Adsorbent For Wastewater Treatment Research Articles

Effective removal of cationic methylene blue dye using nano‐hydroxyapatite synthesized from fish scale bio‐waste

AbstractNano‐hydroxyapatite (NHAp) with a novel rod shape was synthesized from an economical and easily accessible Labeo rohita fish scale bio‐waste by facile and straightforward alkaline heat treatment method. The purity, functionality, morphology, and surface area of the green synthesized NHAp powder were well‐characterized via X‐ray diffraction (XRD), Fourier‐transform infrared (FT‐IR) spectroscopy, transmission electron microscopy (TEM), and Brunauer‐Emmett‐Teller (BET). The TEM and BET results indicate that the apatite is prepared as a rod‐like particle and highly porous with high surface area (112.36 m2 g−1). The NHAp powder was used for the adsorptive removal of cationic dye‐methylene blue (MB) from the aqueous samples. Batch experiments were performed to evaluate the mechanism of adsorption and kinetic models. The NHAp achieved an enhanced adsorption efficiency (666.67 mg g−1) for the adsorption process. The obtained results perfectly obeyed the pseudo‐second‐order model, and the Langmuir isotherm exhibited an excellent relationship with the experimental data. Furthermore, thermodynamic studies reveal that the adsorption process was exothermic and spontaneous. Thus, the results proved that Labeo rohita fish scale bio‐waste derived NHAp can be inventively utilized as a cost‐effective and eco‐friendly adsorbent for wastewater treatment.

Removal of 4-nitrophenol from aqueous solution by using recycled carbon black from waste tyres

The conversion of industrial waste into adsorbent for wastewater treatment is desirable as it promises cost-effective adsorbent and reduces waste productions. Adsorption of the 4-nitrophenol by recycled carbon black (rCB) and modified rCB (MCB) was investigated in this research to determine their adsorption capacity by varying various parameters: initial concentration, pH, contact time and adsorbent dosage. The surface morphology, surface chemistry, iodine adsorption number and ash content of both samples were also analysed. The adsorption characteristic of 4-nitrophenol was determined by equilibrium and kinetic studies. Equilibrium isotherm was tested by using Langmuir and Freundlich models. The maximum adsorption capacity of 4-nitrophenol onto rCB and MCB was found to be 7.46 mg/g and 21.83 mg/g, respectively. The adsorption kinetic data of both rCB and MCB fit better to pseudo-second-order kinetic model. This study also demonstrated MCB adsorbent better capability to remove 4-nitrophenol compounds in neutral and basic environments.

Copper(II)-Activated carbon from biomass waste for methylene blue uptake

Biomass wastes such as date seeds could be used as a raw material in the preparation of activated carbon (AC). The AC has been acknowledged as one of the popular adsorbents in wastewater treatment in removing azo dyes that has a negative impact on the aquatic and human lives. In this study, the efficiency of copper(II)-activated carbon (Cu(II)-AC) from biomass waste as a precursor material for removal of methylene blue (MB) in an aqueous solution was investigated. The batch study was conducted at MB dye concentration of 10 ppm for 90 min with a various variable on the parameters such as different adsorbents, the effect of light, pH, and mass of Cu(II)-AC. The percentage of dye removal was determined by using UV–Visible spectroscopy (UV–Vis) for each treatment. The results revealed that the 0.1 g Cu(II)-AC is an efficient MB dye removal for a wide range of pH (2, 7, 10) with or without the presence of light in a short time of 15 min.

Magnetic zeolite: A green reusable adsorbent in wastewater treatment

Zeolite is a type of crystalline aluminium - containing silicate made by the allocation of oxygen atoms in the framework of aluminium and silicate tetrahedral structure resulting in an open framework structure of three-dimension tetrahedral units. Magnetic zeolite is the combination of adsorption properties of zeolite with the magnetic properties of magnetic oxides which together forms a novel magnetic adsorbent. In recent years, it has attracted a huge attention in order to synthesize magnetically modified zeolite as magnetic materials can be separated easily from solution. Recent year studies on the application of magnetic zeolite on wastewater treatment indicate that magnetic zeolite can be used to remove dyes like methylene blue, antibiotics such as cephalexin, heavy metals such as Cr6+, Cu2+, Pb2+, from water and can be separated easily by a simple magnetic proces.

Alkali activated porous material with nano graphene oxide as adsorbent in wastewater treatment

Removal of contaminants, impurities and suspended solid matter are termed as water treatment. The possible water treatment methods are coagulation, filtration, ion exchange, aerobic and non aerobic methods. But all this involves high cost. Earlier filtration using granular sand was termed as the efficient way of water treatment. But due to the non-availability of sand this method is no more adopted. The most effective and easy means of treatment of water and waste water is adsorption method because it is an easy and convenient method. Though there are many adsorbents like activated carbon, clay minerals, zeolite, plant based and industrial based by products, the commonly used material is activated carbon which is again a costly investment. The next effective material is the zeolite. It has proved to perform well than the granular media and conventional activated carbon in removing heavy metals and ammonia. The advantage of using zeolite is that it adsorbs these contaminants in its pores and forms a strong bond which prevents leaching of these contaminants back to the ground water. The other advantages are the high specific surface area which facilities efficient adsorption, reduces the number of back-wash cycles, non-toxic and environmental friendly. Zeolites are hydrated aluminosilicates classified as natural and synthetic zeolites. The natural one is gluconites or green sand and the synthetic one is permutit which contains sodium in it. Inspite of many advantages in using zeolite the greatest disadvantage is that the treated water has Na+ ions which replaces the Ca2+ and Mg2+ ions. So when such waters are used sodium bicarbonate hydrolysis to sodium hydroxide which causes corrosion of boilers and also water having high turbidity cannot be effectively treated by this method. This research work will be focused on synthesizing alkali activated aerated concrete with graphene oxide which is porous and which can act as an efficient adsorbent in removing the contaminants from water and waste water respectively.

Synthesis of carbon dots-assisted MgAl-LDH hollow microspheres with hierarchical structure for the effective removal of Congo red from wastewater

Hierarchical hollow Mg-Al layered double hydroxide microspheres (HHMs) are successfully prepared by hydrothermal treatment in the presence of carbon dots (CDs). Morphology and structure of the as-prepared samples are characterized using XRD, SEM, FT-IR, and TEM techniques. The growth process of HHMs has been investigated in detail, and Ostwald ripening mechanism is suggested for the hierarchical growth of HHMs. Adsorption isotherms and adsorption kinetics of HHMs for congo red (CR) are investigated. Langmuir and Temkin model are more fitted to the experimental data of CR isotherm adsorption. Adsorption kinetic data obeys the pseudo-second-order kinetic model. Moreover, thermodynamic parameters (ΔGo, ΔHo and ΔSo) show that the CR adsorption onto HHMs is an endothermic and spontaneous process. The as-prepared HHMs could be a potential adsorbent for wastewater treatment containing anion dyes.

Evaluation of novel activated carbons from chichá-do-cerrado (Sterculia striata St. Hil. et Naud) fruit shells on metformin adsorption and treatment of a synthetic mixture

Chichá-do-cerrado (Sterculia Striata St. Hil. et Naud) is a Brazilian native plant whose nuts have interesting nutritional value. However, the fruit shells (CH) have never been evaluated for potential uses. This study aimed to characterize the biochar (BC–CH) and the activated carbons synthesized by chemical (K–CH) and physical (C–CH) processes. The activated carbons were evaluated on metformin adsorption and treatment of a synthetic mixture. Pyrolysis increased the carbon content and the H/C ratio indicated higher aromatization for C–CH. BC–CH presented low surface area, which was increased mainly with KOH activation (1273.6 m2 g−1). FTIR demonstrated the degradation of lignocellulosic compounds and zeta potential inferred a higher number of oxygenated groups for C–CH. Regarding the adsorption studies, the kinetics demonstrated an equilibrium time of 60 min and the isotherm resulted in a maximum experimental adsorption capacity of 33.75 and 45.50 mg L−1 for C–CH and K–CH, respectively. Interestingly, C–CH presented the highest removal percentage of the synthetic mixture, indicating the role of Cu (II) interactions and synergistic effects. In summary, it was verified the potential of the adsorbents in wastewater treatment, and the importance of evaluating the composition of the aqueous matrix, which can alter the adsorption mechanisms.

Introduction of Flexibility into a Metal-Organic Framework to Promote Hg(II) Capture through Adaptive Deformation.

The development of a practical Hg(II) adsorbent is highly important for both environmental protection and public health. Herein, an adaptive metal-organic framework (MOF; FJI-H30) has been prepared from a highly flexible ligand [tris(pyridin-4-ylmethyl)amine] and Co(SCN)2 with cheap Hg(II) adsorption sites (SCN- groups) that not only has excellent chemical stability but also can capture Hg(II) from aqueous solution with high adsorption capacity (705 mg g-1). Moreover, it also has good anti-interference ability and can be used repeatedly and large-scale prepared. Further researches demonstrate that the relatively high Hg(II) adsorption capacity originates from the adsorbed Hg(II)-induced deformation of FJI-H30, and such an adaptive deformation will reduce the potential repulsive forces between the adsorbed Hg(II) ions, enabling almost all Hg(II) absorption sites to adsorb Hg(II) ions. Finally, how to induce the deformation of FJI-H30 by adsorbed Hg(II) also has been studied in detail. Our work not only provides a practical Hg(II) adsorbent for wastewater treatment but also offers a novel strategy for the design of novel MOFs for efficient heavy-metal-ion removal.

Bio-sorption for tannery effluent treatment using eggshell wastes; kinetics, isotherm and thermodynamic study

Since, cobalt, zinc, mercury and lead ions are high toxic heavy metals; this work aims to investigate the efficiency of eggshell as a low cost sorbent for their ions from aqueous solution. Adsorption of heavy metals on surfaces of eggshell obeyed second order kinetics. Adsorption isotherm belonged to Freundlich model and displayed multilayer adsorption. The maximum adsorption capacity was estimated as 204, 153, 121 and 98 mg/g for Co3+, Zn2+, Hg2+ and Pb2+ respectively. The values of free energy of adsorption evidenced the physical adsorption occurrence. It is demonstrated that eggshell, as an industrial waste, was efficiently used as an adsorbent for wastewater treatment. Eggshells powder removed efficiently heavy metal ions from a tannery wastewater and removal efficiency reached up to 99%.

Synthesis rod-like mesoporous MgO using sodium polystyrenesulfonate (PSS) as structure-direct template and its application to plumbum absorption in waste water

Porous materials MgO has been synthesized using desalinated concentrated seawater and sodium carbonate with polystyrenesulfonate (PSS) as structure-direct agent. The as-prepared precursor is MgCO3·3H2O which transformed to mesoporous MgO at the temperature of 500 ℃ with rod-like microstructure. The BET specific surface area of the sample calculated from N2 isotherms is found to be 161 m2/g, the pore volume is 0.3 cm3/g and average pore diameter is 7.9 nm. Mesoporous MgO showed excellent absorption property for plumbum in waste water, it will be a potential adsorbent for waste water treatment containing heavy metals.

Magnetic graphene oxide-biomass activated carbon composite for dye removal

A magnetic composite was synthesized using palm kernel shell-based activated carbon, graphene oxide (GO) and iron oxide. The morphology, textural properties, magnetic properties, crystal structure and functional groups of the composite were studied. The characterization shows the successful formation of the ternary composite with a high specific surface area (280.39 m2/g) and abundant surface functional groups. The magnetic properties of the composite indicate a saturation magnetization of 33.72 emu/g, signifying that the composite can be easily separated with an external magnetic field. The performance of the composite was then investigated through the removal of an anionic azo dye, Acid Blue 113, from aqueous solution. The effect of initial pH of the solution, adsorbent dosage and adsorption contact time was studied. The composite achieved an adsorption capacity of 32.2 mg/g and 96.3% dye removal. Effective dye removal was still achieved after five cycles of adsorption-regeneration, with the dye removal of 74% after the fifth cycle. The analyses of adsorption isotherm and kinetics show that the adsorption process fits pseudo-second-order kinetic and Langmuir isotherm models, indicating a monolayer chemisorption process. The excellent adsorption performance and reusability of the composite and its magnetic separability signify its potential as an adsorbent for wastewater treatment.

Amphiphilic polymer-grafted palygorskite nanorods via surface olefin cross-metathesis for versatile applications

As an abundant natural nanomaterial, clay mineral has been intensely investigated for various applications, especially after surface modification with polymer. Here, amphiphilic polymer-grafted palygorskite (P-Pal) nanorods were prepared via surface olefin cross-metathesis reaction between the vinyl modified palygorskite (V-Pal) nanorods and acrylonitrile-butadiene rubber (NBR). After the surface olefin cross-metathesis reaction under the optimized condition, the resultant P-Pal nanorods could be well dispersed into water and toluene respectively, indicating the amphiphilic property with the grafted polymer molecules as the hydrophobic groups and clay nanorods as hydrophilic substance. The P-Pal nanorods showed promising applications as nano-reinforcing agent in polymer-based nanocomposites, self-separable adsorbent for waste water treatment, and hybrid surfactant for Pickering emulsion.

Applicability of TiO2(B) nanosheets@hydrochar composites for adsorption of tetracycline (TC) from contaminated water

We test the feasibility of TiO2(B)@carbon composites as adsorbents, derived from wheat straws, for tetracycline (TC) adsorption from aqueous solutions. Hydrochar (HC), biochar (BC), and hydrochar-derived pyrolysis char (HDPC) are synthesized hydrothermally from the waste and then functionalized with TiO2(B), named as ‘Composite-1′, ‘Composite-2′, and ‘Composite-3′, respectively. A higher loading of TiO2(B) into the HC was also synthesized for comparison, named as ‘Composite-4′. To compare their physico-chemical changes before and after surface modification, the composites are characterized using FESEM-EDS, XRD, BET, FRTEM, and FTIR. The effects of H2O2 addition on TC removal are investigated. Adsorption kinetics and isotherms of TC removal are studied, while TC adsorption mechanisms are elaborated. We found that the Composite-4 has the highest TC removal (93%) at pH 7, 1 g/L of dose, and 4 h of reaction time at 50 mg/L of TC after adding H2O2 (10 mM). The TC adsorption capacities of the Composite-1 and Composite-4 are 40.65 and 49.26 mg/g, respectively. The TC removal by the Composite-1 follows the pseudo-second order. Overall, this suggests that converting the wheat straw into HC and then functionalizing its surface with TiO2(B) as a composite has added values to the waste as an adsorbent for wastewater treatment.

Triphosphonic acid modified multi-walled carbon nanotubes for gold ions adsorption

Triphosphonic acid modified multi-walled carbon nanotubes (TPA-MWCNTs) have been developed in a facile method and then characterized and used for gold ion adsorption. The adsorption behaviors of TPA-MWCNTs for Au(III), including the effect of pH, adsorption isotherm, adsorption kinetics, adsorption thermodynamics, and regeneration properties have been investigated, and the maximum adsorption capacity of TPA-MWCNTs obtained from the Langmuir isotherm is 980.39 mg/g at 35 °C. Moreover, the adsorption process optimization has been conducted by using response surface methodology (RSM) and the analysis of variance (ANOVA). Therefore, TPA-MWCNTs can be used as an efficient adsorbent in wastewater treatment and gold uptake.

A review on grafted, crosslinked and composites of biopolymer Xanthan gum for phasing out synthetic dyes and toxic metal ions from aqueous solutions

Biopolymer Xanthan gum (XG), an exo-polysaccharide obtained from the fermentation of simple sugars by bacteria Xanthomonas campestris under aerobic conditions exhibits interesting properties like biodegradability, high viscosity at a low shear rate and stability under a wide range of temperature and pH. These characteristics properties render it accessible to utilize as a stabilizer, suspending as well as an emulsifying agent in food industries, petroleum and oil refining industries, cosmetic industries, and as an adsorbent in wastewater treatment. However, XG hydrophilicity and water solubility characteristics not only restrict its application domain but also affect its thermal stability during processing. Therefore, the efforts are directed to improve its application spectrum by modifying the physical and chemical characteristics of biopolymer, taking advantage of the presence of different amenable functional moieties in XG. The chemical modifications of XG include the formation of cross-linked polymers, grafting of monomer to base polymers manipulating the functionality by removal/addition of chemical groups. Currently, the emphasis is on the development of XG based grafted/crosslinked bionanocomposites which can be tailored as a noble adsorbent for wastewater treatment for the remotion of toxic metals, coloured synthetic dyes and other industrial effluents from the aqueous medium. The emphasis of present review article is to address the structural, physical characteristics along with the focus on the development of chemically modified XG viz. grafted, crosslinked, nanocomposites, and functionally modified biopolymer. The potential applications of these modified XG polymers for phasing out synthetic dyes and transition metals ions from aqueous systems have been deliberated.

Catalytic aspect of biomass in microcontroller-assisted esterification

ABSTRACT This research work pertains to the synthesis of carbon catalyst from abundantly available agro-waste, cajanus cajan husk (CCH) by chemical activation process using10 M H2SO4 at 500°C.Characterization of sulfonated carbon catalyst was accomplished through Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Brunauer-Emmet Teller (BET). The resultant catalyst exhibited excellent porosity and high surface area. In addition to the catalyst synthesis, the research work was accompanied with the application of microcontroller-based automated reactor (MBAR) for the enhancement of esterification of acetic acid with n-butanol. The effect of temperatures at 90, 95, and 100°C as well as catalyst loading at 1.36, 2.69, 4% (w/w) on the conversion of acetic acid was studied using synthesized catalyst and MBAR. The rationale behind introducing MBAR was to remove the water generated in esterification continuously by absorbing into silica gel. Silica gel comprised of two limbs operating in rotation in such a way that when one silica bed is in operation, simultaneously, the other is regenerating. The study revealed that the rate of water removal increased initially; but after 50% conversion, the rate declined. Conversion of acetic acid up to 90% has been reported by using newly invented apparatus. The analysis of uncertainty was performed for conversion % of acetic acid at various operating conditions at 95% confidence level. MBAR can be scaled up to the food processing-based industrial unit so that individual can start business and receive a consistent income. Pyrolysis product of CCH, in this case being catalyst, can be used not only for the synthesis of ester along a pathway of energy recovery but also for the development of many industrially useful products like adsorbent for wastewater treatment.

Adsorption dynamics of phenol by crab shell chitosan

Abstract The performance of crab shell chitosan (600 µm) as prospective adsorbent for phenol removal was studied in dynamics mode. The chitosan adsorbent had specific surface area of 191 m2/g and showed the surface characteristics linked to amine/amide groups. The effects of operating conditions on phenol adsorption at different concentrations (100 and 200 mg/L), flow rates (2.17 and 2.90 mL/min) and bed heights (1.75 and 3.5 cm) were evaluated. Results showed that the maximum phenol adsorption capacity by the crab shell chitosan was recorded at 190 mg/g. Thomas, Yoon–Nelson and Adam–Bohart models displayed good correlation with experimental data, hence best described the dynamics breakthrough of phenol removal. External and internal diffusion were the rate controlling mechanism, while the entire system was predominated by a simultaneous steady state process of intraparticle diffusion and ionic interactions. The crab shell chitosan shows a promising potential as adsorbent for wastewater treatment.

Investigation of methylene blue adsorption capacity of porous chitosan particles

Chitosan obtained from shrimp shells and SiO2 nanoparticles obtained from rice husk ash were used to synthesize chitosan - SiO2 composite materials. In order to obtain a porous chitosan adsorbent, the SiO2 particles in the chitosan - SiO2 composite material were removed with NaOH solution. With the orientation of applying adsorbent in wastewater treatment of textile industry, the ability of methylene blue adsorption of chitosan with porous structure has been investigated. Survey results show that chitosan has porous structure with good adsorption capacity of methylene blue. The adsorption capacity of materials depends on many factors such as: structure of particles; pH of adsorption medium and temperature. Adsorbent material is made of composite chitosan - SiO2 with the ratio of chitosan/SiO2 equal to 1/1 (w/w) with the best adsorption capacity. Materials with good adsorption capacity at pH = 6, at low pH, the adsorption capacity of the material is significantly reduced. Temperature has a great influence on the adsorption capacity of the material. The suitable temperature for adsorption of materials is 40 oC. With a higher temperature, the desorption process will be accelerated. This makes the adsorption capacity of the material decrease. The maximum methylene blue adsorption capacity of the material is determined about 7.25 mg/g after 40 minutes of adsorption time.

Novel design of microsphere adsorbent for efficient heavy metals adsorption

AbstractThe fabrication of high‐efficiency and low‐cost adsorbent for the wastewater treatment is a challenging task. In this study, a hollow sphere adsorbent was synthesized from solid waste coal gangue through a facile spray drying method and subsequent calcination. The structure of the synthesized coal gangue microsphere (CM) have been characterized by multimethods including X‐ray diffraction, scanning electron microscope, Fourier transform infrared, and others. The factors influencing the adsorption for Cu2+ and Pb2+ by CM were also investigated systemically; pH between 6 and 8 was found to be optimal for Cu2+ and Pb2+ adsorption. The isotherm and kinetic analysis reveal that the adsorption process could be well represented by Langmuir and pseudo–second‐order model with a higher R2 and low χ2 value. According to Langmuir model, the maximum adsorption capacity was calculated to be 6.570 and 18.904 mg/g for Cu2+ and Pb2+ at 25°C, respectively. The adsorption mechanism was proposed to contain not only the surface reaction process, but also the diffusion process. Consequently, the economic and environmental benefits make CM a promising adsorbent in wastewater treatment.

Ipomoea aquatica roots as environmentally friendly and green adsorbent for efficient removal of Auramine O dye

This study presents Ipomoea aquatica root (“kangkong” root or KR) as a plausible environmentally friendly adsorbent. This readily available adsorbent, after oven drying, demonstrates strong adsorption characteristics toward Auramine O (AO) dye exhibiting 2.0 h equilibration time and stable efficiency within a sufficiently broad range in both pH and ionic strength. Adsorption kinetics was best described by the pseudo second order and Elovich models, indicating that chemisorption of two reactive moieties could be involved. Application of the experimentally obtained adsorption equilibrium data to investigate the conformity among many adsorption isotherm models, namely Langmuir, Freundlich, Temkin, Redlich-Peterson and Sips, together with corresponding error analyses, identified that the Sips model be the best-fit model, leading to attractive maximum adsorption capacity of 455.74 mg g−1. Further, regeneration and reuse of the spent adsorbent would be possible with ~ 75% AO dye being adsorbed even at the 5th cycle, when using base treatment. Hence, the utilization of Ipomoea aquatica root as a low-cost, effective adsorbent in wastewater treatment could be possible.