Carbon nanoparticles (CNPs) were produced from the leaves of Cocos nucifera and chemically activated using phosphoric acid. The activated CNPs were characterized using Brunauer-Emmett-Teller (BET) (surface area: 122.53 m2/g; mean pore diameter: 16.29 nm) and Field Emission Scanning Electron Microscopy (FE-SEM) (particle size: 20-30 nm). Batch adsorption experiments were conducted to optimize chromium (VI) removal from leather industry effluent. Response surface methodology with Central Composite Design (CCD) was employed to investigate the effects of four parameters: Cr concentration (10-100 ppm), CNP dosage (1-10 g/L), contact time (10-60 min), and pH (1-7). Under optimized conditions (Cr concentration 100 ppm, CNP dosage 10 g/L, contact time 30 min, and pH 2), the maximum removal efficiency achieved was 83% with an adsorption capacity of 83 mg/g. ANOVA analysis confirmed the quadratic model adequacy (F-value = 74.65, p < 0.0001, and R² = 0.9896). CNP concentration emerged as the most influential parameter. Isotherm modeling analysis demonstrated that the chromium biosorption process follows Langmuir isotherm behavior with an R² value of 0.9951, a Chi-squared error (χ²) value of 0.2452, and a root mean square error (RMSE) of 1.0002 mg/g, indicating monolayer adsorption. The Cocos nucifera carbon nanoparticles demonstrated high efficiency for chromium removal from tannery effluents under acidic conditions.
The toxic heavy metals in waste printed circuit boards (PCBs) in electrical and electronic devices make them particularly challenging to manage. This research emphasized the bioleaching and biosorption potential of two effective fungal strains for removing Cu²⁺, Pb²⁺, and Cd²⁺ from laptop PCBs. The bioleaching experiment demonstrated that the two-step bioleaching process using Aspergillus niger effectively extracted heavy metal ions from laptop PCBs. One kilogram of laptop PCB samples contained 130.25±1.53 g of Cu, 18.81±0.09 g of Pb, and 0.037±0.004 g of Cd. The results suggest that Cu2+, Pb2+, and Cd2+ achieved maximum bioleaching efficiencies of 73.06%, 63.91%, and 70.53%, respectively, after a 21-day incubation period. The biosorption experiment using immobilized Humicola phialophoroides biomass pretreated with NaOH demonstrated higher efficiency in removing heavy metal ions from leachate than non-immobilized biomass in bioremediation processes. The maximum heavy metal biosorption by the immobilized cells was achieved at a solution at 30 oC after an equilibrium time of 120 minutes at pH 7. The heavy metal ion biosorption capacities were 184.10±3.65 mg Cu g-1dry wt., 39.60±1.21 mg Pb g-1dry wt., and 2.28±0.04 mg Cd g-1 dry wt. The temperature had little effect, while the pH value significantly influenced the sorption process.
In the present research, a magnetic nanostructure based on graphene oxide and iron oxide modified by the amino acid tryptophan was synthesized. The properties of the adsorber were determined using a Fourier transform infrared spectrometer, elemental analysis, X-ray diffraction, a scanning electron microscope, and a vibrating-sample magnetometer. Optimum parameters such as pH, contact time, amount of used adsorbent, initial concentration of copper ions, and the effect of temperature were investigated. Adsorption isotherm studies were conducted using the Langmuir and the Freundlich models, and the Langmuir isotherm model was found to be more consistent with the adsorption process. The theoretical maximum adsorption capacity of the adsorbent was 125 mg of copper per gram of adsorbent, which was close to the maximum adsorption capacity of the adsorbent in the real state (118 mg of copper per gram of adsorbent). To investigate the thermodynamics of adsorption, the Van't Hoff Equations were used. The results indicated that the adsorption process was endothermic. In addition, the removal rate of copper ions from the real wastewater sample in the presence of other ions was determined to be 46%.
Due to increasing environmental concerns and requirements, the adoption of modern heating methods is strongly recommended. The microwave-based system has attracted considerable attention due to its efficiency, low carbon footprint, low energy consumption, and short process timing. Our studies on microwave heating for synthesizing cobalt and various alloys showed a significant need for novel predictors to model microwave heating processes. This paper is novel in its evaluation of the performance of outstanding numerical methods for solving microwave-based reactions in both kinetic and environmental aspects. As a case study, the experimental results related to the reaction of cobalt metal oxide with syngas under microwave heating were compared to the orthogonal collocation outcomes, and outstanding results were reported with a mean error lower than 5%. The emissions from a microwave and an electrical furnace, based on kinetic values, were also compared. To evaluate numerical methods for different types of reactions in the mentioned microwave heating process, the governing equations from the modeling of gas-solid catalyzed reactions with different reaction orders were solved using the perturbation and orthogonal collocation methods. The environmental analysis demonstrated that the microwave process offered notable environmental and operational advantages over the furnace process, including significantly faster CO removal, more controllable CO₂ emissions, higher energy efficiency, and a reduced overall carbon footprint by possibly reducing energy consumption.
The pervasive presence of nanoplastics and antibiotics in wastewater systems presents a dual threat to environmental and public health. Nanoplastics, with particle sizes under 1 μm, have become a major environmental contaminant, primarily due to their durability and potential to absorb harmful chemicals. These particles not only threaten aquatic ecosystems by disrupting microbial communities and harming marine life but also pose risks to human health through bioaccumulation in the food chain. Similarly, antibiotics frequently found in wastewater promote the development of antibiotic-resistant bacteria, further endangering ecological stability and human health. The synergistic effects of nanoplastics and antibiotics exacerbate their impacts, particularly by increasing the bioavailability and toxicity of contaminants in aquatic systems. This paper explores the sources, transport pathways, and combined ecological and health impacts of these pollutants. Additionally, it discusses the limitations of current wastewater treatment technologies in mitigating the effects of nanoplastics and antibiotics and proposes advanced strategies for reducing their environmental footprint. Addressing these contaminants requires a multifaceted approach, integrating technological, regulatory, and community-based solutions to safeguard the ecosystem, biodiversity, and human health.
