and endothermic.

Cationic and anionic modifications of oil palm empty fruit bunch fibers for the removal of dyes from aqueous solutions

Oil palm empty fruit bunch (EFB) fibers were employed to remove dyes from aqueous solutions via adsorption approaches. The EFB fibers were modified using citric acid (CA) and polyethylenimine (PEI) to produce anionic and cationic adsorbents, respectively. The CA modified EFB fibers (CA-EFB) and PEI-modified EFB fibers (PEI-EFB) were used to study the efficiency in removing cationic methylene blue (MB) and anionic phenol red (PR) from aqueous solutions, respectively, at different pHs, temperatures and initial dye concentrations. The adsorption data for MB on the CA-EFB fitted the Langmuir isotherm, while the adsorption of PR on the PEI-EFB fitted the Freundlich isotherm, suggesting a monolayer and heterogeneous adsorption behavior of the adsorption processes, respectively. Both modified fibers can be regenerated up to seven adsorption/desorption cycles while still providing as least 70% of the initial adsorption capacity.

Cellulose nanofibrils: a rapid adsorbent for the removal of methylene blue

Cellulose nanofibrils (CNF) were prepared from kenaf core (KC) using acidified-chlorite bleaching method and followed by disintegration using a high speed blender. The effects of disintegration time and acid treatment on the defibrillation of holocellulose were studied. Hemicellulose was found to facilitate defibrillation, as CNF without any acid treatment was fully defibrillated after 30 min. The adsorption kinetics of CNF toward cationic dye cannot be accurately determined due to its quick adsorption performance, in which the equilibrium is achieved immediately after 1 min of contact time. The effects of acid treatment on holocellulose, pH, adsorbent dosage, temperature and dye concentration were studied and optimized. Adsorption data were fitted to both Langmuir and Freundlich models where the Langmuir model was found to be the better model to describe the adsorption process. The maximum adsorption capacity was found to be 122.2 mg g−1 at pH 9, 20 °C for the non-acid treated CNF. The CNF can be regenerated by desorption at low pH where as much as 70% of the dye adsorbed can be desorbed after 6 cycles of adsorption–desorption.

Bifunctional graphene oxide–cellulose nanofibril aerogel loaded with Fe(III) for the removal of cationic dye via simultaneous adsorption and Fenton oxidation

A highly porous cellulose nanofibril (CNF) aerogel loaded with graphene oxide–iron(III) (GO–Fe) nanocomposites was produced and used for the treatment of methylene blue (MB) in aqueous solution. The CNF aerogel serves as an adsorbent for the dye, while the GO–Fe nanocomposites play a role in the decomposition of the dye via the Fenton oxidation reaction. The aerogel exhibits rapid adsorption performance (less than 10 min) for removing MB, with a maximum adsorption capacity of 142.3 mg g−1. On the side of enhancing the MB removal, the GO in the GO–CNF nanocomposite aerogel was loaded with 1 wt% of Fe(III) to perform as a catalyst for the Fenton oxidation reaction. The MB continues to decolorize by 30.4% more after 24 h of the reaction process. Moreover, by performing Fenton oxidation for adsorbent regeneration, the adsorption capacity for nanocomposite adsorption was reduced by 52.2% after five cycles of adsorption–oxidation.

A porous aerogel nanocomposite of silver nanoparticles-functionalized cellulose nanofibrils for SERS detection and catalytic degradation of rhodamine B

Herein, cellulose nanofibrils (CNFs) were functionalised with silver nanoparticles (AgNPs) via a green in situ hydrothermal synthesis approach. The presence of active functional groups on the CNFs favours the direct synthesis and growth of AgNPs on the nanofibrils without the use of an external reducing agent. The freeze-dried CNF–AgNPs aerogel nanocomposite exhibited a highly porous structure, as revealed by FESEM. An organic dye, rhodamine B (RhB), was chosen to investigate the characteristics of the produced nanocomposite. Detection of the dye via Raman spectroscopy and analysis of catalytic capabilities by degradation of the dye were used to define the nanocomposites properties. The nanocomposite showed significant enhancement in detection of signal for RhB in aqueous solution, as compared to the neat CNF, which is attributed to the surface-enhanced Raman scattering effect (SERS) of the immobilized AgNPs. Moreover, the CNF–AgNPs nanocomposite also showed sensitivity for detecting RhB at different concentrations, ranging from 5 × 10−3 M to 5 × 10−7 M. In addition, the nanocomposite exhibited a notable catalytic effect on the degradation of RhB in the presence of sodium borohydride.

Removal of Copper(II) Ions from Aqueous Solution Using Alkali-treated Kenaf Core Fibres

In this study, the sorption of Cu(II) ions from aqueous solution onto NaOH-treated kenaf core fibres was investigated. The kenaf core fibres were milled into different sizes and treated with NaOH before being used to investigate their efficiency in removing Cu(II) ions from aqueous solutions. Sorption studies were performed at a pH value of 5. Sorption of the Cu(II) ions increased and the sorption yield decreased with increasing initial Cu(II) ion concentration. The sorption data were correlated with the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherms. The values of the correlation coefficients obtained indicated that the Langmuir isotherm fitted the experimental data better than the Freundlich and D–R isotherms. Kenaf core fibres with fibre sizes in the range 150–300 μm possessed the highest sorption capacity. The calculated parameters of the isotherms suggest that the uptake of Cu(II) ions occurred at the homogeneous active sites on the surfaces of the kenaf core fibres.

Fixed-bed column studies for the removal of cationic and anionic dyes by chemically modified oil palm empty fruit bunch fibers: single- and multi-solute systems.

AbstractThe adsorption performance of cationically and anionically modified oil palm empty fruit bunch fibers toward methylene blue (MB) and phenol red (PR) was investigated using single- and multi-solute systems in a fixed-bed system. The experimental data were fit with Thomas and Clark column adsorption models to evaluate different experimental conditions (adsorbate dose, bed height, column temperature, and flow rate). The results suggest that the adsorption mechanism was that of monolayer and heterogeneous. The service time of each bed was estimated using a bed depth service time model by considering the adsorption rate. The regeneration of the adsorbent for up to five adsorption/desorption cycles was investigated, suggesting the excellent reusability of the adsorbent column. The simultaneous removal of mixed MB and PR was achieved using both fibers packed with different configurations.

Chemically crosslinked hydrogel and its driving force towards superabsorbent behaviour

Dissolved oil palm empty fruit bunch (EFB) cellulose in NaOH/urea solvent was mixed with sodium carboxymethylcellulose (NaCMC) to form a green regenerated superabsorbent hydrogel. The effect of concentration of epichlorohydrin (ECH) as the crosslinker on the formation, physical, and chemical properties of hydrogel was studied. Rapid formation and higher gel content of hydrogel were observed at 10% concentration of ECH. The superabsorbent hydrogel was successfully fabricated in this study with the swelling ability >100,000%. Hydrogel with higher concentration of ECH showed opposite trend by having higher superabsorbent property than that of lower concentration. The covalent bond of COC was observed with Attenuated total reflectance fourier transform infrared (ATR-FT-IR) spectroscopy to confirm the occurrence of crosslinking. The physical and chemical properties of hydrogel were affected by swelling phenomenon. Hydrogel with higher degree of swelling exhibited lower moisture retention and higher transparency. Moreover, the weight of the superabsorbent hydrogel increased with the decrement of pH value of external media (distilled water). This study provided substantial information on the effect of different percentage of ECH as crosslinker on hydrogel basic properties. Furthermore, this study affords correlation of many essential driving forces that affected hydrogel superabsorbent property.