Meso-microporous activated carbon derived from Raffia palm shells: optimization of synthesis conditions using response surface methodology

This study investigated the optimal synthesis conditions for the production of Raffia Palm Shell Activated Carbon (RPSAC) using phosphoric acid as activation agent. The optimization of the synthesis conditions was achieved using the Central Composite Design (CDD) in Response Surface Methodology (RSM). The influences of impregnation ratio, temperature, time and concentration on the specific surface area and yield of RPSAC were evaluated. Based on the CDD, 2FI and quadratic models were developed for the two responses. Analysis of Variance (ANOVA) was utilized to determine the significant factors and factor interactions for each response. All process variables except impregnation ratio were observed to significantly influence the quality of RPSAC. The optimal synthesis conditions for RPSAC were; 523.68 °C, 76.91%, and 103.83 min for temperature, concentration, and time respectively which provided a specific surface area and yield of 1762.92 m2/g and 77.98 % respectively. The Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) analyses proved that RPSAC had a meso-micro-porous morphology with high carbon and oxygen contents. Fourier-transform infrared spectroscopy (FTIR) revealed the abundance of hydroxyl, carbonyl and carboxylic groups on RPSAC. X-ray Powder Diffraction (XRD) analysis showed that RPSAC composed mainly of amorphous and disordered microcrystalline phases ascribed to the high quartz content of the precursor. The Brunauer–Emmett–Teller (BET) surface area, average pore diameter, total pore volume, and pHpzc of RPSAC were obtained as 456.10 m2/g, 0.25 cm3/g, 2.13 nm and 2.10 correspondingly. Thus, RSM was found to be an excellent and desirable tool for optimal synthesis of RPSAC that possess high surface area and porosity suitable for application in the adsorption of both large and small molecular sized pollutants such as dyes and fluoride in real and aqueous solution

Novel aluminium (hydr) oxide-functionalized activated carbon derived from Raffia palm (Raphia hookeri) shells: Augmentation of its adsorptive properties for efficient fluoride uptake in aqueous media

In this study a novel activated carbon derived from Raffia palm shells was synthesized firstly by activating the precursor with phosphoric acid to produce Raffia Palm Shell Activated Carbon (RPSAC) and further functionalized by coating its surface with aluminium hydroxide to produce a composite called Aluminium Oxide-coated Raffia Palm Shell Activated Carbon (ACRPSAC). These adsorbents were extensively characterized and tested for fluoride adsorption in aqueous media using batch adsorption experiment in comparison with a commercially available activated carbon (CAC). ACRPSAC demonstrated excellent qualities and fluoride adsorption capacity as compared to RPSAC. SEM/EDX revealed that ACRPSAC developed both micro and meso-pores on its surface with BET-surface area and pore volume of 715.80 m2/g and 0.47 cm3/g respectively. FTIR and XRD proved that ACRPSAC was largely amorphous and had sufficient functionality for fluoride uptake in solution. Batch adsorption studies showed that the fluoride removal abilities were in the order of ACRPSAC > RPSAC > CAC with maximum Langmuir adsorption capacity of 4.10 > 2.26 > 2.24 mg/g. respectively. The experimental data was well described by the Langmuir (R2 = 0.8802–0.9751) and the pseudo-second order kinetic (R2 = 0.9974–0.9999) models, signifying that fluoride uptake by the adsorbents was a chemisorption process. Thermodynamic studies revealed that the process was spontaneous, endothermic and feasible for ACRPSAC and RPSAC but was non-spontaneous for CAC. It was concluded that ACRPSAC is an excellent activated carbon for eliminating fluoride from groundwater and can be further studied for its commercialization

A novel oil palm frond magnetic biochar for the efficient adsorption of crystal violet and sunset yellow dyes from aqueous solution: synthesis, kinetics, isotherm, mechanism and reusability studies

Abstract This study presented a facile synthesis route via the precipitation method for the production of magnetic biochar from oil palm frond (OPF). The physicochemical characteristics including surface, functional, and magnetic properties of the synthesized magnetic biochar revealed that the surface morphology, porosity, and magnetic properties enhanced its adsorption capacity for the removal of crystal violet (CV) and sunset yellow (SY) from aqueous solution. The saturation magnetization of OPF biochar was found to be 8.41 emu/g, coercivity (Hc) of 83.106 G, and retentivity (Mr) of 1.475 emu/g which implies that OPF magnetic biochar can be facilely separated from aqueous solution. The result also demonstrated superparamagnetic properties which provided suitable magnetic responsive characteristics to an external magnetic field. The interactive effect of the operational conditions of pH, adsorbent dosage, initial concentration, and temperature was investigated in a batch adsorption study using the central composite design (CCD) of the response surface methodology (RSM). It was indicated that an increase in adsorbent dosage to 1.0 g/L at a lower initial concentration (50 ppm) conducted at 20 °C favoured optimum removal of CV and SY at pH 11 and 4, respectively. The Langmuir isotherm model with maximum adsorption capacity ( $$q_{\max }$$ q max ) of 149.03 and 342.47 mg/g was achieved for CV and SY dyes, respectively. The kinetic data proved to be best fitted to the pseudo-second-order kinetic model. Thermodynamic parameters revealed spontaneous and endothermic reactions. The suitability and sustainability of the magnetic biochar were enhanced by its regeneration potential for effective adsorption of CV and SY after 5 cycles which indicates its outstanding reusability. Hence, OPF magnetic biochar exhibited prospective application for the removal of dyes from wastewater

An insight into a sustainable removal of bisphenol a from aqueous solution by novel palm kernel shell magnetically induced biochar: synthesis, characterization, kinetic, and thermodynamic studies

Recently Bisphenol A (BPA) is one of the persistent trace hazardous estrogenic contaminants in the environment, that can trigger a severe threat to humans and environment even at minuscule concentrations. Thus, this work focused on the synthesis of neat and magnetic biochar (BC) as a sustainable and inexpensive adsorbent to remove BPA from aqueous environment. Novel magnetic biochar was efficiently synthesized by utilizing palm kernel shell, using ferric chloride and ferrous chloride as magnetic medium via chemical co-precipitation technique. In this experimental study, the influence of operating factors comprising contact time (20–240 min), pH (3.0–12.0), adsorbent dose (0.2–0.8 g), and starting concentrations of BPA (8.0–150 ppm) were studied in removing BPA during batch adsorption system using neat biochar and magnetic biochar. It was observed that the magnetically loaded BC demonstrates superior maximum removal efficiency of BPA with 94.2%, over the neat biochar. The functional groups (FTIR), Zeta potential, vibrating sample magnetometer (VSM), surface and textural properties (BET), surface morphology, and mineral constituents (FESEM/EDX), and chemical composition (XRD) of the adsorbents were examined. The experimental results demonstrated that the sorption isotherm and kinetics were suitably described by pseudo-second-order model and Freundlich model, respectively. By studying the adsorption mechanism, it was concluded that π-π electron acceptor–donor interaction (EAD), hydrophobic interaction, and hydrogen bond were the principal drives for the adsorption of BPA onto the neat BC and magnetic BC

A novel oil palm frond magnetic biochar for the efficient adsorption of crystal violet and sunset yellow dyes from aqueous solution: synthesis, kinetics, isotherm, mechanism and reusability studies

This study presented a facile synthesis route via the precipitation method for the production of magnetic biochar from oil palm frond (OPF). The physicochemical characteristics including surface, functional, and magnetic properties of the synthesized magnetic biochar revealed that the surface morphology, porosity, and magnetic properties enhanced its adsorption capacity for the removal of crystal violet (CV) and sunset yellow (SY) from aqueous solution. The saturation magnetization of OPF biochar was found to be 8.41 emu/g, coercivity (Hc) of 83.106 G, and retentivity (Mr) of 1.475 emu/g which implies that OPF magnetic biochar can be facilely separated from aqueous solution. The result also demonstrated superparamagnetic properties which provided suitable magnetic responsive characteristics to an external magnetic field. The interactive effect of the operational conditions of pH, adsorbent dosage, initial concentration, and temperature was investigated in a batch adsorption study using the central composite design (CCD) of the response surface methodology (RSM). It was indicated that an increase in adsorbent dosage to 1.0 g/L at a lower initial concentration (50 ppm) conducted at 20 °C favoured optimum removal of CV and SY at pH 11 and 4, respectively. The Langmuir isotherm model with maximum adsorption capacity (qmax) of 149.03 and 342.47 mg/g was achieved for CV and SY dyes, respectively. The kinetic data proved to be best fitted to the pseudo-second-order kinetic model. Thermodynamic parameters revealed spontaneous and endothermic reactions. The suitability and sustainability of the magnetic biochar were enhanced by its regeneration potential for effective adsorption of CV and SY after 5 cycles which indicates its outstanding reusability. Hence, OPF magnetic biochar exhibited prospective application for the removal of dyes from wastewater. © 2024, The Author(s)

Recent advances in the rejection of endocrine-disrupting compounds from water using membrane and membrane bioreactor technologies: a review

Water is a critical resource necessary for life to be sustained, and its availability should be secured, appropriated, and easily obtainable. The continual detection of endocrine-disrupting chemicals (EDCs) (ng/L or µg/L) in water and wastewater has attracted critical concerns among the regulatory authorities and general public, due to its associated public health, ecological risks, and a threat to global water quality. Presently, there is a lack of stringent discharge standards regulating the emerging multiclass contaminants to obviate its possible undesirable impacts. The conventional treatment processes have reportedly ineffectual in eliminating the persistent EDCs pollutants, necessitating the researchers to develop alternative treatment methods. Occurrences of the EDCs and the attributed effects on humans and the environment are adequately reviewed. It indicated that comprehensive information on the recent advances in the rejection of EDCs via a novel membrane and membrane bioreactor (MBR) treatment techniques are still lacking. This paper critically studies and reports on recent advances in the membrane and MBR treatment methods for removing EDCs, fouling challenges, and its mitigation strategies. The removal mechanisms and the operating factors influencing the EDCs remediation were also examined. Membranes and MBR approaches have proven successful and viable to eliminate various EDCs contaminants

Augmenting pomelo juice quality through membrane-based clarification and bioactive compounds recovery

The presence of impurities, microorganisms, enzymes, suspended solids, and impurities in unclarified pomelo juice negatively affected the quality and shelf-life of the product in the food industry. The objective of this study focuses on the clarification of fresh pomelo juice using an ultrafiltration (UF) process. The study examined the influence of the operating pressure (OP) on the various quality attributes of pomelo juice, such as pH, total soluble solids (TSS), turbidity, color, total phenolic content (TPC), ascorbic acid content (AAC) and fouling mechanisms and permeate flux (J) behavior. To perform the clarification of pomelo juice, a 100 kDa membrane (polymeric) was used in a dead-end system, and the process was carried out in batch mode at OP values of 1.0, 1.5, 2.0, 2.5 and 3.0 bar. The findings revealed that increasing OP led to higher flux during ultrafiltration with limiting pressure (Plim). The limiting pressure (Plim) was anticipated to be beyond 3.0 bar due to the enzymatic pretreatment. The primary fouling mechanism during the clarification process was total pore blocking. After filtration, the resulting juice showed a significant reduction in turbidity of over 97, while TSS was lowered by 7–17 compared to fresh juice. The pomelo juice was efficiently clarified while the pH remained stable at ∼3.8. The clarified juice showed a minor decline of 10.1–13.9 in TPC and a 10.8–16.7 reduction in AAC compared to the fresh unclarified juice. In conclusion, a pressure of 3.0 bar is recommended for conducting the ultrafiltration process in order to attain desirable flux behavior and optimum properties of the juice

Effects of irradiation time on the structural, elastic, and optical properties of hexagonal (wurtzite) zinc oxide nanoparticle synthesised via microwave-assisted hydrothermal route

Zinc oxide (ZnO) is a vital nanomaterial highly valued in electronics and optoelectronics due to its remarkable multifunctional properties. This study prepared ZnO nanoparticles using a simple hydrothermal microwave process. The influence of irradiation time on the structural, elastic and optical properties of the ZnO nanoparticles was investigated. X-ray diffraction (XRD) analysis confirmed the hexagonal (wurtzite) structure of the ZnO nanoparticles. In addition, various XRD profile analysis techniques were used in this study, including Scherer method, strain size plot method, Halder–Wagner method, Monshi–Scherer method, and Williamson–Hall method consisting of a uniform deformation model, a uniform stress density model and a uniform deformation energy density model. The estimated mean crystallite size was found to be at 43.53–56.08 nm. Furthermore, atomic force microscopy and transmission electron microscopy were used to investigate the average particle size of the ZnO nanoparticles at different irradiation times. The results were consistent with the mean crystallite size calculated using the X-ray diffraction peak profile analysis techniques. Furthermore, a decrease in the energy band gap estimated by diffuse reflectance spectroscopy was observed, transitioning from 3.32s to 3.29 eV with increasing irradiation time. This observation was confirmed by the distinct and unique ultraviolet photoluminescence emission peaks of the synthesized ZnO nanoparticles, supporting the results of the diffuse reflectance analysis. Based on the presented results, it can be concluded that the X-ray diffraction peak profiling technique is a practical approach for determining the average crystallite size of ZnO nanoparticles prepared using the microwave hydrothermal technique and that it can be used for size-dependent applications

Adsorptive removal of copper (II) Ions from aqueous solution using a magnetite nano-adsorbent from mill scale waste: synthesis, characterization, adsorption and kinetic modelling studies

In this study, magnetite nano-adsorbent (MNA) was extracted from mill scale waste products, synthesized and applied to eliminate Cu2+ from an aqueous solution. Mill scale waste product was ground using conventional milling and impacted using high-energy ball milling (HEBM) for varying 3, 5, and 7 milling hours. In this regard, the prepared MNA was investigated using X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), field emission scanning electron microscopy-energy-dispersive X-ray spectroscopy (FESEM-EDS), UV-Vis spectroscopy, Fourier-transform infrared (FTIR), Brunauer-Emmett-Teller (BET) and zeta potential. The resultant MNA-7 h milling time displayed a crystalline structure with irregular shapes of 11.23 nm, specific surface area of 5.98 m2g-1, saturation magnetization, Ms of 8.35 emug-1, and isoelectric point charge at pH 5.4. The optimum adsorption capacity, qe of 4.42 mg.g-1 for the removal of Cu2+ ions was attained at 120 min of contact time. The experimental data were best fitted to the Temkin isotherm model. A comparison between experimental kinetic studies and the theoretical aspects showed that the pseudo-second-order matched the experimental trends with a correlation coefficient of (R2 > 0.99). Besides, regeneration efficiency of 70.87% was achieved after three cycles of reusability studies. The MNA offers a practical, efficient, low-cost approach to reutilize mill scale waste products and provide ultra-fast separation to remove Cu2+ from water