Antibiotic contaminants in aquatic media pose a significant threat to both human health and environmental sustainability. This study investigated an effective approach for removing ciprofloxacin (CIP) from aqueous solutions utilizing iron oxide-modified biochar derived from sugarcane bagasse (BioKFe). The modified biochar exhibited exceptional properties, including a high specific surface area (525.07 m2/g), a substantial pore volume (0.29 cm3/g), and numerous functional groups on its surface. The results revealed a removal efficiency exceeding 95%, with nearly complete removal of CIP achieved in the presence of H2O2 through Fenton oxidation. The adsorption data were best described by the Langmuir model (R2 = 0.943) and pseudo-second-order kinetics (R2 = 0.988), indicating that the CIP removal followed a monolayer adsorption process primarily governed by physisorption. The adsorption process of CIP by BioKFe was exothermic, with a maximum adsorption capacity of 42.63 mg/g. The proposed mechanisms for CIP removal include pore filling, hydrogen bonding, electrostatic attraction, pi-pi interactions, and Fenton oxidation. These interactions contributed to the high efficacy of CIP removal, which was approximately 96%. Furthermore, the BioKFe exhibited high stability and reusability, maintaining above 70% of its removal performance after four cycles of use. These findings suggested that iron-based biochar from sugarcane bagasse is promising for wastewater treatment, offering an efficient, sustainable, and cost-effective approach.
The aim of this research was to synthesize a new nitrogen-rich and insensitive catalyst for the thermal decomposition of ammonium perchlorate (AP). To this end, a new cobalt complex, [Co(BTM)2](NH4)2 (CoC), was synthesized using 5,5 '-methylenebis(1H-tetrazole) (H2BTM) ligand and characterized by elemental analysis, ICP-AES, PXRD, and FT-IR spectroscopy. To evaluate its catalytic activity on the thermal decomposition of AP, a mixture containing 25 wt.% of the CoC with AP was analyzed via thermal analysis techniques, and nonisothermal kinetic parameters were determined via the Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall methods. This study revealed that the activation energy of AP decreased from 194 to 138 kJ mol-1 by this catalyst. Also, the logarithm of the frequency factor (log(A/s-1)) decreased from 14.12 to 9.88, and reveals a four-stage mechanism for the AP thermal decomposition phenomenon. Furthermore, it increases the heat of decomposition of AP from 1100 to 2100 Jg-1 and reduces the maximum decomposition temperature from 432 to 343 degrees C.
Lead (Pb) is one of the most hazardous heavy metals found in wastewater. Adsorption in a continuous fixed-bed column is used for treating large volumes of wastewater, and the efficiency of this process can be monitored using the breakthrough curve. In this study, fibrous nanosilica (KCC-1) from rice husk ash was employed as an adsorbent and modified using granular sand to prevent it from being difficult to separate from the Pb. The study fabricates a continuous fixed-bed adsorption column loaded with modified-sand KCC-1 to examine the impact of flow rate (10-40 mL min-1), bed height (3-12 cm), and concentrations (50-200 mg L-1) on Pb2+ adsorption. The experiment operated for 5 h, with samples taken every 30 min and analyzed using a UV-Vis spectrophotometer. The results showed that the highest percentage of Pb2+ removal arose at a flow rate of 10 mL min-1, with an adsorption capacity, q, of 29.49 mg g-1, a residence time of 5.0 min, and a removal efficiency of 94.50%. In addition, the adsorption breakthrough was obtained by the Thomas, Adam-Bohart, and Yoon-Nelson models. Based on the adsorption efficiency findings using sand-modified KCC-1, all three models are suitable for describing the adsorption process.
In this study, a composite electrode was developed for non-enzymatic glucose oxidation, consisting of a polyaniline (PANI) film modified with graphene oxide (GO) on a platinum-iridium (Pt-Ir) substrate (GO-PANI@Pt-Ir). GO was synthesized by a modified Hummers approach, and the composite coating was formed through electrochemical polymerization of aniline in 0.5 M H2SO4. The process conditions were optimized using response surface methodology (RSM) in two phases. In the first phase, the influences of scan rate (20-100 mV/s), number of cycles (20-100), GO content (1-3 mg/mL), and aniline concentration (0.1-0.3 M) were evaluated for the oxidation of 0.5 mM glucose. Optimal electrode fabrication obtained at 2.5 mg/mL GO, 0.25 M aniline, 60 mV/s, and 40 cycles. In the second phase, the effects of glucose concentration (0.5-2.5 mM), applied potential (0.5-1.5 V), and temperature (20-60 degrees C) were examined. The highest glucose removal (310.17 & micro;M) occurred at 1.8 mM glucose, +1.1 V, and 25 degrees C, producing gluconic acid as the dominant product. Kinetic analysis indicated a pseudo-second-order (PSO) model consistent with Langmuir-Hinshelwood (L-H) kinetic model, with the surface reaction step being rate-limiting. GO-PANI@Pt-Ir electrode thus exhibits promising electrocatalytic behavior for environmental electrochemical applications.
