Shell Adsorbent Research Articles

Effect of Contact Time on the Sorption of Metal Ions Associated with Produced Water on Pulverized Oyster Shell (OS) as Adsorbent

The aim of this research is to investigate Metal ion sorption potentials of pulverized Oyster Shell as adsorbent in produced water from selected flow stations in the Niger Delta region of Nigeria. Produced water samples were collected from six (6) different oil drilling installations (CC7T, CC8T, WELL 2 GSS, WELL 8 TEB, AZUZUAMA ST 1, AZUZUAMA ST 2) around the Niger Delta area of Nigeria. The waste oyster shell was collected in Akpan-Andem Market in Uyo, Akwa-Ibom State and processed using well established protocols. Atomic Absorption Spectrometer (AAS) was used to determine selected metals’ Nickel (Ni), Cobalt (Co), Copper (Cu), Iron (Fe), Lead (Pb), Calcium (Ca) and Potassium (K) concentrations. The obtained values for Nickel ranged from 0.076mg/l at AZUZU-AMA ST1 flow station to 2.882 mg/l at WELL2-GSS flow station with average value of 0.745 mg/l. The obtained value for Cobalt ranged from ˂0.001 mg/l at CC-8T and CC-7T to 0.277 mg/l at AZUZUAMA ST1. Values obtained for Cu, Fe, Pb, Ca, and K ranged between: 0.195 mg/l at WELL2-GSS to 0.449 mg/l at AZUZU-AMA ST1; 2.785 mg/l to 89.279mg/l; ˂0.001 mg/l to 0.483 mg/l; 16.217 mg/l to 92.714 mg/l and 96.386 mg/l to 105.416 mg/l respectively. Generally, the amount of metal ions absorbed/adsorbed onto pulverized Oyster shell (OS) increased swiftly within 2 hours and slowly with further increase of contact time and then tended to be stable. For pulverized Oyster shell adsorbent, the adsorption/absorption capacity decreases with the increasing contact time. The adsorbent (OS) isn’t good material for removal of Calcium and Cobalt in produced water but was very effective adsorbent for Ni, Fe, and Pb removal in produced water and less effective for Cu and K removal from produced water. The study underscores the need to further probe outcome of above research at different pH and other relevant variables as well as compares its efficiency with other detoxification technologies like Detoxification by chemical reaction (DCR) technology.

Simultaneous removal of Pb(II) and Cr(VI) from a steel company wastewater using various green adsorbents: Material characterization and numerical optimization

ABSTRACT This study focuses on the simultaneous uptake of Pb(II) and Cr(VI) from industrial wastewater by walnut shell (WS), almond shell (AS), peanut shell (PS), and coconut shell (CS) adsorbents. Among the used adsorbents, the CS adsorbent exhibited the greatest BET surface area of 18.97 m2/g and porosity of 63.17% and the WS adsorbent also had the highest pore volume of 0.3536 m3/g. Lead and chromium removal were optimized using response surface methodology via a central composite design (CCD) approach. The efficiency of lead and chromium uptake from the wastewater was enhanced by increasing the concentration of WS, AS, PS, and CS adsorbents (Cads.) and decreasing the flow rate (Q) of the wastewater. Under the optimal conditions (Cads. = 0.85 g/L and Q = 2.5 mL/min), the maximum lead and chromium uptake from steel company wastewater was achieved using CS (92%) and WS (97.2%) adsorbents, respectively. The actual lead and chromium removal values were well-fitted based on a high Rpred2, confirming the validity of the CCD model. The acceptable performance of these green adsorbents in the simultaneous removal of chromium and lead from the wastewater introduces the WS, AS, PS, and CS adsorbents as inexpensive and available candidates for industrial wastewater treatment containing heavy metals.

Modeling of adsorptive treatment of lead (II) ions contaminated effluents using cashew nut shell alkali activated carbon: Batch kinetic, isothermal and thermodynamic studies

The numerical study of the decontamination of lead(II) ions-rich effluent employing activated carbon derived from cashew nut shell was the central focus of this work. Chemical activation with zinc chloride (ZnCl2) was used to produce powdered activated carbon at optimized activation conditions of impregnation ratio (0.531), activation temperature (1083 K) and activation time (63min). The physiochemical properties of raw and activated cashew nut shell were determined using Fourier transform infrared spectroscopy, scanning, X-ray diffractor (XRD), scanning electron microscopy (SEM), and Brunauer-Emmet-Teller (BET) analyses. Batch adsorption experiments were performed at varied process conditions of temperature (303–323) K, contact time (5–80min), and initial lead(II) ion concentrations (100–400 mg.L−1). The adsorption behavior of the batch–type operation was mathematically described in the form of non-linear parabolic partial differential equations (PDE’S) incorporating film, pore and surface diffusion mechanisms. The batch mathematical model was solved by implementing a custom MATLAB program-OkiyNwabannebatch and calibrated to predict the desired response (percentage removal) using measured adsorption data. The equilibrium adsorption, kinetics and thermodynamics of lead(II) ions adsorption onto activated cashew nut shell were also assessed using nonlinear isotherm, kinetic and thermodynamic models. Sensitivity analysis unveiled that temperature with sensitivity value of 37.31 % had a predominant effect on the model performance. The simulated equilibrium data was well explicated by the Freundlich model for lead(II) ions adsorption onto activated cashew nut shell. The pseudo-second order kinetic model best reproduced the simulated adsorption data for lead(II) ions uptake by cashew nut shell adsorbent. Likewise, the kinetic data followed Boyd model, indicating that the adsorption process is controlled by external (film) diffusion for the uptake of lead(II) ions by alkali activated cashew nut shell. Thermodynamic analysis using the Gibbs and Van’t Hoff’s models indicated that lead(II) ions adsorption by modified cashew nut shell is spontaneous and exothermic. The physical nature of the adsorption process was elucidated from the low values of the isosteric heats of adsorption (ΔHX) evaluated (<80 kJ mol−1). This study showed that zinc chloride activated cashew nut shell has good potential to be used as a cost-effective and efficient adsorbent for the uptake of lead(II) ions from aqueous solution.

Insight into the molecular mechanism of organic pollutants’ adsorption on magnetic ZIF-8 synthesized via a transformational route

This study presents the synthesis of Fe3O4@Zeolite Imidazolate Framework-8 (Fe3O4@ZIF-8), a novel magnetic core–shell adsorbent engineered for enhance adsorption of organic pollutants. The process begins with the formation of spherical magnetite aggregates (i.e., Fe3O4) via a solvothermal method, using polyacrylic acid for stabilization and capping. A ZIF-8 shell is then grown through a sol gel process followed by reaction with 2-methylimidazole, resulting in a crystalline shell approximately 60 nm thick. Characterization techniques, including energy dispersive X-ray analysis and X-ray diffraction, confirm the successful preparation of Fe3O4@ZIF-8. The adsorption capabilities were evaluated using methylene blue (MB) and diclofenac sodium (DCF) as model pollutants. Fe3O4@ZIF-8 demonstrated rapid removal efficiencies, with 98 % removal of MB (6.01 × 10-4 mg·g−1·min−1) and DCF (4.43 × 10-4 g·mg−1.min−1) within 15 and 30 min, respectively, significantly outperforming conventional activated carbon. Thermodynamic studies indicate that the adsorption processes are spontaneous; enthalpic changes drive MB adsorption, while DCF is influenced by entropic factors. Molecular modeling reveals preferential adsorption behaviors on different ZIF-8 facets, with stronger interactions for MB due to π-π stacking and hydrogen bonding. These findings underscore the potential of Fe3O4@ZIF-8 as an effective adsorbent for water purification, highlighting its substantial adsorption capacity (73.2 mg·g−1 for MB and 53.8 mg·g−1 for DCF), stability, and reusability.

Ultrasonic assisted adsorption of methylene blue using blood clam shell as a low-cost adsorbent

Methylene blue is a synthetic dye used in various industries, such as wood, linen, and silk. Generally, as much as 10–200 mg/L of methylene blue is released into the environment and potentially polluting the environment. One of methylene blue removal method from wastewater is adsorption, particularly using blood clam (Anadara granosa) shells adsorbent. Blood clam shells contain CaCO3 (up to 98.7 %) that can be utilized to adsorb methylene. Furthermore, methylene blue adsorption can be enhanced by employed the ultrasonic wave. This research aims to prepare, characterize, and employ blood clam shells as a low-cost adsorbent in the ultrasonic-assisted methylene blue adsorption. The parameters studied were the adsorbent preparation method, adsorbate pH, adsorbent mass, contact time, and initial concentration. The adsorbent preparation method affected the morphology, elemental composition, functional groups, and average particle size, which were confirmed using SEM-EDX, FTIR, and PSA, where this kind of investigation has never been conducted before. Optimum conditions for methylene blue adsorption were obtained for adsorbent A3, pH 12, adsorbent mass of 0.5 g, contact time of 60 min, and initial concentration of 10 ppm, with a removal percentage of 98.614 %. This removal percentage increased by 63.119 % (espescially in A3) compared to without ultrasonic waves, which could only remove methylene blue by 35.495 %. Ultrasonic-assisted adsorption of methylene blue using blood clam shells adsorbent proceeded according to the Sips isotherm model (R2 = 0.9953) and pseudo-second-order kinetics (R2 = 0.939). A3 shows an extraordinary performance, with reusability up to six cylces. The adsorption occurs by electrostatic interaction between adsorbent's surface and cations in methylene blue, chemisorption, and the formation of monolayer adsorbate in heterogenous A3's surface.

Preparation of alcohol/znso4-modified shrimp shell adsorbent and its cyanobacterial removal efficiency

Water pollution caused by toxic cyanobacteria is a worldwide problem that increases with eutrophication. A shrimp shell adsorbent modified by alcohol/ZnSO4 was employed herein to remove Microcystis aeruginosa. The modification effects of the volume ratios of the alcohol/ZnSO4 solutions, modification reaction temperature, and modification reaction time on the shrimp shells were studied using single factor experiments. The optimum modification parameters were also obtained. Under optimal conditions, the removal efficiency of the alcohol/ZnSO4-modified shrimp shell adsorbent on the M. aeruginosa cells was 78.38 % when the added concentration of the modified shrimp shell adsorbent was 14 g/L. The present study provides a promising technique of removing toxic cyanobacterial blooms.

Improved greywater quality after biofiltration with a fibre-biofilter derived from plantain pseudo stem

In this study, we addressed the prevalent issue of untreated greywater discharge into waterbodies in many developing countries, despite the associated public health risks. Our approach involved utilizing fibers extracted from plantain pseudo-stems to enhance the quality of greywater through simple biofiltration setups. Greywater sourced from the GETFund Hostel of the University of Energy and Natural Resources in Sunyani, Ghana, served as the focal point of our investigation. Through the application of this biofilter, we achieved notable reductions in two crucial parameters for assessing greywater quality: biochemical oxygen demand (BOD) and chemical oxygen demand (COD), averaging at 30.4 % and 28.67 %, respectively. Furthermore, we conducted comparative analyses between the efficacy of plantain pseudo-stem fibers and carbonized coconut shell adsorbent, both individually and in composite form as biosorbents. While certain combinations of biofilters led to slight increases in conductivity, pH, and total dissolved solids (TDS) in the treated greywater, these variations were anticipated and attributed to potential organic matter leaching during the biofiltration process. Employing Fourier-transform infrared (FT-IR) spectroscopy, we detected significant spectral changes indicative of successful organic matter removal from the greywater. Specifically, we observed an intensified phenolic hydroxyl (OH) peak at 3300 cm⁻¹, which shifted marginally to 3335 cm⁻¹ post-biofiltration. Additionally, the emergence of a carboxylic hydroxyl stretch at 2850 cm⁻¹ post-biofiltration provided strong evidence supporting the efficacy of our approach in mitigating organic contaminants in greywater.

Dispersive solid-phase extraction based on zirconium metal-organic framework coupled with gas chromatography-mass spectrometry for determining sugar phosphates in biological samples

BackgroundSugar phosphates (SPx) play important role in the metabolism of the organism. SPx such as glycerate 3-phosphate, fructose 6-phosphate and glucose 6-phosphate in biological samples have the poor stability, similar structure and low abundance, which make their separation and detection more challenging. MethodUiO-66-NH2 and ZrO2 coated SiO2(SBA-15) hard-core–shell adsorbents (UiO-66-NH2@SBA-15 and ZrO2@SBA-15) were synthesized, which were further used for dispersive solid-phase extraction for enriching the SPx in biological samples. The protocol was developed by UiO-66-NH2@SBA-15 and ZrO2@SBA-15 coupled with gas chromatography-mass spectrometry for the detection of trace SPx. The univariate experiment and response surface methodology were used to optimize the adsorption and desorption conditions. ResultsThe adsorbents showed excellent adsorption capacity and specificity towards SPx, which were proved by adsorption and selective experiments. Under the optimized conditions, there were good linearity within the range of 5.0–5000.0 ng mL−1, low limits of detection (0.001–1.0 ng mL−1), low limits of quantification (0.005–5.0 ng mL−1) and good precision (relative standard deviation less than 14.7 % for intra-day and inter-day). The satisfactory recoveries (89.1–113.8 %) and precision (0.5–14.6 %) were obtained when the sorbents were used to extract SPx from serum, saliva and cell samples. Moreover, UiO-66-NH2@SBA-15 was applied to the quantitative analysis of SPx from gastric cancer patients, because of a higher adsorption capacity (169.5–196.1 mg g−1). ConclusionsUiO-66-NH2@SBA-15 showed great potential in the extraction of SPx in biological samples, which was beneficial to find out the metabolic change of SPx and explain the pathogenesis of the disease.

Experimental Study on Removal of Cod and Colour from Textile Industry Wastewater using Groundnut Shell Adsorbent

Experimental Study on Removal of Cod and Colour from Textile Industry Wastewater using Groundnut Shell Adsorbent

Enhancing the CO2 adsorption with dual functionalized coconut shell-hydrochar using Chlorella microalgae and metal oxide: Synthesis, physicochemical properties & mechanism evaluations

This study aims to develop an inexpensive, environmentally-friendly adsorbent for capturing CO2 using coconut shells, widely abundant in Asian agricultural waste. The raw coconut shell adsorbent (CS) has undergone dual functionalization utilizing Chlorella microalgae and magnesium oxide (MgO) to enhance its physicochemical properties. Through dual functionalization, minimizing the loss of surface area and reducing the temperature sensitivity often occurring during CO2 adsorption is possible. The surface morphology, functional groups, and thermochemical properties of CS-hydrochar were characterized and evaluated. The characterization demonstrates the successful development of the ternary composite (HCS-A-Mg), with a specific surface area of 1045 m2/g and containing nitrogen and metal oxide functional groups. XRD analysis of HCS-A-Mg reveals crystalline peaks at 36.8°, 42.9°, and 63°, confirming the successful impregnation of MgO. The adsorption result showed that HCS-A-Mg exhibits a higher CO2 adsorption capacity of 2.63 mmol/g, 50% higher than pristine hydrochar (HCS). The adsorption study revealed that the CO2 adsorption capacity of HCS-A-Mg can be maximized to 3.23 mmol/g at 101 °C and 4.6 bar. Adsorption isotherms shows that the non-linear Sips model best describes the adsorption process, indicating a multilayer adsorption mechanism with profound surface heterogeneity of n = 2.3 for HCS-A-Mg, signifying higher accessibility of gas molecules deep into pores, enabling a variety of adsorption sites for CO2 binding. Selectivity and reusability studies were conducted to validate the adsorbent applicability for industrial applications. HCS-A-Mg has higher CO2/N2 selectivity by 41–57% and 0.05% loss of adsorption capacity after the 10th cyclic operation, suggesting their suitability for industrial applications. This finding underscores the potential of microalgae and magnesium oxide in advancing carbon capture technology and addressing environmental challenges.

Zeolite-based core–shell adsorbent for the removal of toxic pollutants from aquatic environment: current challenges and opportunities

Zeolite-based core–shell adsorbent for the removal of toxic pollutants from aquatic environment: current challenges and opportunities

Preparation and Characterization of Magnetic Walnut Shell Adsorbents

Preparation and Characterization of Magnetic Walnut Shell Adsorbents

Analysis of coconut shell adsorption capability as greywater waste adsorbent

As coconut plantations increase in Indonesia, coconut shell waste has the potential to damage the environment if it is not processed properly. Various studies state that coconut shell waste can be used as a greywater adsorbent. Greywater is a domestic waste that is much less polluted than domestic wastewater because it does not contain urine, feces, and toilet paper, and only contains about 30% of the total organic load. Therefore, it is important to determine the right adsorbent for appropriate processing. So this research will test the adsorption capacity of coconut shell waste as a greywater adsorbent using iodine absorption analysis. In the analysis of iodine absorption capacity, coconut shell adsorbents have high adsorption capabilities in absorbing adsorbate (iodine molecules) with high molecular concentrations. Based on iodine absorption analysis data, it is known that the coconut shell waste adsorbent has a maximum adsorption capacity of 2.86 x 10-3 mg g-1 by following the Langmuir isotherm model. The coconut shell waste adsorbent used as a medium in the adsorption column was able to reduce total dissolved solids by 3.7 %, total suspended solids by 23.3 %, and phosphate removal efficiency by 6.3 % in greywater waste samples. This proves that coconut shell waste can act as an adsorbent in managing greywater waste.

Recyclable Fe3O4@UiO-66-PDA core–shell nanomaterials for extensive metal ion adsorption: Batch experiments and theoretical analysis

With the ever-increasing challenge of heavy metal pollution, the imperative for developing highly efficient adsorbents has become apparent to remove metal ions from wastewater completely. In this study, we introduce a novel magnetic core–shell adsorbent, Fe3O4@UiO-66-PDA. It features a polydopamine (PDA) modified zirconium-based metal–organic framework (UiO-66) synthesized through a simple solvothermal method. The adsorbent boasts a unique core–shell architecture with a high specific surface area, abundant micropores, and remarkable thermal stability. The adsorption capabilities of six metal ions (Fe3+, Mn2+, Pb2+, Cu2+, Hg2+, and Cd2+) were systematically investigated, guided by the theory of hard and soft acids and bases. Among these, three representative metal ions (Fe3+, Pb2+, and Hg2+) were scrutinized in detail. The activated Fe3O4@UiO-66-PDA exhibited exceptional adsorption capacities for these metal ions, achieving impressive values of 97.99 mg/g, 121.42 mg/g, and 130.72 mg/g, respectively, at pH 5.0. Moreover, the adsorbent demonstrated efficient recovery from aqueous solution using an external magnet, maintaining robust adsorption efficiency (>80%) and stability even after six cycles. To delve deeper into the optimized adsorption of Hg2+, density functional theory (DFT) analysis was employed, revealing an adsorption energy of -2.61 eV for Hg2+. This notable adsorption capacity was primarily attributed to electron interactions and coordination effects. This study offers valuable insights into metal ion adsorption facilitated, by magnetic metal–organic framework (MOF) materials.

Remediation of malachite-green dye from textile wastewater using biosorbent almond shell-based cellulose

The presence of malachite green (MG) in surface waters represents a major health hazard for aquatic organisms and communities living near contaminated water sources. In this study, almond shell adsorbents prepared from the four almond types Marcona (M), Fournat de Brézenaud (FZ), Ferraduel (FD) and Ferriages (FG), used to clean wastewater from the textile industry that had been contaminated with the color MG. Optimal adsorption parameters were determined through batch experiments using a standard dye solution. Further, SEM, XRD, BET, and FTIR were employed for characterizing the biosorbents. The examination of the experimental data using isotherms and kinetic models revealed that the adsorption of the MG occurs in a monolayer, with chemical adsorption as the rate-controlling step. The maximum adsorption capacities, under pH around 7 and temperature of 35 °C were 41.0, 61.0, 48.1, and 118.0 mg/g for M, FD, FG, and FZ, respectively. In addition, Monte-Carlo simulation models, and density functional theory calculations were performed to provide a more detailed understanding of the adsorption mechanism. Topological studies such as NCI, RDG, LOL, and ELF were conducted and discussed using Multiwave function (Multiwfn) and VMD programs in liquid phase. In conclusion, chemisorption limits the rate of the adsorption process, and that green cation malachite is more susceptible to nucleophilic than electrophilic attacking. Based on these experimental and theoretical results, it is possible to consider these materials as an inexpensive and viable solution to eliminate MG from wastewater. Adsorption on cellulose can be considered as a feasible strategy for wastewater treatment, and the adsorbents can be optimized for use in real wastewater samples at even lower concentrations. This approach offers an inexpensive and effective technological alternative to conventional methods for the retention of MG.

Pemanfaatan Limbah Padat Kelapa Sawit untuk Pemurnian Minyak Goreng Bekas

The solid wastes of palm oil are palm shell and boiler ash which can be used as adsorbents. Adsorbent is a solid substance that an adsorption process which is used for the refining process of used cooking oil. Used cooking oil is oil derived from leftover cooking oil which has a higher saturated fatty acid content than new vegetable oil. This study aims to determine the process of making adsorbents, the process of refining used cooking oil, and the effect of adsorbent variations on the purification of used cooking oil. This research was carried out with the adsorption process, adding 15% of the adsorbent variation. The process of making the adsorbent was carried out by dehydration, carbonization at 6000C, and activation with 3% HCl for 24 hours. The results of the optimum adsorbent variation were 100% palm shell adsorbent with the results of analysis on used cooking oil after adsorption, namely: 0.05% water content, 0.58% ALB content, and 1.7 mgO2/100g peroxide number.

Thermally modified nanocrystalline snail shell adsorbent for methylene blue sequestration: equilibrium, kinetic, thermodynamic, artificial intelligence, and DFT studies.

In recent years, the quest for an efficient and sustainable adsorbent material that can effectively remove harmful and hazardous dyes from industrial effluent has become more intense. The goal is to explore the capability of thermally modified nanocrystalline snail shells (TMNSS) as a new biosorbent for removing methylene blue (MB) dye from contaminated wastewater. TMNSS was employed in batch adsorption experiments to remove MB dye from its solutions, taking into account various adsorption parameters such as contact time, temperature, pH, adsorbent dosage, and initial concentration. SEM, EDS, XRD, and FTIR were used to characterize the adsorbent. The study further developed and adopted adaptive neuro-fuzzy inference system (ANFIS) and density functional theory (DFT) studies to holistically examine the adsorption process of MB onto the adsorbent. EDX and FTIR confirm the formation of CaO with a sharp peak at 547 cm-1, and C-O and O-H are present, as well. SEM and XRD show an irregularly shaped highly crystalline nanosized (65 ± 2.81 nm) particle with a lattice parameter value of 8.611617 Å. The adsorption efficiency of 96.48 ± 0.58% was recorded with a pH of 3.0 and an adsorbent dose of 10 mg at 30 °C. The findings from the study fit nicely onto Freundlich isotherms, with Qm = 31.7853 mg g-1 and R2 = 0.9985. Pseudo-second-order kinetics recorded the least error value of 0.8792 and R2 = 0.9868, thus indicating chemisorption and multilayer adsorption processes. The exothermic and spontaneous nature of the adsorption process are demonstrated by ΔH° and ΔG°. The performance of the ANFIS-based prediction of removal rate, which was demonstrated by a root mean square error (RMSE) value of 2.2077, mean absolute deviation (MAD) value of 1.1429, mean absolute error (MAE) value of 1.8786, and mean absolute percentage error (MAPE) value of 2.0178, revealed that the ANFIS model predictions and experimental findings are in good agreement. More so, DFT provides insights into the molecular interactions between MB and the adsorbent surface, with a calculated adsorbate-adsorbent binding affinity value of -1.3 kcal mol-1, thus confirming the ability of TMNSS for MB sequestration. The findings of this study highlight the promising potential of thermally modified nanocrystalline snail shells as sustainable and efficient adsorbents for MB sequestration.

Two-component irreversible adsorption with pore diffusion control – Experimental verification of a theory for protein adsorption on core–shell resins

The adsorption rates of mixtures of BSA monomer and dimer and of fibronectin and thyroglobulin are measured for core–shell adsorbents and compared with a pore-diffusion limited irreversible binding model. Measurements are conducted for individual particles, batch, and packed columns. The proteins in this work are irreversibly bound but have different binding capacities and effective pore diffusivities resulting in different one-component rates. Consistent with the theoretical model, mixture adsorption results in a single adsorption front within the particles, batch uptake curves with no overshoot in the amount adsorbed, and breakthrough curves without roll-up and with the stronger binding dimer emerging first from the column. Quantitatively, the model accounts for the different capacities and diffusivities and for the inert shell through a modified Biot number. Based on one-component measurements, the model accurately predicts mixture adsorption and is useful for describing flow-through purifications where multiple contaminants are removed from an unbound product.

Adsorption of Phenol from Both Acidic and Basic Industrial Waste via Newly Synthesized Metal Organic Framework Hybrid Smart Adsorbents

Newly prepared pH-responsive metal organic frameworks (MOFs) having a specific surface area of 1400 m2/g could be exploited in the total removal of pollutants from wastewaters in this work. Smart core–shell structures of COP-150@ZIF-8 and NPC@ZIF-8 were successfully synthesized in large scales through internal extended growth under polyvinylpyrrolidone (PVP) regulation and used in phenol removal from aqueous media. The essential factors on the removal, namely pH, initial concentration of phenol, contact time, adsorbent dosage, and temperature, were studied and optimized. The experimental data were investigated by different kinetic and isotherm models, in which the removal of phenol by these smart sorbents is correlated with the Freundlich isotherm model and was found to follow the pseudo-second-order kinetic model. Excellent adsorption capacity of 1670 mg·g–1 and high efficiency were achieved in phenol removal (mixing time of only 20 min) that suggest the application of smart NPC@ZIF-8 core–shell in water filtration. Also, the optimal concentration of smart NPC@ZIF-8 and smart COP@ZIF-8 core–shell adsorbents was obtained as 300 and 250 mg·L–1, respectively. On the other hand, more than 94% removal of phenol was observed at pH = 3 for both smart nanosorbents (mere use of 0.1 g adsorbent). The results of thermodynamics confirm that the process of adsorption is exothermic and spontaneous. Moreover, having simulated the atomistic investigation of phenol removal via molecular dynamics, it was concluded that the different designed adsorbents in this work have a high capacity to remove phenol, specifically NPC@ZIF-8.

Preparation of paramagnetic ferroferric oxide-calcined layered double hydroxide core–shell adsorbent for selective removal of anionic pollutants

Adsorption is one of the most common methods of pollution treatment. The selectivity for pollutants and recyclability of adsorbents are crucial to reduce the treatment cost. Layered double hydroxide (LDH) materials are one type of adsorbent with poor recyclability. Prussian blue (PB) is a sturdy and inexpensive metal–organic framework material that can be used as the precursor for synthesizing paramagnetic ferroferric oxide (Fe3O4). It is intriguing to build some reusable adsorbents with magnetic separation by integrating LDH and PB. In this work, paramagnetic Fe3O4-calcined LDH (Fe3O4@cLDH) core–shell adsorbent was designed and prepared by the calcination of PB-ZnAl layered double hydroxide (PB@LDH) core–shell precursor, which exhibits high anionic dyes selectivity in wastewater solutions. The paramagnetism and adsorption capability of Fe3O4@cLDH come from the Fe3O4 core and calcined ZnAl-LDH shell, respectively. Fe3O4@cLDH shows an adsorption capacity of 230 mg g−1 for acid orange and a high selectivity for anionic dyes in cation–anion mixed dye solutions. The regeneration process indicates that the high selectivity for anions is related to the specific hydration recovery process of ZnAl-LDH. The synergistic effect of the paramagnetic Fe3O4 core and calcined ZnAl-LDH shell makes Fe3O4@cLDH an excellent magnetic separation adsorbent with high selectivity to anions.