Removal of Fluoride from Groundwater by Carbonised <i>Punica granatum</i>Carbon (“CPGC”) Bio-Adsorbent

This study applies the development and application of low cost, Punica granatum bio-adsorbent for the removal of fluoride in groundwater. The batch adsorption study was carried out to analyze the defluoridation by contact time variation, adsorbent dose, adsorbate concentration, adsorbent particle size and presence of co-anions at neutral pH. The analysis of the isotherm equilibrium data using the Langmuir and Freundlich equations by linear methods showed that the data fitted better with Freundlich model (R2 > 0.980). Prepared adsorbent showed enhanced removal of fluoride concentration by 78.1% at equilibrium contact time of 75 minutes. Carbonised Punica granatum Carbon (CPGC) seeds showed a high affinity for fluoride ions compared with other conventional adsorbents. Therefore, it can be considered as a potentially “good”, low-cost bio-adsorbent for de-fluoridation of water compared to other bio-adsorbent.

Investigation on Adsorption of Lithospermum erythrorhizon onto Fungal Cell Wall Polysaccharides

A culture of Lithospermum erythrorhizon adsorbed on fungal cell wall polysaccharides, a novel bio-adsorbent made from fungal cell wall, has been established in this paper. Three steps were involved in this immobilization. The first step was preparation of suspended plant cells from tightly aggregated plant cell clumps. The disassembled ratio of 0.715g·g-1 (the disassembled cells over total cells) was obtained under optimum condition for the enzymatic reaction. Then, the adsorption of plant cells onto fungal cell wall polysaccharides was conducted and the saturated capacity of 12 g cell per gram of carrier was obtained in adsorption immobilization. Finally, the culture of cells adsorbed on fungal cell wall polysaccharides was compared with that of cells entrapped in alginate or suspension cell culture. While exposed to in situ liquid paraffin extraction coupled with cell culture, the shikonin productivity of immobilized cells by adsorption was 10.67g·L-1, which was 1.8 times of that in suspension culture and 1.5 times of that entrapped in alginate.

Heavy metals adsorption by banana peels micro-powder: Equilibrium modeling by non-linear models

In this study the copper and lead adsorption efficiency onto banana peels powder was investigated. The agroindustrial waste recovery represents one of the Circular Economy pillars. In the view of the synthesis of an environmentally friendly adsorbent material, the powder was used without any preliminary chemical or thermal activation, but only after simple washing, drying and grinding. The bio-adsorbent was characterized by the FTIR technique and tested in batch mode on synthetic aqueous solutions containing Pb and Cu in the range 10–90 mg·L^(-1). A selection of two(Langmuir, Freundlich) and three(Sips, Redlich–Peterson, Koble–Corrigan) parameter isotherm models was chosen to fit adsorption equilibrium data by non-linear regression procedure. The best fit isotherm model was selected relying on the error function with the lowest average percentage error(APE) value, among those characterized by the highest R^2 values. As expected, the three-parameter models are found to better represent both metals bio-adsorption, with APE and R^2 values always lower and higher, respectively, than the corresponding values obtained for the two-parameter models.

Biosorption of Crude Oil Spill Using Groundnut Husks and Plantain Peels as Adsorbents

Adsorption techniques using meshed groundnut husks and plantain peels have provided cheap alternative to the conventional methods of crude oil spillage control and also for good waste management approach. The biodegradable nature of these adsorbents makes it a better alternative to the non biodegradable synthetic polymers. Dry unripe plantain peels and groundnut husks were used to prepare the adsorbents. The adsorption and percentage removal of crude oil from effluent produce water was dependent on adsorbent dosage, contact time,temperature and particle size. The particle size of the adsorbents should not be less than 150 μm to avoid making the particles so loosed thus posing difficulty in recovery. The two adsorbents exhibit high affinity for oil adsorption with time especially at 75 μm, groundnut husk has a better performance because of its larger surface area and the presence of residual oil in the plantain peels. Agitation at 150 r.min-1 and contact time between 15 - 75 min are recommended. The optimum adsorption temperature ranged between 25°C - 45°C and 15°C - 45°C for groundnut husks and plantain peels respectively. The adsorption data indicated that a pseudo-second- order equation could be used to study the adsorption kinetics of both adsorbents.

Immobilization of nano-zero-valent irons by carboxylated cellulose nanocrystals for wastewater remediation

Nano-zero-valent irons(nZVI)have shown great potential to function as universal a nd low-cost magnetic adsorbents.Yet,the rapid agglomeration and easy surface corrosion of nZVI in solution greatly hinders their overall applicability.Here,carboxylated cellulose nanocrystals(CCNC),widely available from renewable biomass resources,wer e prepared and applied for the immobilization of nZVI.In doing so,carboxylated cellulose nanocrystals supporting nano-zero-valent irons(CCNC-nZVI)were obtained via an in-situ growth method.The CCNC-nZVI were characterized and then evaluated for their performances in wastewater treatment.The results obtained show that nZVI nanoparticles could attach to the carboxyl and hydroxyl groups of CCNC,and well disperse on the CCNC surface with a size of〜10nm.With the CCNC acting as corrosion inhibitors improving the reaction activity of nZVI,CCNC-nZVI exhibited an improved dispersion stability and electron utilization efficacy.The Pb(II)adsorption capacity of CCNC-nZVI reached 509.3 mg·g^-1(298.15 K,pH=4.0),significantly higher than that of CCNC.The adsorption was a spontaneous exothermic process and could be perfectly fitted by the pseudo-second-order kinetics model.This study may provide a novel and green method for immobilizing magnetic nanomaterials by using biomassbased resources to develop effective bio-adsorbents for wastewater decontamination.