Column Adsorption Studies Research Articles

Column Adsorption Studies for the Removal of Cr(VI) Ions by Ethylamine Modified Chitosan Carbonized Rice Husk Composite Beads with Modelling and Optimization

The objective of this present study is the optimization of process parameters in adsorption of Cr(VI) ions by ethylamine modified chitosan carbonized rice husk composite beads (EAM‐CCRCBs) using response surface methodology (RSM) and continuous adsorption studies of Cr(VI) ions by ethylamine modified chitosan carbonized rice husk composite beads (EAM‐CCRCBs). The effect of process variables such as initial metal ion concentration, adsorbent dosage and pH were optimized using RSM in order to ensure high adsorption capacity at low adsorbent dosage and high initial metal ion concentration of Cr(VI) in batch process. The optimum condition suggested by the model for the process variable such as adsorbent dosage, pH and initial metal ion concentration was 0.14 g, 300 mg/L and pH2 with maximum removal of 99.8% and adsorption capacity of 52.7 mg/g respectively. Continuous adsorption studies were conducted under optimized initial metal ion concentration and pH for the removal of Cr(VI) ions using EAM‐CCRCBs. The breakthrough curve analysis was determined using the experimental data obtained from the continuous adsorption. Continuous adsorption modelling such as bed depth service model and Thomson model were established by fitting it with experimental data.

Preparation of char from lotus seed biomass and the exploration of its dye removal capacity through batch and column adsorption studies

Char was obtained from lotus seed biomass by a simple single-step acid treatment process. It was used as an adsorbent for the removal of malachite green dye (MG) from simulated dye bath effluent. The adsorbent was characterized for its surface morphology, surface functionalities, and zero point charge. Batch studies were carried out by varying the parameters such as initial aqueous pH, adsorbent dosage, adsorbent particle size, and initial adsorbate concentration. Langmuir and Freundlich isotherms were used to test the isotherm data and the Freundlich isotherm best fitted the data. Thermodynamic studies were carried out and the thermodynamic parameters such as ∆G, ∆H, and ∆S were evaluated. Adsorption kinetics was carried out and the data were tested with pseudofirst-order model, pseudosecond-order model, and intraparticle diffusion model. Adsorption of MG was not solely by intraparticle diffusion but film diffusion also played a major role. Continuous column experiments were also conducted using microcolumn and the spent adsorbent was regenerated using ethanol and was repeatedly used for three cycles in the column to determine the reusability of the regenerated adsorbent. The column data were modeled with the modeling equations such as Adam-Bohart model, Bed Depth Service Time (BDST) model, and Yoon-Nelson model for all the three cycles.

Potential application of dodecylamine modified sodium montmorillonite as an effective adsorbent for hexavalent chromium

Clay materials are well suited for heavy metal adsorption in view of their excellent surface area and cation exchange capacity. In this paper, we report the detailed study on the adsorption of hexavalent chromium using dodecylamine intercalated sodium montmorillonite as a potential adsorbent. The adsorption involves primarily the electrostatic interaction of hydrogentetraoxochromate(VI) anion with the protonated dodecylamine and the surface hydroxyl groups of the clay material. The pseudo second order kinetic model fits the experimental data and an adsorption capacity of 23.69mgg−1 was obtained from the Langmuir isotherm model. The exothermically favorable spontaneous adsorption process and the decrease in entropy explain the thermodynamics of the adsorption. The adsorbent could be regenerated using NaOH and column adsorption studies provide a sample break through volume of 300mL on a laboratory scale. The adsorbent could be utilized for the successful removal of chromium from tannery wastewater.

Removal of ethinylestradiol (EE2) from water via adsorption on aliphatic polyamides

This study demonstrates the use of aliphatic polyamides (PAs) as efficient adsorbents for the removal of ethinylestradiol (EE2), a synthetic hormone and high-potency estrogenic contaminant, from water via strong adsorptive interactions. PA612 and PA12 showed significantly higher adsorption capacities than PA6 for EE2 adsorption from water. Isothermal adsorption studies showed that PA612 had an adsorption capacity for EE2 comparable to the benchmark macroreticular polymeric adsorbent, AMBERLTIE XAD4 (XAD4), despite its nonporous structure and far smaller surface area. The substantial adsorption of EE2 on PA612 is predominantly driven by Lewis acid-base interactions between EE2 and PA612 amide functionalities and facilitated by the hydrophobic partitioning of EE2 solutes in water. Rapid column adsorption tests demonstrated efficient removal of EE2 from water on a continuous flow basis. With an empty bed contact time of 0.8–1.0 min, the fixed-bed column with 1.0 g PA612 particles removed the EE2 from 24.1 L of 30 μg L−1 EE2 spiked solution to non-detectable levels by HPLC analysis. Regeneration was readily effected by rinsing the exhausted column with 4 wt.% NaOH solution at room temperature. Regenerated PA612 particles showed consistent performance to fresh PA612 particles in subsequent batch and column adsorption studies.

Column Adsorption and Desorption Studies of Fluoride on Perchloric Acid Cross‐Linked Calcium Alginate Beads

Contamination of drinking water due to fluoride is a severe health hazard problem. Excess of fluoride (>1.5 mg/L) in drinking water is harmful to the human health. Various treatment technologies for removing fluoride from ground water have been investigated in the past. Present investigation aims to remove fluoride by perchloric acid cross‐linked calcium alginate (PCA). Column flow adsorption data were utilized to obtain breakthrough curves and desorption experiment have been carried out with a view to recover the adsorbed fluoride and regenerate the PCA beads using 0.05 M EDTA. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) studies were used for the characterization of the adsorbent.

Neem leaf utilization for copper ions removal from aqueous solution

Adsorption of copper onto neem leaf powder was studied in batch and continuous mode. Langmuir and Freundlich models were used to fit the equilibria data of which Langmuir model is considered better in correlation. The maximum adsorption capacity of neem leaf powder was 18.29 mg/g (0.288 mmol/g). Column adsorption study to obtain the breakthrough curves was also presented on which Thomas model were chosen to represent the dynamic sorption data. Thermodynamics data indicated that the adsorption process is spontaneous, irreversible and endothermic.

Separation of Proanthocyanidins into Oligomeric and Polymeric Components Using a Novel Collagen Fiber Adsorbent

A novel collagen fiber adsorbent (CFA) was prepared by modification of natural collagen fiber using glutaraldehyde, and its adsorption behaviors to proanthocyanidins were investigated. Both batch and column adsorption experiments indicated that CFA has high adsorption selectivity to polymeric proanthocyanidins because of the stronger trend of these polymers to combine with collagen fiber through hydrophobic and hydrogen bonds. Based on this character of CFA, the purified oligomeric proanthocyanidins was obtained by using CFA as adsorbent. Meanwhile, it was found that the polymeric proanthocyanidins adsorbed on CFA can be easily desorbed by 50% (v/v) acetone-water solution. Thus, as a cost effective approach, CFA can be used to separate proanthocyanidins extracts into two parts, oligomeric proanthocyanidins and polymeric proanthocyanidins, which would favor the fine uses of proanthocyanidins extracts. Column adsorption studies showed that CFA used can be regenerated by using acetone-water solution as eluant, and its adsorption selectivity to polymeric proanthocyanidins was almost unchanged in 6 cycles.

Recovery of Th(IV) from aqueous solution by reassembled collagen-tannin fiber adsorbent

A novel adsorbent, collagen immobilized tannin adsorbent (CITA), was prepared and its adsorption behaviors to Th(IV) were investigated. CITA was in fibrous state due to the reassembly of collagen molecules by the inducement of tannin. This adsorbent loaded a greater amount of tannin and exhibited higher adsorption capacity to Th(IV) than the tannin immobilized adsorbent prepared from collagen fiber. The adsorption of CITA to Th(IV) is mainly attributed to surface complexation, which is a pH- rather than an ionic strength-dependent process. The adsorption kinetics and isotherms were described by pseudo-second-order rate model and Freundlich equation, respectively. Column adsorption studies indicated that CITA is available for effectively recovering Th(IV) from aqueous solution.

Removal of Copper (II) and Nickel (II) Ions from Aqueous Solutions by a Composite Chitosan Biosorbent

A composite chitosan biosorbent (CCB) was prepared by coating chitosan on to ceramic alumina. The adsorption characteristics of the sorbent for copper and nickel ions were studied under batch equilibrium and dynamic flow conditions at pH 4.0. The equilibrium adsorption data were correlated with Langmuir, Freundlich, and Redlich‐Peterson models. The ultimate monolayer capacities, obtained from Langmuir isotherm, were 86.2 and 78.1 mg/g of chitosan for Cu(II) and Ni(II), respectively. In addition, dynamic column adsorption studies were conducted to obtain breakthrough curves. After the column was saturated with metal ions, it was regenerated with 0.1 M sodium hydroxide. The regenerated column was used for a second adsorption cycle.

Adsorptive Separation of Arsenic and Phosphorus from an Aquatic Environment Using Metal-loaded Orange Waste

Orange waste has been loaded with various metal ions to create suitable adsorption sites for arsenic and phosphorus. Batch adsorption studies revealed that arsenate and arsenate removal was favorable at pH 5-9 and 9-11, respectively, while phosphate removal occurred at pH 7-10. The maximum adsorption capacity of the prepared gel was evaluated as 42 mg/g for both As (V) and As (III) while 13.9 mg/g for phosphate. Column adsorption studies confirmed that the gel has the potential to adsorb and elute arsenate and phosphate in continuous mode. The excellent anion separation capability of this gel could lead to the development of cost-effective technology for arsenic and phosphorus removal.

Comparison of Pb(II) uptake by coir and dye loaded coir fibres in a fixed bed column

The possibility of adsorbing Pb(II) from solution using coir, a cheap lignocellulosic fibre, was assessed in a fixed bed column. The coir fibres were also chemically modified by covalent loading of a reactive dye, C.I. Reactive Orange 13, and used as adsorbent. Column adsorption studies were carried out at different initial Pb(II) concentrations and it was observed that the breakthrough time decreased with increase in the initial Pb(II) concentration. The column packed with dye loaded coir fibres was operated for longer duration than the one packed with unmodified coir fibres. The total Pb(II) adsorbed was also higher in a column packed with dye loaded coir fibres. The desorption level in the fixed bed column packed with coir fibres was of the order of 85%, whereas the one packed with dye loaded coir fibres was more than 90%. Both the columns were regenerated and used upto five cycles.

Adsorption and removal of As(V) and As(III) using Zr-loaded lysine diacetic acid chelating resin

An adsorption process for the removal of As(V) and As(III) was evaluated under various conditions using zirconium(IV) loaded chelating resin (Zr-LDA) with lysine- N α, N α diacetic acid functional groups. Arsenate ions strongly adsorbed in the pH range from 2 to 5, while arsenite was adsorbed between pH 7 and 10.5. The sorption mechanism is an additional complexation between arsenate or arsenite and Zr complex of LDA. Adsorption isotherm data could be well interpreted by Langmuir equation for As(V) at pH 4 and As(III) at pH 9 with a binding constant 227.93 and 270.47 dm 3 mol −1 and capacity constant 0.656 and 1.1843 mmol g −1, respectively. Regeneration of the resin was carried out for As(V) using 1 M NaOH. Six adsorption/desorption cycles were performed without significant decrease in the uptake performance. Column adsorption studies showed that the adsorption of As(V) is more favorable compared to As(III), due to the faster kinetics of As(V) compared to As(III). Influence of the coexisting ions on the adsorption of As(V) and As(III) was studied. The applicability of the method for practical water samples was studied.

Adsorption of phenol and p-chlorophenol from their single and bisolute aqueous solutions on Amberlite XAD-16 resin

Removal of phenol and p-chlorophenol from synthetic single and bisolute aqueous solutions at 303.15 K through adsorption on Amberlite XAD-16 resin under batch equilibrium and dynamic column experimental conditions was investigated. The equilibrium adsorption data from single component solutions were fitted to Langmuir and Freundlich adsorption isotherm models to evaluate the model parameters and the parameters in turn were used to predict the extent of adsorption from bisolute aqueous solutions using Ideal Solution Adsorption (IAS) model. The effect of pH on removal of phenol and p-chlorophenol from single and bisolute systems was studied. The breakthrough capacity and total capacity of the resin for the adsorbates at different concentrations were evaluated through column adsorption studies. Attempts were made to regenerate the resin by solvent washing using methanol as an eluent. The limited number of adsorption–desorption cycles indicated that the adsorption capacity of the resin remained unchanged.

Performance of Waste Activated Carbon as a Low-Cost Adsorbent for the Removal of Anionic Surfactant from Aquatic Environment

In the present study, different low cost adsorbents were screened for their sodium dodecyl sulfate (SDS, an anionic surfactant) removal capacity. Waste activated carbon (WAC) from the aqua purifier has shown high efficiency for SDS removal. The performance evaluation in the presence of various ions (Ca2+, , and Cl−) and at various pH was studied. Desorption studies were conducted using simple sonication and pH variation technique. Column adsorption studies were performed. SEM and EDS studies were done on the adsorbing material before adsorption, after adsorption and after desorption of SDS.

A comparison of conventional and non-conventional treatment technologies on arsenic removal from water

In this study, four treatment methods were used to remove arsenic from water, namely: (i) chemical precipitation, (ii) arsenic adsorption onto iron-oxide-coated sand, (iii) high-rate saturated floating-medium flocculator/filter and (iv) membrane hybrid system (adsorption-microfiltration). The results indicated that more than 90% of total arsenic was removed by using FeCl3 (40 mg/L) as coagulant. The removal efficiency was 10% lower when polysilicato-iron (PSI, 2.5 mg/L) was used as a flocculant. The results of both the batch and column adsorption studies showed that iron-oxide-coated sand can effectively be used to achieve very high levels of arsenic removal (less than 5 μm/L as As in drinking water). Arsenic was removed up to 78% from the packed polystyrene beads filter with in-line FeCl3 addition at a high loading rate of 30 m3/m2.h. When powder activated carbon (PAC) was used in the membrane hybrid system, 87% removal of arsenic was achieved. A mixing time of 2.7 min with the mixing intensity of 87.8 s-1 were used. A very high filtration (permeate flux of 760 L/m2.h) was observed with a membrane of pore size of 0.2 μm.

Removal of phenol from aqueous solution and resin manufacturing industry wastewater using an agricultural waste: rubber seed coat

Activated carbon prepared from rubber seed coat (RSCC), an agricultural waste by-product, has been used for the adsorption of phenol from aqueous solution. In this work, adsorption of phenol on rubber seed coat activated carbon has been studied by using batch and column studies. The equilibrium adsorption level was determined to be a function of the solution pH, adsorbent dosage and contact time. The equilibrium adsorption capacity of rubber seed coat activated carbon for phenol removal was obtained by using linear Freundlich isotherm. The adsorption of phenol on rubber seed coat activated carbon follows first order reversible kinetics. The suitability of RSCC for treating phenol based resin manufacturing industry wastewater was also tested. A comparative study with a commercial activated carbon (CAC) showed that RSCC is 2.25 times more efficient compared to CAC based on column adsorption study for phenolic wastewater treatment.

Laboratory study of biological retention for urban stormwater management.

Urban stormwater runoff contains a broad range of pollutants that are transported to natural water systems. A practice known as biological retention (bioretention) has been suggested to manage stormwater runoff from small, developed areas. Bioretention facilities consist of porous soil, a topping layer of hardwood mulch, and a variety of different plant species. A detailed study of the characteristics and performance of bioretention systems for the removal of several heavy metals (copper, lead, and zinc) and nutrients (phosphorus, total Kjeldahl nitrogen [TKN], ammonium, and nitrate) from a synthetic urban stormwater runoff was completed using batch and column adsorption studies along with pilot-scale laboratory systems. The roles of the soil, mulch, and plants in the removal of heavy metals and nutrients were evaluated to estimate the treatment capacity of laboratory bioretention systems. Reductions in concentrations of all metals were excellent (> 90%) with specific metal removals of 15 to 145 mg/m2 per event. Moderate reductions of TKN, ammonium, and phosphorus levels were found (60 to 80%). Little nitrate was removed, and nitrate production was noted in several cases. The importance of the mulch layer in metal removal was identified. Overall results support the use of bioretention as a stormwater best management practice and indicate the need for further research and development.

Screening of Adsorbents for Boron in Brine.

Boron adsorptivity was measured on 46 kinds of inorganic and 12 kinds of organic adsorbents, using the residual brine after salt production from seawater. Hydrous cerium oxide, hydrous zirconium oxide, and N-glucamine type resin with N-methyl (polyhydroxyl) amino group each showed a high adsorptive capacity (above 5 mg/g) for boron. Adsorption isotherms of boron on these samples suggested that hydrous cerium oxide and glucamine type resin had adsorption sites selective for boron in a diluted solution. A column adsorption study of the resin showed that boron was effectively removed from the brine by passing it through the resin at a space velocity of 4 h-1. The adsorbed boron could be effectively eluted by using a 2 M HCl solution as an eluent.

Potential for Land Disposal of Two Nonbiodegradable Wastes

ABSTRACT THE potential for land disposal of two nonbiodegrad-able nylon processing wastes was evaluated in a series of laboratory and greenhouse experiments with an Evesboro sand. Soil column, soil lysimeter and soil ad-sorption studies were conducted to determine the effect the wastes had on groundwater. Phytotoxicity ex-periments were conducted in the greenhouse on a mix-ture of Kentucky 31 fescue and reed canary grass. The degradation rate of the wastes by soil microorganisms was measured in a series of Warburg respirometer and soil dehydrogenase experiments. Both wastes showed limited COD adsorption in the soil column and soil lysimeter experiments. The adsorp-tion characteristics of the wastes did not fit the Langmuir or Freundlich isotherms. The dehydrogenase and respirometer experiments indicated the wastes were broken down slowly by the soil microorganisms. Both wastes would cause serious groundwater contamination if applied to land.

Environmental Impact of Cadmium: A Review by the Panel on Hazardous Trace Substances

Environmental Impact of Cadmium: A Review by the Panel on Hazardous Trace Substances