Investigating Removal Efficiency of Tetracycline Antibiotic from Aqueous Solutions Using Nanoclay Adsorbent and Study of Effective Parameters, Kinetic Models, and Adsorption Isotherms

Pharmaceutical contaminants are one of the most important environmental problems that must be cleared of aqueous environments before they enter the environment. Adsorption method is operationally easy and cost-effective if the adsorbent is not expensive. The purpose of this study is optimization the process of removal of tetracycline from aqueous solutions by nanoclay adsorbent and investigation the kinetics and adsorption isotherms. In this study, after preparing the nanoclay, optimization of parameters was done with Design Expert software. The parameters effect of pH, initial concentration and amount of adsorbent were investigated and SEM, XRD and FTIR analyzes were done to identify nanoclay properties. The optimal values ​​of parameters were pH equal to 9.5, adsorbent amount equal to 1.2 g and initial concentration equal to 21.15 mg /l at 25 °C, time of 30 min and stirring speed of 1000 rpm. The study of kinetic models and equilibrium isotherms showed that the adsorption follows the Pseudo-second Order (R2=0.999(   and   the Langmuir model, respectively. Under optimal condition, nanoclay as a low cost and environmentally friendly adsorbent has a good ability to adsorb tetracycline from aqueous solutions

Cadmium elimination from wastewater using potato peel biochar modified by ZIF-8 and magnetic nanoparticle

A recyclable and magnetic nanocomposite was fabricated from biochar of potato peel (BPP), MnFe2O4, and ZIF-8 (BET area: 174.92m2/g). The Cd2+ removal using BPP/MnFe2O4@ZIF-8 was maximized at pH 6, a temperature of 45 °C, and a time of 100 min. The capacity of Cd adsorption using BPP, BPP/MnFe2O4, and BPP/MnFe2O4@ZIF-8 was computed to be 33.76, 45.02, and 80.52 mg/g, respectively. The influence of coexistence ions on cadmium elimination by BPP/MnFe2O4@ZIF-8 was explored. Shipbuilding wastewater was treated to an acceptable level using the nanocomposite. The Cd adsorption was endothermic and followed the pseudo-second-order (R2 > 0.98). Therefore, BPP/MnFe2O4@ZIF-8 is an affordable material for treating cadmium

Denoising deep brain stimulation pacemaker signals with novel polymer-based nanocomposites: Porous biomaterials for sound absorption

Deep brain stimulation (DBS) pacemakers are sophisticated medical devices that deliver electrical signals to targeted areas of the brain via implanted electrodes, effectively regulating abnormal brain activity and relieving symptoms of treatment-resistant neurological disorders. However, proximity to other electromagnetic equipment may introduce additional noise, which can be disruptive to individuals. To mitigate this issue, we propose a novel polymer-based nanocomposite for pacemakers for signal denoising. This research focused on the development and analysis of nanocomposites comprising polypropylene (PP) combined with montmorillonite nanoclay and graphene nanosheets (GNs). The nanocomposites were created by blending them through melting, using varying ratios of clay to GNs, with a total loading of 4 wt.%. This study focused on enhancing the signal-to-noise ratio for brain pacemakers by using nanocomposites. It investigated the noise reduction properties of PP nanocomposites, specifically in the outlet gate of the pacemaker. This research aimed to find the ideal ratio of clay to GNs in the PP matrix. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were conducted to analyze the crystalline structure and filler dispersion, as well as thermal behavior and filler–matrix interactions in the material. Scanning electron microscopy was employed to observe the dispersion of the nanofillers in the PP, and sound tube testing was conducted to evaluate the noise levels of the composites. The findings indicated that a porous structure of the nanocomposite with dispersed microspheres within the PP matrix and a long pathway facilitated increased dissipation of acoustic waves, making it suitable for denoising in brain pacemakers. Furthermore, the nanocomposite containing 2.75 wt.% of nanoclay and 1.25 wt.% of graphene components within the polypropylene matrix demonstrated a favorable signal-to-noise ratio compared to other evaluated nanocomposites

Physical, mechanical, and antibacterial characteristics of bio-nanocomposite films loaded with Ag-modified SiO2 and TiO2 nanoparticles

In this study, starch-based films incorporating metal oxide (MO2) nanoparticles (NPs) of TiO2 and SiO2 (at a concentration of 1 to 4 wt. %) were produced by solution casting method. In order to exhibit antimicrobial properties, MO2 NPs were modified by synthesizing silver (Ag) ions over the NPs using cationic adsorption method. Ag ions were then reduced to metallic Ag by sodium borohydride solution. Scanning electron microscopy showed a smooth surface for the pure starch film. Incorporating MO2@Ag NPs in the films increased surface roughness with agglomerated NPs within starch matrix. Energy dispersive X-ray analysis exhibited a uniform dispersion of Ag-loaded MO2 NPs, which increases surface contact between these NPs and the biopolymer matrix leading to improved physical and mechanical properties of the resulting films. With increasing in the NPs concentrations, the tensile strength and elongation at break % of the films increased and decreased, respectively. Incorporating MO2@Ag NPs into starch matrix decreased solubility in water and water vapor permeability of the obtained films, and significantly inhibited the growth of Escherichia coli and Staphylococcus aureus. The most antibacterial effect was obtained for the films containing higher weight concentrations of Ag-loaded SiO2-NPs

Adsorption of crystal violet dye using activated carbon of lemon wood and activated carbon/Fe3O4 magnetic nanocomposite from aqueous solutions: a kinetic, equilibrium and thermodynamic study

Activated carbon prepared from lemon (Citrus limon) wood (ACL) and ACL/Fe3O4 magnetic nanocomposite were effectively used to remove the cationic dye of crystal violet (CV) from aqueous solutions. The results showed that Fe3O4 nanoparticles were successfully placed in the structure of ACL and the produced nanocomposites showed superior magnetic properties. It was found that pH was the most effective parameter in the CV dye adsorption and pH of 9 gave the maximum adsorption efficiency of 93.5% and 98.3% for ACL and ACL/Fe3O4, respectively. The Dubinin–Radushkevich (D-R) and Langmuir models were selected to investigate the CV dye adsorption equilibrium behavior for ACL and ACL/Fe3O4, respectively. A maximum adsorption capacity of 23.6 and 35.3 mg/g was obtained for ACL and ACL/Fe3O4, respectively indicating superior adsorption capacity of Fe3O4 nanoparticles. The kinetic data of the adsorption process followed the pseudo-second order (PSO) kinetic model, indicating that chemical mechanisms may have an effect on the CV dye adsorption. The negative values obtained for Gibb’s free energy parameter (−20 < ΔG < 0 kJ/mol) showed that the adsorption process using both types of the adsorbents was physical. Moreover, the CV dye adsorption enthalpy (ΔH) values of −45.4 for ACL and −56.9 kJ/mol for ACL/Fe3O4 were obtained indicating that the adsorption process was exothermic. Overall, ACL and ACL/Fe3O4 magnetic nanocomposites provide a novel and effective type of adsorbents to remove CV dye from the aqueous solutions

Decoration of Citrus limon wood carbon with Fe3O4 to enhanced Cd2+ removal: A reclaimable and magnetic nanocomposite

In the present study, the activated carbon of lemon (ACL) was generated from Citrus limon wood waste and composited with Fe3O4 nanoparticles. The ACL/Fe3O4 magnetic composite was effectively used to eliminate Cd2+ from an aqueous solution. The active surface area values for ACL and ACL/Fe3O4 magnetic composite were 25.99 m2/g and 38.70 m2/g, respectively indicating the effectiveness of Fe3O4 nanoparticles in improving ACL active surface area. The response surface methodology with central composite design (RSM-CCD) was used to determine optimal values of pH, ACL/Fe3O4 dose, contact time, and Cd2+ concentration on the decontamination efficiency. The Langmuir and Freundlich isotherm models had more potential to describe the adsorption process using ACL and ACL/Fe3O4, respectively. The Langmuir-based adsorption capacity was obtained as 28.2 mg/g (ACL) and 39.6 mg/g (ACL/Fe3O4). A pseudo-second order (PSO) model was successfully applied to evaluate the adsorption process kinetic behavior. A higher value of α parameter for ACL/Fe3O4 (5.7 mg/g.min) than that of ACL (3.5 mg/g.min) indicated that the magnetic composite had a greater tendency to absorb Cd2+. In addition, the Weber–Morris model showed that various mechanisms such as intraparticle diffusion and boundary layer effects may have a role in the adsorption process. The study of ad(de)sorption behavior showed that the adsorbents have a good ability to adsorb Cd2+ and no significant change in their performance has been made up to 4 times of reuse. Our results showed that ACL modification using Fe3O4 nanoparticles improved the adsorption efficiency of ACL to remove Cd2+ from the aqueous solutions. © 2021 Elsevier Lt

Physical, Mechanical and Antibacterial Properties of Nanobiocomposite Films Bosed on Carboxymethyl Cellulose/Nanoclay

Hypothesis: In order to achieve safe and high-quality food products, the use of suitable packaging materials with excellent physical and chemical properties is a key requirement. Pollution resulting from packaging materials made of oil-based plastics and the problems associated with burning, disposal and recycling of these plastic products have attracted the attention of researchers to find appropriate solutions in recent years. Carboxymethyl cellulose (CMC) is one of the important polysaccharide polymers with capability of producing transparent films with relatively good mechanical and inhibition properties that have been used broadly in studies concerning the food stuff packaging. Methods: Nanocomposite films have been prepared by solution casting method in the presence of clay nanoparticles. Pure and modified montmorillonite noanoparticles and Cloisite 30B along with silver and copper were used for improving the functional properties of carboxymethyl cellulose nanobiocomposite films.Findings: It was observed that the clay nanoparticles incorporated into the nanocomposite films increased the UV absorption and mechanical properties and reduced the vapor permeability of the films. The XRD results showed that the silver was successfully inserted into the gallery space of the nanoclay, because the basal spacing of Ag-modified Cloisite 30B increased from 1.841 nm to 1.855 nm. Also, the compatibility of the nanoparticles with carboxymethyl cellulose was examined by SEM images. The SEM micrographs showed that the Cloisite 30B nanoparticles displayed better interface compatibility with CMC films than Na-montmorillonite. The results of antimicrobial tests showed that the nanobiocomposite film containing 4 wt% of Ag-modified Cloisite 30B exhibited maximum antimicrobial property against Staphylococcus aureus and Escherichia coli bacteria

Cadmium ion removal from aqueous media using banana peel biochar/Fe3O4/ZIF-67

In the present study, banana peel waste was used as a suitable source for biochar production. The banana peel biochar (BPB) was modified using Fe3O4 magnetic and ZIF-67 nanoparticles. The modification of the BPB surface (4.70 m2/g) with Fe3O4 and Fe3O4/ZIF-67 significantly increased the specific surface of the nanocomposites (BPB/Fe3O4: 78.83 m2/g, and BPB/Fe3O4/ZIF-67: 1212.40 m2/g). The effect of pH, temperature, contact time, adsorbent dose, and concentration of Cd2+ on the efficiency of the Cd2+ adsorption was explored. Maximum adsorption efficiencies for BPB (97.76%), BPB/Fe3O4 (97.52%), and BPB/Fe3O4/ZIF-67 (99.14%) were obtained at pH 6, Cd2+ concentration of 10 mg/L, times of 80 min, 50 min, and 40 min, and adsorbent doses of 2 g/L, 1.5 g/L, and 1 g/L, respectively. Thermodynamic measurements indicated that the process is spontaneous and exothermic. The maximum capacity of Cd2+ adsorption using BPB, BPB/Fe3O4, and BPB/Fe3O4/ZIF-67 were obtained 20.63 mg/g, 30.33 mg/g, and 50.78 mg/g, respectively. The Cd2+ adsorption using magnetic nanocomposites followed the pseudo-first-order kinetic model. The results showed that studied adsorbents especially BPB/Fe3O4/ZIF-67 have a good ability to adsorb-desorb Cd2+ and clean an effluent containing pollutants

Development of new magnetic adsorbent of walnut shell ash/starch/Fe3O4 for effective copper ions removal: Treatment of groundwater samples

The goal of this investigation was to develop a new magnetic nanocomposite of walnut shell ash (WSA)/starch/Fe3O4 to remove Cu (II) present in groundwater samples. The desired nanocomposites were successfully synthesized by the chemical deposition method. The specific active surface area for pristine WSA and WSA/starch/Fe3O4 magnetic nanocomposites was determined to be 8.1 and 52.6 m2/g, respectively. A central composite design for the response surface method was utilized to study the influence of pH, adsorbent quantity, initial content of Cu (II), temperature, and contact time. This method showed the success of the model to design process variables and to estimate the appropriate response. The P- and F-value determined for the quadratic polynomial model showed the significance and accuracy of the proposed model in examining experimental and predicted data with R2 and Adj.R2 of 0.994 and 0.991, respectively. The Cu adsorption onto WSA and WSA/starch/Fe3O4 obeyed the Freundlich and Langmuir models, respectively. The highest Cu (II) sorption capacity of 29.0 and 45.4 mg/g was attained for WSA and WSA/starch/Fe3O4, respectively. The free energy of Gibbs had a negative value at 25–45 °C indicating that the adsorption process is spontaneous. Also, negative ΔH values for copper adsorption showed that the processes are exothermic. The kinetic adsorption data for WSA and WSA/starch/Fe3O4 followed the pseudo-second order (PSO) model. The ability of the composite adsorbent to remove copper from three groundwater samples showed that it could be reused at least 3 times with appropriate efficiency, depending on the water quality

Generation of biodiesel from edible waste oil using ZIF-67-KOH modified Luffa cylindrica biomass catalyst

To produce biodiesel from edible waste oil, a new heterogeneous catalyst based on Luffa cylindrica biomass was used. For this purpose, first, Luffa cylindrica carbon was modified using zeolite imidazole metal-organic framework (ZIF-67) and KOH and used in the biodiesel production. Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Powder Diffraction (XRD), Brunauer–Emmett–Teller (BET), Transmission Electron Microscopy (TEM), Raman, and Thermogravimetric Analysis (TGA) techniques were used to investigate the properties of the synthesized catalyst. BET values for activated carbon of Luffa cylindrica (ACL), ZIF-67, ACL/ZIF-67, and ACL/ZIF-67/KOH samples were determined to be 99.714, 1695.7, 956.99, and 2.322 m2/g, respectively, indicating that modification of biomass using ZIF-67 improved its specific active surface, which can retain more KOH in the pores of catalyst. To evaluate the ability of the synthesized catalyst, the effect of various parameters such as reaction time, temperature, amount of catalyst, the molar ratio of oil to methanol, and mixing speed were investigated. The results showed good catalytic activity in converting edible waste oil to biodiesel and maximum efficiency of biodiesel production (98.31%) in laboratory conditions such as a temperature of 65 °C, a catalyst concentration of 3 wt%, a reaction time 3 h, a methanol: oil ratio of 15:1 and a mixing speed of 600 rpm. After determining the optimal laboratory conditions, the study of regeneration and reuse of the catalyst showed that the catalyst had a suitable catalytic activity and can use more than 4 steps in the biodiesel production process. The properties of biodiesel obtained under optimal conditions were evaluated according to the international standards (ASTM D6751 and EN-14214). The results showed that the produced biodiesel possess suitable properties and can replace fuels derived from fossil fuels