Bimetallic Fe/Al-MOF for the Adsorptive Removal of Multiple Dyes: Optimization and Modeling of Batch and Hybrid Adsorbent-river Sand Column Study

Bimetallic Metal organic framework (MOF) has garnered interest over the years with its application in various environmental remediation. In this study, Fe-Al-1,4-Benzene di-Carboxylic acid (FeAl(BDC)) MOF was synthesized, and adsorptive removal of Rhodamine B dye in batch and unique hybrid FeAl (BDC)-River sand fixed-bed column was achieved. The experimental data from the batch studies corroborated well with the Pseudo second-order (PSO) and Freundlich adsorption isotherm models. Furthermore, a fixed-bed column study was conducted to assess the effect of varying flow rate (2, 5, 8 mL/min), bed height (5, 9, 13 cm), and feed concentration (10, 20, 30 mg/L) on the adsorption performance of FeAl(BDC) in continuous mode of operation. A uniform mixture of river sand and FeAl(BDC) by weight ratio (9:1) was achieved prior to packing the column. The column study reveals that Sand-FeAl(BDC) can achieve the maximum adsorption capacity of 113.05 mg/g at a flow rate of 5 mL/min, feed concentration of 20 mg/L, and bed height of 13 cm. The experimental data of the column study were successfully fitted with BDST, Thomas, Yoon-Nelson, and Dose-response models. The fitting parameter values from the BDST model raise the scope of possible upscaling of the fixed-bed column. Hence, it is proposed that these River sand-FeAl(BDC)-based filters can be widely used in areas facing critical contamination and in poor communities with a high demand for water.

Preparation of Palm Oil Industry’s Biomass-Based Graphene Composite for the Adsorptive Removal of Methylene Blue

The ability of POME-based graphene shell composite (P-GSC), an adsorbent generated from oil palm wastes abundantly available in Malaysia such as POME and PKS, was examined in removing methylene blue (MB) dye by adsorption. Adsorption experiments, involving a batch column study and a batch equilibrium study, were conducted to investigate the efficiency of synthesized P-GSC from PKS as a base material in the removal of MB dye. The batch column study demonstrated that small-sized synthesized P-GSC from PKS as a base material could remove up to 98.5% for concentration. Therefore, the following batch equilibrium study was carried out on small-sized P-GSC only. Adsorption isotherms and kinetic isotherms were studied, from which the experimental data showed that the adsorption exhibited a good fit with the Freundlich model ( R 2 = 0.8923 ) and followed the pseudo-second order model ( R 2 > 0.98 ). FESEM, XPS, and XRD morphological and elemental analysis indicated the successful graphinization of POME on the P-GSC surface. The concept of deploying POME as the carbonaceous source to produce P-GSC, and then, deploying the resultant P-GSC as the adsorbent for MB dye removal has presented promising practical potential. Such cost-effective and environmentally friendly reuse of waste materials is envisioned to promote a ‘zero-waste industry.’