Investigation of the adsorptive removal of methylene blue using modified nanocellulose.

In this study, Ethylenediamine tetraacetic acid (EDTA) embedded nanocellulose (NCED) has been used to study the adsorptive removal of methylene blue (MB) from simulated wastewater. The morphological characterizations have been checked with FESEM, FETEM, AFM, and BET pore analysis, while the fingerprinting of the material has been analyzed with the help of FTIR, Raman spectroscopy, EDS, XRD and TGA. For the experimental designing involving four parameters that affect the removal efficiency of MB, the layout has been prepared with the help of Central Composite Design (CCD). For the correlation among the parameters and their subsequent impact on the removal percentage, response surface methodology (RSM) has been employed. Maximum removal percentage of MB using NCED was found out to be 91.14%. The adsorption process was found to be good fit with the Langmuir isotherm and Elovich kinetics model. From the thermodynamics study, the spontaneity and the endothermic nature of the process was confirmed. With the help of all the obtained data and the associated removal efficiency, NCED could play a role of cost-effective and eco-friendly alternative to the expensive methods of toxic dye removal from wastewater.

Magnetic nanocellulose from Cyperus rotundas grass in the absorptive removal of rare earth element cerium (III): Toxicity studies and interpretation.

In this study a very common grass named Cyperus rotundas was used to extract cellulose which was converted to magnetic grass nano cellulose (MGNC) to adsorb rare earth element Cerium (Ce (III)). The prepared MGNC was analyzed with sophisticated technique to determine the alteration in physical and chemical properties before and after adsorption with the pollutant Cerium. Parameters like pH, temperature, MGNC dosage and initial concentration of Ce were optimized to check parameters influencing the adsorption of Ce (III). The optimized experimental data were perfectly modelled into Langmuir model with adsorption capacity of 353.04 mg g -1 for Ce (III). For kinetics the data fitted into pseudo second order model. To check the efficacy of MGNC in real scenario, untreated and treated Ce was used for phototoxicity studies with 4 different plant seeds. Apart from this, model fish, Danio rerio was used to check the toxicity level on aquatic organism before and after adsorption of Ce (III) with MGNC. This study showed the efficient use of MGNC and maximum removal of Cerium from wastewater and the magnetic behavior incorporated adds advantage of easy retrieval.

Ecotoxicological assessment of micropollutant Diclofenac biosorption on magnetic sawdust: Phyto, Microbial and Fish toxicity studies.

Diclofenac (DCF), a persistent pharmaceutical micropollutant which occurs in the ecosystems causing adverse effects on aquatic as well as terrestrial organisms. In this study, magnetic sawdust (MSD) was prepared using co-precipitation method for biosorptive removal of DCF from water. The MSD was characterized using various analytical techniques like microscopic and spectroscopic analysis. Magnetometer study confirms the ferromagnetic behavior of the biosorbent which is a key advantage in the separation of MSD after biosorption. The effect of experimental parameters was optimized in batch mode with evaluated maximum efficiency of 86.12 % at pH 6, biosorbent dosage 25 mg for 50 mg/L of DCF. Ecotoxicological assessment has been performed for the treated and untreated sample using plant seeds, microbes and zebra fish to check the adverse effects of DCF on these organisms. Evaluation of toxicity studies revealed that inhibition concentration of DCF for various seeds (60.91 mg/L to 43.11 mg/L), E. coli (48.82 µg/mL) and B. subtilis (31.55 µg/mL). The lethal concentration of DCF on the Danio rerio was found to be 156.99 mg/L. In contrast, significant increase in both the concentration measures of DCF after biosorption was observed making this biosorbent a potent alternative to other available treatment measures.

Use of Nanocellulose extracted from grass for adsorption abatement of Ciprofloxacin and Diclofenac removal with phyto, and fish toxicity studies.

The present study deals with the adsorption of antibiotic Ciprofloxacin (CPXO) and anti-inflammatory agent Diclofenac (DCF) on Grass nanocellulose (GNC) extracted from Cyprus rotundas grass. The adsorbent GNC was characterised using various microscopic, elemental and spectroscopic analysis to monitor the physicochemical alterations of the surface before and after adsorption. The size of the converted nanocellulose was found to be 40-50 nm. The experimental measures influencing the adsorption of CPXO and DCF that were optimised are initial solution pH, GNC dosage, temperature and initial concentration of the adsorbate. Halsey isotherm model and pseudo-second order kinetic model agreed best with the experimental outcome for both the adsorbate. The maximum adsorption capacity of GNC were 227.223 and 192.307 mg/g for CPXO and DCF respectively. Phytotoxicity studies were performed using 6 different types of seeds to evaluate the effect of GNC treated effluent on plants. Similarly, acute fish toxicity on zebra fish analysis showed to have lesser mortality rate of the effluent after adsorption of CPXO and DCF on GNC.

Kinetic and thermodynamic studies on biosorption of Cr(VI) on raw and chemically modified Datura stramonium fruit.

Biosorption of Cr(VI) on sulfuric and phosphoric acid-treated Datura stramonium fruit was investigated in batch mode. The various parameters that influence the biosorption process such as Cr(VI) initial concentration, biosorbent dosage, contact time, temperature, and pH value were optimized. Both linear and non-linear regression analysis of isotherm data suggest that Langmuir isotherm model mimics the behavior of Cr(VI) ion biosorption onto Datura stramonium fruit biosorbent. The maximum Cr(VI) ions adsorption capacity of 138.074 mg/g at pH 2 is achieved with phosphoric acid treated Datura stramonium (PDSF). The kinetics of adsorption process is well described by pseudo-second-order model with high R2 and low χ2 value. The estimated activation energy of < 8 kJ/mol obtained for both raw and chemically modified adsorbents suggests that the adsorption occurs mainly via physisorption. Besides, thermodynamic results reveal that biosorption of Cr(VI) on both treated and untreated Datura stramonium was endothermic, spontaneous, and randomness in nature.

Comparative assessment of raw and acid-activated preparations of novel Pongamia pinnata shells for adsorption of hexavalent chromium from simulated wastewater.

Current study deals with the comparative assessment for efficient adsorption of Cr(VI) from simulated wastewater using raw (NPP), phosphoric acid-activated (PPP) and sulphuric acid-activated (SPP) Pongamia pinnata shells. Physico-chemical alterations of the adsorbent were characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), zeta-potential analysis, energy-dispersive X-ray spectroscopy (EDS) and total pore analysis using Brunauer-Emmett-Teller (BET). Parameters influencing the efficient biosorption of Cr(VI) species viz. initial pH of Cr(VI) solution, dosage of biosorbent, biosorbent-Cr(VI) contact period, initial concentration of Cr(VI) ions and reaction temperature were optimised. Various two-parameter and three-parameter isotherm models, kinetic models and thermodynamic studies were performed using equilibrium data. Langmuir adsorption capacity for NPP (raw biomass), PPP (phosphoric acid-activated biomass) and SPP (sulphuric acid-activated biomass) was found to be 96.2, 152 and 192 mg/g, respectively. All the biosorbents gave best fit for pseudo-second-order model. Thermodynamic studies suggest spontaneous and endothermic interaction with increased degree of randomness. Effect of co-existing cations and anions on Cr(VI) biosorption onto the biosorbents implied that minimal competition and the biosorption capacity of the biosorbents for Cr(VI) species remained unaffected. Regeneration studies suggest that activated biosorbents can be used up to three times with continuous desorption.

Surface modification of nanocellulose using polypyrrole for the adsorptive removal of Congo red dye and chromium in binary mixture.

In this study, nanocellulose was synthesised by acid hydrolysis of cellulose and was coupled with polypyrrole supporting matrix. The synthesised nanocellulose polypyrrole composite (NCPPY) was characterised by FESEM, XRD, FTIR, BET, TGA/DSC and NMR. These analysis showed the conversion of cellulose to nano sized crystalline structure with excellent thermal stability and higher surface area. The effect of different parameters like pH, temperature, contact time, adsorbent dosage and initial concentration of Chromium (Cr(VI)) and Congo Red (CR) were optimised in batch mode. Response Surface Methodology (RSM) has been employed as an optimization tool for the efficient removal of Cr(VI) and CR and the maximum removal efficiency was found to be 80% and 85% respectively. The Langmuir and Freundlich isotherm well fitted the equilibrium data for CR and Cr(VI) respectively. Thermodynamic data showed that the biosorption of Cr(VI) and CR on NCPPY is an endothermic, spontaneous, and entropy-driven process. The adsorption kinetic followed pseudo-second-order for Cr(VI) and intraparticle diffusion for CR. Effect of co-existing ions were checked using several common salts and heavy metals. Results indicated that NCPPY has great potential to remove Cr(VI) and CR binary mixture under simulated conditions.

Hexavalent chromium adsorption on virgin, biochar, and chemically modified carbons prepared from Phanera vahlii fruit biomass: equilibrium, kinetics, and thermodynamics approach.

A novel biosorbent Phanera vahlii fruit biomass (PVF) and its biochar and chemically modified forms were studied for the elimination of Cr(VI) from synthetic solutions. Biosorbents were characterized through BET, FTIR, FESEM, EDX, and TGA technique. The parameters influencing biosorption were optimized and found as pH 2.0, temperature 303 K, initial metal concentration 500 mg/L, and biosorbent dosage 0.5 g/L. The ideal contact time was 180 min for all biosorbents. Freundlich isotherm was found to have good correlation with investigational data, which indicated that biosorption takes place in multiple layer style. Langmuir adsorption isotherm yielded the highest biosorption capacity (Qo) to be 159.1, 225.1, 244.1, and 278.5 mg/g for Phanera vahlii fruit biomass, Phanera vahlii biochar, Phanera vahlii phosphoric acid activated carbon, and Phanera vahlii zinc chloride activated carbon, respectively. Experimental data had good correlation with pseudo-second-order kinetic model fitted. Thermodynamic studies indicated the biosorption process to be spontaneous, stable, and endothermic. Thus, it was concluded that Phanera vahlii fruit biomass and the derived activated carbons are promising biosorbents for adsorption of chromium from aqueous solutions. Graphical abstract.