Adsorption Process Of Cu Research Articles

Adsorptive removal of Cu(II) from aqueous solution by fermented sweet sorghum residues as a novel biosorbent

Sweet sorghum straw is a kind of natural wood cellulose with high porosity and high specific surface, which is theoretically conducive to the physical adsorption of heavy metal ions. In this paper, we reported a new biosorbent, the fermented sweet sorghum residues (FSSR), which is a byproduct of bioethanol production by fermentation of sweet sorghum straw, for the removal of Cu(II) from aqueous solution. The properties of the adsorption of Cu(II) on SSR and FSSR were studied and compared. The adsorption process of Cu(II) by SSR and FSSR conformed to the Elovich kinetic model. The isothermal adsorption process conformed to the Freundlich and the Tempkin models. The adsorption capacity of FSSR for Cu(II) was increased with the increase of pH. The adsorption mechanism of Cu(II) by FSSR was mainly attributed to ion exchange. SSR and FSSR were characterized by SEM-EDS, FTIR and XRD. The surface of FSSR had microporous structure, the content of –OH and other active functional groups increased. The fermentation has a certain destructive effect on the crystal structure of cellulose with the increase of amorphous structure. Therefore, fermentation process could be regarded as an effective means of microbial modification, to destroy the structure of the straw and result in the porous structure, which improved the adsorption capacity of SSR for heavy metals. FSSR could be used as a potential biosorbent for heavy metal removal from aqueous solution. Ethanol fermentation might be an effective method to improve performance of biosorbent for Cu adsorption.

Preparation of In Situ ZIF-9 Grown on Sodium Alginate/Polyvinyl Alcohol Hydrogels for Enhancing Cu (II) Adsorption from Aqueous Solutions

Metal–organic framework materials(ZIF-9) were loaded on Sodium alginate/polyvinyl(PVA/SA) hydrogel by in situ growth method for adsorption of heavy metal Cu (II). The structure of hydrogels composited with MOFs and polymers was designed to improve the poor mechanical properties of natural polymer gel materials and the inconvenience of powdered MOFs materials in practical applications. The adsorption results showed that the optimum adsorption process of Cu (II) pH was 5.0. The adsorption kinetics and isotherm suggest that the adsorption process follows the Freundlich isotherm and the pseudo-second-order models. The experimental maximum adsorption capacity was 98.98 mg/g, 2.6 times and 1.5 times higher than ordinary SA and PVA/SA hydrogel spheres. Synthesized hydrogel spheres were characterized by FT-IR, SEM, XRD, and XPS, which confirmed that MOF materials have grown in situ on PVA/SA hydrogel spheres. More importantly, PVA/SA@ZIF-9 exhibited exceptional mechanical stability and showed excellent recycling capability in the cyclic adsorption process.

Synthesis and characterization of an activated carbon-supported silver-silica nanocomposite for adsorption of heavy metal ions from water

We report synthesis and characterization of an activated carbon-supported silver-silica nanocomposite (AC-Ag-SiO2) for removal of Cu2+, Pb2+, Cd2+ and Zn2+ ions from single and multi-metal aqueous solutions. Characterization experiments included Atomic force microscopy (AFM), Ultraviolet–visible spectrophotometry (UV–Vis), Fourier transform Infrared spectrophotometry (FT-IR) and X-ray diffraction (XRD) analysis. Adsorption of heavy metals onto the composite strongly depended on contact time (280 min maximal), adsorbent dosage (0.1–0.4 g), solution pH (5.5 ± 0.5 maximal), temperature (298–328 K) and initial metal concentration. Equilibrium data were fitted to the Langmuir, Freundlich and Temkin isotherm models. Kinetic data were fitted to pseudo-first-order and pseudo-second-order kinetic models with the Freundlich isotherm model (R2 ˃ 0.99) and pseudo-second-order kinetic mode (R2 ˃ 0.999) providing a better fit to the experimental data. The maximum adsorption capacity was found to be 84.75 ± 0.24, 81.30 ± 0.2, 87.72 ± 0.96 and 81.97 ± 0.39 mg/g for Cu2+, Pb2+, Cd2+ and Zn2+ ions, respectively. The obtained values of thermodynamic parameters such as ΔG° (−13.72 ± 0.20 to −5.45 ± 0.35 kJ/mol), ΔH° (95.10 ± 14.33 to 162.4 ± 27.17 J/K.mol), and ΔS° (22.81 ± 4.50 to 39.12 ± 8.70 kJ/mol) showed that the adsorption process of Cu2+, Pb2+, Cd2+ and Zn2+ ions onto AC-Ag-SiO2 composite was spontaneous, feasible, endothermic and physical in nature. Regeneration studies suggested that AC-Ag-SiO2 composite could be reused effectively with no statistical significance among the cycles (p > 0.9 for all the four metal ions).

Simultaneous Removal of Cu2+, Cd2+ and Pb2+ by Modified Wheat Straw Biochar from Aqueous Solution: Preparation, Characterization and Adsorption Mechanism.

As an eco-friendly and efficient adsorbent for removal of potential toxic metals from aqueous solution, biochar has received widespread attention. In the present study, wheat straw biochar (BC) and corresponding modified biochar (HNC) were used to remove Cu2+, Cd2+ and Pb2+ from an aqueous solution. The influence of the environment factors on metals adsorption and adsorption mechanism were discussed in detail. The results showed that the HNC had porous structures and owned ample functional groups (−OH, −COOH and C−N groups) compared with the BC. In the single system, the adsorption capacities of HNC for Cu2+, Cd2+ and Pb2+ at a pH of 5.5 were 18.36, 22.83 and 49.38 mg/g, which were 76.89%, 164.36% and 22.75% higher than that of the BC, respectively. In addition, the adsorption process of Cu2+ and Cd2+ on BC and HNC fitted to the Langmuir isotherm model and pseudo-second-order kinetics, but the adsorption of Pb2+ on BC and HNC fitted to the Langmuir isotherm model and pseudo-first-order kinetics. Adsorption isotherms indicated that the adsorption of Cu2+, Cd2+ and Pb2+ by BC and HNC was a spontaneous endothermic process. The competitive adsorption of mixed metal ions (Cu2+, Cd2+ and Pb2+) revealed that HNC was more preferential to adsorb Cu2+ compared with Cd2+ and Pb2+. Furthermore, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses revealed that the main adsorption mechanisms were surface complexation and precipitation, and the adsorbed Cu2+, Cd2+ and Pb2+ on HNC mainly exist as CuO, Cd(OH)2, Pb3O4 and Pb(OH)2.

Kinetics and Equilibrium Studies of the Adsorption of Copper(II) Ions from Industrial Wastewater Using Activated Carbons Derived from Sugarcane Bagasse

The monocomponent adsorption process of Cu(II) ions in synthesized industrial wastewater were investigated using activated carbons (BACs) derived from sugarcane bagasse as the precursor. Batch adsorption studies were done by treating the precursor with H3PO4 (BAC-P) and ZnCl2 (BAC-Zn) in order to observe the effects of experimental variables such as contact time, pH of the solution, and adsorbent dose. The Langmuir isotherm model excellently described the adsorption data for both the derived BACs, indicating monolayer coverage on the BACs with the determination coefficients close to the value of one. Furthermore, the maximum adsorption capacities of 589 and 225 m g g − 1 at 30°C were obtained for BAC-P and BAC-Zn adsorbents, respectively. The modeling of kinetic data of Cu(II) ions adsorption onto BAC-P and BAC-Zn adsorbents illustrated that the Elovich kinetic model fitted well. Here, the adsorption process was film-diffusion controlling, while being principally governed by external mass transport where the slowest step is the diffusion of the particles through the film layer. The mechanism of the adsorption process was proposed taking into cognizance of the ion exchange and surface complexation on active sites between the negatively charged surface of the BACs and the positively charged Cu(II) ions. The BACs were characterized using analytical methods such as SEM, FTIR, EDX, XRD, BET surface area, and zeta potential measurements. Both BACs mainly composed of mesopores and bonds of O-H, C-O, C=O, and C-O-C. The BET surface area of BAC-P and BAC-Zn was 427.5 and 282 m2/g before adsorption, and their isoelectric point (pHIEP) 3.70 and 5.26, respectively.

Physically-crosslinked activated CaCO3/polyaniline-polypyrrole-modified GO/alginate hydrogel sorbent with highly efficient removal of copper(II) from aqueous solution

• A 3D activated CaCO 3 /PAN-PPy-modified GO/alginate hydrogel sorbent was fabricated. • Synergism among components help to gel network formation and pollutants removal. • CaCO 3 as pore-former, pH buffer and activated additive was help to Cu(II) removal. • High sorption capacity and fast kinetics for the alginate-based hydrogel sorbent. • The gel can be easily separated and show good environment adaptability and stability. Herein, alginate-based porous nanocomposite hydrogel (CPGA) was produced using alginate as entrapment agent, polyaniline-polypyrrole-modified graphene oxide (GPP) as functional filler, and CaCO 3 as pore-former for enhanced Cu(II) removal from water. Synergism among tri-components help to 3D network formation and Cu(II) removal. The parameters of components, solution pH, contact time, adsorbate concentration, temperature, coexisting substances and dosage were investigated in batch sorption mode. Spontaneous and endothermal adsorption process of Cu(II) by CPGA followed pseudo-second-order model and Freundlich model with experimental maximum adsorption capacity of ∼ 291.2 mg/g, which was better than most of reported alginate-based sorbents. CPGA showed good anti-interference ability in the presence of NaCl and humic acid as well as in actual Cu(II)-polluted lake water. In the multi-ions system, little sorption loss was observed for Pb(II), Cu(II) and Cd(II) capture, and even strengthened Cr(VI) removal relative to those in the single system. Furtherly, minor discrepancy (<10%) was noted after eight successive adsorption-desorption cycles. FTIR and XPS revealed that reactive N-/O-containing groups was mainly responsible for Cu(II) removal; the residual CaCO 3 acted the role of pH-buffer and provided refresh binding sites for the gel. This work could expand the potential applicability of alginate-based sorbents for heavy metal removal from water.

Study on the Performance of Composite Adsorption of Cu2+ by Chitosan/β-Cyclodextrin Cross-Linked Zeolite

In order to remove Cu2+ from wastewater, a kind of microsphere adsorbent (SCDO) with high efficiency for Cu2+ adsorption was prepared by the microdrop condensation method, where chitosan (CTS) and sodium alginate (SA) were used as the matrix to crosslink β-cyclodextrin (β-CD) and zeolite (Zeo). The structure and properties of SCDO were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Upon that, the adsorption performance of SCDO for Cu2+ was studied, in which the effects of pH, initial concentration, dosage, adsorption time and temperature were investigated. The results showed that the removal rate of Cu2+ reached 97.08%, and the maximum adsorption capacity was 24.32 mg/g with the temperature at 30 °C, the dosage of SCDO at 12 g/L, the initial concentration of Cu2+ at 100 mg/L, the pH of the solution at 6.0 and the adsorption time at 120 min, respectively. The adsorption process of Cu2+ by SCDO occurred in accordance with quasi-second-order kinetics model and Langmuir adsorption isotherm. After four repeats of continuous adsorption and desorption, the regenerative removal rate of Cu2+ could still reach 84.28%, which indicated that SCDO had outstanding reusability.

Langmuir and Freundlich isotherm equation test on the adsorption process of Cu (II) metal ions by cassava peel waste (Manihot esculenta crantz)

This Study aims to determine the adsorption process of Cu (II) metal by cassava peel waste (Manihot esculenta crantz) meeting the Langmuir equation and Freundlich. Research method cassava peel made into activated carbon, then determine the mass, pH and optimum contact time. Then the determination of the maximum adsorption capacity was carried out by testing with the Langmuir isotherm and Freundlich isotherm equations. The results showed that the best conditions (optimal conditions) were obtained with the addition of 0.5 grams of active carbs from cassava peels. The percentage of Cu ion adsorption in these conditions was 97.72%, at pH 6 and a contact time of 60 minutes and the absorption capacity was 98.49%. The maximum adsorption capacity of cassava peel activated carbon to Cu(II) ions at the optimum condition was determined based on the Langmuir and Freundlich isotherm equations. The results obtained were-51.813 mg/g and 26,792 mg/g, respectively.

Preparation of bio-absorbents by modifying licorice residue via chemical methods and removal of copper ions from wastewater

Abstract In this paper, a series of bio-adsorbents (LR-NaOH, LR-Na2CO3 and LR-CA) were successfully prepared by modifying Licorice Residue (LR) with NaOH, Na2CO3 and citric acid, and were used as the adsorbents to remove Cu2+ from wastewater. The morphology and structure of bio-adsorbents were characterized by Fourier Transform Infrared, scanning electron microscopy (SEM), thermogravimetry (TG) and X-ray diffraction (XRD). Using static adsorption experiments, the effects of the adsorbent dosage, the solution pH, the adsorption time, and the initial Cu2+ concentration on the adsorption performance of the adsorbents were investigated. The results showed that the adsorption process of Cu2+ by the bio-adsorbents can be described by pseudo-second-order kinetic model and the Langmuir model. The surface structure of the LR-NaOH, LR-Na2CO3 and LR-CA changed obviously, and the surface-active groups increased. The adsorption capacity of raw LR was 21.56 mg/g, while LR-NaOH and LR-Na2CO3 significantly enhanced this value up to 43.65 mg/g and 43.55 mg/g, respectively. After four adsorption–desorption processes, the adsorption capacity of LR-NaOH also maintained about 73%. Therefore, LR-NaOH would be a promising adsorbent for removing Cu2+ from wastewater, and the simple strategy towards preparation of adsorbent from the waste residue can be a potential approach for use in the water treatment.

KINETIC STUDIES OF Cu ADSORPTION FROM SASIRANGAN LIQUID WASTE USING RICE HUSK ACTIVATED CARBON

The industry of sasirangan – traditional fabric of Banjar Tribe – has been one of prime commodities of South Kalimantan. The coloring process in sasirangan production used a lot of chemical elements containing heavy metals and its waste potentially pollute the environment. One of the heavy metal waste contained is copper (Cu) which is toxic to aquatic organisms and humans. The treatment for sasirangan liquid waste can be done by adsorption process using activated carbon as adsorbent. This study aims to determine the appropriate kinetic model for adsorption of Cu metal from sasirangan liquid waste using activated carbon adsorbent made from rice husks.The process was conducted by batch system with chemical and physical activation. Chemical activation was done by soaking the activated carbon of rice husk with HCl solution for 24 hours. While physical activation was carried out by burning in a furnace at 500̊C for 2 hours. The adsorption treatment was given on sasirangan waste samples with variations on contact time (30, 60 and 120 minutes). The results of kinetics study showed that the adsorption process of Cu from sasirangan liquid waste onto rice husk activated carbon adsorbent followed first-order reaction kinetics with a correlation coefficient value (R2) of 0.96 and adsorption rate constant (k1) of 0.0044 min-1.

Green synthesis of a novel functionalized chitosan adsorbent for Cu(II) adsorption from aqueous solution.

Pollution generated by heavy metals has become a global environmental issue with much public concern. Herein, a functionalized chitosan-based adsorbent (CS-PAR) was synthesized via a simple one-step method for the adsorption of copper ions in solutions. A series of characterization methods have shown that CS-PAR was successfully synthesized. The experimental results showed that the maximum adsorption capacity of CS-PAR for Cu(II) ions was 170.23 mg/g. The adsorption process of Cu(II) on CS-PAR conformed to Langmuir and pseudo second-order models and belonged to a single-layer chemical adsorption process on the surface of a homogeneous medium. The adsorption mechanism of the adsorbent to Cu(II) ions was the complexation between the N-containing functional groups existing on the surface of the adsorbent and Cu(II). These results also showed that the adsorbent was an efficient material for removing heavy metal copper in wastewater and had very important practical significance.

Experimental study on adsorption characteristics of Cu2+ and Zn2+ by datong lignite

In view of the high content of Cu2+ and Zn2+ in acid mine drainage (AMD), the adsorption properties of lignite for Cu2+ and Zn2+ were studied. The adsorption performance of lignite for Cu2+ and Zn2+ was revealed by combining with FT-IR, XPS and EDS. The results showed that the adsorption kinetic model of lignite for Cu2+ and Zn2+ conformed to the quasi-first-order kinetic model. The isothermal adsorption line fitting models of lignite for Cu2+ and Zn2+ were in accordance with the Langmuir model and the Freundlich model, respectively. The maximum equilibrium adsorption capacities of lignite for Cu and Zn were 67.84 mg/g and 55.5 mg/g. The adsorption process of Cu2+ and Zn2+ by lignite involved electrostatic, coordination and ion exchange. Under the condition of coexistence of two kinds of ion, the adsorption site of lignite had stronger binding ability to copper ions.

Adsorption behaviors of the pristine and aged thermoplastic polyurethane microplastics in Cu(II)-OTC coexisting system

In this work, the hypothesis that thermoplastic polyurethane (TPU) microplastics (MPs) could form complex toxic pollution by absorbing both antibiotics and heavy metals simultaneously was proposed. The unique features of the adsorption of Cu(II) and oxytetracycline (OTC) on the pristine TPU and photo-aged (aged) TPU MPs in single and coexisting system were investigated, which included the kinetics, isothermal equilibrium and thermodynamics. The possibly synergistic or competitive effects between Cu(II) and OTC were also evaluated. The results showed that the adsorption process of Cu(II) and OTC could be described well by pseudo-second-order kinetic equation. The entire process could be divided into two stages: internal diffusion and external diffusion. The Sips model could give good fitting for the isothermal adsorption equilibrium. The thermodynamic parameters depicted the endothermic nature of adsorptions and the process was spontaneous. In the coexisting system, synergistic or competitive effects depended critically on the ratio of concentrations (Cu(II) vs OTC). When the ratio was 1:1, Cu(II) significantly enhanced the adsorption of OTC, while OTC showed a weak effect on Cu(II) adsorption. The synergies could be attributed to the formation of Cu(II)-OTC complex and the bridging effect of Cu(II). Overall, the adsorption capacity of aged TPU was higher than that of pristine TPU, which was due to the differences in morphological characteristics and functional groups. FTIR studies revealed that ester carbonyl and acylamino groups in the TPU may be involved in the adsorption of Cu(II) and OTC.

Efficient and selective removal of copper from aqueous solution by nanosized hydrated zirconium oxides loaded in vermiculite

Novel nanosized hydrated zirconium oxide (ZrO(OH)2) loaded in vermiculite (VMT) was successfully prepared and used to remove Cu2+ from aqueous solution. The adsorbent was characterized by XRF, XRD, SEM and TEM. The adsorption process of Cu2+ could reach equilibrium within 30 min and its kinetic data could be well described by pseudo-second-order model. The isotherm data could be described better by Langmuir model and the calculated maximum adsorption capacity was 96.23 mg/g. The adsorption of Cu2+ on nanosized ZrO(OH)2 loaded in vermiculite (NZV) was intensively affected by solution pH and different electrolytes. NaClO4 inhibited the adsorption of Cu2+, while NaCl and NaNO3 promoted the Cu2+ adsorption on NZV. The adsorption enhancement by NaNO3 was much significant than that of NaCl due to more ternary complexes forming among Cu2+, NO3- and the surface of NZV. The adsorption speed and capacity of Cu2+ were apparently reduced in the presence of Ni2+ in solution, while Cu2+ showed a higher affinity to adsorbent than Ni2+. The selective adsorption of Cu2+ in Cu-Ni mixed solution could be easily achieved in the presence of 0.8 mol/L of NaNO3, leading to 100% removal of Cu2+ and around 5% removal of Ni2+.

Modified sugarcane bagasse as effective biosorbent for copper ions removal

In this study, sugarcane bagasse (SCB) as a cheap and effective biosorbent was used for copper ions (Cu(II)) removal and modification was performed on SCB with HCl chemical washing and mercerization with strong NaOH in order to improve the removal capability of Cu(II) from aqueous solution. The effects of three influencing parameters including pH, temperature and initial metal ion concentration on Cu(II) adsorption were investigated for both untreated and modified SCB samples (U-SCB, HCl-SCB and M-SCB). The maximum removal efficiency obtained in the experiments was 98.75% for HCl-SCB while M-SCB was 93.1% at pH 5 with an initial metal ion concentration of 10 mg L−1. Four isotherm models including Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm were used to describe the adsorption process of Cu(II) ions for each SCB sample. Among these four isotherms, the experimental data was best fitted to Langmuir isotherm with R2 above 0.95. Based on the Langmuir isotherm, the maximum monolayer adsorption capacity was 0.523, 2.006 and 0.938 for U-SCB, HCl-SCB and M-SCB. It was concluded that the modification performed on SCB with HCl was able to improve the removal efficiency of Cu(II) from 71.6% up to 98.75%.

Adsorption Studies of Silica Adsorbent Using Rice Husk as a Base Material for Metal Ions Removal from Aqueous Solution

This study was carried out to evaluate the efficiency of metal ions removal from aqueous solution using silica adsorbent. Silica was extracted from rice husk using sol-gel method. The silica was modified with 1.0 M of nitric acid. Using batch adsorption technique, the effects of temperature, pH, contact time and adsorbent dosage on adsorption process of Cu (II), Zn (II), Mn (II) and Pb (II) ions were studied using standard solutions of their salts. Percentage removal of the metals ions studied decreased as the temperature was varied between 28°C and 43°C. Percentage removal of metal ions studied showed an increase at different pH varying from 4 to 8 and decreased after the pH 8. The variation of contact time between 2 and 8 hours showed a sharp increase in metals removal from 2 to 6 hours but a slow increase after 6 hours. The percentage removal of metal ions increase as the adsorbent dosage increased between 0.5 g and 2.0 g. The maximum percentage removal of metal ions was found to be 99.48%. The general observed trend of efficiency being Cu>Pb>Zn>Mn. The experimental data was also tested using adsorption isotherm models of Langmuir and Freundlich and Langmuir model was found to be the best fit for the data.

Polyhexamethylene guanidine functionalized chitosan nanofiber membrane with superior adsorption and antibacterial performances

Although various nanofiber membranes have been developed for sewage treatment, only a few membranes possess antibacterial activities. Thus, poly-hexamethylene guanidine (PHMG) with broad-spectrum antimicrobial activity was used to functionalize the oxidized chitosan (OCS) nanofibers in solid state. Scanning electron microscope (SEM) investigation indicated that polyvinyl alcohol (PVA) introduced leads to the significantly improved spinnability. Fourier transform infrared spectroscopy (FTIR) and elemental analysis indicate that the as-proposed solid phase grafting strategy is successful and the graft ratio of PHMG is about 36.5%. As expected, PHMG grafted can significantly enhance the antibacterial activity of OCS-PVA nanofibers, but leads to the decrease of the specific surface area and total pore volume. Further adsorption analysis shows that the adsorption capacities of the PHMG-OCS-PVA fiber membrane for Cu(II) and Congo red are 57.0 mg g−1 and 183.3 mg g−1, respectively. Kinetic and isotherm model studies indicate that the pseudo second-order kinetic and Freundlich models can well match the adsorption process of Cu(II) and Congo red. The PHMG-OCS-PVA fiber membrane also shows excellent selectivity towards the separation of various anionic dyes from an aqueous dye mixture. In conclusion, the as-fabricated PHMG-OCS-PVA fiber membrane may be used as a new sewage treatment membrane with superior anti-biofouling performance.

Removal of Cu(II) from wastewater using doped HAP-coated-limestone

Reducing copper content in copper-containing water is a worldwide environmental problem. It has been shown that hydroxyapatite (HAP) has a significant adsorption effect on heavy metals (including Cu2+). In this study, doped HAP-coated-limestone was synthesized using waste limestone, diammonium hydrogen phosphate and two kinds of chloride (Mg2+, Sr2+). The materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), thermogravimetric analysis (TGA), Brunner-Emmet-Teller (BET) measurements and scanning electron microscope (SEM). It was found that the structure of Mg2+ and Sr2+ doped HAP-coated-limestone was similar to that of HAP-coated-limestone. The surface of doped HAP-coated-limestone is rougher, and the specific surface area is larger than that of HAP-coated-limestone. Some factors have been investigated affecting the uptake behavior, such as doped element, contact time, temperature and Cu2+ concentration to optimize the conditions. The adsorption isotherms of Langmuir and Freundlich were studied, and it was proved that the adsorption isotherm of Langmuir was more consistent with the adsorption process of doped HAP-coated-limestone. The quasi-second-order dynamics can be better used to describe the experimental results compared with quasi-first-order dynamics. At the temperature of 30 °C, the adsorption capacity of HAP-coated-limestone for Cu (II) is 90.90 mg·g−1, while the adsorption capacity is 214.20 and 121.61 mg·g−1 for Mg2+ and Sr2+ doped HAP-coated-limestone, respectively. Through the calculation of thermodynamic parameters, the results show that the adsorption process of Cu (II) on HAP-coated-limestone and doped HAP-coated-limestone becomes easier with the increase of temperature in a certain temperature range. The adsorption process on HAP-coated-limestone and doped HAP-coated-limestone is spontaneous and endothermic.

A novel adsorbent of core-shell construction of chitosan-cellulose magnetic carbon foam: Synthesis, characterization and application to remove copper in wastewater

Developing a environmental and cost-effective adsorbents for removal of Cu(II) from industrial wastewater is a quite serious problem. This study prepared a novel adsorbent of chitosan-cellulose enwrapped magnetic carbon foam (CCMF) to remove Cu(II) from industrial sewage. Magnetic core-shell construction facilitated the solid-liquid separation after adsorption. Groups of adsorption experiments for the adsorbability of CCMF were systematically studied at various conditions, such as pH (3.0–6.0), adsorbent dosage (1.0–4.0 g/L), initial concentration of Cu(II) (25–600 mg/L), temperature (20–30 °C) and adsorption time (10–1800 min). Fourier-transform infrared (FTIR) spectroscopy indicated that the amino and hydroxyl groups of chitosan were involved in the adsorption reaction and that N and O atoms were the adsorption sites. X-ray photoelectron spectroscopy (XPS) further confirmed that the N atom was the main adsorption site. The adsorption isotherm of Cu(II) on the CCMF was well correlated with the Langmuir isotherm model, the adsorption processes were a monolayer reaction and controlled by homogeneous adsorption sites on the surface, and the maximum adsorption capacity was 115.65 mg/g at pH 6.0 and 30 °C. The adsorption process of Cu(II) on the CCMF followed the pseudo-first-order kinetic equation within the initial 120 min. Meanwhile, the entire process fitted well with the pseudo-second-order kinetic model. Results have demonstrated that CCMF is a potential environmental adsorbent for the removal of Cu(II) in industry wastewater.

Recycling of incinerated sewage sludge ash as an adsorbent for heavy metals removal from aqueous solutions

The management of large quantities of incinerated sewage sludge ash (ISSA) is problematic. Environmental and economic benefits can be achieved by using ISSA as an adsorbent for heavy metals removal due to its exceptionally porous structure and active components. In this study, the feasibility of using ISSA to treat heavy metals (Cd(II), Cu(II) and Zn(II)) contaminated waters from both single- and binary-metal systems were investigated. The results showed that the pH of the solution played a pivotal role in the adsorption of heavy metals by ISSA and the optimal pH for the adsorption of these metals was around 6.00. The adsorption process of Cu(II), Cd(II), and Zn(II) in a single-metal system was similar and fast. The equilibrium data followed the Freundlich isotherm model and the corresponding adsorption capacity was 0.13, 0.11 and 0.06 mmol/g, respectively. However, the presence of other competitive metal ions had adverse effects on both the adsorption rate and the adsorption capacity for the target metal ions. The affinity of ISSA towards the metals followed the order of Cu(II) > Cd(II) > Zn(II). The difference in pH value and Ca or Na concentration of the solution after adsorption revealed that cation exchange played a fundamental role in the adsorption of the target metals, while electrostatic attraction and precipitation were insignificant. Over all, the application of ISSA as an adsorbent would be a promising option to both relieve the waste disposal pressure and mitigate the complex heavy metals pollution.