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In the current investigation, MnFe 2 O 4 /ZIF-8 nanocomposite was generated as a magnetic nanoadsorber using the extract of Dracocephalum plant and characterized by XRD, FTIR, VSM, BET, FESEM, EDS-mapping, TEM, XPS, TPD-NH 3 , and TGA analyses. Also, to determine its efficiency in the adsorption process of tetracycline, the effect of pH (3–9), nanocomposite dose (0.025–2 g/L), initial pollutant concentration (5–100 mg/L), contact time (5–200 min), and temperature (5–50 °C) were studied. The results of the morphological properties of the magnetic nanocomposite confirmed the spherical shape of this nanoadsorber with an average size of 54 ± 31 nm. BET analysis showed that modification of MnFe 2 O 4 material with ZIF-8 as a new nanoadsorber leads to excellent modification of S BET (143.8 m2/g) and V Total (0.44 cm3/g). The highest removal efficiency of tetracycline in optimal conditions (pH = 7, contact time = 120 min, nanocomposite dose = 1.5 g/L, and temperature = 20 °C for a tetracycline concentration of 20 mg/L) was 90.11%. As the temperature increased, the removal efficiency increased from 40.46% to 95.06% during 120 min, which indicates that the adsorption reaction is endothermic. In addition, the data obtained from the isotherms of Langmuir (R2 = 0.958), Freundlich (R2 = 0.534), and Temkin (R2 = 0.747) showed that the tetracycline adsorption is monolayer and on the homogeneous surface of the synthesized magnetic nanoadsorber. The elimination process of tetracycline by nanoadsorber followed the pseudo-second order model (R2 = 0.998). Investigating the effect of interfering ions also confirmed the decrease in the adsorption efficiency. Also, the investigation of the reusability of the synthesized magnetic nanoadsorber in tetracycline adsorption indicates that after eight cycles, the efficiency decreases by %16.51. According to the results, the magnetic nanocomposite synthesized in this work can be a suitable and economical adsorber for the removal of tetracycline from aqueous environments. [Display omitted] • Adsorption of TC on the MnFe 2 O 4 /ZIF-8 nanocomposite in neutral environment. • 16% decrease in efficiency of MnFe 2 O 4 /ZIF-8 adsorbent during 8 cycles. • Very high resistance of MnFe 2 O 4 /ZIF-8 adsorbent against high temperatures. • High efficiency of adsorbent in removal of TC in the presence of interfering ions. [ABSTRACT FROM AUTHOR]

In the present work, the biomass of Aspergillus flavus (AF) was modified using magnetic nanoparticles MnFe 2 O 4 and metal-organic framework of ZIF-67, and its ability to remove tetracycline antibiotic (TCH) was investigated. With the help of physicochemical tests, AF biomass modification with ZIF-67 and MnFe 2 O 4 magnetic nanoparticles was confirmed. Based on the BET value, AF-MnFe 2 O 4 -ZIF-67 (139.83 m2/g) has a higher surface value than AF (0.786 m2/g) and AF/MnFe 2 O 4 (17.504 m2/g). Also, the magnetic saturation value revealed that the modified biomass can be isolated from the treated solution using a simple magnetic field. Maximum TCH elimination (99.04%) using AF-MnFe 2 O 4 -ZIF-67 was obtained at pH 7, adsorber mass of 1 g/L, adsorption time of 40 min, and TCH content of 10 mg/L. The thermodynamic study indicated that the TCH abatement using the desired composite is spontaneous and exothermic. The experimental results showed that the adsorption process is compatible with the pseudo-second-order kinetic and Freundlich model. The maximum adsorption capacity for AF, AF-MnFe 2 O 4 , and AF-MnFe 2 O 4 -ZIF-67 was quantified to be 9.75 mg/g, 25.59 mg/g, and 43.87 mg/g, respectively. The reusability of the desired adsorbers was examined in up to 8 steps. The outcomes showed that the adsorbers can be used several times in TCH elimination. The provided composite can remove TCH from hospital wastewater, so it can be suggested for use in water and wastewater treatment works. • The A. flavus biomass was modified with MnFe 2 O 4 and ZIF-67 to remove tetracycline. • The magnetic sorbent was stable as it was reutilized 8 times with efficiency >86%. • The adsorbent had good efficiency in the presence of cations (Na+, K+, and Ca2+). • Tetracycline adsorption obeyed pseudo-first order and Freundlich models (R2 > 0.9). • > 99% of tetracycline was removed at pH 7, sorbent mass of 1 g/L, and time 40 min. [ABSTRACT FROM AUTHOR]

The presence of antibiotics in the environment can threaten the ecosystem. The current work was an aim to degrade the sulfamethoxazole (SMX) antibiotic from the aqueous solution and hospital wastewater by the photo-Fenton process. The experiments were carried out in a quartz reactor and effects of operational parameters such as pH, H2O2 :Fe2+ ratio, reaction time, and SMX antibiotic concentration were evaluated. After optimizing the parameters, the efficiency of the photo-Fenton process was tested for eliminating SMX from the hospital wastewater. The optimal conditions for SMX removal by the photo-Fenton process were obtained at pH 3, H2O2 :Fe2+ ratio of 11:2, the initial SMX concentration of 25 mg/L, and the reaction time of 15 min. At optimized conditions, the removal efficiency of the SMX and chemical oxygen demand was attained 98.06% and 87.65%, respectively. The efficiency of the photo-Fenton system for removing SMX antibiotics from the hospital wastewater was obtained 67.42%. The pseudo-first-order kinetic model was well fitted the data for SMX removal using the photo-Fenton process. Accordingly, the photo-Fenton process is an effective method for removing SMX antibiotics from aqueous solutions and hospital wastewaters. [ABSTRACT FROM AUTHOR]

The present study investigated the performance of catalytic ozonation with C-MgO-doped reduced graphene oxide support (rGO/C-MgO) in humic acid (HA) removal from aqueous solution in a labscale batch reactor. The analyses of scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, UV-Vis, and Brunauer-Emmett-Teller showed that the rGO/C-MgO has been synthesized successfully. Photoluminescence analysis confirmed that the number of oxygen vacancy defect in C-MgO structure increased strongly rather than MgO because of the presence of carbon in the structure of MgO. Response surface methodology-central composite design (RSM-CCD) suggested a quadratic polynomial model (F-value = 363.38 and R² = 0.9971) for describing the effects of independent variables on the response (removal efficiency). The optimum values of the independent parameters based on the maximum removal efficiency were obtained at pH = 8.46, contact time = 12 min, catalyst dose = 1 g/L and NaCl = 10 mg/L. The salicylic acid and chloroform application as radical scavengers in the reaction solution demonstrated that non-hydroxyl radical mechanisms are the main reactions involved in HA degradation. Synergetic effect exhibits a noticeable enhancement in the hybrid catalytic ozonation process in comparison with the separate processes. The behavior of HA degradation under the process was described as well by pseudo-first-order kinetic model with a rate constant of 0.2092 min-1. The efficiency of total organic carbon removal was determined to be 86.8% and 25.3% at 100 and 10 min reaction times. In conclusion, the rGO/C-MgO composite can be suggested as a promising catalyst in catalytic ozonation process for treating water polluted with organic compounds such as HA. [ABSTRACT FROM AUTHOR]

The present paper describes the sono-assisted adsorption (sono-adsorption) of methylene blue (MB), methyl violet (MV), and Nile blue (NB) from aqueous solution by AC/CoFe2O4 magnetic composite. FT-IR, TGA-DTG, VSM, XRD, TEM, SEM, EDX, Map, and Raman analysis were used to characterize the magnetic composite. The magnetization saturation value of AC/CoFe2O4 magnetic composite was determined to be 53.06 emu/g. Dye sono-adsorption efficiency was increased by increasing adsorbent dose, pH value, and contact time, but not dye concentration. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were used to study the kinetic behavior of the cationic dye sono-adsorption. The sono-adsorption kinetics was reasonably followed by pseudo-second-order model (R2 > 0.998). The results showed that the Freundlich model (R2 > 0.976) was more able to describe the sono-adsorption equilibrium behavior than Langmuir, D-R, and Scatchard models. The maximum sono-adsorption capacity of NB, MV, and MB was determined as 86.24, 83.90, and 87.48 mg/g, respectively. Based on the parameters derived from isotherm modeling (RL, n, and E), the sono-adsorption process of cationic dyes is desirable and physical. An increase in NaCl concentration reduced the sono-adsorption efficiency for all dyes. Also, the adsorption-desorption of AC/CoFe2O4 magnetic was studied up to 10 stages, and it was confirmed that the sono-adsorption efficiency is acceptable up to the eight stage. AC/CoFe2O4 magnetic composite is, therefore, an affordable and recyclable adsorbent to remove the molecule of NB, MV, and MB dyes from aqueous media. [ABSTRACT FROM AUTHOR]

Alizarin red-S (ARS) is a type of azo dye that is widely used for dyeing of wool and nylon. It is toxic and carcinogenic and can cause a serious hazard to aquatic ecosystems. The ARS removal was experimentally conducted using the Saccharomyces cerevisiae biomass under various parameters of pH (3-11), contact time (20-180 min), the ARS concentration (25-100 mg L-1), and yeast dose (0.1%-1.3% w v-1). After completing each run, the suspensions were centrifuged at 10,000 rpm for 7 min. Finally, the absorbance of samples was read by UV-visible spectrophotometer at the wavelength of 427 nm. The maximum removal efficiency of ARS (68.51%) occurred at the conditions of ARS concentration of 50 mg L-1, S. cerevisiae dose of 0.4% w v-1, solution pH of 3, and contact time of 120 min. Biosorption process is desired at low pH under acidic conditions. The equilibrium data of the biosorption process were well fitted with the Langmuir model (R2 = 0.99). Results indicated that the removal efficiency of ARS has an increasing rate from 10 to 80 min. The best kinetic model to fit experimental data was the pseudo-second-order. The results of the current study confirmed that S. cerevisiae could be used as a low-cost biosorbent for eliminating ARS from aqueous solutions. [ABSTRACT FROM AUTHOR]

This study was designed to present a facile and effective biosorbent from Prosopis cineraria and Syzygium cumini leave (PCL and SCL) for fluoride removal. The test was done in batch mode and the effect of contact time (5, 25, 60, 90, and 120 min), initial fluoride concentration level (3, 5, 8, and 12 mg/L), and biosorbent dose (1, 3, 5, 10, and 25 g/L) on the biosorption process were examined. The optimum conditions for the maximum fluoride removal were occurred at 1 g/L biosorbent dose and contact time of 120 (for PCL) and 90 min (for SCL). The results suggested that the pseudo‐second‐order and Langmuir isotherm models described the experimental data well. According to the Langmuir model, the maximum adsorption capacity of fluoride for PCL and SCL was attained 11.52 and 7.4 mg/g, respectively. Based on Boyd and intra‐diffusion models, the biosorption of fluoride onto PCL and SCL was mainly controlled by film‐diffusion. The study revealed the potential use of PCL and SCL as two new effective biosorbents for the removal of fluoride from aqueous solution. © 2019 American Institute of Chemical Engineers Environ Prog, 38: S429–S440, 2019 [ABSTRACT FROM AUTHOR]

In the current study, the bio-adsorption potential of Callinectes sapidus biomass for control of cadmium, nickel, and lead from the aqueous stream was assessed. Spectrum analysis of FTIR, AFM, EDAX, mapping, SEM, TEM, and XRF was used to study the properties of the C. sapidus biomass. The XRF analysis revealed that C. sapidus bio-adsorbent has various effective metal oxides that can be useful to adsorb pollutants. The best model to describe the equilibrium data was Freundlich isotherm. The Langmuir bio-adsorption capacity was reported at 31.44 mg g−1, 29.23 mg g−1, and 29.15 mg g−1 for lead, cadmium, and nickel ions, respectively. Pseudo-first-order and pseudo-second-order kinetic models were studied to test the kinetic behavior of the process. An intra-particle diffusion model was used to determine the effective mechanisms involved in the bio-adsorption. Based on t1/2, it can be concluded that the equilibrium speed of the bio-adsorption process is high. The thermodynamic study showed that the metal bio-adsorption process using C. sapidus biomass is exothermic and spontaneous. The field applicability of the crab bio-adsorbent for eliminating concurrently several contaminants (metal ions, antibiotics, sulfate, nitrate, and ammonium) from an actual wastewater was successfully examined. [ABSTRACT FROM AUTHOR]

This study reports a new approach of alga amendment in a live mode. The Caulerpa sertularioides alga was modified with sulfur-containing materials of methionine (C5H11NO2S) and sodium sulfate (Na2SO4) to more concentrate the sulfur content of the yielded biomass (adsorbent). The simple and amended C. sertularioides alga was fully characterized with FTIR, SEM, EDX, BET, BJH, and pHzpc techniques. The copper adsorption from aqueous media was done by three adsorbents of C. sertularioides-simple (CSS), C. sertularioides-Na2SO4 (CSN), and C. sertularioides-C5H11NO2S (CSC). The parameters of pH (2-6), adsorbent dosage (2-10 g/L), and contact time (3-80 min) were optimized at 5, 5 g/L, and 60 min, respectively. According to Langmuir isotherm (the best-fitted model), the maximum adsorption capacity of CSN (98.04 mg/g) was obtained 2.4 times higher than CSC (40.73 mg/g) and 9.5 times higher than CSS (10.29 mg/g). The Cu adsorption process by the adsorbents was best-fitted pseudo-second-order kinetic model. The CSN, CSC, and CSS biomasses were successfully reused 5, 4, and 4 times, respectively. The thermodynamic study revealed that the copper adsorption process by CSN is exothermic and non-spontaneous. Finally, the suitability of adsorbents prepared from algae was tested by cleaning a simulated wastewater. [ABSTRACT FROM AUTHOR]

This study compared the sun- and oven-dried powdered Malva sylvestris for removing Cu(II) from aqueous solution. The fresh and Cu-loaded adsorbents characteristics were analyzed by Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller testing and scanning electron microscopy. The studied parameters that affect adsorption capacity were pH (2-7), initial copper concentration (50-150 mg/L), contact time (3-60 min), adsorbent dosage (1-20 g/L) and temperature (10-35 °C). The results showed that the maximum removal of Cu(II) was observed at pH 5 for both adsorbents. The amount of Cu(II) adsorbed onto both adsorbents increased as the contact time and the initial concentration of Cu(II) increased. The adsorbents exhibited the highest Cu(II) removal at a temperature of 35 °C. The adsorption data obtained at different temperatures was described well by the Langmuir isotherm (qm = 172.61-202.81 mg/g for oven-dried and 118.49-133.45 mg/g for sun-dried) and the pseudo second-order kinetic model (R2 = 0.999 and 0.993-0.997 for oven- and sun-dried, respectively). An electroplating wastewater sample was effectively treated using oven-dried powdered M. sylvestris. The adsorption efficiency of the oven- and sun-dried M. sylvestris after five reuses was 70.4% and 26.1%, respectively. Generally, the oven-dried adsorbent was shown to be more effective than the sun-dried for removal of Cu(II) from wastewater. The cost assessment indicated that the oven-dried M. sylvestris is a more economical adsorbent than sun-dried one. [ABSTRACT FROM AUTHOR]

The purpose of this study was the modification of zeolite with the cationic surfactant of cetyltrimethylammonium bromide for enhancing the adsorption of cyanide (CN− ) from aqueous solution. Hence, the batch tests were conducted under different conditions for CN− removal by the surfactant-modified zeolite (SMZ). The effect of pH (3–10), SMZ dosage (0.25–5 g/L), CN− concentration (50, 100, and 200 mg/L), and contact time (5–400 min) was evaluated. More than 95% of cyanide was removed at the conditions of pH of 10, the initial cyanide concentration of 100 mg/L, the SMZ dosage of 4 g/L, and the contact time of 250 min. The analysis of kinetics adsorption showed that cyanide ions adsorption onto the SMZ clearly followed the pseudo-second-order model. The isotherm adsorption data were mostly matched by Langmuir model with maximum adsorption capacity of 49.57 mg/g. The fresh and used SMZ was fully characterized by Brunauer–Emmett–Teller, Barrett–Joyner–Halenda, loss of ignition, X-ray powder diffraction, scanning electron microscope, Fourier transform infrared spectroscopy, and pH of zero point charge (pHzpc). The surface study indicated that the adsorbent is mesoporous and crystalline. The adsorption–desorption study was done using three reagents of HNO3 , HCl, and NaOH. A metal plating wastewater was successfully treated using SMZ. Accordingly, the SMZ was found to be an effective adsorbent for the removal of different concentrations of cyanide from aqueous solution. [ABSTRACT FROM AUTHOR]

In this work, carbon nanotubes (CNT) and β-cyclodextrin (CD) was used to generate magnetic composites (CNT/MnFe 2 O 4 and CNT/β- CD/MnFe 2 O 4) to remove the emerging contaminant of tetracycline (TC) antibiotic from various aqueous solutions. Various techniques were used to investigate the structural and surface characteristics of the adsorptive composites. Brunauer–Emmett–Teller (BET) test illustrated that the synthesized magnetic composites have a higher specific active surface than CNT. The effect of water pH, temperature, sorption time, TC content, and type of aqueous solution on the elimination efficiency was explored. Our data followed the isotherm models of Redlich-Peterson and Temkin. The peak of TC adsorption capacity from distilled water using CNT, CNT/MnFe 2 O 4 , CNT/β-CD/MnFe 2 O 4 was determined 82.66 mg/g, 86.48 mg/g, and 89.53 mg/g, respectively. The TC adsorption capacity using CNT/β-CD/MnFe 2 O 4 magnetic composite from urban drinking water and wastewater was determined at 55.02 mg/g and 40.36 mg/g, respectively. The adsorption process revealed that the removal of TC from distilled water using the synthesized adsorbents follows the pseudo-first-order model. In contrast, the removal of TC from municipal drinking water and wastewater follows the pseudo-second-order kinetic model. The TC decontamination process was spontaneous and exothermic and could be performed well at ambient temperature. Overall, the studied adsorbents (CNT and CNT-based magnetic composites) can be used as promising adsorbents in the TC removal processes from aqueous solutions. [Display omitted] • The CNT/β-Cyclodextrin/MnFe 2 O 4 nanocomposite had a BET value of 166 m2/g. • Tetracycline (TC) from different solutions was adsorbed to the magnetic composite. • The TC uptake capacity from wastewater using nanocomposite was obtained 40 mg/g. • The TC adsorption onto nanocomposite followed Redlich-Peterson and Temkin models. • The TC removal from distilled water was obeyed pseudo-first-order model. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Zeolite 4A/WO 3 /CuO composite catalyst was synthesized to degrade the anionic dyes simultaneously by the sonophotocatalytic process. • The composite catalyst system exhibited a specific surface area of 10.76 m2/g. • The findings indicate that the sonophotocatalytic process demonstrates high efficiency and performance. • The reusability of the Zeolite 4A/WO 3 /CuO catalyst showed that it maintained over 90% of its performance even after five cycles of reuse. • The findings suggest that the sonophotocatalytic process has a faster degradation rate and shorter half-life. • The Zeolite 4A/WO 3 /CuO composite can be confidently recommended as an efficient catalyst for dye removal from aqueous solutions using the sonophotocatalytic process. In this study, a novel composite catalyst system, Zeolite 4A/WO 3 /CuO with a Z-scheme design, was synthesized for photocatalysis, sonocatalysis, and sono-photocatalysis methyl orange (MO) and indigo carmine (IC) dyes simultaneously. The properties of the Zeolite 4A/WO 3 /CuO composite were thoroughly investigated using various techniques, and the results confirmed the synthesis of the desired catalyst system. In the sono-photocatalytic process, using the Zeolite 4A/WO 3 /CuO composite, the maximum efficiency for MO (99.12 %) and IC (97.24 %) was achieved at pH of 2 and 3, with a catalyst dosage of 0.15 g/L, a dye concentration of 10 mg/L, a contact time of 25 min, and H 2 O 2 dosage of 30 µL/100 mL. The dye elimination efficiency using the sono-photocatalytic process was reduced in the presence of Cl- and PO 4 3- in the distilled water. The efficiency also declined in the medium of river and well water resources. Moreover, the Zeolite 4A/WO 3 /CuO catalyst maintained over 90 % of its performance even after five reuse cycles. Based on the kinetic study, the sono-photocatalytic process exhibited higher activation for the removal of MO (k: 0.1946 min−1 and t 1/2 : 3.561) and IC (k: 0.1433 min−1 and t 1/2 : 4.836) than other processes. The synergy values for the MO and IC degradation using the Zeolite 4A/WO 3 /CuO composite were determined to be 2.167 and 2.303, respectively. The impact of various scavengers demonstrated that in the degradation processes of the target dyes using the sono-photocatalytic process, different active species like OH•, e-, h+, and O 2 –• are involved. The purification of dye-laden water using the sono-photocatalytic process was not toxic for plant germination, microorganisms, and fish, highlighting the successful biocompatibility of the process for dye removal. [ABSTRACT FROM AUTHOR]

The activated carbon prepared from Phoenix dactylifera fruit stones was tested for the removal of methylene blue (MB) dye from aqueous solutions. Batch studies were carried out to evaluate the impacts of initial solution pH (2-12), chemically activated carbon (CAC) concentration (0.25-5 g/L), MB concentration (50-400 mg/L), and contact time (20-430 min) on the adsorption of MB onto CAC. Results showed that the adsorption of MB was favorable at neutral pH. The results demonstrated that the Langmuir isotherm model best represented the equilibrium data with a maximum MB adsorption capacity of 478.32 mg/g. Pseudo-second-order kinetic model was found to adequately describe the adsorption process. The calculated thermodynamic parameters showed that adsorption process was spontaneous endothermic and physisorption was possible under examined conditions. In the final part of the study, the efficacy of CAC was examined by analyzing the removal of dye from industrial wastewater. [ABSTRACT FROM AUTHOR]

Cationic synthetic dyes are one of the hazards in aqueous solutions that can affect the health of humans and living organisms. In the current work, polyacrylamide (PAM)- g -gelatin hydrogel and modified PAM- g -gelatin hydrogel using activated carbon of Luffa cylindrica (ACL) and ACL/Mg–Fe LDH were applied to eliminate crystal violet (CV), a cationic dye, from water media. The hydrogels were synthesized using free radical polymerization approach, and the hydrogels were characterized using FTIR, XRD, TGA-DTG, BET, SEM, and EDX-Map. The surface area of ACL, ACL/Mg–Fe LDH, PAM-g-gelatin, PAM-g-gelatin/ACL, and PAM-g-gelatin/ACL/Mg–Fe LDH were 99.71, 141.99, 0.74, 1.47, and 1.65 m2/g, respectively, which shows that the presence of ACL and ACL/Mg–Fe LDH improved the area of the hydrogels. The maximum abatement of CV using PAM-g-gelatin (92.81%), PAM-g-gelatin/ACL (95.71%), and PAM-g-gelatin/ACL/Mg–Fe LDH (98.25%) was obtained at pH = 9, temperature 25 °C, 10 mg/L CV, 60 min time, and adsorber dose of 2 g/L (for PAM-g-gelatin) and 1.5 g/L (other samples). The value of thermodynamic factors confirmed that the abatement process is exothermic and spontaneous. The kinetics data followed the pseudo-second kinetic (PSO) model. The Langmuir isotherm model had a more remarkable ability to describe the equilibrium data. The maximum adsorption capacity for PAM-g-gelatin, PAM-g-gelatin/ACL, and PAM-g-gelatin/ACL/Mg–Fe LDH was determined 35.45, 39.865, and 44.952 mg/g, respectively. Generally, the studied hydrogels can eliminate dyes from wastewater and be used as effective adsorbers. • A new polyacrylamide- g -gelatin/ACL/Mg–Fe LDH composite hydrogel was produced. • The hydrogel had an area of 1.65 m2/g and used to remove crystal violet (CV). • The maximum CV abatement (98.25%) was obtained at pH 9 and 10 mg/L CV. • The data followed the pseudo-second-order and Langmuir models (R2 > 0.99). • Textile wastewater was effectively cleaned with hydrogel. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The powdered biochar of oak fruit shell was combined with Fe 3 O 4 (=OP/Fe 3 O 4). • Physical-chemical properties of OP/Fe 3 O 4 magnetic composite were fully assessed. • The optimal pH to absorb Co, Ni, and Pb by the powdered OP/Fe 3 O 4 was found to be 6. • Heterogeneous surface was more effective than a homogeneous one in adsorbing metals. • Based on thermodynamic study, the metals adsorption was spontaneous and exothermic. Abstract In this study, the capability of a magnetic composite of oak powder/Fe 3 O 4 (OP/Fe 3 O 4) for the adsorption of lead, cobalt, and nickel ions from aqueous solutions was examined. Characteristics and structure of oak powder (OP) and OP/Fe 3 O 4 magnetic composite were explored by FTIR, SEM, TGA-DTG, VSM, and XRD analysis. The XRD results showed that OP/Fe 3 O 4 magnetic composite and OP were in crystalline form. Kinetic behavior of adsorption process was studied using pseudo-first-order, pseudo-second-order, and Elovich models. Results indicated that the pseudo-second-order model (R2 > 0.999) can better describe the kinetic behavior of the metal adsorption process. Equilibrium behavior of the adsorption process was also tested using Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Scatchard isotherm models. The results revealed that the adsorption equilibrium data for three metals match with the Freundlich isotherm model (R2 > 0.99). This indicates the effectiveness of heterogeneous surfaces in comparison with homogeneous ones in the adsorption process of metal ions. Moreover, the results showed that the adsorption process of metal ions with the OP/Fe 3 O 4 magnetic composite is physical. Finally, negative values of enthalpy and entropy indicated that the process of the metal ion adsorption is spontaneous and exothermic. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydroxyapatite was provided from chicken waste bone and composited by ZIF-8. • The composite had a suitable surface (267 m2.g−1) for decontaminate nickel. • Nickel was effectively removed from aqueous solutions and shipbuilding effluent. • The Ni adsorption capacity by composite was obtained 63.49 mg.g−1. • >99% Ni was removed using composite at pH7 and sorbent mass: 1 g.L-1 during 40 min. In this work, a biocompatible material from chicken beak containing hydroxyapatite (HApB) was modified by the zeolitic imidazolate framework-8 (ZIF-8) compound and used in the Ni2+ abatement from aqueous solutions. Different experimental techniques were used to investigate the properties of adsorbents (HApB and HApB/ZIF-8). The active surface values ​​of ZIF-8, HApB, and HApB/ZIF-8 were determined to be 1063.6, 12.2, and 267.2 m2.g−1, respectively. The synthesized adsorbents had a crystalline structure. Maximum Ni2+ adsorption using HApB (98.82%) and HApB/ZIF-8 (99.12%) was recorded at pH7, Ni2+ quantity of 10 mg.L-1, sorbent mass of 2 and 1 g.L-1, and treatment time of 80 and 40 min, respectively. The kinetic data followed a pseudo-first-order kinetic equation. The intra-particle diffusion equation revealed that penetration through water film and diffusion into particles are effective in Ni absorption. The solid-adsorbent equilibrium using HApB/ZIF-8 followed the Freundlich equation. The maximum decontamination capacity using HApB and HApB/ZIF-8 was determined 24.27 and 63.49 mg.g−1, respectively. Changes in thermodynamic factors showed that the Ni absorption is optimal, exothermic, and spontaneous. The adsorbents were recycled up to 5 cycles and the main adsorbent (HApB/ZIF-8) had a severe efficiency drop in cycles 4 and 5. Investigation of industrial wastewater treatment showed that the desired adsorbents have a nice potential to decontaminate metal ions from aqueous media and wastewater of shipbuilding industries. [ABSTRACT FROM AUTHOR]