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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.

A B S T R A C TThe adsorption behavior of m-phenylene diamine (m-PDA) from aqueous solution onto activated carbon was investigated under various experimental conditions, such as contact time, adsorbate concentration, and temperature. Maximum adsorption capacity for m-PDA was found to be 33.17 mg g −1 at pH 7.0 and temperature 303 K. The adsorption kinetics data were best described by the pseudo-second-order rate equation and the equilibrium was achieved after 120 min. The m-PDA adsorption was governed by film diffusion process. Besides, equilibrium data were very well represented by the Redlich-Peterson model. A model for prediction of the dose of adsorbent required to achieve a range of m-PDA removals for a given number of adsorption-desorption cycles has been developed and validated based on the Langmuir isotherm. Thermodynamic parameters indicated the spontaneous, endothermic, and increased random nature of m-PDA adsorption. The amide, carboxylic acid, and nitro groups of the activated carbon were involved in chemical interaction with the m-PDA molecules. Results suggested that the activated carbon has good potential for remediation of m-PDA contaminated waters.

This study deals with the potential of bioflocculant for the treatment of various industrial wastewaters. Bioflocculant (BFBl) produced by Bacillus licheniformis NJ3, showed 97% flocculating activity in primary screening (kaolin assay). The characteristics of the BFBl such as temperature and pH stability, cation‐independency makes the flocculation process more economic as harmful coagulants and stabilizers are not required. BFBl efficiently treated synthetic wastewaters as compared to alum by reducing turbidity (69–87%), chemical oxygen demand (50–80%) and oil (87%). Further BFBl was used to treat pesticide, petroleum, pharmaceutical and starch processing industrial wastewaters having diversified pH. It reduced total suspended solids (61.9–80%), turbidity (54–94%), total dissolved solids (11–54%), oil and grease (75%) and heavy metals (62–100%) from wastewaters in the absence of cations without altering the temperature and pH. Additionally, Sludge settling process in the presence of BFBl was three times faster as compared to alum. Thus, BFBl successfully treats various wastewaters reducing multiple pollution indices. BFBl was a glycoprotein with 92% polysaccharide and 7% protein contents providing biodegradable nature. As a result, BFBl emerged as environment‐friendly and economical alternative for the bioremediation of various industrial wastewaters. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S306–S314, 2019

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