Recently, a great attention has been given for applying a low-cost and effective adsorbents instead of expensive and dangerous chemical materials as a promising approach to treat wastewater. In this work, residue powder of brown macroalga Padina gymnospora (RPG), after extracting most of its active components by 70% methanol, was used as an adsorbent material for wastewater treatment. This work also reduces the costs of residue disposal. The adsorption ability of RPG is studied for removing Cd2+ and Cr3+from wastewater. We investigated metal adsorption isotherms and kinetics, the effect of initial metal concentration, contact time, adsorbent dosage, temperature, pH and the RPG reusability on metal ions removal. The results showed that the removal % generally increases with decreasing concentration of metal ions. RPG has higher metal removal percentages reaching 96.2% and 78.8% for Cd2+ and Cr3+, respectively, with a maxiumum adsorption capacity of 96.46 and 31.52 mg/g for Cd 2+ and Cr3+,respectively at pH 6.2, 50 mg, 25 °C and initial metal concentration of 100 mg/L. The metal ions removal % increased by increasing the dosage of adsorbent and it decreased after a certain limit. The metal removal % slightly changes with increasing temperature for Cd2+ and decreased at high-temperature for Cr3+. The adsorption increased with increasing pH value from 3 to 5, and decreases at pH value of 6.2 then it increased again at pH 8. The removal % and adsorption capacity at pH 8 reaches 99.58%, 99.65%, 99.85 mg/g and 39.86 mg/g for Cd2+ and Cr3+, respectively. The results also showed that RPG can be reused several times for metal ions removal. In addition, Tempkin isotherms and pseudo-second-order kinetic fit the adsorption of Cd2+ and Cr3+ well.

Different novel 1,2,4-triazolo[4,3-b][1,2,4,5]tetrazines and 1,2,4-triazolo[4,3-b][1,2,4]triazines have been obtained from heterocyclization of 3-substituted-4-amino-5-substituted-amino-1,2,4-triazoles (3a-d) and 3-substituted-4-amino-5-hydrazino-1,2,4-triazoles (9a,b) with (α and β) bifunctional compounds like chloromethyl biphenyl-phosphanoxide, pyruvic acid, phenacyl bromide, diethyl oxalate, triethyl orthoformate, triethyl phosphite, fluorinated benzaldehydes, carbon disulfide and ethyl chloroformate under different experimental settings. Fourier transformer infrared analysis (FTIR), Proton nuclear magnetic resonance (¹H NMR) and ¹³C nuclear magnetic resonance (¹³C NMR), as well as that of the mass spectral data, were used as the appropriate characterization techniques for the chemical structures of all newly synthesized compounds. The newly prepared compounds were examined as an anti-inflammatory, antibacterial agents (against E. coli (Escherichia coli) and P. aeruginosa (Pseudomonas aeruginosa) as examples for Gram-negative bacteria and S. aureus (Staphylococcus aureus) as examples for Gram-positive bacteria), as well as antifungal (against C. albicans (Candida albicans)) agents. The newly prepared compound showed high antibacterial, antifungal, and anti-inflammatory activities in comparing with the commercial antibiotics Indomethacin, Nalidixic acid, Imipenem, and Nystatin. Docking of the most active compounds was performed depending on the results of antibacterial screening and the anti-inflammatory assay.

Systematic investigations involving laboratory, analytical, and field trials were carried out to obtain the most efficient adsorbent for the removal of congo red (CR) dye from industrial effluent. Modification of the zeolite (Z) by the Acanthophora Spicifera algae (AS; marine algae) was evaluated in terms of adsorption capability of the zeolite to remove CR dye from aqueous solution. The zeolite/algae composite (ZAS) was fabricated using the wet impregnation technique. The AS, Z, and the synthesized ZAS composite were analyzed utilizing various characterization techniques. The newly synthesized ZAS composite has an adsorption capacity that is significantly higher than that of Z and AS, particularly at low CR concentrations. Batch experiments were carried out to explore the effects of different experimental factors, as well as the dye adsorption isotherms and kinetics. Owing to the presence of intermolecular interactions, the computational analysis showed that the adsorption of the CR molecule on zeolite surfaces is exothermic, energetically favorable, and spontaneous. Furthermore, growing the zeolite surface area has no discernible effect on the adsorption energies in all configurations. The ZAS composite may be used as a low-cost substitute adsorbent for the removal of anionic dyes from industrial wastewater at lower dye concentrations, according to the experimental results. Adsorption of CR dye onto Z, AS, and ZAS adsorbents was adequately explained by pseudo-second-order kinetics and the Langmuir isotherm. The sorption mechanism was also evaluated using Weber’s intra-particle diffusion module. Finally, field testing revealed that the newly synthesized adsorbent was 98.0% efficient at extracting dyes from industrial wastewater, proving the foundation of modern eco-friendly materials that aid in the reuse of industrial wastewater.

A dependent step-by-step study that included experimental and field study was applied to explore the simplest and most effective system that could be applied for adsorption of Congo Red (CR) dye from the effluent of wastewater that comes out from different industries. Zeolite (Z) surface and pores were subjected to a modification process using green seaweed (GS) algae. Thereafter, each Z, GS, and composite from both were evaluated based on the adsorption efficacy to clean up CR dyes from aqueous solutions. A wet impregnation method was followed to fabricate the zeolite/algae (ZGS) nanocomposite which was characterized using the most appropriate characterization techniques. Batch experiments were selected to be the method of choice in order to follow up the performance of the adsorption process versus different practical variables. Moreover, dye adsorption kinetics and isotherms were investigated as well. At lowered concentrations of CR, the novel nanocomposite ZGS revealed more efficacy than its counterparts, Z and GS, in terms of the adsorption capacity. The maximum adsorption capacities were found to be 8.10, 10.30, and 19.70 mg/g for Z, GS, and ZGS, respectively. Laboratory tests confirmed that the novel nanocomposite ZGS could be introduced as a new and economical nanoadsorbent to capture and remove negatively charged dyes from wastewater effluents that come out from industries at lower concentrations of CR dye and analogous compounds. The dye adsorption on GS, Z, and ZGS coincide with the pseudo-first, Langmuir isotherm, and second-order models. Evaluation for the sorption mechanism was conducted using a diffusion model known as Weber’s intraparticle. Depending on the last findings, field experiments on removing dyes from industrial wastewater revealed optimistic findings as the efficiency of our modern and eco-friendly nanoadsorbent reached 91.11%, which helps in the reuse of industrial wastewater.

A comprehensive study that combined both experimental and computational experiments was performed to evaluate the usage of organo-metal oxide nanocomposite for the elimination of disperse red 60 dye (DR) from aqueous solutions. Chitosan was modified by Schiff base to form nanoneedles chitosan-4-chloroacetophenone derivative. The derivatives were then impregnated with CeO₂–CuO–Fe₂O₃ or CeO₂–CuO–Al₂O₃ metal oxides to prepare a novel quarternary organo-metal oxide nanocomposite. The novel nanocomposite, chitosan-4-chloroacetophenone/CeO₂–CuO–Fe₂O₃ (CF) and chitosan-4-chloroacetophenone/CeO₂–CuO–Al₂O₃ (CA) are cheap and effective nano adsorbents that can be used for the uptake of DR from aqueous solution. The CF and CA nano-composites were characterized using different techniques. Moreover, the effect of adsorption parameters (initial DR concentration, time of contact, pH, temperature, and adsorbent mass) as well as CA and CF reusability tests were performed. Langmuir adsorption isotherm and pseudo-second-order kinetics models were best fitted with the adsorption process. The maximum amount of DR adsorbed was 100 mg/g on CF and CA at pH 2 and 4, respectively with a physical spontaneous, and exothermic adsorption process. Monte Carlo (MC) simulation studies indicated the adsorption of DR molecule on the CF and CA surfaces following a parallel mode in most of all studied configurations, confirming the strong interactions between the DR and surfaces atoms of CF and CA. The molecular structure analysis of DR dye adsorbed on the surface of CF and CA indicated that the adsorption process related to Van der Waals dispersion force. Consequently, this helps to trap DR dye molecules on the surface of CF and CA (i.e., physical adsorption), which supports our experimental results.

Despite the superiority of glass-ionomer cements (GICs) over composites in treating white spot lesions (WSLs), there is still a concern about their preventive and antibacterial properties. Efforts have been made to improve the strength of their bond to demineralized enamel, fluoride release and antibacterial properties by adding nanoparticles of chitosan, which seems to be a promising method. The aim of the present study was to assess the antibacterial effect, the microshear bond strength (μSBS) to enamel at the WSL area, and the fluoride and nano-chitosan release after modifying the polyacrylic acid liquid phase of a traditional GIC with different nano-chitosan volumes. A total of 120 samples were prepared, and then divided into 4 groups (n = 30): G1 - non-modified GIC, which served as a control group, while G2, G3 and G4 were modified with different nano-chitosan volumes (50%, 100% and 150%, respectively). Microshear bond strength was assessed using a universal testing machine (UTM) after storage in distilled water for 24 h. Fluoride and nanochitosan release was measured with the use of spectrophotometers at different time points (initially, and at 1 h, 24 h, 48 h, 72 h, 1 week, 2 weeks, 3 weeks, and 6 weeks) after storage in distilled water. The antibacterial effect against the Streptococcus aureus strain was assessed with the agar diffusion test. The data was statistically analyzed. After 24-hour storage, G2 recorded a slight, yet non-significant, increase in the μSBS values (4.1 ±0.94 MPa) as compared to G1 (3.9 ±1.30 MPa). With regard to fluoride release, the amount recorded for G1 was significantly greater at the end of the 24-hour storage period (0.70 ±0.30 μmf/cm2) than modified nano-chitosan GIC groups; G1 was followed by G4 (0.54 ±0.34 μmf/cm2). The highest amount of nano-chitosan release after 24-hour storage was noted for G3 (0.85 ±0.00 μmf/cm2). The highest inhibition zone value was recorded for G2. Glass-ionomer cement modified with 50% nano-chitosan was shown to positively affect μSBS and the antibacterial effect, while modification with 150% nano-chitosan significantly increased fluoride release.