Functionalized coconut husks for rhodamine-B dye sequestration

Abstract

This study investigates the efficacy of acid activated coconut husk (CHA) for the removal of rhodamine-B (Rh-B) dye from aqueous solutions. The CHA prepared was characterized using various techniques: SEM, FTIR EDX, Boehm titration and pH pzc , respectively. The effects of different operational parameters including initial concentration, contact time and solution temperatures were examined. Kinetic data for Rh-B dye adsorption onto CHA fitted best to pseudo-second-order kinetic model considering the correlation regression (R 2 ) and the sum of squares of error values. Adsorption data were fitted to Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. Langmuir isotherm was the most fitted among all the models used with maximum monolayer sorption capacity of 1666.67 mg g −1 and the highest regression value of 0.99 indicating that CHA has greater affinity for Rh-B dye adsorption due to increased pore development via acid activation. Thermodynamic studies revealed an endothermic adsorption process with the ΔH 0 value of 62.77 kJ mol −1 . Spontaneity was ascertained based on the negative values of ΔG o (ranging from − 26.38 kJ mol −1 to − 20.93 kJ mol −1 ). The positive value of ΔS 0 (0.276 kJ mol −1 K −1 ) suggests increased randomness that exists between CHA and Rh-B dye. Cost analysis results revealed that CHA is six times cheaper than commercial activated carbon (CAC), providing a savings of 217 US$ kg −1 . CHA adsorbent was found to be suitable for Rh-B dye removal from aqueous solution.

Various Methods for Removal, Treatment, and Detection of Emerging Water Contaminants

“…Generally, the adsorption takes place by complexation, ion exchange, and hydrogen bonding [48,49]. Cheap and readily available resources of agricultural solid wastes such as rice husk and straw [50,51], coconut husk and coir dust [52,53], wood sawdust and chips [54,55], and fruit peels and stones [56][57][58][59] have been investigated for the removal of pollutants from aqueous solutions.…”

“…The ability to remove dye using coconut husk and its coir dust as adsorbents was investigated by Bello et al [53] and Etim et al [52], respectively. The coconut coir dust is a remaining dust after the extraction of fiber from the coconut husk, which is about 70% of the coconut husk weight.…”

“…Bamboo chips, corn cob, eucalyptus bark, rice husk, and rice straw Pesticides (atrazine and imidacloprid) [50] Rice husk Metal ions (Fe, Pb and Ni) [51] Coconut coir dust Dye (methylene blue) [52] Coconut husk Dye (Rhodamine-B) [53] Wood chips Phenol [54] Wood sawdust Metal ions (Co, Ni, Cu, and Zn) [55] Orange, pomelo, and passion fruit peels Dye (Rhodamine-B) [56] Orange peel Dye (methylene blue) [57] Pomegranate peel Metal ion (Copper) [58] Peach stones Stimulant (caffeine), anti-inflammatory drug (diclofenac) and psychiatric drug (carbamazepine) [59] Rice husk Personal care and veterinary drug (tetracycline) [60] Peach stones Dye (methylene blue) [61] Peach stones Metal ion (Platinum) Nonbiological processes or pressure-driven membrane technology known as reverse osmosis (RO), nanofiltration (NF), MF, or UF utilizes high pressures across the membranes to accomplish the filtration of contaminants from the produced water [65]. These technologies are the most common membrane techniques of water purification.…”

Improved phenol sequestration from aqueous solution using silver nanoparticle modified Palm Kernel Shell Activated Carbon

“…This was responsible for speedy phenol molecules uptake at the beginning which later decreased before reaching equilibrium. At the equilibrium, the maximum phenol uptake was attained because the vacant sites on the adsorbent could not be loaded with phenol molecules due to the repulsive forces between the phenol molecules and the adsorbent surfaces ( Bello et al., 2019 ). The initial phenol concentration influenced both the phenol removed and the equilibrium time.…”

“…To improve the performance of AC derived from various materials, chemical or physical activation is often performed. In the physical activation, the feedstock is carbonized to its char at a predetermined temperature to eliminate volatile components and the char further heated under purified nitrogen before activated under CO 2 at specific temperature and time to produce the desired activated carbon ( Bello et al., 2019 ). On the other hand, in chemical activation, the feedstock is impregnated with acid or alkali for a specific time followed by carbonization or vice versa ( Okeowo et al., 2020 ).…”