Fabrication, characterization, and dye adsorption capability of recycled modified polyamide nanofibers

One-Step Fabrication of Novel Polyethersulfone-Based Composite Electrospun Nanofiber Membranes for Food Industry Wastewater Treatment

Using an environmentally friendly approach for eliminating methylene blue from an aqueous solution, the authors developed a unique electrospun nanofiber membrane made of a combination of polyethersulfone and hydroxypropyl cellulose (PES/HPC). SEM results confirmed the formation of a uniformly sized nanofiber membrane with an ultrathin diameter of 168.5 nm (for PES/HPC) and 261.5 nm (for pristine PES), which can be correlated by observing the absorption peaks in FTIR spectra and their amorphous/crystalline phases in the XRD pattern. Additionally, TGA analysis indicated that the addition of HPC plays a role in modulating their thermal stability. Moreover, the blended nanofiber membrane exhibited better mechanical strength and good hydrophilicity (measured by the contact angle). The highest adsorption capacity was achieved at a neutral pH under room temperature (259.74 mg/g), and the pseudo-second-order model was found to be accurate. In accordance with the Langmuir fitted model and MB adsorption data, it was revealed that the adsorption process occurred in a monolayer form on the membrane surface. The adsorption capacity of the MB was affected by the presence of various concentrations of NaCl (0.1–0.5 M). The satisfactory reusability of the PES/HPC nanofiber membrane was revealed for up to five cycles. According to the mechanism given for the adsorption process, the electrostatic attraction was shown to be the most dominant in increasing the adsorption capacity. Based on these findings, it can be concluded that this unique membrane may be used for wastewater treatment operations with high efficiency and performance.

Bioremediation of potentially toxic metal and reactive dye-contaminated water by pristine and modified Chlorella vulgaris

This is the first study on the biosorption of Cu²⁺ and reactive yellow 145 (RY145) dye by citric acid (CA), NaOH, and heat-treated Chlorella vulgaris (Cv). Influence of contact time, initial adsorptive concentration, and biomass dosage on the biosorption process was explored. The biosorption kinetics and isotherm were comprehensively investigated as well. The Fourier transform infrared analysis proved the successful insertion of carbonyl groups on Cv surface by CA modification and the intensification of all Cv functional groups by heat treatment. CA modified Cv was the best biosorbent for RY145, 0.5 g/L removes 97% of 10 mg/L solution (pH_i 2) in 40 min. The biosorption was favorable, occurred via the formation of a monolayer of RY145 on the homogenous surface of CA-modified Cv and followed the pseudo-second-order kinetics. On the other hand, heat-treated Cv was the best biosorbent for Cu²⁺, 0.5 g/L removes 92% of 10 mg/L solution (pH_i 5) in 5 min. The biosorption of Cu²⁺ on heat-treated Cv was complex and involves more than one mechanism. The Langmuir theoretical monolayer saturation capacity of RY145 on CA-modified Cv was comparable to other biosorbents, while that of Cu²⁺ on heat-treated Cv was drastically superior.

Removal of Hazardous Contaminants from Water by Natural and Zwitterionic Surfactant-modified Clay

In this study, natural clay (NC) was collected from Saudi Arabia and modified by cocamidopropyl betaine (CAPB) at different conditions (CAPB concentration, reaction time, and reaction temperature). NC and modified clay (CAPB-NC) were characterized using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, and N2 adsorption at 77 K. The adsorption efficiency of NC and CAPB-NC toward Pb2+ and reactive yellow 160 dye (RY160) was evaluated. The adsorption process was optimized in terms of solution initial pH and adsorbent dosage. Finally, the adsorption kinetics and isotherms were studied. The results indicated that NC consists of agglomerated nonporous particles composed of quartz and kaolinite. CAPB modification reduced the specific surface area and introduced new functional groups by adsorbing on the NC surface. The concentration of CAPB affects the adsorption of RY160 tremendously; the optimum concentration was 2 times the cation exchange capacity of NC. The equilibrium adsorption capacity of CAPB-NC toward RY160 was about 6 times that of NC and was similar for Pb2+. The adsorption process followed the pseudo-second-order kinetics for both adsorptive. RY160 adsorption on CAPB-NC occurs via multilayer formation while Pb2+ adsorption on NC occurs via monolayer formation..

Facile Synthesis of Porous Carbon for the Removal of Diclofenac Sodium from Water

In this work, a series of porous carbon materials (PCs) were obtained at different carbonization temperatures (800, 900, 1000, and 1100 °C) by a simple and fast solvent-free method. Moreover, the feasibility of PCs as reliable and efficient adsorbents to capture diclofenac sodium (DCF) from the water was evaluated. Notably, porous carbon (PC) prepared at 1000 °C (PC-1000) was found to be the best candidate for the adsorption of DCF. Remarkably, adsorption equilibrium was achieved within 3 h, which followed a pseudo-second-order kinetic model with a high correlation coefficient (R ² > 0.994). Furthermore, experimental data obtained from adsorption isotherm indicated that the capture of DCF onto PC-1000 followed the Langmuir adsorption model (R ² > 0.997), wherein its maximum adsorption capacity was calculated to be 392 mg/g. In addition, based on the results obtained from the zeta potential of PC-1000 under different pH and the adsorbed quantity of DCF along with functional groups created on the surface of PC-1000, electrostatic and H-bonding interactions were proposed as the possible adsorption mechanisms. Due to its high stability and excellent reusability, PC-1000 has been testified as a promising candidate for removing DCF from contaminated water.