Guava seed activated carbon loaded calcium alginate aerogel for the adsorption of diclofenac sodium: Characterization, isotherm, kinetics, and optimization via Box-Behnken design.

This study aimed to develop a novel adsorbent designed for the removal of diclofenac sodium (DS) from water. The synthesized adsorbent, a composite sponge known as guava seeds activated carbon loaded calcium alginate (GSAC@CA aerogel), was created through the combination of powdered activated carbon derived from guava seeds and loaded onto a calcium alginate hydrogel. Characterization through SEM, XRD, FT-IR, BET, and XPS revealed a confirmed surface area of 738.82 m2/g. The investigation delved into assessing the influence of pH, initial DS concentration, and adsorbent dose on the adsorption of DS. Isotherm studies on adsorption suggested that a Langmuir model provided a good fit, indicating a monolayer adsorption process. Kinetic studies revealed a well-fitted pseudo-second-order model, shedding light on the dynamics of the reaction. The chemisorption nature was elucidated by the Dubinin-Radushkevich model, demonstrating an adsorption energy of 22.6 kJ/mol. These results affirm the potential of the GSAC@CA aerogel composite sponge as an efficient adsorbent for removing diclofenac sodium from water. Examination of the impact of temperature on the adsorption process revealed an endothermic behavior, indicating an increase in temperature. The positive change in entropy suggested the spontaneous nature of the reaction. Remarkably, the GSAC@CA aerogel composite sponge exhibited strong adsorption capabilities, achieving a maximum adsorption capacity of 489.97 mg/g. Across five consecutive cycles, the composite consistently demonstrated high-level adsorption, maintaining a removal efficiency of 87.77 %. The adsorption mechanism of diclofenac sodium (DS) on the GSAC@CA aerogel composite sponge was determined to encompass various processes, such as hydrogen bonding, π-π interactions, ion exchange, and electrostatic pore filling. Additionally, the adsorbent demonstrated successful regeneration over three cycles when applied to a real-world sample. The incorporation of the Box-Behnken design (BBD) introduced a strategic aspect to enhance adsorption outcomes, offering valuable insights for optimizing the adsorption process in practical applications.

Chitosan-nano CuO composite for removal of mercury (II): Box-Behnken design optimization and adsorption mechanism.

The study aimed to develop an adsorbent for extracting mercury (II) from water by combining chitosan beads with green copper oxide nanoparticles. This resulted in the synthesis of the CuO NPs@CSC composite sponge, achieved by loading CuO NPs onto citrate-crosslinked chitosan (CSC). Characterization involved X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The BET method confirmed a higher surface area of the adsorbent at 285.55 m2/g, suggesting its potential for effective mercury (II) removal from water. This research aligns with broader efforts in environmental science and nanotechnology to create advanced materials for water purification. The characterization techniques ensure the suitability of the synthesized material for its intended application, and the significant surface area enhances its capacity for contaminant adsorption. The study investigated the impact of adsorbent dosage, pH, and initial Hg (II) concentration on mercury (II) adsorption. Results showed a fit with the pseudo-second-order kinetic model and Langmuir adsorption isotherm model. Using the Dubinin-Radushkevich model (adsorption energy: 22.74 kJ mol-1), chemisorption was identified. Notably, the adsorption process was found to be endothermic, indicating that higher temperatures led to increased removal capacity and related parameters. This temperature influence was explored systematically. Additionally, the study concluded that the adsorption reaction was spontaneous, evidenced by a positive entropy change. This analysis contributes valuable insights into the thermodynamics and kinetics of mercury (II) adsorption in the studied system. The CuO NPs@CSC composite sponge achieved an impressive adsorption capacity of 672 mg/g. Even after five consecutive cycles, it maintained strong adsorption capabilities with 84.5 % removal efficiency. Remarkably, over six reuse cycles, there were no observable changes in chemical composition, and XRD peaks remained consistent before and after each cycle. The study delved into the interaction mechanism between the CuO NPs@CSC composite sponge and heavy metals. Utilizing the Box-Behnken design (BBD), the adsorption process was optimized for enhanced efficiency.

A qualitative Design and optimization of CIGS-based Solar Cells with Sn2S3 Back Surface Field: A plan for achieving 21.83 % efficiency.

Conventional Copper Indium Gallium Di Selenide (CIGS)-based solar cells are more efficient than second-generation technology based on hydrogenated amorphous silicon (a-Si: H) or cadmium telluride (CdTe). So, herein the photovoltaic (PV) performance of CIGS-based solar cells has been investigated numerically using SCAPS-1D solar simulator with different buffer layer and less expensive tin sulfide (Sn2S3) back-surface field (BSF). At first, three buffer layer such as cadmium sulfide (CdS), zinc selenide (ZnSe) and indium-doped zinc sulfide ZnS:In have been simulated with CIGS absorber without BSF due to optimized and non-toxic buffer. Then the optimized structure of Al/FTO/ZnS:In/CIGS/Ni is modified to become Al/FTO/ZnS:In/CIGS/Sn2S3/Ni by adding a Sn2S3 BSF to enhanced efficiency. The detailed analysis have been investigated is the influence of physical properties of each absorber and buffer on photovoltaic parameters including layer thickness, carrier doping concentration, bulk defect density, interface defect density. This study emphasizes investigating the reasons for the actual devices' poor performance and illustrates how each device's might vary open-circuit voltage (VOC), short-circuit current density (JSC), fill factor (FF), power conversion efficiency (PCE), and quantum efficiency (QE). The optimized structure offers outstanding power conversion efficiency (PCE) of 21.83 % with only 0.80 µm thick CIGS absorber. The proposed CIGS-based solar cell performs better than the previously reported conventional designs while also reducing CIGS thickness and cost.