Removal of Hexavalent Chromium from Aqueous Solution by Adsorption on Palm Oil Fuel Ash (POFA)

Abstract

This study investigated the removal of hexavalent chromium, Cr(VI) from aqueous solution by adsorption using palm oil fuel ash (POFA), an agricultural waste from the palm oil industry. POFA adsorbent was characterized by X-ray diffraction (XRD) analysis. Batch adsorption study revealed that the optimum conditions for the removal were as follows: pH 2, adsorbent dosage 80 g/L and contact time of 6 min, which resulted in 92% removal and 0.464 mg/g maximum adsorption capacity. Adsorption isotherm and kinetic studies showed that Freundlich isotherm and pseudo-second-order kinetic models fitted best to the experimental data. Column adsorption study at 5 mL/min of flow rate showed that 90% removal was obtained at 2 min of contact time which represented its breakthrough point. The column reached saturation at 30 min and the maximum column adsorption capacity recorded was 0.412 mg/g. The column adsorption behavior showed good fit with both Thomas and Yoon-Nelson kinetic models. These findings suggested that the utilization of POFA as a low-cost adsorbent to remove Cr(VI) from wastewater, either in batch or fixed bed adsorption system is not only effective, but concurrently will help to reduce wastes from the palm oil industry.

Equilibrium, Kinetics and Thermodynamics of Chromium (VI) Adsorption on Inert Biomasses of Dioscorea rotundata and Elaeis guineensis

“…Oil palm fuel ash pH = 2, 200 rpm, 80 g/L of adsorbent 0.462 [5] Banana peel dust pH = 1, 0.4 g of adsorbent dose, 300 rpm, 50 • C 26.46 [12] Modified lychee peel 50 • C, pH = 2, 130 rpm, 0.08 g of adsorbent and 20 mL of solution 9.76 [17] Foxtail millet shell 4 g/L of adsorbent dose, 0.25-0.35 mm of particle size, 30 mL of solution, 120 min, 350 rpm, and 25…”

“…Several removal methods have been used in the capture of hexavalent chromium due to its toxic health effects [5]. These technologies include filtration, chemical precipitation, Water 2022, 14, 844 2 of 15 adsorption, electrodeposition and membrane systems or even ion exchange processes [6].…”

“…Among these methods, bio-adsorption is one of the most economically favorable methods; it is technically easier, with high availability of adsorbents and the possibility of reuse [7]. The removal of hexavalent chromium has been studied using biomasses from different origin, such as corn residues [8], coffee pulp [3], kenaf [9], oil palm ash [5] and peels of lime [4], nut [10], orange [11] and plantain [12], obtaining good performance of biomaterials due to the presence of hydroxyl, carboxyl, amino and carbonyl functional groups, due to their lignocellulosic nature [13].…”

Optimization of the Effect of Temperature and Bed Height on Cr (VI) Bioadsorption in Continuous System

“…He also considers Langmuir's adsorption-desorption kinetics and considers that the driving force is governed by reversible second-order kinetics; however, q0 and kT are treated as empirical parameters that are estimated by fitting the model to experimental data [46]. On the other hand, the Yon-Nelson model assumes that the rate of decrease in the probability of adsorption of each adsorbate molecule is proportional to the probability of adsorbate advancement in the adsorbent [47]. According to the correlation coefficient (R 2 ) it was established was found that Thomas and Yoon-Nelson's model moderately describe the experimental data by a similar fit of 0.599 and 0.612 respectively, while the other 2 models were further away, so it is suggested that for the scaling up of this type of processes work should be done on the development of an own model [48].…”

Batch and Packed Bed Column Study for the Removal of Cr (VI) and Ni (II) Using Agro-Industrial Wastes

“…Various adsorbents have been tested for the removal of heavy metals from aqueous solutions with promising results based on living biomass (fungi, algae, and bacteria) and agricultural biomass (husks, sawdust, agricultural and agroindustrial wastes) [13][14][15][16][17]. Different lignocellulosic biomasses have been used in heavy metal remotion, such as millet [18], lime [19,20], rice husks [18,21], black walnut bark [22], eucalyptus [23], palm residues [24], plantain [25], and kenaf [26], among others [27][28][29][30][31], presenting high removal yields. The use of bio adsorbents of residual lignocellulosic origin has advantages, such as low cost, high availability, and excellent performance at high and low concentrations [32].…”