Chitosan-based membranes comprising pristine chitosan (CS), PEG 4000-blended chitosan (CP), and PEG 4000-blended chitosan crosslinked with malonic acid (COP), malic acid (CAP), and adipic acid (CDP) were prepared at casting volumes of 5, 7.5, and 10 mL for potential hemodialysis applications. This study evaluated the effects of PEG blending, crosslinker type, and membrane thickness on physicochemical properties, solute transport, and hemocompatibility. FTIR analysis revealed changes in O–H, N–H, C=O, and C–N bands, suggesting hydrogen bonding between chitosan and PEG and ionic interactions between protonated amino and carboxylate groups. Zeta potential values ranged from +55.8 to +74.58 mV. AFM analysis showed that CAP had the highest average roughness (Ra) and root-mean-square roughness (Rq), whereas CDP exhibited the highest maximum height (Rz). PEG blending and dicarboxylic acid crosslinking improved porosity, swelling, water uptake, pH stability, and biodegradability. Increasing casting volume increased membrane thickness, mechanical properties, porosity, and swelling but decreased 6-hour water uptake and solute transport, potentially due to longer diffusion pathways. The 5 mL CAP membrane achieved the highest solute transport, with urea transport increasing from 28.06% for CS to 61.16% and creatinine transport from 14.34% for CS to 49.68%. The modified membranes also retained larger molecules, including vitamin B12 and bovine serum albumin (BSA). The CAP membrane exhibited the lowest hemolysis (0.39%), the lowest thrombus formation (40.36%), and the longest Partial Thromboplastin Time (PTT) (176 s). Overall, CAP demonstrated balanced performance, highlighting its potential for hemodialysis membrane development.
Cadmium (Cd) heavy metal pollution from industrial activities poses a serious threat to aquatic ecosystems and human health. This study focuses on creating Cd(II)-imprinted polymers (Cd(II)-IPs) as selective adsorbents for Cd(II) ions and assessing the ability of extractant agents to form specific cavities within the polymer structure. The adsorbent’s ability to regenerate was also analyzed to support the development of eco-friendly adsorbents. Cd(II)-IPs were made using 8-hydroxyquinoline, methacrylic acid, ethylene glycol dimethacrylate, and azobisisobutyronitrile. The Cd(II) ions were extracted from the polymer matrix with HNO3, HCl, and H2SO4. The results showed that HNO3 was the most effective extractant for releasing Cd(II) ions from the polymer, yielding a selective Cd(II) adsorbent with an adsorption capacity of 63.46 mg/g. X-ray diffraction analysis confirmed the successful removal of Cd(II) ions, as indicated by the disappearance of the characteristic peak of Cd(NO3)2·4H2O after extraction with HNO3. Brunauer–Emmett–Teller (BET) analysis showed that Cd(II)-IPs had a larger surface area, pore volume, and pore diameter compared to non-imprinted polymers (NIPs) as a control. Cd(II)-IPs could retain adsorption activity and competitive performance after repeated regeneration, with a regeneration ability of up to five adsorption-desorption cycles and a recovery efficiency of 21.2%. Cd(II)-IPs have the potential to be applied in selective and sustainable industrial wastewater treatment.
This study aimed to synthesize two new complexes, [Co(3-ampy)2(Bz)2(H2O)] (1) and [Ni(μ-3-ampy)2(Bz)2(H2O)]n (2), as antibacterial agents (3-ampy = 3-aminopyridine; Bz = benzoate). The complexes were synthesized by reacting cobalt(II) chloride or nickel(II) chloride with 3-ampy and sodium benzoate at a molar ratio of 1:2:2. The reactions were stirred at 40°C for 4 h and 3.5 h, respectively. The products were characterized using melting point analysis, electrical conductivity measurements, ATR-FTIR, SEM-EDX, SC-XRD, and UV–Vis spectroscopy. Hirshfeld surface analysis and antibacterial assays were also performed against Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 23235) using the disc diffusion method. Complexes 1 and 2 formed elongated prismatic red crystals and plate-shaped dark green crystals, respectively. Their melting points were 127–129°C and 224–226°C, respectively, and both were non-electrolytes in methanol. Complex 1 exhibited distorted octahedral geometry and crystallized in the monoclinic system, with benzoate ions coordinating in monodentate and bidentate modes. Its coordination environment was associated with d–d and ligand-to-metal charge-transfer (LMCT) bands in the UV–Vis spectrum. At equal mass concentrations, the complexes exhibited antibacterial activity with inhibition zones of 4.90–13.67 mm, whereas the free ligands showed no activity. Complex 1 inhibited E. coli and S. aureus, with inhibition zones of 12.20 and 13.67 mm, respectively. In contrast, complex 2 showed limited activity against E. coli (4.90 mm) and no activity against S. aureus (0.00 mm). The cobalt(II) complex exhibited broader antibacterial activity than the nickel(II) complex against the tested bacterial strains.
This study explores the use of vermicompost humic acid (VCHA) as a low-cost, eco-friendly adsorbent for the removal of Pb(II) from artificial liquid waste. VCHA was extracted and purified from vermicompost, then characterized using SEM-EDS, FTIR, and UV-Vis to determine its surface morphology, elemental composition, and functional groups. The characterization results confirmed the presence of oxygen-containing functional groups, such as carboxylate and phenolic hydroxyl groups, which are involved in metal binding. Adsorption studies demonstrated that the optimum pH for Pb(II) removal was 4, achieving a maximum removal efficiency of 96.78%. Equilibrium data were best fitted by the Langmuir isotherm model, yielding a maximum calculated adsorption capacity (qmax) of 129.05 mg/g. Kinetic data aligned most closely with the Ho pseudo-second-order model (kHo = 0.0012 g/mg), indicating that the rate of adsorption is governed by chemical interactions between Pb(II) ions and VCHA surface sites. These findings highlight the significant potential of VCHA as a waste-derived adsorbent for removing Pb(II) from an artificial liquid waste system.
The use of non-edible oil as a raw material and the use of biomass waste as a catalyst in the biodiesel production process is a strategic step due to the various advantages it offers. Palm acid oil (PAO), which is a waste from the palm oil processing industry, has great potential to be used as a raw material in biodiesel production, while rice husks can be processed and their properties modified to be used as a catalyst in the biodiesel formation reaction. This study aims to determine the characteristics and catalytic performance of sulfonated activated carbon from rice husks in the synthesis of biodiesel from PAO. Biodiesel was synthesized at various molar ratios of PAO to methanol of (1:16), (1:24), and (1:32). The reaction was carried out at a temperature of 65°C for 2 hours, with catalyst levels varied at 2, 3, and 5%. The results of the study showed that the best catalytic performance of sulfonated rice husk activated carbon in the synthesis of biodiesel from PAO was achieved at a mole ratio of PAO to methanol of (1:32) and a catalyst content of 2%. Under these synthesis conditions, the highest degree of conversion of free fatty acids into biodiesel was achieved, namely 85.08%, and biodiesel was produced with a yield of 99.20%. Further quality parameter testing of the biodiesel obtained density, kinematic viscosity, acid number, iodine number, cetane number, total glycerol content, and methyl ester content of biodiesel were 861.12 kg/m3, 5.38 mm2/s, 2.88 mg KOH/g, 63.45 g I2/100 g, 62.51, 0.29%, and 95.37%, respectively.
