Isotherm

The potential of using corncobs a typical agro-based waste as an adsorbent for removal of oil contaminated water was investigated in this work. Gradually, the awareness of the impact of spilled crude oil and products from it on human health and environment is on the increase. Corncobs wastes generated in local maize flour processing plants, road-side corn vendors and individuals, were converted into an adsorbent. The corncobs were treated and meshed to adsorb crude oil from water at various experimental conditions. Investigations carried out include the effects of parametric variations of different adsorbate and adsorbent masses, time, temperature, particle size and mixing speed on the adsorption of crude oil. Meshed corncobs, especially the 80 micrometer particle size exhibited high affinity for crude oil adsorption. The maximum adsorption was observed at 15 °C for the temperature range considered. The results demonstrated that a crude oil adsorption with this readily available and biodegradable waste material is feasible. Due to its high affinity for oil and low water pick up, meshed corncobs adsorbent is convincingly oleophilic or hydrophobic.

In this research, activated carbon (coconut husk waste) is prepared using sulfuric acid activation from coconut husk waste which is a cheap material that shows agreed scavenging actions by adsorption for eliminating the toxic textile dyes (methylene blue MB, crystal violet CV, as well as Brilliant Blue BB) from the aqueous solutions. In a shaker water bath, different physio-chemical factors like contact time, adsorbent dose, pH, temperature of the dye solution and initial concentration of the dye have been measured and the adsorption time is 120 minutes. The results show that adsorption of MB, CV is favorable at a high pH value, but at acidic pH, the brilliant blue BB dye is favorable. The activated carbon thermodynamic analysis is conducted using three dyes: The Gibbs free energy, entropy and also enthalpy. According to the results, the adsorption is a Physical (endothermic). It is also found that the activated carbon is regulated by the equations of Freundlich and Temkin. Finally,...

The potential of garlic peel (GP), agricultural waste, to remove methylene blue (MB) from aqueous solution was evaluated in a batch process. Experiments were carried out as function of contact time, initial concentration (25–200 mg/L), pH (4–12) and temperature (303, 313 and 323 K). Adsorption isotherms were modeled with the Langmuir, Freundlich, and Temkin isotherms. The data fitted well with the Fre-undlich isotherm. The maximum monolayer adsorption capacities were found to be 82.64, 123.45, and 142.86 mg/g at 303, 313, and 323 K, respectively. The kinetic data were analyzed using pseudo-first-order and pseudo-second-order models. The results indicated that the garlic peel could be an alternative for more costly adsorbents used for dye removal.

In the present study, spent tea leaves (STL) were used as a new non-conventional and low-cost adsor-bent for the cationic dye (methylene blue) adsorption in a batch process at 30 • C. Equilibrium sorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Fre-undlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to the Langmuir isotherm and the monolayer adsorption capacity was found to be 300.052 mg/g at 30 • C. The kinetic data obtained at different initial concentrations were analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion equations. The results revealed that the spent tea leaves, being waste, have the potential to be used as a low-cost adsorbent for the removal of methylene blue from aqueous solutions.

In this work, the banana leaf, an agricultural waste, widely used for wrapping of food was utilized as a low-cost adsorbent for removing methylene blue (MB) dye from the aqueous solution. The effects of initial concentration, contact time, and solution pH on the adsorption performance were investigated in a batch mode study at 30°C. The adsorptive uptake of MB increased with increasing the initial MB concentration and solution pH. Equilibrium data were simulated using the Langmuir and Freundlich isotherms, pseudo-first-order, pseudo second-order and intraparticle diffusion models. The data were well fitted to the Langmuir isotherm model, showing a maximum monolayer adsorption capacity of 109.89 mg/g. Adsorption kinetics were best described by the pseudo-second-order and intraparticle diffusion models. The results illustrated the potential use of waste banana leaves for the removal of colors and dyes from the textile wastewater.

In this paper, the ability of coconut bunch waste (CBW), an agricultural waste available in large quantity in Malaysia, to remove basic dye (methylene blue) from aqueous solution by adsorption was studied. Batch mode experiments were conducted at 30 • C to study the effects of pH and initial concentration of methylene blue (MB). Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to Langmuir isotherm and the monolayer adsorption capacity was found to be 70.92 mg/g at 30 • C. The kinetic data obtained at different concentrations have been analyzed using a pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model.

The adsorption characteristics of 2,4,6-trichlorophenol (TCP) on coconut husk-based activated carbon prepared under optimized conditions were evaluated. Batch adsorption studies were conducted to study the effects of various parameters such as initial concentration, agitation time and solution pH on TCP adsorption. Adsorption capacity was found to increase with increase in initial concentration and agitation time, while acidic pH was more favourable for the adsorption of TCP. Equilibrium data were analyzed by the Langmuir, Freundlich, Temkin and Redlich–Peterson models by using non-linear regression technique. The equilibrium data were best represented by the Langmuir isotherm, yielding maximum monolayer adsorption capacity of 716.10 mg/g at 30 • C. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The mechanism of the adsorption process was determined from the intraparticle diffusion model. Boyd plot revealed that the adsorption of TCP on the activated carbon was mainly governed by particle diffusion. Coconut husk-based activated carbon was shown to be an efficient adsorbent for removal of TCP from aqueous solutions.

In general, the biosorption of heavy metals by various types of non-living organisms appears to be a very effective, low-cost and innovative method for their removal from aquatic environments. The aim of this study was to determine the applicability of adsorption isotherms and kinetic models during the biosorbent activity of non-living Chlorella to the removal of Cd, Cu and Pb. Dead cells of Chlorella vulgaris were used to remove these heavy metals from aqueous solution in experimental conditions, i.e. under various condition of pH, biosorbent dosage and contact time. Afterwards, the Langmuir and Freundlich adsorption isotherm models and the sorption kinetics (pseudo-first and pseudo-second order models, and intraparticle diffusion) were applied to the experimental data to check the effectiveness of the removal process. The removal of heavy metals on C. vulgaris following the order of Pb +2 > Cu +2 > Cd +2 was confirmed by the maximum biosorption capacities (q max), the Langmuir constant (b), separation factor (R L) and Freundlich intensity parameter (1/n) values. The equilibrium data were well fitted with the Langmuir and Freundlich isotherm models. The adsorption process followed the pseudo-second-order model and it suggested that such kinetics is the most effective. The present results confirmed highly efficient biosorbent activity of C. vulgaris in the removal of heavy metals, especially Cd, Cu and Pb, from aqueous solution. The environmentally friendly origin indicates that non-living cells of C. vulgaris could find many broad-scale, cost-effective and alternative applications.

In the present work, melon seed hull (MS), an industrial effluent abundantly available from the melon seed oil processing plants was utilized as a feedstock for preparation of activated carbon (MSAC) by microwave assisted NaOH chemical activation. MSAC was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analysis, and nitrogen adsorption–desorption study. The adsorptive properties of MSAC were
quantified using methylene blue (MB), cationic dye, and acid blue 15 (AB); anionic dye as model adsorbates. The surface chemistry was examined by zeta potential measurement and evaluation of surface acidity/basicity. Result showed that the monolayer adsorption capacities
of MSAC for MB and AB were 333.50 and 341.96 mg/g, respectively. The BET surface area, Langmuir surface area, and total pore volume of MSAC were identified to be 1,187m2/g, 1,804 m/g, and 0.68cm3/g, respectively. The findings revealed the potential use of MS derived activated carbon for cationic and anionic dyes removal.

In this study, papaya stem, an agricultural biomass abundantly available in Malaysia, was utilized as low-cost adsorbent for removing methylene blue from the aqueous solution. The textural and functional characterization was evaluated using the scanning electron micros-copy and Fourier transform infrared analysis. The adsorption data were simulated using the nonlinear Langmuir, Freundlich and Temkin isotherm models. Kinetic modeling and adsorp-tion mechanism were fitted to the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Thermodynamic parameters, enthalpy, entropy, and Gibb free energy changes were established. Equilibrium data were best described by the Langmuir isotherm equation, with a monolayer adsorption capacity of 260.95 mg/g. The results supported the potential use of papaya stem as an efficient adsorbent for the treatment of cationic dye.

The present research explores the viability of pineapple peel, an agricultural effluent discharged from the food can processing industries for removing methylene blue (MB) dye from the aqueous solution. The effects of contact time, initial concentration, and solution pH on the adsorptive uptake of MB were investigated in a batch mode study. The morphological and functional characterization of the adsorbent was performed using the scanning electron microscopy and Fourier transform infrared analysis. The adsorption equilibrium was simulated using the Langmuir, Freundlich and Temkin isotherm models. Kinetic modeling was fitted to the pseudo-first-order and pseudo-second-order kinetic equations, while the adsorption mechanism was determined using the intraparticle diffusion model. Equilibrium data were favorably described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 97.09 mg/g. The results provide a strong evidence to support the potential use of pineapple waste as an effective adsorbent for the treatment of textile wastewater.

Water scarcity and pollution rank equal to climate change as the most intricate environmental turmoil for the 21st century. Today, the percolation of textile effluents into the waterways and ecosystems remain a fastidious conundrum towards the public health and food chain interference. In such circumstances, it becomes mandatory for each dye emitting industry or facility to opt for proper dye control measures. With the renaissance of activated carbon, there has been a steadily growing interest in this research field. This paper attempts to postulate a state of the art review of dye processing industry, its fundamental characteristics and environmental implications. Moreover, the key advance of proposed precursors, activated agents, together with the effects of adsorbent dosage, concentration, contact time, pH, particle size, temperature competition, and isotherms, kinetic and thermodynamic studies for adsorption of dyes onto activated carbons are summarized and discussed. Conclusively, the expanding of adsorption science in dye treatment represents a plausible tool for accruing the worldwide environmental benefit and shaping the national economy.

Objectives: Increasing use of colored materials in various industries and their discharge into the environment through industrial wastewater, can create many problems for humans and other beings. In the present study, the effect of removing Reactive Blue 21 (RB 21) dye using Multi-Wall Carbon Nanotubes (MWCNTs) as adsorbent is studied. Materials & Methods: The research was carried out on a laboratory scale and in a discontinuous system. Factors affecting dye removal such as pH, adsorption dose, concentration of dye and contact time were investigated. Also two Langmuir and Freundlich isotherms were studied in different concentrations of dye. UV-visible spectrophotometer was used to determine the dye removal. It should be noted that all experiments were carried out at 25°C. Results: Regarding the results in an environment with pH=3, in 30 minutes time, with 0.05 g/L of adsorbent (MWCNTs) to remove 50 mL of RB 21 dye with a concentration of 40 ppm, the best adsorption and maximum dye removal was obtained as 81%. Conclusion: According to the results of the experiments, it was found that MWCNTs are very suitable for comparison with other synthetic adsorbents used to remove RB 21 dye.

Activated carbon derived from rattan sawdust (ACR) was evaluated for its ability to remove phenol from an aqueous solution in a batch process. Equilibrium studies were conducted in the range of 25–200 mg/L initial phenol concentrations, 3–10 solution pH and at temperature of 30 • C. The experimental data were analyzed by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. Equilibrium data fitted well to the Langmuir model with a maximum adsorption capacity of 149.25 mg/g. The dimensionless separation factor R L revealed the favorable nature of the isotherm of the phenol-activated carbon system. The pseudo-second-order kinetic model best described the adsorption process. The results proved that the prepared activated carbon was an effective adsorbent for removal of phenol from aqueous solution.

In this research, activated carbon (coconut husk waste) is prepared using sulfuric acid activation from coconut husk waste which is a cheap material that shows agreed scavenging actions by adsorption for eliminating the toxic textile dyes (methylene blue MB, crystal violet CV, as well as Brilliant Blue BB) from the aqueous solutions. In a shaker water bath, different physio-chemical factors like contact time, adsorbent dose, pH, temperature of the dye solution and initial concentration of the dye have been measured and the adsorption time is 120 minutes. The results show that adsorption of MB, CV is favorable at a high pH value, but at acidic pH, the brilliant blue BB dye is favorable. The activated carbon thermodynamic analysis is conducted using three dyes: The Gibbs free energy, entropy and also enthalpy. According to the results, the adsorption is a Physical (endothermic). It is also found that the activated carbon is regulated by the equations of Freundlich and Temkin. Finally,...

In this research, activated carbon (coconut husk waste) is prepared using sulfuric acid activation from coconut husk waste which is a cheap material that shows agreed scavenging actions by adsorption for eliminating the toxic textile dyes (methylene blue MB, crystal violet CV, as well as Brilliant Blue BB) from the aqueous solutions. In a shaker water bath, different physio-chemical factors like contact time, adsorbent dose, pH, temperature of the dye solution and initial concentration of the dye have been measured and the adsorption time is 120 minutes. The results show that adsorption of MB, CV is favorable at a high pH value, but at acidic pH, the brilliant blue BB dye is favorable. The activated carbon thermodynamic analysis is conducted using three dyes: The Gibbs free energy, entropy and also enthalpy. According to the results, the adsorption is a Physical (endothermic). It is also found that the activated carbon is regulated by the equations of Freundlich and Temkin. Finally, field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FT-IR) have been used to show adsorption.

Natural convection in enclosed cavities is widely studied because of its importance in many engineering applications. The most commonly used enclosures in the industries are rectangular, cylindrical, trapezoidal, triangular etc. In recent years, natural convection in triangular shaped enclosures have received a considerable attention. The reason for considering this geometry is, it has application in various fields such as building and thermal insulation systems. In the present study natural convection inside a triangular enclosure is analyzed. The analysis is conducted as 3 different cases. For the first case the bottom wall is heated and other two sides are kept at ambient temperature. For the second case, left wall is heated and other two sides are kept at ambient temperature and for the final case right wall is heated and other two sides are kept at ambient temperature. Simulations are carried out for varying Rayleigh number. Heat transfer rate from the hot surface is obtained numerically. The fluid flow characteristics and heat transfer characteristics are analyzed using computational fluid dynamic software ANSYS FLUENT 14.0.

Dodecyltrimethylammonium bromide (DTAB)-modified and unmodified calcium bentonite were both used for the competitive adsorption of aromatics (xylene, ethylbenzene and toluene) and petroleum products (gasoline, dual purpose kerosene and diesel) from their aqueous solution. Infrared spectroscopy (IR) and expansion tests (adsorption capacity and Foster swelling) measurement were performed in order to evaluate the performance of the adsorbents. The Foster swelling index and adsorption capacity of the DTAB modified calcium bentonite in the organic solvents follow the trend: xylene > ethylbenzene > toluene > gasoline > dual purpose kerosene (DPK) > diesel > water. However, the adsorption capacity of the adsorbent in diesel outweighed the adsorption capacity in DPK at high concentration of DTAB indicating that diesel has higher affinity for high DTAB concentration than DPK. The percentage removal of the solvent is directly proportional to the concentration of DTAB used in modifying the bentonite as well as the contact time between the adsorbent and the solvent, hence modified calcium bentonite adsorbed a higher percentage of organic solvents than the unmodified calcium bentonite. The adsorption characteristics of both adsorbents improved remarkably after proper agitation of the organic solvents, the unmodified calcium bentonite however adsorbed more water than the modified bentonite. Data obtained from adsorption isotherm models confirms that Freundlich adsorption isotherm model was favored more than Langmuir adsorption isotherm model with the correlation factor (R 2) of the former tending more towards unity. The adsorption of ethylbenzene using DTAB modified and unmodified calcium bentonites follow a pseudo second order kinetics mechanism, suggesting that the rate determining step of adsorption involves both the adsorbent and the organic solvent. Capsule Summary: DTAB modified calcium bentonite has a higher adsorption capacity than the unmodified calcium bentonite as such can be deployed in the adsorption of aromatics (xylene, ethylbenzene and toluene) and petroleum products (gasoline, dual purpose kerosene and diesel) from waste water and effluents thereby protecting the environment and humans from their hazardous effects. Cite This Article As: T. N. Chikwe, R. E. Ekpo and I. Okoye. Competitive adsorption of organic solvents using modified and unmodified calcium bentonite clay mineral.

Concern about environmental protection has increased over the years from a global viewpoint. To date, the prevalence of adsorption separation in the environmental chemistry remains an aesthetic attention and consideration abroad the nations, owning to its low initial cost, simplicity of design, ease of operation, insensitivity to toxic substances and complete removal of pollutants even from dilute solutions. With the renaissance of isotherms modeling, there has been a steadily growing interest in this research field. Confirming the assertion, this paper presents a state of art review of adsorption isotherms modeling, its fundamental characteristics and mathematical derivations. Moreover, the key advance of the error functions, its utilization principles together with the comparisons of linearized and non-linearized isotherm models have been highlighted and discussed. Conclusively, the expanding of the nonlinear isotherms represents a potentially viable and powerful tool, leading to the superior improvement in the area of adsorption science.

Preparation of activated carbon has been attempted from coconut husk (CHAC) via microwave assisted chemical activation. The operational parameters including the effects of activation agents, chemical impregnation ratio (0.25-2.00), microwave power (90-800 W) and irradiation time (4-8 min) on the carbon yield and adsorption capability were investigated. CHAC was examined by pore structural analysis, Scanning Electron Microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption isotherm, elemental analysis, and zeta potential measurement, while the adsorptive property was quantified using methylene blue (MB) as dye model compound. The best conditions (KOH as activating agent, IR of 1.25, microwave power of 600 W and radiation time of 6 min) resulted in CHAC with a monolayer adsorption capacity of 418.15 mg/g for MB and carbon yield of 80.75%. The BET surface area, Langmuir surface area and total pore volume were identified to be 1356.25 m 2 /g, 2040.01 m 2 /g and 0.780 m 3 /g, respectively. Equilibrium data were favorably described by the Langmuir isotherm, while the adsorption kinetic was satisfactory fitted to the pseudo-second-order model.

To date, the indiscriminate discharge of pesticide contaminant into the water bodies is an imminent danger to the environment protection and natural ecosystems. Ametryn, a new generation of toxic pesticide with the annual application of 190 tonnes/year, has emerged to be a worldwide concern among the environmentalists. Considerable researches have been devoted to the developmental of the natural, non-conventional and functionalized adsorbents, which are abundantly available for the wide-scale treatment of toxic pesticides and their metabolites. In the present study, the feasibility of an acid modified montmorillonite (AM) for the adsorptive treatment of the hazardous ametryn was investigated. The physical, chemical and physicochemical behaviour of the prepared adsorbent was examined. Equilibrium data were simulated by the nonlinear Langmuir, Freundlich, Temkin and Redlich-Peterson isotherm models, while the adsorption kinetics were analysed by the pseudo-first order and pseudo-second order kinetic equations. The adsorption behaviour was well interpreted by the Langmuir isotherm model, with amonolayer adsorption capacity for ametryn of 207.71 mg/g. Kinetic data was fitted closely to the pseudo-second order kinetic equation, suggesting a chemisorp-tion process. Thermodynamic parameters including the ΔG o , ΔH o and ΔS o were evaluated. The adsorption process was found to be feasible, spontaneous and exothermic in nature. The findings illustrated the great applicability of AM as an ideal solution for the adsorptive treatment of the heavy polluted ametryn pesticide contaminated agricultural runoff.

The present study investigated the adsorption of molecular fluoroquinolone (FLQ) from  aqueous solution onto active carbon (AC), magnetic activated carbon (MagAC), styrene-butadiene styrene magnetic activated carbon (SBS/MagAC) and poly charbon magnetic activated carbon (PC/MagAC) as adsorbent materials. The process optimization was carried by investigating the effects of pH, temperature, solid-liquid ratio, adsorbent type and initial concentration of FLQ. The data showed that adsorption reached equilibrium in as little as one hour. The adsorption cacapcity was comparatively less at low pH values than at approximately pH 5.0. The results also showed that the polymer coated magnetic materials did not perform very well at high pH values. However, all the materials performed well at room temperature when the situation was examined in terms of kinetics. It was also observed that AC, SBS/MagAC and PC/MagAC are more effective than MagAC to remove FLQ from aqueous medium. The kinetic data ...

The Local Production Arrangement, located in the Pernambuco’s Agreste state, has been significantly developing the region's economy. Despite its importance, industrial activity has caused relevant environmental concerns regarding the disposal of textile effluents, especially from industrial laundries. This waste is made up of many chemicals, and among them are various types of heavy metals. The evaluation of the sorption behavior of contaminant transport mechanisms such as heavy metals is essential to assess the risk of contamination of alluvial aquifers. This study evaluated the sorption of heavy metals (Cu and Cd) in an alluvial sediment deposit in the Capibaribe River. Kinetics and isotherm experiments allowed the analyses of Cu and Cd sorption. Kinetics sorption showed an equilibrium tendency after 16 h for Cu and 18 h for Cd and was better described by a pseudo-second order model. The isotherm data were adjusted to the Linear, Freundlich and Langmuir models. Both linear and Freundlich models satisfactorily described sorption isotherms for the two pollutants. The metals in the study represent a risk of contamination of the groundwater of alluvial aquifers, mainly due to physicochemical attributes of the soil, such as high sand content (85%), low MO (2.1 g kg-1) and alkaline pH (8.2). The environmental conditions decrease absorption and facilitate metal mobility, greatly increasing the environmental risks inherent in pollutant leaching. Cu showed a higher affinity with the soil studied in all assays performed compared with the results of the tests for Cd.

In today’s world, water scarcity affects every corner of the world. More than 1.2 billion people do not have access to clean water resources. This problem happens due to several reasons such as climate changes, natural disasters, contamination of water catchment area, and many more. Since water is a necessity for living organisms to live, a sustainable solution to water deficiency should be thought of to avoid the same problem from happening continuously. To materialize the solution, thorough research on adsorption should be pursued to clean out contaminated water as it is a valuable resource. The solution should use adsorbents that are as cheap as possible to make it sustainable throughout the process. The objective of this research is to find out the parameters that can affect the performance of adsorbents, to calculate the effectiveness of each adsorbent to remove nickel ions from water, and to find out the economic potential of the adsorbent. Several parameters will be tested on the adsorbent to find out the optimum adsorption rate that an adsorbent could achieve. In conclusion, this research is targeted to find out whether corn cob could be used to produce cheap adsorbent without compromised the adsorption abilities of nickel in the contaminated water. The removal of nickel from the simulated aqueous solution using corn cob was carried out. The batch study was used; Parameters such as pH, contact time, adsorbent dose, and metal concentration were manipulated at room temperature. The findings showed that the full removal of nickel could be achieved within 100 minutes and at Ph 8. The Langmuir isotherm was better suited to experimental results because the correlation coefficient for the Langmuir isotherm was higher than that for the Freundlich isotherm. The optimum adsorption capacity of Langmuir was 7.5 mg / g.

The use of low-cost adsorbent papaya leaf was investigated as a replacement for current costly methods of removing methylene blue dye (MB) from the aqueous solution. The adsorption equilibrium was determined as a function of contact time, initial adsorbatem concentration, and solution pH. The adsorptive uptake of MB increased with increasing the initial MB concentration and solution pH. The adsorption isotherms were correlated with a comparison of linear and nonlinear regression analysis. Langmuir isotherm model provided the best-fit for the adsorption of MB onto papaya leaf, with a maximum monolayer adsorp-tion capacity of 231.65 mg/g. This locally available adsorbent was found to be low cost and promising for the remediation of textile wastewater.

The composite hydrogels based on rice straw (RS) and N-vinyl-2-pyrrolidone (NVP) or acrylamide (AAm) were successfully prepared by gamma irradiation. The effect of the radiation dose and the monomer content on the gel percent was studied. The composite hydrogels were confirmed by (FTIR), (TGA) and (SEM). It was found that the diffusion of water into the prepared composites was Fickian character. The removal of congo red (CR) and methyl orange (MO) dyes by (NVP/RS) and (AAm/RS) composite hydrogels were investigated as a function of the pH, contact time, initial dye concentration solution and temperature. It was achieved that the adsorption capacity of (NVP/RS) composite hydrogel towards (CR) and (MO) was higher than (AAm/RS) one. The kinetic data was tested by the pseudofirst-order and the pseudo-second-order kinetic models. The adsorption isotherm was closely fitted with the Freundlich model for adsorption of CR and MO onto (NVP/RS) and the Langmuir model for adsorption of the dyes onto (AAm/RS). A high adsorption capacity was obtained in the second adsorption cycle of MO onto the composite hydrogels loaded with CR. Improvement in the adsorption of MO onto (NVP/RS) and (AAm/ RS) composite hydrogels loaded with Co(II).

In this work, tamarind fruit seed derived granular activated carbon (TSAC) was prepared by microwave heating for the adsorptive treatment of semi-aerobic landfill leachate. TSAC was examined by pore structural analysis and determination of surface acidity/basicity. The effects of adsorbent dosage, contact time, and solution pH on the adsorptive removal of color and non-biodegradable constituents, expressed in term of chemical oxygen demand (COD) were quantified. The experimental results manifested that the adsorptive removal of color and COD increased with increasing the adsorbent dosage and contact time, with the adsorptive removal of color and COD of 91.23% and 79.93%, respectively, at the adsorbent dosage of 6 mg/200 mL and pH 6. The adsorption kinetic was satisfactory fitted to the pseudo-second-order kinetic model. Equilibrium data were favorably described by the Langmuir isotherm model, showing a monolayer adsorption capacity for color and COD of 168.57 Pt–Co/g and 64.93 mg/g at 30 C, respectively.

Coconut coir dust contains a large proportion of lignin and cellulosic groups which act as potential pollutants absorber in effluents. This study investigated the crosslinking of polyvinyl alcohol having one –OH group on its molecule with coconut coir dust in order to introduce functions to the polymer and increase its hydrophilicity by physical means. The application of the adsorbent to remove cationic dye malachite green from effluent was very feasibly. Adsorption was studied as a function of solution pH, contact time and initial dye concentration. Adsorption data were analysed using various isotherms models and was found to conform to the principle of Lagmuir, Freundlich and FloryHuggins models with good correlation coefficients (R 2 > 0.95). The kinetics was also studied to elucidate the mechanistic pathway of the process. Results revealed that pseudo second order kinetic model provided better fit than the pseudo-first order in terms of adsorption capacity of the sorbent. Cha...