Phenol Uptake Research Articles

Multi-functional PGPR Serratia liquefaciens confers enhanced resistance to lead stress and bacterial blight in soybean (Glycine max L.)

Lead toxicity and bacterial blight disease caused by Pseudomonas savastanoi pv. glycinea have destructive impacts on soybean growth and productivity. Plant growth-promoting rhizobacteria have been used as an eco-friendly approach for augmenting crop growth and stress resistance. The current study investigated the efficacy of Serratia liquefaciens ZM6 strain in enhancing soybean resistance to lead (Pb) stress and bacterial blight. Two pot experiments were performed. In the first pot experiment, soybean plants were inoculated with S. liquefaciens ZM6 and grown under variable Pb stress levels (0, 200 and 400 µM of Pb(NO3)2). In the second experiment, S. liquefaciens-inoculated soybean plants were infected with P. savastanoi pv. glycinea, and disease severity was assessed two weeks post infection. The results revealed that S. liquefaciens strain resisted Pb stress up to 400 µM Pb(NO3)2 and exhibited the highest levels of solubilized phosphate, solubilized zinc, siderophore, indole acetic acid, exopolysaccharide, trehalose and antioxidant enzymes at 400 µM Pb compared to the other treatments. Moreover, Pb stress (200 and 400 µM) significantly decreased the growth, yield, nutrient uptake, gas exchange, and contents of chlorophyll, soluble proteins, sugars, and phenolics of soybean plants. Pb stress also induced the levels of proline, glycine betaine, Pb, oxidative stress markers, antioxidant enzymes, ascorbate, glutathione and expression of stress-responsive genes (CAT, APX, POD, Fe-SOD, CHS7, CHI1A, PAL, IFS2, P5CS and WRKY54) in soybean plants. On the other hand, S. liquefaciens application markedly boosted the growth, yield and levels of nutrients, gas-exchange, chlorophyll, osmolytes, antioxidant enzymes and expression of stress-tolerant genes of Pb-stressed soybean plants. The bacterial inoculation significantly diminished oxidative stress indicators and Pb content in stressed plants. Inoculation of soybean plants with S. liquefaciens also caused significant reductions in blight disease symptoms in P. savastanoi pv. glycinea-infected plants, indicating the efficiency of this strain in controlling harmful blight disease. Overall, this study demonstrated S. liquefaciens ZM6 effectiveness in enhancing soybean resistance to Pb stress and bacterial blight.

Evaluating the Susceptibility of Different Crops to Smoke Taint

The potential for grapes and wine to be tainted following vineyard exposure to wildfire smoke is well established, with recent studies suggesting hops and apples (and thus beer and cider) can be similarly affected. However, the susceptibility of other crops to ‘smoke taint’ has not yet been investigated. Smoke was applied to a selection of fruits and vegetables, as well as potted lavender plants, and their volatile phenol composition determined by gas chromatography–mass spectrometry to evaluate their susceptibility to contamination by smoke. Volatile phenols were observed in control (unsmoked) capsicum, cherry, lavender, lemon, spinach and tomato samples, typically at ≤18 µg/kg, but 52 µg/kg of guaiacol and 83–416 µg/kg of o- and m-cresol and 4-methylsyringol were detected in tomato and lavender samples, respectively. However, significant increases in volatile phenol concentrations were observed as a consequence of smoke exposure; with the highest volatile phenol levels occurring in smoke-exposed strawberry and lavender samples. Variation in the uptake of volatile phenols by different crops was attributed to differences in their physical properties, i.e., their surface area, texture and/or cuticle composition, while the peel of banana, lemon, and to a lesser extent apple samples, mitigated the permeation of smoke-derived volatile phenols into pulp. Results provide valuable insight into the susceptibility of different crops to smoke contamination.

Artificial intelligence-based neural network modeling of adsorptive removal of phenol from aquatic environment

In this study, adsorptive uptake of phenol from aqueous system using Arachis hypogaea (groundnut) shell-based adsorbent was experimentally investigated and modelled using artificial intelligence-based neural network approach. Artificial neural networks with different number of neurons were designed using Levenberg-Marquardt algorithm to find the best model for phenol adsorption. The feedforward back propagation neural network comprising TRAINLM, LARNGDM and TANSIG as training, adaptation learning and transfer functions, respectively, with ten neurons in the hidden layer exhibited the optimal architecture with the strongest correlation R2=0.9901 and the smallest mean square error MSE=0.045. The studies indicated a maximum adsorptive uptake of phenol to be 37.31 mg/g onto the activated shell powder. The kinetic analysis favored pseudo second order R2=0.9999and the equilibrium data was best represented by Freundlich isotherm modelR2=0.9976. Phenolic remediation phenomenon ensued in a spontaneous manner, was exothermic ∆H0=−34.25kJ/moland involved physisorption. The experimental results are agreement with model.

Fabrication of phenolic loaded spray-dried nanoliposomes stabilized by chitosan and whey protein: Digestive stability, transepithelial transport and bioactivity retention of phenolics

Low bioavailability of phenolic compounds (phenolics) results in low in vivo bioactivity, thus their co-encapsulation could enhance potential health benefits. In this study, reconstitutable nanoliposomes loaded with phenolics varying in solubility were fabricated using spray drying after stabilized by chitosan (CH) or whey protein (WP). The physicochemical properties, biocompatibility, digestive fate, and bioactivity retention of phenolics in different forms were investigated. The surface charge of nanoliposomes (NL) shifted from −18.7 mV to positive due to conjugation with cationic CH (53.1 mV) and WP (14 mV) after spray drying while it was −26.6 mV for only spray-dried phenolics (SDP). Encapsulation efficiency of the tested phenolics ranged between 64.7 % and 95.1 %. Simulated gastrointestinal digestion/Caco-2 cell model was used to estimate the digestive fate of the phenolics yielding up to 3-fold higher bioaccessibility for encapsulated phenolics compared to their native form, combined or individually. However, the cellular uptake or transepithelial transport of phenolics did not differ significantly among formulations, except trans-resveratrol in WP-NL. On the contrary, the suppressive effect of phenolics on fatty acid induced hepatocellular lipid accumulation was strongly dependent on the encapsulation method, no activity was retained by SDP. These findings suggested that reconstitutable nanoliposomes can improve the absorption of phenolics by facilitating their bioaccessibility and thermal and/or processing stability during spray drying.

Evaluation of Functional Spray Coatings for Mitigating the Uptake of Volatile Phenols by Pinot Noir Wine Grapes via Blocking, Absorption, and/or Adsorption.

Spray coatings have shown promising potential in preventing the uptake of smoke phenols from wildfires into wine grapes. Three cellulose nanofiber-based coatings with low methoxyl pectin or varying concentrations of chitosan were made into films and their potential for blocking, absorption, or adsorption of phenols (guaiacol, m-cresol, and syringol) was evaluated using a custom-built smoke diffusion box. The coatings were also applied to Pinot noir grapes in a vineyard. GC-MS analysis for smoke phenols from headspace gases of diffusion study and extractions of films indicated that chitosan-based films can block guaiacol and syringol, and all films are able to capture m-cresol. The type of coating and application time in a vineyard did not affect (P < 0.05) physicochemical properties, size, and weight of the berries, whereas chitosan-based coatings resulted in a higher anthocyanin content of berries. This study provided new information about the key mechanisms (i.e., blocking phenols) of coatings to mitigate smoke phenol uptake in wine grapes.

Microwave-assisted one-pot preparation of magnetic cactus-derived hydrochar for efficient removal of lead(Ⅱ) and phenol from water: Performance and mechanism exploration

A novel magnetic hydrochar derived from cactus cladode (MW-MHC) was successfully synthesized through one-pot microwave-assisted process for efficiently removing lead(Pb)(Ⅱ) and phenol. From batch adsorption experiments, MW-MHC possessed the highest uptake amounts for Pb(Ⅱ) and phenol of 139.34 and 175.32 mg/g within 20 and 60 min, respectively. Moreover, the removal of Pb(Ⅱ) and phenol by MW-MHC remained essentially stable under the interference of different co-existing cations, presenting the excellent adaptability of MW-MHC. After three cycles of regeneration experiments, MW-MHC still had preferable adsorption performance and could be easily recycled, indicating its excellent reusability. Significantly, the uptake mechanisms of Pb(Ⅱ) on MW-MHC were regarded as chemical complexation, pore filling, precipitation, and electrostatic attraction. Meanwhile, the phenol uptake might be dominated by π-π interaction and hydrogen bonding. The above consequences revealed that MW-MHC with high removal performance was a promising adsorbent for remediating wastewater containing heavy metals and organics.

Investigating the potential of using solid waste generated from stone cutting factories for phenol removal from wastewater: A study of adsorption kinetics and isotherms

Remarkably toxic, phenol requires efficient elimination from water. This study investigates the utilization of solid waste generated by stone-cutting factories for extracting phenol from wastewater. The solid waste underwent thermal treatment at 105 °C for 3 h for characterization. Batch adsorption experiments systematically assessed parameters like phenol concentration, adsorbent mass, contact time, temperature, and pH. Optimal removal transpired at pH 7.5, reaching equilibrium within 4 h. Phenol uptake equilibrium values were 8.1, 13.3, 16.2, 20.2, and 28.1 mg/g for initial concentrations of 50, 100, 150, 200, and 300 mg/L, respectively using 1 g of adsorbent at ambient temperature. The Langmuir model fit acceptably, yet the Freundlich model surpassed it. The most suitable kinetics model for phenol adsorption was the pseudo-second-order. The nature of the adsorption process was endothermic. Importantly, this study pioneers the promising application of solid waste generated from stone-cutting factories as an adsorbent material for effective phenol removal, offering a sustainable approach. Notably, no previous study has been conducted on phenol removal from wastewater using this specific adsorbent, rendering this work pivotal in exploring its potential. This solid waste presents an economical, readily available, and environmentally benign material for the adsorption process, expected to exhibit substantial adsorption capacity.

Montmorillonite an efficient oral nanocarrier for punicalagin-rich pomegranate peel extract: An in vitro study

Pomegranate (Punica granatum L.) bioactive phenolics have multiple beneficial effects on human health and play a protective role against many degenerative diseases. Pomegranate peel is rich in bioactive phenolics, mainly punicalagin and ellagic acid, which cannot be uptaken by human intestinal epithelial cells (enterocytes) efficiently. This study is aimed to improve the cellular uptake of the bioactive phenolics using Food and Drug Administration-approved mucoadhesive montmorillonite (Mt) as a nanocarrier. Pomegranate peel extract (PPE) soluble in water (W-PPE, rich in punicalagin), methanol (M-PPE, rich in ellagic acid), and 75% aqueous methanol (WM-PPE) was prepared by maceration method, and corresponding PPE/Mt composites were made by intercalation technique. The thermogravimetry, X-Ray diffraction and Fourier transform infrared spectroscopy data demonstrated that the compounds of all the extracts were selectively adsorbed on the interlayer surfaces of Mt, leading to a 1.8- to 2.7-fold increase in their thermal stability and an increase and decrease in the basal space and interlayer water of Mt, respectively. Cell assays using MCF-7 (estrogen receptor-positive breast cancer), MDA-MB-231 (estrogen receptor-negative breast cancer), HepG2 (liver cancer) and HT-29 (colon cancer) cells showed that after intercalation into Mt, the cellular uptake of punicalagin-rich W-PPE and WM/PPE, but not ellagic acid-rich M-PPE, was considerably improved especially in enterocyte-like HT-29 cells. High performance liquid chromatography data also confirmed that Mt effectively adsorbed and carried hydrophilic phenolics, mainly punicalagin, but not ellagic acid. The adsorbed phenolics were released from Mt in a controlled manner which was fitted to the Bhaskar equation and parabolic diffusion kinetic models with R2 values of 0.995, implying that the release mechanism was diffusion and the diffusion through the particle was the rate limiting step. These results suggest that Mt can be an efficient oral nanocarrier for poorly absorbed punicalagin-rich W-PPE as a multifunctional traditional medicine.

Removal of Phenol from Water by Commercial Coconut Shell Charcoal

In this study, phenol was adsorbed by commercial coconut shell charcoal (CSC), which is inexpensive, commercially available, non-toxic, and environmentally friendly. The measurements, namely the density functional theory (DFT) calculation, the energy-dispersive X-ray spectroscopy (EDS), and the Fourier-transform infrared spectroscopy (FTIR), were conducted to characterize the features of the CSC. The highest phenol removal efficiency reached 78.62% at optimal conditions (pH: 7, initial concentration of phenol: 20 mg/L, adsorption time: 120 minutes, and dosage of CSC: 2.5 g/L). The phenol adsorption process follows the Langmuir adsorption model with the coefficient R2 = 0.9964. The maximum adsorption capacity by the CSC was determined to be 14.32 mg/g. The process of desorption of phenol from CSC was most effective in the NaOH solution. On the other hand, the adsorption efficiency of CSC gradually decreased after five consecutive cycles. At the fifth use, the phenol uptake efficiency reached 22.2%.

Effectiveness and mechanisms of the adsorption of phenol from wastewater onto N-doped graphene oxide aerogel

Phenol, as a representative toxic substance in coking wastewater, will cause harm to the ecology and human beings. Therefore, advanced treatment of phenol is urgently needed. However, most adsorbents have the problems of low adsorption capacity and difficult recovery in water dephenolization. It is imminent to develop a recyclable and effective adsorbent. Herein three-dimensional (3D) N-doped graphene oxide aerogel (NGOA) was synthesized by using ammonium citrate as reductant and nitrogen source. NGOA exhibits large specific surface area, developed pores, excellent hydrophilicity and mechanical properties. The static and dynamic adsorption properties of NGOA were investigated. NGOA has good adsorption performance and reusability. The static saturated adsorption capacity of NGOA for phenol reached 108.19 mg g−1, which was obviously higher than most adsorbents. Furthermore, the dynamic adsorption capacity of NGOA was 43.69 mg g−1, which illustrates that NGOA has immense potential in the uptake of phenol for industrial application. Importantly, monolithic NGOA could be easily separated and recovered after adsorption saturation. The adsorption behavior conforms to the endothermic physical adsorption process, which is matched with the Pseudo-first-order kinetic model and Langmuir-Freundlich isotherm model. This work has good scientific research value and practical application prospect.

Role of immobilised Chlorophyta algae in form of calcium alginate beads for the removal of phenol: isotherm, kinetic and thermodynamic study

In this work, sodium alginate-immobilised Chlorophyta algae were evaluated for phenol uptake. The algae/alginate bead (AAB) characteristics were analysed by means of BET-BJH, FTIR, and SEM-EDX methods, while the adsorption performance of AABs with respect to phenol removal was investigated using batch studies. The parameters found to affect the biosorption capacity of AABs included pH, contact time, initial phenol concentration, adsorbent dosage, stirring rate, particle size, and temperature, with the optimal operating variables identified as a pH of 6, an initial phenol concentration of 50 mg/L, AAB dosage of 5 g/L, and a 200 rpm stirring rate. The adsorption process in such cases reached equilibrium within 120 min, demonstrating a maximum phenol elimination capacity of 9.56 mg/g at 30 °C. The isotherm and kinetic models used to determine this were evaluated using the Chi-square test (X2), the coefficient of determination (R2), and the value of equilibrium capacity, with results that revealed that the Freundlich isotherm provides the best fit for the relevant equilibrium data, as shown by its high R2 value (0.96) and low X2 value (1.16135); the theoretical data produced by that model were thus closer to the experimental data than that from the Langmuir model. Kinetic analysis showed that the phenol adsorption followed a pseudo-second-order kinetic model. The thermodynamic parameters were thus explored, revealing that the phenol biosorption process is based on spontaneous physisorption with an exothermic reaction due to negative (ΔG°) and (ΔH°) values. The low cost, natural origin, biodegradability, and eco-friendliness of algae/alginate bead sorbents also make them ideally suited for phenol removal in aqueous solutions.

Hormesis effects of phenol on growth and cellular metabolites of Chlorella sp. under different nutritional conditions using response surface methodology

The present study investigated the effects of different phenol concentrations (200 – 1000 mg L−1) towards Chlorella sp. under different culture conditions (light vs. dark) and NaNO3 concentrations (0 – 0.1 g L−1) using central composite design. Phenol induced hormesis effects on the algal growth and cellular metabolites. Nitrate was identified as a crucial factor for promoting the uptake of phenol by Chlorella cells, while light was a limiting factor for growth, but the phyco-toxicity of phenol was decreased in the dark. The pigment contents were generally increased in the treated cells to protect against the oxidative phenol stress. The incorporation of 200 mg L−1 phenol and 0.05 g L−1 NaNO3 to the illuminated cells markedly promoted biomass and lipid contents to 0.22 g L−1 and 26.26% w/w, which was 44 and 112% higher than the phenol-less control, respectively. Under the same conditions, the increase of phenol concentration to 600 mg L−1, the protein contents were increased to 18.59% w/w. Conversely, the algal cells were able to accumulate more than 60% w/w of soluble carbohydrates under dark conditions at 600 mg L−1 of phenol. Nitrate replete conditions stimulated lipid accumulation at the expense of protein biosynthesis. Furthermore, most of the treatments showed an increase of H2O2 and malonaldehyde contents, especially for the illuminated cells. However, catalase activity tended to increase under dark conditions, especially at low phenol and nitrate concentrations. This study is valuable in indicating the effects of phenol on microalgae by exploiting response surface methodology, which can be applied as a powerful tool in growth monitoring and toxicity assessment.

Toward a mechanistic understanding of adsorption behavior of phenol onto a novel activated carbon composite

In this research, the solid–liquid adsorption systems for MSAC (PbFe2O4 spinel-activated carbon)-phenol and pristine activated carbon-phenol were scrutinized from the thermodynamics and statistical physics (sta-phy) viewpoints. Experimental results indicated that MSAC composite outperformed pristine AC for the uptake of phenol from waste streams. By increasing the process temperature, the amount of phenol adsorbed onto both adsorbents, MSAC composite and pristine AC, decreased. Thermodynamic evaluations for MSAC demonstrated the spontaneous and exothermic characteristics of the adsorption process, while positive values of ΔG for pristine AC indicated a non-spontaneous process of phenol adsorption in all temperatures. In a mechanistic investigation, statistical physics modeling was applied to explore the responsible mechanism for phenol adsorption onto the MSAC composite and pristine AC. The single-layer model with one energy was the best model to describe the experimental data for both adsorbents. The adsorption energies of phenol onto both adsorbents were relatively smaller than 20 kJ/mol, indicating physical interactions. By increasing temperature from 298 to 358 K, the value of the absorbed amount of phenol onto the MSAC composite and pristine AC at saturation (Qsat) decreased from 158.94 and 138.91 to 115.23 and 112.34 mg/g, respectively. Mechanistic studies confirm the significant role of metallic hydroxides in MSAC to facilitate the removal of phenol through a strong interaction with phenol molecules, as compared with pristine activated carbon.

Impact of functional spray coatings on smoke volatile phenol compounds and Pinot noir grape growth.

The frequency and intensity of wildfires have been increasing over the last 50 years and negatively impacted the wine industry. Previous methods of smoke mitigation during grape processing have shown little impact in reducing smoke taint in wines. Therefore, a novel method of using edible spray coatings for vineyard application was developed to help prevent volatile smoke phenol uptake in wine grapes. Four cellulose nanofiber-based coating suspensions incorporated with chitosan and/or β-cyclodextrin were evaluated. Films derived from the coating suspensions were exposed to volatile phenols found in wildfire smoke (guaiacol, 4-methyl guaiacol, m-cresol, o-cresol, p-cresol, syringol, and 4-methyl syringol) and evaluated with ultraviolet-visible spectroscopy where the results indicated that the coatings could uptake smoke phenols in varying degrees. The coatings were also applied in a vineyard at three different application times during grape growth: pea-sized, pre-bunch closure, and both at pea-sized and pre-bunch closure. The results showed that the application time did not have a significant (p < 0.05) effect on berry size, weight, °Brix, pH, or titratable acidity. The type of coating, time of application and washing were found to impact the number of volatile phenols in the grapes after a smoke event. Results from this study indicated that edible coatings could help mitigate smoke uptake in wine grapes without sacrificing the growth and key composition parameters of wine grapes. PRACTICAL APPLICATION: This research provides a novel spray coating that can be applied to wine grapes in the vineyard to potentially mitigate volatile smoke compounds in wine grapes without impacting fruit growth and key compositional parameters of wine grapes, thus maintaining high quality of wines for consumers. Results from this study can also be potentially applied to other agricultural commodities to solve the issues caused by the wildfire smoke.

Kinetic studies on the uptake of phenols by linear and cyclic organic sulfonic acid-modified Cu-Al layered double hydroxides

• The adsorption follows a pseudo-second-order kinetic equation. • The Δ G values for adsorption systems ranged from −20 to 0 kJ/mol. • It indicates that adsorption could be classified as physical adsorption. • NP was adsorbed on OS•Cu-Al LDH by hydrophobic interaction. • AP was adsorbed on SCD•Cu-Al LDH by CH/π interactions. Our previous study revealed that Cu-Al layered double hydroxides (LDHs) intercalated with 1-octanesulfonate and sulfonated β-cyclodextrin showed good adsorption selectivity toward m -nitrophenol (NP) and m -aminophenol (AP), respectively. We also found that the adsorption behaviors of these LDHs fit the Freundlich equation. Herein, we performed a kinetic analysis to elucidate the adsorption mechanism of the LDHs for phenols in greater detail. The adsorption results were fitted to a pseudo-first-order kinetic equation, a pseudo-second-order kinetic equation, and an intraparticle diffusion model. The correlation coefficients of the pseudo-second-order kinetic equation for each adsorption process were fairly high, and the measured and calculated equilibrium adsorption amounts were relatively close. Thus, the adsorption of NP and AP by OS•Cu-Al LDH and SCD•Cu-Al LDH, respectively, fits the pseudo-second-order kinetic equation. Because the ΔG values for each system ranged from −20 to 0 kJ/mol, the adsorption processes in these systems may be classified as physical adsorption. Specifically, NP was adsorbed on OS•Cu-Al LDH by hydrophobic interactions, whereas AP was adsorbed on SCD•Cu-Al LDH by CH/π interactions. Our findings provide new insights into the adsorption of phenols onto modified Cu-Al LDHs and could serve as a foundation for future studies on the adsorption properties of LDHs intercalated with anions as guest layers.

Resource utilization of bovine bone to prepare biochar as persulfate activator for phenol degradation

Designing non-metallic catalyst as persulfate (PS) activator for effective organic pollutants degradation in water is challenging. Herein, bovine-derived bone chars (BBCs) were prepared with different temperatures (300, 500 and 700 °C), which contained ordered mesoporous structures, thus realizing great phenol uptake (149.84 mg/g) with 100% degradation in combination with PS within 180 min. Furthermore, both reactive species (SO4•−; ·OH, O2•− and 1O2) and electron transfer process contributed to phenol removal due to the abundant defects and functional groups on BBC700. Owing to the multiples mechanisms, the BBC700/PS system exhibited an excellent phenol mineralization rate of 89.6 ± 1.85%, accompanied by strong anti-jamming capacity to relatively extensive pH range (3.0–7.0), various co-existing constituents and water bodies. Additionally, DFT calculations and GC-MS were used to illustrate the 7 kinds of degradation intermediates and the overall toxicity was efficiently alleviated, thus proposing a tailored non-metallic catalyst with great potential in water purification.

Application of Pb-Fe spinel-activated carbon for phenol removal from aqueous solutions: fixed-bed adsorption studies.

Fixed-bed studies for phenol uptake from water were carried out using a novel Pb-Fe spinel-activated carbon adsorbent. A characterization phase including TGA, FTIR, SEM, and BET analyses was performed for the developed active carbon. In column studies, the influence of initial phenol concentration, column bed height, and the solution flow rate was investigated at natural pH. Adsorption of phenol onto Pb-Fe spinel-activated carbon composite and pristine activated carbon was analyzed in the form of breakthrough curves. Under optimum conditions, the maximum adsorption capacities for the magnetic active carbon composite and pristine activated carbon were found to be 113.95 and 102.61mg/g, respectively. Results indicated that the adsorption capacity of adsorbent for all examined conditions was higher than that obtained for unmodified activated carbon because the composite contains additional metal hydroxides compared with the pristine activated carbon. The Yoon and Nelson, Thomas, and instantaneous local equilibrium (ILE) models were used to explain column data collected under different operating conditions. Finally, the results of the continuous adsorption process were explained successfully using the Yoon-Nelson and Thomas models. Thus, the phenol adsorption on Pb-Fe@MAC was a feasible operation to be performed in fixed-bed mode.

Response surface methodology for modeling the adsorptive uptake of phenol from aqueous solution using adsorbent polyethylene terephthalate microplastics

Optimization modeling and the interpretation of the adsorptive uptake of phenol from aqueous solution using pristine (Pr), modified (Mod-) and aged (Ag-) polyethylene terephthalate microplastics (PET MPs) as adsorbents at optimum conditions have been investigated. The surface morphology and functional groups of the MPs were evaluated using SEM and FTIR-ATR systems, while the surface area of the MPs was estimated using the Brunauer-Emmett Teller (BET) model. Experimentally determined optimization and Response Surface Methodology (RSM) were used to simulate and interpret the adsorption of phenol onto PET MPs, to determine the effects of four adsorption factors (contact-time, initial concentration, pH, and temperature) on the response (removal efficiency) using central composite design (CCD). The results showed that optimum operating conditions for the PET MPs adsorption of phenol from aqueous solution corresponds to contact-time of 77 minutes, 50 mg/L initial concentration, pH of 6, and temperature of 298 K respectively. The maximum removal efficiency of phenol ions under this operating condition was found to be 93.72%, 92.78% and 95.80% for Pr-PET MPs, Mod-PET MPs and Ag-PETMPs respectively. To understand the nature of the PET MPs sorption process, Redlich−Peterson (R-P), Elovich and Dubinin-Radushkevich (D-R) isotherms were employed. The results proved that, D-R model best fitted the PET MPs sorption process at 0.7214 ≤ R2 ≤ 0.9043. Elovich model confirmed the performances of the PET MPs uptake of phenol ions occurred by physical and exothermic processes. Their adsorption capacities followed Pr-PET MPs (0.226 mg/g) > Ag-PET MPs (0.216 mg/g) > Mod-PET MPs (0.126 mg/g) respectively.

Lead ferrite-activated carbon magnetic composite for efficient removal of phenol from aqueous solutions: synthesis, characterization, and adsorption studies

A novel lead ferrite-magnetic activated carbon (lead ferrite-MAC) composite was developed using the chemical co-precipitation method. Instrumental analyses such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis were performed to characterize adsorbent. The uptake of phenol from aqueous solutions using the developed adsorbent was compared to that of pristine activated carbon. The maximum adsorption capacity of lead ferrite-MAC composite (145.708 mg/g) was more than that of pristine activated carbon (116.606 mg/g) due to the metal hydroxides coated on activated carbon since they improve the retention of phenol on the available active sites of adsorbent and create an additional electrostatic interaction with the phenol adsorbate. Regarding the high value of the coefficient of determination (R2) and adjusted determination coefficient (R2adj), coupled with the lower values of average relative error (ARE) and minimum squared error (MSE), it can be found that the isothermal data for the lead ferrite-MAC adsorbent were in agreement with the isotherm models of Redlich-Peterson and Langmuir. From the kinetic viewpoint, pseudo-second-order and linear driving force models explained the phenol adsorption data for both adsorbents. The reusability tests for lead ferrite-MAC composite revealed that after six cycles, 85% of the initial adsorption capacity was maintained. The developed adsorbent can be successfully applied to uptake phenol from aqueous solutions.

Utilization of nanosize spent oil shale for water treatment: application of top-down nanonization technology for solid residues.

Since the dawn of nanoscience, producing nanomaterials in a simple, low-cost, and high-yield manner has been a major issue. For the commercial manufacturing of nanomaterials, various bottom-up and top-down methodologies have been established. High-energy dry ball milling is widely used for the production of diverse nanomaterials, nanograins, nanoalloys, and nanocomposites. Physical grinding of inorganic solid waste into nanosize (1-100nm) has improved their industrial applications particularly as water adsorbent. Application of nanosize spent oil shale by top-down methodology as adsorbent for phenol is addressed in the current research. The collected spent oil shale (SiO2 and Al2O3 making 45% of the material) has microstructure with average particle size of 56.6μm. The dry grinding was performed in a vibrating ball mill at various grinding time (5-150min) while keeping the grinding parameters constant including number of balls, ball size, total mass, vibration frequency, and amplitude. Upon grinding, the mean particle diameter of the bulk material was reduced to 191.8 and 85.2nm using 0.5 and 0.1mm grinding balls, respectively. The effect of grinding time on particle size and surface area was investigated; both particle size and surface area were not affected after 60min of grinding. Physical grinding by 0.1mm balls has notably improved surface area and total pore volume by 52% and 62%, respectively. Although nanosize particles (85.2nm) perform better than bulk material for phenol uptake, they underwent serious aggregation at pH > 2 and ionic strength > 1.0mM. Hence, the 191.8-nm size is selected to assess the effect of mechanical grinding on adsorption rate and equilibrium capacity for phenol as a common pollutant. Upon nanonization, adsorption rate of phenol was highly increased from 0.39 to 4.43mgg-1min-1 as analyzed by pseudo-second-order model. Adsorption isotherms were adequately presented by Sips model (prediction error 5.4-7.2%) with a maximum phenol retention capacity of 39.29mg/g after nanonization compared to 10.71mg/g for the raw material. The performance of the nanosize spent oil shale for phenol retention was promising when compared with advanced adsorbents like multiwalled carbon nanotube.