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The current article reports an effective and low-cost removal of Acid blue 93 dye using synthesised peanut (Arachis hypogaea) shells. In first step, the adsorbents were examined using pHpzc, TG-DTG, FTIR and SEM characterisation techniques. In the second phase, the parameters such as contact time (CT), pH, adsorbent dosage (AD) and initial concentration of dye (ICD) were assessed using one parameter at a time adsorption study (OPAT). Selecting the same parameters an effort was also made using design of experiment (DoE). It was found that, for maximum removal both the studies, OPAT and DoE delivered similar optimum conditions as CT 60 min, pH 7, AD 7 g l−1 and ICD 50 mg l−1. In addition, DoE added an edifying output in terms of percentage of contribution: ICD (36.35%) > AD (31.39%) > CT (27.03%)> pH (5.24%). In accordance with the above studies, kinetics, isotherm and thermodynamic analysis were also performed followed by error analysis. In kinetics, pseudo-second-order model was superior; in isotherm study, Langmuir model was dominant with a q m value of 23.36 mg g−1. Thermodynamic parameters such as Δ G ∘ , Δ H ∘ and Δ S ∘ stated the adsorption endothermic and spontaneous. The novelty of this work is in the development of the pre-treated peanut (A. hypogaea) shells for efficient and low-cost removal of Acid blue 93 dye from aqueous media. [ABSTRACT FROM AUTHOR]

In the present article, an attempt is made for simple, low‐cost, and efficient removal of Auramine dye using peanut (Arachis hypogaea) shells as adsorbents. Two different forms of adsorbents distilled water washed peanut shells (DPS) and NaOH treated peanut shells (NPS) were used as adsorbents. Both the adsorbents were studied using BET, pHPZC, FTIR, SEM, TGA, and XRD characterization techniques. Adsorption parameters such as effect of contact time, pH, initial dye concentration, adsorbent dose, and temperature were also assessed. Isotherm analysis at optimum conditions showed Langmuir fitted better with a qm value of 96.15 mg/g for DPS and 294.12 mg/g for NPS; while in kinetic analysis, pseudo‐second order was superior. Thermodynamics study stated that adsorption process was endothermic in nature. Overall outcomes establish that the two forms of peanut shells, DPS, and NPS were excellent in removal of Auramine dye and are low cost also as preparation cost of DPS and NPS is 68.73 INR and 106.19 INR per kg, respectively. Practitioner points: Removal of Auramine dye from aqueous media using different forms of peanut (Arachis hypogaea) shells as adsorbents is discussed.qm (Langmuir) using DPS and NPS were found to be 96.15 and 294.12 mg/g, respectively.Preparation cost of DPS was 68.73 INR per 1 kg, whereas for NPS it was 106.19 INR per 1 kg. [ABSTRACT FROM AUTHOR]

The present investigation is based on utilizing chemically treated Areca catechu husk as a low-cost agro-waste adsorbent to replace expensive activated carbon for the removal of Basic red 2 (BR2) dye from water-based solution. Initial experiments have shown that sodium hydroxide treated Areca catechu husk provides maximum adsorption of 97.05% compared to the other chemical treatment [distilled washed Areca catechu husk (DWAH) 85.34%, sodium carbonate treated Areca catechu husk (SCAH) 82.30%, dipotassium phosphate treated Areca catechu husk (DPAH) 80.52% and phosphoric acid-treated Areca catechu husk (PAAH) 46.33%). Application of Fourier-transform infrared spectroscopy allows identify and characterize unknown components and contamination present on or in the adsorbent. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy analysis was performed with a field emission gun - scanning electron microscopy (FEG-SEM) machine to comprehend surface morphology and elemental arrangement of the husk. Batch experiments were done and optimum adsorption condition of different parameters like pH, rotation per minute, adsorbent dose, initial concentration and temperature as 7, 200 RPM, 10 mg/L, 100 mg/L and 298 K. Four different types of isotherm models were used for study, among these Langmuir isotherm model better suited, with the maximum adsorption potential of 23.87 mg/g. The activation energy was analyzed as 10.23 kJ/mol and thermodynamic analysis indicated the endothermic and spontaneous nature of adsorption. The adsorption kinetics investigation pursued the pseudo-second-order kinetics model. Thus, it can be concluded that Areca catechu husk treated with sodium hydroxide is a good alternative, non-conventional, low-cost agro-waste adsorbent for removal of BR2 dye from wastewater and can be an alternative to costly activated carbon. [ABSTRACT FROM AUTHOR]

A new adsorbent for removing copper ions from aqueous solutions has been developed and characterized. The present study deals with the sorption of Cu(II) from aqueous solution on chemically pretreated sodium carbonate-treated rice husk (SCRH). The physico-chemical characteristics of rice husks were investigated to analyze their suitability to adsorb Cu(II) ions from water and wastewater. The raw rice husk (RRH), SCRH and Cu(II) adsorbed rice husk were analyzed by SEM-EDAX analysis. FTIR spectroscopy was also applied to identify functional groups, capable of adsorbing metal ions. Batch kinetic studies were conducted for the adsorption of Cu(II) on SCRH. It has been observed that 92.9–96.0% removal of Cu(II) is achieved at 4.8 mg of Cu(II)/g of adsorbent, adsorbent dose of 10 g L–1 and initial Cu(II) concentration of 10 mg L–1 in a temperature range of 15–50 °C. It was observed that the adsorption of Cu(II) on SCRH followed pseudo second-order kinetic and time to achieve equilibrium was found to be 60 min. The maximum uptake (97%) of Cu (II) was observed at pH 6. In this paper, an attempt has also been made to develop simple and readily understandable thermodynamic parameters related to sorption process at the equilibrium for understanding the adsorption mechanism. The Gibbs free energy ΔG° values for the adsorption processes of Cu(II) at 15, 30, 40 and 50 °C were calculated as –6.16, –6.84, –8.01 and –8.53 kJ mol–1, respectively. The negative value of ΔG° indicates spontaneity of adsorption. The values of ΔH° and ΔS° for Cu(II) adsorption were calculated as 14.37 kJ mol–1 and 70.92 J K–1 mol–1, respectively. The activation energy for the adsorption of Cu(II) was found to be 9 kJ mol–1 which is a characteristic for diffusion limited processes. [ABSTRACT FROM AUTHOR]

The present research is based on the removal of safranin (cationic) dye, an emerging contaminant from wastewater by sodium bicarbonate modified Bambusa tulda (variety of bamboo and a bioadsorbent) using adsorption technology. Characterization study of sodium bicarbonate-treated bamboo was done through scanning electron microscope analysis and it was found that after treatment with sodium bicarbonate, pore structure of B. tulda gets widened increasing active pore cavity in the adsorbent resulting in larger surface area for higher adsorption. Energy dispersive X-ray analysis showed the presence of Na, Cl, etc., in safranin dye adsorbed adsorbent; in Fourier transform infrared spectroscopy analysis presence of Hydroxyl and Carboxyl group helps largely for adsorption of safranin dye. The batch study experiment gave optimum results for safranin dye at pH 7; rpm 200, temperature 298 K, with an initial concentration of 50 mg/L and a dose of 10 g/L with maximum adsorption capacity of 32.26 mg/g, followed by pseudo second order rate equation and a removal rate of 98.15% for 60 min of time duration. The activation energy was 17.376 kJ/mol. Two algorithms are used in artificial neural network (ANN), that is, Levenberg–Marquardt (LM) and Bayesian Regularization algorithm with different nodes. LM algorithm with three hidden nodes has higher R2 value with the lesser value of statistical error. Time, dose, and initial concentration can be considered for t-test. Intensive research has been carried out on the modified B. tulda along with characteristic study and modeling analysis by ANN and regression analysis Model Study and Error analysis. Taking considerations of all experimental results and model analysis, it is concluded that sodium bicarbonate treated B. tulda is a good, low cost, and effective adsorbent in comparison to commercially activated carbon for the removal of safranin (cationic) dye from wastewater. [ABSTRACT FROM AUTHOR]

Adsorption of Congo red onto NaOH-modified jute fibre was studied for different concentrations of dye solutions (50, 100, 150 and 200 mg/L). Experiments were carried out as function of contact time, initial solution pH (3–9), adsorbent dose (10–20 g/L) and temperature (293, 303 and 313 K). Adsorption data fit better to Langmuir model in comparison with the Freundlich model. This indicates the monolayer adsorption on the homogeneous surface of the adsorbent with identical binding sites of the adsorbent. The adsorption process followed the pseudo-second-order kinetic model. The maximum sorption capacity (qmax) was found to be 32.24 mg/g. The maximum adsorption occurred at pH 7.0. The effect of adsorption dose was studied and optimum adsorption was obtained at a jute dose of 16 g/L. [ABSTRACT FROM AUTHOR]

Abstract: A fixed bed of sodium carbonate treated rice husk was used for the removal of Cd(II) from water environment. The material as adopted was found to be an efficient media for the removal of Cd(II) in continuous mode using fixed bed column. The column having a diameter of 2cm, with different bed depths such as 10, 20 and 30cm could treat 2.96, 5.70 and 8.55l of Cd(II) bearing wastewater with Cd(II) concentration 10mg/l and flow rate 9.5ml/min. Different column design parameters like depth of exchange zone, adsorption rate, adsorption capacity, etc. was calculated. Effect of flow rate and initial concentration was studied. Theoretical breakthrough curve was drawn from the batch isotherm data and it was compared with experimental breakthrough curve. An amount of 0.01mol/l HCl solution was used for desorption of adsorption column. Column regeneration and reuse studies were conducted for two cycles of adsorption–desorption. [Copyright &y& Elsevier]