Akeem Adeyemi Oladipo

Bifunctional composite from spent "Cyprus coffee" for tetracycline removal and phenol degradation: Solar-Fenton process and artificial neural network.

Removals of tetracycline and photocatalytic degradation of phenol by Fe3O4/coffee residue (MCC) were investigated. Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM) and Boehm titration were employed to characterize MCC. Artificial neural network (ANN) model was developed to predict the tetracycline (TC) concentration in the column effluent. Maximum tetracycline adsorption capacity of 285.6mg/g was observed in a batch system. High removal efficiency (87%) was obtained at 3.3mL/min flow rate, 8.0cm bed height and 50mg/L influent TC concentration in a column system. Complete degradation of phenol by solar-Fenton was attained at 60min irradiation time. Total organic carbon (TOC) removal increased to 63.3% in the presence of 1.0g/L MCC, 1.2g/L H2O2 and solar irradiation. MCC showed remarkable potential to remove antibiotics from wastewater even in the presence of heavy metal (Ni(2+)) via magnetic separation.

Two-stage batch sorber design and optimization of biosorption conditions by Taguchi methodology for the removal of acid red 25 onto magnetic biomass

Biomagnetic material (MFC) was synthesized via simple co-precipitation and used as biosorbent for the removal of acid red 25 (AR25) under optimized conditions. The characteristics of MFC were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), Boehm titration and scanning electron microscopy (SEM). Optimum removal of AR25 was achieved at pH=5.0. The equilibrium data were well described by the Sips and Freundlich models. Taguchi methodology was employed to optimize the biosorption experiments. 411.56 mg/g and 96.8% were obtained as the biosorption capacity and removal efficiency, respectively, at the optimum conditions of ionic strength (0.5 M), influent volume (300 L) and MFC dosage (4 g). The contact time for removal of 96% AR25 in two-stage batch system is 400.8 min which is lower than the single-stage treatment process (895 min).

Facile synthesis of glucose-sensitive chitosan–poly(vinyl alcohol) hydrogel: Drug release optimization and swelling properties

The study describes the development of glucose-sensitive hydrogel and optimization of bovine serum albumin release profile from the hydrogel. To enhance the glucose sensitivity and improve the swelling behaviors of the hydrogel system, boric acid crosslinking, and freeze-thawing cycle techniques were used to prepare chitosan-poly(vinyl alcohol) hydrogel. The structure of the resultant hydrogel was confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. The experimental results revealed that the swelling of the hydrogel was influenced by the pH of the medium, and the hydrogel displayed explicit glucose-sensitivity under physiological conditions. The values of the diffusion exponent range between 0.34 and 0.44 and the diffusion of water into the gel system are assumed to be pseudo-Fickian in nature. Under optimized conditions, the cumulative Bovine serum albumin (BSA) drug releases ranged between 69.33±1.95% and 86.45±1.16% at 37°C in the presence of glucose and pH 7.4, respectively.

Fixed-bed column sorption of borate onto pomegranate seed powder-PVA beads: a response surface methodology approach

Pomegranate seed powder (PS) was functionalized with polyvinyl alcohol (PVA) and utilized for boron removal from the aqueous system. Results of Brunauer--Emmett--Teller (BET) surface area analysis and Boehm titration indicated notable decrease in total surface area and increase in acidic surface functional groups of PS after PVA modification. Enhanced sorption is indicative of complex formation between diol groups of the pomegranate seed powder--polyvinyl alcohol (PS–PVA) and borate ions. Under column test, the saturated sorption capacity of boron was noted to be dependent on flow rate and bed height. The developed central composite design (CCD) was adequate to elucidate the sorption mechanism. Mathematical modeling of the column data was conducted, and a modified-dose-response model was the most suitable to describe the breakthrough curve and observed to be consistent with CCD analysis. This is further supported by extensive error analyses conducted between the model predicted and experimental data.

Uptake of Ni2+ and rhodamine B by nano-hydroxyapatite/alginate composite beads: batch and continuous-flow systems

Alginate encapsulated nano-hydroxyapatite beads were synthesized and characterized by Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface analysis, and X-ray diffraction. Their adsorptive potential for Ni2+ and rhodamine B was explored in batch mode and by fixed-bed column passage. In the batch system, maximum uptake capacity for Ni2+ was 360 mg g−1 and 480 mg g−1 for rhodamine B. In the presence of humic acid, sorption was enhanced. For the continuous-flow system, adsorption was effective at low flow rate. For both pollutants, mass transport resistance increased during adsorption. The overall rates of rhodamine B and Ni2+ uptake were found to be controlled by external mass transfer.

High-performance magnetic chicken bone-based biochar for efficient removal of rhodamine-B dye and tetracycline: competitive sorption analysis

Magnetic chicken bone-based biochar (MCBB) was successfully prepared and efficiently adsorbed rhodamine-B (RB) dye and tetracycline (TC) in multi-component systems. The magnetisation value, surface area, and pHpzc of the MCBB were found to be 66.5 emu/g, 328 m2/g, and 8.3, respectively. RB has higher saturation capacity (96.5 mg/g) and occupies more active sites on MCBB, thus limiting the sorption of TC with lower saturation capacity (63.3 mg/g). Langmuir isotherm suitably describes the sorption process in a single-component system; however, the multi-component system was well fitted to the Sheindorf-Rebhun-Sheintuch model. The selectivity factor values confirmed that MCBB had higher adsorption affinity toward RB than TC. The intraparticle diffusion model played a significant role in the sorption process. The MCBB can be easily desorbed with base-spiked H2O and reused without loss in stability or structural integrity.

Highly efficient magnetic chicken bone biochar for removal of tetracycline and fluorescent dye from wastewater: Two-stage adsorber analysis

Magnetic chicken bone biochar (MCB) was fabricated and characterised. The specific surface area, magnetisation value and pHpzc of the MCB were found to be 328 m2 g-1, 64.7 emu/g and 8.3 respectively. The adsorptive performance of MCB for rhodamine B dye (RB) and tetracycline (TC) removal in a single and two-stage stirred adsorber (TSA) was evaluated. The TSA reduced the pressure drops, mass transfer resistances, and fouling of the adsorbent. 63.0 g MCB is required to remove 75% of RB and TC in a single-stage system within 12 h. However, the optimised TSA confirmed that 33.2 g of MCB is needed to achieve 96% removal of TC and 22.2 g for RB within 180 min of 100 mgL-1 effluent solutions. The sorption was suitably described by the Freundlich mechanism. Based on the comparative performance, the MCB is considered a viable efficient and magnetically separable alternative adsorbent.

High-Performance Nanocatalyst for Adsorptive and Photo-Assisted Fenton-Like Degradation of Phenol: Modeling Using Artificial Neural Networks

High-performance activated carbon-zinc oxide (Ac–ZnO) nanocatalyst was fabricated via the microwave-assisted technique. Ac–ZnO was characterized and the results indicated that Ac–ZnO is stable, had a band gap of 3.26 eV and a surface area of 603.5 m2g−1, and exhibited excellent adsorptive and degrading potentials. About 93% phenol was adsorbed within 550 min of reaction by Ac–ZnO. Impressively, a complete degradation was achieved in 90 min via a photo-Fenton/Ac–ZnO system under optimum conditions. An artificial neural network (ANN) model was developed and applied to study the relative significance of input variables affecting the degradation of phenol in a photo-Fenton process. The ANN results indicate that increases in both H2O2 and Ac–ZnO dosage enhanced the rate of phenol degradation. The highest rate constant at the optimum conditions was 0.093 min−1 and it was found to be consistent with the ANN-predicted rate constant (0.095 min−1).

Application of Hydroxyapatite-Based Nanoceramics in Wastewater Treatment: Synthesis, Characterization, and Optimization

In recent years, increasing environmental issues, particularly relating to biogenic and chemical pollution of water, have become a significant threat to both human health and the ecosystems. Many of these wastewaters contain a high level of contaminants which are undesirable because they create odor, bad taste, toxic effects aside the unpleasant aesthetic nature of the water. Hence, the removal of these toxic pollutants is necessary and, has attracted considerable efforts particularly via adsorption technology. Hydroxyapatite is among the most representative ceramic materials and considered promising for long-term containment of toxic pollutants due to its eco-friendly nature, good dispersibility, outstanding stability, and abundant modifiable surface functional groups. This chapter highlights the significance of sol–gel synthesis routes for producing hydroxyapatite-based nanoceramic for environmental applications. General summary of other synthesis methods and recent applications of hydroxyapatite-based nanoceramic as adsorbents and catalysts are reviewed. The wastewater parametric conditions and the synthesized hydroxyapatite-based materials covered herein is expected to inspire and stimulate further applications of nanoceramic-based materials in the environmental science.

Highly efficient and magnetically separable palm seed-based biochar for the removal of nickel

ABSTRACT Magnetic biocomposite (MB) was fabricated by co-precipitation of palm seed-based biochar in the presence of Fe3O4 particles. The MB sorption behaviour was investigated using nickel as the target pollutant. The MB characterisation revealed that its maintained micro-mesoporous character and high saturation magnetisation (65.8 Am2/kg) enable it to be separated from a solution using a magnet. The nickel removal efficiency of MB, 87% (28 mg/g), was achieved at pH 3; however, this was reduced to 45–75% (15–24 mg/g) in the presence of competing ions. The isotherms and kinetics studies revealed a monolayer interaction via a two-stepped sorption mechanism.