Mono- and Multicomponent Biosorption of Caffeine and Salicylic Acid onto Processed Cape Gooseberry Husk Agri-Food Waste

There is an increasing need to find cost-effective andsustainablesolutions for treating wastewater from contaminants of emerging concern(CECs). In this regard, cape gooseberry husk-typically an agri-foodwaste-is investigated for the first time as a potential biosorbentfor the removal of model pharmaceutical contaminants of caffeine (CA)and salicylic acid (SA) from water. Three different preparations ofhusks were investigated and characterized using Fourier transforminfrared spectroscopy, scanning electron microscopy, Brunauer-Emmett-Telleranalysis, zeta potential, and point of zero charge measurements. Theactivation of the husk led to an increase in the surface area, porevolume, average pore size, and adsorption favorability. The single-componentadsorption of SA and CA onto the three husks was investigated at differentinitial concentrations and pH values to determine the optimal operatingconditions. The maximal removal efficiencies of SA and CA reachedup to 85 and 63%, respectively, for the optimal husk which also offersa less energy-intensive option in its activation. This husk also exhibitedhigh rates of adsorption that exceeded other husk preparations byup to four times. It was proposed that CA interacts electrostaticallywith the husk, while SA binds through weak physical interactions (e.g.,van der Waals and H-bonding). In binary systems, CA adsorption washighly favored over SA adsorption, owing to its electrostatic interactions.The selectivity coefficients alpha(CA)(SA) varied with initial concentration and rangedbetween 61 and 627. The regeneration of husk was also successful resultingin its re-use for up to four full consecutive cycles, further demonstratingthe efficiency of cape gooseberry husk use in wastewater treatment.

Automated summary

The study investigates the potential use of cape gooseberry husk as a biosorbent for removing pharmaceutical contaminants from water. The activated husk showed increased surface area, pore volume, and adsorption efficiency. It can be regenerated and reused for multiple cycles.