A Fixed-Bed Column with an Agro-Waste Biomass Composite for Controlled Separation of Sulfate from Aqueous Media

Abstract

An agro-waste composite with a pelletized form was prepared and characterized via IR and 13C solids NMR spectroscopy. Thermal gravimetry analysis (TGA) was used to study the weight loss profiles, while SEM images provided insight on the biocomposite morphology, along with characterization of the sulfate adsorption properties under equilibrium and dynamic conditions. The sulfate monolayer adsorption capacity (qe = 23 mg/g) of the prepared agro-waste pellets was estimated from the adsorption isotherm results by employing the Langmuir model, and comparable fitting results were obtained by the Freundlich model. The dynamic adsorption properties were investigated via adsorption studies with a fixed bed column at pH 5.2. The effects of various parameters, including flow rate, bed height and initial concentrations of sulfate, were evaluated to estimate the optimal conditions for the separation of sulfate. The experimental data of the breakthrough curves were analyzed using the Thomas and Yoon–Nelson models, which provided satisfactory best-fits for the fixed bed kinetic adsorption results. The predicted adsorption capacities for all samples according to the Thomas model concur with the experimental values. The optimum conditions reported herein afford the highest dynamic adsorption capacity (30 mg/g) as follows: 1100 mg/L initial sulfate concentration, 30 cm bed height and 5 mL/min flow rate. The breakthrough time was measured to be 550 min. This study contributes to a strategy for controlled separation of sulfate using a sustainable biocomposite material that is suitable for fixed-bed column point-of-use water treatment systems.

Eggshell incorporated agro-waste adsorbent pellets for sustainable orthophosphate capture from aqueous media

“…In turn, torrefaction of biomass affords improved properties such as handling, processing, and environmental stability. 11,17–23…”

“…In turn, torrefaction of biomass affords improved properties such as handling, processing, and environmental stability. 11,[17][18][19][20][21][22][23] Global egg production steadily rose from 35 million metric tons in 1990 to more than 86 million metric tons in 2021, where a typical eggshell (ES) constitutes ca. 10 wt% calcite of the egg bioproduct.…”

“…32,33 The utility of eggshells as additives for P i capture and release media has been reported for ES in calcined forms. 34 This research aims to expand the development of sustainable adsorbents for orthophosphate capture and release through the design of composites that require lower energy and less demanding synthesis via physical compositing of renewable feedstocks 11,21,22 to afford enhanced P i capture.…”

Pyridinium-furfuryl-modified granular agro-waste adsorbent for orthophosphate recovery

“…For the case of aqueous media in many river systems, pH conditions reside near 7–8, where anion adsorption by chitosan can become attenuated or negligible. 24,25…”

Remediation of Amitriptyline Pharmaceutical Wastewater by Heteroatom-Doped Graphene Oxide: Process Optimization and Packed-Bed Studies

“…Fixed-bed column adsorption is typically applied in the industry owing to its cost-effectiveness, flexibility in continuous operation and ease of upscaling. To evaluate the column parameters, the experimental breakthrough data can be fitted to dynamic column correlations such as the Bohart-Adams, Thomas, and Yoon-Nelson models [23]. There are very limited published data on the adsorption of pharmaceuticals onto fixed-bed columns; for instance, tetracycline adsorption onto biochar fixed-bed columns [24], metformin onto silica-alumina composite fixed-bed columns [25], and diclofenac and naproxen onto sugarcane ash-polyethylene terephthalate fixed-bed columns [26].…”