Fabrication and Application of Zeolite/Acanthophora Spicifera Nanoporous Composite for Adsorption of Congo Red Dye from Wastewater

Modeling of methylene blue removal on Fe3O4 modified activated carbon with artificial neural network (ANN)

In this study, AC/Fe3O4 adsorbent was first synthesized by modifying activated carbon with Fe3O4. The structure of the adsorbent was then characterized using analysis techniques specific surface area (BET), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), and Fourier Transform Infrared Spectroscopy (FTIR). Equilibrium, thermodynamic and kinetic studies were carried out on the removal of methylene blue (MB) dyestuff from aqueous solutions AC/Fe3O4 adsorbent. The Langmuir maximum adsorption capacity of AC/Fe3O4 was 312.8 mg g-1, and the best fitness was observed with the pseudo-second-order kinetics model, with an endothermic adsorption process. In the final stage of the study, the adsorption process of MB on AC/Fe3O4 was modeled using artificial neural network modeling (ANN). Considering the smallest mean square error (MSE), The backpropagation neural network was configured as a three-layer ANN with a tangent sigmoid transfer function (Tansig) at the hidden layer with 10 neurons, linear transfer function (Purelin) the at output layer and Levenberg-Marquardt backpropagation training algorithm (LMA). Input parameters included initial solution pH (2.0-9.0), amount (0.05-0.5 g L-1), temperature (298-318 K), contact time (5-180 min), and concentration (50-500 mg L-1). The effect of each parameter on the removal and adsorption percentages was evaluated. The performance of the ANN model was adjusted by changing parameters such as the number of neurons in the middle layer, the number of inputs, and the learning coefficient. The mean absolute percentage error (MAPE) was used to evaluate the model's accuracy for the removal and adsorption percentage output parameters. The absolute fraction of variance (R2) values were 99.83, 99.36, and 98.26% for the dyestuff training, validation, and test sets, respectively.

Accurate data prediction by fuzzy inference model for adsorption of hazardous azo dyes by novel algal doped magnetic chitosan bionanocomposite

A bionanocomposite comprising of magnetic chitosan doped with algae isolated from native habitat was fabricated and utilized as an efficient adsorbent for the removal of hazardous azo dyes, namely, Direct Red 31 (DR31) and Direct Red 28 (DR28). The algal doped magnetic chitosan (Alg@mCS) was comprehensively characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction analysis (XRD), and Brunauer-Emmett-Teller (BET). On the sorption of dyes, the influence of various process variables such as pH, adsorbent dosage, contact time, temperature, and initial dyes concentration were addressed. The adsorbent demonstrated maximal removal of DR31 and DR28 at pH 5 and 3, respectively. The maximum adsorption capacity of DR31 and DR28 was observed at Alg@mCS dose of 0.6 g L^-1 and 7 g L^-1 in 10 and 20 min, respectively. The Redlich Peterson isotherm model was shown to be appropriate for dye adsorption, indicating monolayer coverage of the dyes on the adsorbent surface (R² > 0.99). The adsorption process followed pseudo-second-order kinetics (R² > 0.99). Based on 320 experimental datasets from batch studies and interpolated data, adaptive neuro-fuzzy inference system (ANFIS) models were utilized to estimate dye elimination (percent). A number of parameters were calculated to validate the model's applicability. The Alg@mCS was proven to be a useful adsorbent for eliminating toxic and harmful azo dyes from aqueous solutions.

In-Situ SERS Detection of Hg2+/Cd2+ and Congo Red Adsorption Using Spiral CNTs/Brass Nails

Brass spiral nails were functionalized with CoFe₂O₄ nanoparticles and utilized as a substrate for the growth of extremely long CNTs with helical structures and diameters smaller than 20 nm. Different methods were used to characterize the grown CNTs' structures and morphologies. The characteristic Raman peaks of CNTs were amplified four times after being uploaded on the spiral nail, making the substrates for surface-enhanced Raman spectroscopy (SERS) more sensitive. To detect Hg²⁺ and Cd²⁺ at concentrations ranging from 1 to 1000 ppb, a CNT/spiral brass nail was used as a SERS substrate. The proposed sensor demonstrated high sensitivity and selectivity between these heavy metal ions. As a result, the proposed CNTs/spiral brass sensor can be an effective tool for identifying heavy metal ions in aqueous solutions. In addition, Congo red (CR) adsorption as a function of initial dye concentration and contact time was investigated. For CR dye solutions with concentrations of 5, 10, and 20 mg/L, respectively, the highest removal percentage was determined to be ~99.9%, 85%, and 77%. According to the kinetics investigation, the pseudo-first-order and pseudo-second-order models effectively handle CR adsorption onto CNTs/spiral nails. The increase in the dye concentration from 5 ppm to 20 ppm causes the rate constant to drop from 0.053 to 0.040 min^-1. Therefore, our sample can be employed for both the effective degradation of CR dye from wastewater and the detection of heavy metals.

Design and Characterization of Zeolite/Serpentine Nanocomposite Photocatalyst for Solar Hydrogen Generation

In this work, a low-cost, high-yield hydrothermal treatment was used to produce nanozeolite (Zeo), nanoserpentine (Serp), and Zeo/Serp nanocomposites with weight ratios of 1:1 and 2:1. At 250 °C for six hours, the hydrothermal treatment was conducted. Various methods are used to explore the morphologies, structures, compositions, and optical characteristics of the generated nanostructures. The morphological study revealed structures made of nanofibers, nanorods, and hybrid nanofibril/nanorods. The structural study showed clinoptilolite monoclinic zeolite and antigorite monoclinic serpentine with traces of talcum mineral and carbonates. As a novel photoelectrochemical catalyst, the performance of the Zeo/Serp (2:1) composite was evaluated for solar hydrogen generation from water splitting relative to its constituents. At -1 V, the Zeo/Serp (2:1) composite produced a maximum current density of 8.44 mA/g versus 7.01, 6.74, and 6.6 mA/g for hydrothermally treated Zeo/Serp (1:1), Zeo, and Serp, respectively. The Zeo/Serp (2:1) photocatalysts had a solar-to-hydrogen conversion efficiency (STH) of 6.5% and an estimated hydrogen output rate of 14.43 mmole/h.g. Consequently, the current research paved the way for low-cost photoelectrochemical catalytic material for efficient solar hydrogen production by water splitting.

Efficient Removal of Organic Dye from Aqueous Solution Using Hierarchical Zeolite-Based Biomembrane: Isotherm, Kinetics, Thermodynamics and Recycling Studies

Bio adsorbents have received tremendous attention due to their eco-friendly, cheap and non-toxic nature. Recently, bio-adsorbent-based membranes have been frequently employed for water treatment. The work reports the preparation of a novel adsorbent membrane from hierarchical zeolite, polyvinyl alcohol, carboxymethyl cellulose and agar. The fabricated membrane was characterized spectroscopically and microscopically with several techniques such as XRD, UTM, TGA, optical microscopy and FT-IR, as well as contact-angle studies. The result showed that the hierarchical-zeolite-loaded membrane is superior in terms of thermal stability, mechanical properties and surface roughness. The fabricated membrane was investigated for its efficiency in the removal of Congo red dye in aqueous conditions. The influence of pH, temperature, contact period and the initial concentration of dye and zeolite loading on the adsorption process are also explored. The adsorption results highlighted the maximum sorption property of Congo red on agar/zeolite/carboxymethyl cellulose/polymer biomembrane was found to be higher (15.30 mg/g) than that of zeolite powder (6.4 mg/g). The adsorption isotherms and kinetic parameters were investigated via Langmuir, Freundlich and pseudo-first order, pseudo-second order and the intraparticle diffusion model, respectively. The adsorption isotherms fitted well for both considered isotherms, whereas pseudo-second order fitted well for kinetics. The thermodynamic parameter, ΔG at 303 K, 313 K and 323 K was −9.12, −3.16 and −0.49 KJ/mol, respectively. The work further explores the antibacterial efficacy of the prepared membrane and its reusability.

Comparative Evaluation of Membrane Filtration on the Tertiary Treatment of Synthetic Secondary Effluent

Wastewater reuse is essential for sustainable water management. However, it requires tertiary treatment within the plant to ensure suitable water quality. This project aims to investigate the comparative performance of conventional tertiary treatment (sand filtration) against membrane filtration technology to demonstrate the viability of membrane treatment for wastewater reuse. Sand filtration along with two membrane filtrations, Nano Filtration (NF) and Reverse Osmosis (RO), were tested for their efficiency in removing the target pollutants: chromium, phosphate, and UV-254 from secondary effluent. Standard medium-sized laboratory setups were used. Synthetic secondary effluent was used for comparison among the different treatment processes. The synthetic effluent was compared to the real wastewater to demonstrate the reliability of using synthetic effluent. Evaluation of the role of time and pressure on the treatment efficiency was also examined. Based on the experimental results, RO had the highest removal efficiency for all pollutants with more than 90% removal. The experimental results also showed that synthetic wastewater was reliable in representing the treatability of real wastewater. Time did not seem to have an impact on the quality of filtration. Moreover, as pressure increased there was a slight increase in the efficiency. This trend was observed in all pollutants except UV-254. ANOVA showed different results of the effect of pressure on the removal efficiency in both RO and NF as well as time in NF.

Facile and green preparation of solid carbon nanoonions via catalytic co-pyrolysis of lignin and polyethylene and their adsorption capability towards Cu(ii)

Carbon nanomaterials, such as carbon nanoonions (CNOs), possess promising applications in various fields. There are urgent demands to synthesize carbon nanomaterials from a green and renewable carbon source. In this study, solid CNOs with relatively uniform size distribution (with diameters of about 30–50 nm), abundant structure defects and oxygen-containing surface functional groups (such as –OH and –COOH) are developed from co-pyrolysis of lignin (LG) and polyethylene (PE) in the presence of Ni-based catalysts. The type of catalyst, the concentration of catalyst and catalytic co-pyrolysis temperature play important roles in the morphologies and properties of CNOs as confirmed by TEM and SEM. Furthermore, the produced CNOs can act as a low-cost and highly-efficient adsorbent to remove Cu(ii) from aqueous solution according to a homogeneous monolayer, chemical action-dominated, endothermic and spontaneous process. The theoretical maximum adsorption capacity of CNOs calculated from the Langmuir model is 100.00 mg g⁻¹. Surface deposition, complexation, π electron–cation interaction and electrostatic interaction are responsible for the adsorption of Cu(ii) using the prepared CNOs.

Solid carbon nanoonions with relatively uniform size distribution, abundant structure defects and oxygen-containing surface functional groups can be prepared from lignin with the introduction of polyethylene and Ni-based catalysts.