Utilizing olive leaves biomass as an efficient adsorbent for ciprofloxacin removal: characterization, isotherm, kinetic, and thermodynamic analysis.

Olive leaves were utilized to produce activated biomass for the removal of ciprofloxacin (CIP) from water. The raw biomass (ROLB) was activated with sodium hydroxide, phosphoric acid, and Dead Sea water to create co-precipitated adsorbent (COLB) with improved adsorption performance. The characteristics of the ROLB and COLB were examined using SEM images, BET surface area analyzer, and ATR-FTIR spectroscopy. COLB has a BET surface area of 7.763 m2/g, markedly higher than ROLB's 2.8 m2/g, indicating a substantial increase in adsorption sites. Through investigations on operational parameters, the optimal adsorption efficiency was achieved by COLB is 77.9% within 60 min, obtained at pH 6, and CIP concentration of 2 mg/mL. Isotherm studies indicated that both Langmuir and Freundlich models fit the adsorption data well for CIP onto ROLB and COLB, with R2 values exceeding 0.95, suggesting effective monolayer and heterogeneous surface adsorption. The Langmuir model revealed maximum adsorption capacities of 636 mg/g for ROLB and 1243 mg/g for COLB, highlighting COLB's superior adsorption capability attributed to its enhanced surface characteristics post-modification. Kinetic data fitting the pseudo-second-order model with R2 of 0.99 for ROLB and 1 for COLB, along with a higher calculated qe for COLB, suggest its modified surface provides more effective binding sites for CIP, enhancing adsorption capacity. Thermodynamic analysis revealed that the adsorption process is spontaneous (∆Go < 0), and exothermic (∆Ho < 0), and exhibits a decrease in randomness (∆So < 0) as the process progresses. The ΔH° value of 10.6 kJ/mol for ROLB signifies physisorption, whereas 35.97 kJ/mol for COLB implies that CIP adsorption on COLB occurs through a mixed physicochemical process.

A novel co-processed olive tree leaves biomass for lead adsorption from contaminated water.

Olive farming is one of the key agricultural activities in Jordan, where nearly 70% of the cultivated land in Jordan is covered with olive trees. Olive harvesting generates massive quantities of agricultural waste which will be an environmental burden if not managed properly. The present study introduces the use of novel co-processed biomass extracted from the olive tree leaves for the adsorption of lead from contaminated water. Several biomass co-processing techniques using different concentrations of sodium hydroxide, phosphoric acid, and the Dead Sea water were investigated and their effect on the removal efficiency was demonstrated. Moreover, the effect of several parameters on the adsorption efficiency including biomass particle size, solution pH, contact time, adsorbent amount, and lead ion concentration was explored. It was inferred that biomass co-processing enhanced the adsorption capacity of lead. It was also found that the adsorption efficiency increased with decreasing biomass particle size due to the increase in surface area. The highest lead removal was attained at an efficiency value of 70% for the 0.1 mm particle size and at a maximum adsorption capacity recorded at pH 5. The foregoing had a negatively charged biomass surface which, as such, favored the cationic adsorption (pHPZC values around 2.8-4.5). For lead biosorption, the process was a rapid process whereby most adsorption was observed within the first 20 min. Concurrently, there were no considerable changes in lead removal thereafter. Theoretically, this was attributed to the decrease in the available adsorption sites on the biomass surface. On the other hand, a continuous increase in the removal efficiency was recorded upon increasing the adsorbent amount. However, there was a continuous decline in the removal efficiency upon an increase in the initial lead concentration. The experimental data were fitted well with Langmuir isotherm (indicating a monolayer adsorption isotherm), while kinetic data showed the best fit with a pseudo-second-order kinetic model.