The present work reports the adsorption behavior involved in the adsorption of heavy metal ions using a hybrid inulin-tetraethoxysilane (TEOS) adsorbent produced through the sol-gel process. An aqueous multi-element solution was used in order to examine the inulin-TEOS adsorbent efficiency in removing Cd2+, Co2+, and Ni2+ ions. The effects of the contact duration, adsorbent dosage, initial concentration, and solution pH on the adsorption of the targeted metal ions in batch systems were evaluated. The optimal conditions for the removal of all targeted heavy metals were as follows: 30 mg of an adsorbent dosage at pH 4 and 5 minutes of contact time with an initial concentration of 0.5 mg/L. A one-way analysis of variance (one-way ANOVA) with a replication test showed that all parameters had significant differences at a p-value of 0.05. At the optimum condition, 92.59%, 90.27%, and 86.472% of Cd2+, Ni2+, and Co2+ were removed, respectively. Findings from kinetic studies suggest that the pseudo-second order model can successfully describe the overall adsorption process. Additionally, the adsorption process can be adequately explained using an intra-particle diffusion model with diffusion rate constants following the sequence of Kint,1 > Kint,2 for Co2+ and Ni2+ and Kint,1 > Kint,2 > Kint,3 for Cd2+ in each step. The results suggest that Ni2+ fits with the Langmuir isotherm, while Cd2+ and Co2+ better fit the Freundlich one. Finally, the adsorbent can be reused and is able to retain a good percentage of removal, with percentage difference decreases of 1.99%, 3.29%, and 4.12% for Cd2+, Ni2+, and Co2+, respectively, after the fifth cycle. The hybrid inulin-TEOS bio-sorbent has good adsorption capacity and durability, which could offer a low-cost practical cleaner production process for removing targeted analytes from wastewater. Doi: 10.28991/CEJ-2022-08-09-03 Full Text: PDF

A new biopolymer–silica hybrid material consisting of inulin and tetraethoxysilane (TEOS) for use as an adsorbent was successfully synthesized via the sol–gel method in acidic conditions. The hydrolysis and condensation processes were attained in water/ethanol solution. Three molar ratios of inulin:TEOS (1:1, 1:2, and 2:1) were prepared and dried at various temperatures (50, 60, and 70 °C). The optimized molar ratio of 2:1 with a drying temperature of 70 °C was found to obtain the best morphology and characteristics for absorbent properties. Fourier transform infrared spectroscopy (FTIR) analysis showed a strong interaction between inulin and TEOS, which was also observed using energy dispersive X-ray spectroscopy (EDX). Field emission scanning electron microscopy (FESEM) images revealed the presence of nanoparticles on the rough surface of the hybrid sol–gel. X-ray diffractometer (XRD) analysis showed the amorphous state of the silica network where the inulin existed as an anhydrous crystalline phase. Brunauer–Emmet–Teller (BET) analysis confirmed that the composite was mesoporous, with 17.69 m2/g surface area and 34.06 Å pore size. According to thermogravimetric analysis (TGA) results, the hybrid inulin-TEOS adsorbent was thermally stable under a temperature of 200 °C.

A new hydrophobic hexyltrimethoxysilane (HTMS) coating for polyester fabric was successfully synthesized via a one-step water-based sol-gel method under acidic condition. Five different molar ratios of HTMS: water (1;40, 1:30, 1:20, 1:12 and 1:3) were prepared and the solution was deposited onto the polyester fabric by a simple dip-pad-cure process. The effect of water content on hydrophobicity was evaluated by manual testing on the treated polyester fabric samples. The effectiveness of hydrophobicity properties was further characterized using water contact angle (WCA) measurement. The optimized molar ratio of 1:3 was found to obtain the best hydrophobic property of 136.2° with particle size 115.3 µm measured using Particle Size Analyzer (PSA). Fourier transform infrared spectroscopy (FTIR) analysis confirmed the success of sol gel process with the presence of Si-O-Si band, which was also determined using energy dispersive X-ray spectroscopy (EDX). The Scanning Electron Microscopy (SEM) images revealed a good surface morphology of the homogenous thin xerogel coating with no visible cracks. Using HTMS without combinations of other precursors resulted in rough surface structure due to the low surface energy caused by long-chain alkyl silane in the HTMS coating and this provided the treated polyester fabric with good hydrophobicity. Doi: 10.28991/esj-2021-01309 Full Text: PDF