Nanocrystalline cellulose for removal of tetracycline hydrochloride from water via biosorption: Equilibrium, kinetic and thermodynamic studies

tCrystalline nanocellulose, synthesized from green seaweed, Ulva lactuca, was investigated for the sorptionof tetracycline hydrochloride (TC) from aqueous solutions. The effects of pH, contact time, concentra-tion of TC and desorption were studied in batch mode. The kinetics of TC biosorption was very fastand reached equilibrium in almost 2 h. The kinetic data was well described by double exponentialand the pseudo-second-order kinetic models. Film diffusion is the rate-limiting step for the biosorp-tion of TC on to crystalline nanocellulose. Both Redlich–Peterson (R–P) and Polanyi–Manes (P–M)isotherm models described the equilibrium data well. The values of maximum sorption capacities(6.48–7.73 mg/g for R–P and 6.57–7.96 mg/g for P–M models) increased with temperature. A ther-modynamic study (�H◦= 22.64 kJ/mol, �S◦= 9.85 kJ/(mol/K)) demonstrated that biosorption of TC isspontaneous, endothermic and an entropy-driven process. The reusability of sorbent was achieved byHNO3(5 w/w%) with desorption efficiency of 95.20% in 4 h. The overall results have significant implica-tions for the removal of TC from aqueous solution with crystalline nanocellulose

Nanocellulose/TiO2 composites: preparation, characterization and application in the photocatalytic degradation of a potential endocrine disruptor, mefenamic acid, in aqueous media

Nanocellulose (NC)-supported TiO2 nanoparticles, termed NCTs, were prepared by an ultrasonic impregnation method. The as-synthesized NCTs were thoroughly characterized and studied for the photodegradation of mefenamic acid (MEF), an anthranilic acid derivative drug. The adsorption potential of NCTs increased with TiO2 loading and 10 wt% TiO2 NCT showed the highest sorption potential. Adsorption kinetics of MEF onto NC and NCTs indicated that the equilibrium was reached within 50 min. A pseudo-second-order model clearly represented the experimental kinetic data and demonstrated that the MEF sorption was mainly chemisorption. Equilibrium sorption analysis indicated that the adsorption followed the Langmuir model with a monolayer sorption capacity of 22.43 mg g−1 for 10 wt% TiO2 NCT. The photocatalytic degradation rates of NCTs were identical with respect to their adsorption capacities, and the apparent rate constant (kapp) values indicated that the amount of TiO2 in NCTs played a vital role in the degradation of MEF. Furthermore, 10 wt% TiO2 NCT showed excellent catalytic activity and reusability even after five cycles of photodegradation

Nanocellulose for biosorption of chlorpyrifos from water: chemometric optimization, kinetics and equilibrium

The study explores the biosorption potential of nanocellulose (NC) to remove an insecticide, chlorpyrifos (CP), from aqueous solutions using the batch method. Biosorption kinetics were very fast and reached equilibrium in 60 min, and the experimental kinetic data had fit well with the pseudo-second-order model. Film diffusion was the rate-limiting step for the biosorption of CP onto crystalline nanocellulose (CNC). The equilibrium sorption was well described by the Sips and Langmuir isothermmodels. The values of maximum sorption capacities (7.237–5.017 mg/g for the Sips and 12.325–7.247 mg/g for the Langmuir model) decreased with an increase in temperature from 288 to 308 K, signifying biosorption of CP is an exothermic process. Based on the central composite design (CCD), two-factor interaction (2FI) and quadratic models, the correlation between the effects of variable parameters on the CP biosorption onto NC was evaluated. The chemometric analyses suggested that 1.5 g/l NC required 20 min to biosorb 5 mg/l CP to yield an efficiency of 99.3%. Overall, the results demonstrated that NCs can be a promising biosorbent for the removal of pesticides from aqueous streams