Prospective application of diethylaminoethyl cellulose (DEAE-cellulose) with a high adsorption capacity toward the detoxification of 2,4-dichlorophenoxyacetic acid (2,4-D) from water.

Detoxification of pesticide residues requires effective methods. In this regard, the adsorption efficiency of diethylaminoethyl cellulose (DEAE-cellulose) as an adsorbent material for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from water at different concentrations, times, pH and temperature was evaluated comprehensively. The obtained results showed that DEAE-cellulose has greater efficacy to eliminate 2,4-D from water with a high Langmuir maximum adsorption capacity of 429.18 mg g-1 at pH 7.0. Kinetic models and thermodynamics were investigated at length. The adsorption mechanism was understood by way of electrostatic, hydrogen bonding, and Lewis acid-base type interactions. Extensive analytical characterization of the DEAE-cellulose adsorbent before and after 2,4-D adsorption was performed and liquid chromatography with a tandem mass spectrometer (LC-MS/MS) was used for the quantification of 2,4-D. The regeneration of DEAE-cellulose was achievable using dilute formic acid and the DEAE-cellulose adsorbent showed high ability in the removal of 2,4-D from the agriculture run-off water.

Confluence of montmorillonite and Rhizobium towards the adsorption of chromium(vi) from aqueous medium.

Chromium in its hexavalent oxidation state is carcinogenic and wastewater from the electroplating industry is one of the principal sources of pollution. To reduce this toxicity and pave way towards environmental safety, a combination of environmental microbiology and chemistry is quite efficient for developing biosorbents to sequester chromium from waste water. Immobilization of Rhizobium in sodium montmorillonite provides a conducive environment to capture hexavalent chromium. Various characterization techniques such as FTIR, XPS and SEM-EDAX were performed and batch parameters such as pH variation, adsorbent dosage, concentration of metal ion and temperature were optimized. Pseudo second order kinetics coupled with a higher regression coefficient for Freundlich isotherm and a Langmuir adsorption capacity of 22.22 mg g-1 was achieved for the adsorption process. The adsorption was enhanced by the charge interactions between the protonated clay-Rhizobium surface and Cr(vi) ions in acidic medium. The biosorbent was stable and easily regenerated using NaOH. Preliminary column studies were performed to test the efficiency of the developed biosorbent at higher volumes on a laboratory scale.

Potential Application of Saccharomyces cerevisiae and Rhizobium Immobilized in Multi Walled Carbon Nanotubes to Adsorb Hexavalent Chromium.

The presence of harmful contaminants in the waste stream is an important concern worldwide. The convergence of biotechnology and nanoscience offers a sustainable alternative in treating contaminated waters. Hexavalent chromium, being carcinogenic deserves effective and sustainable methods for sequestration. Here in, we report the immobilization of a prokaryote (Rhizobium) and eukaryote (Saccharomyces cerevisiae) in multiwalled carbon nanotubes (MWCNTs) for the effective adsorption of hexavalent chromium. The carboxylic groups were introduced into the MWCNTs during oxidation using potassium permanganate and were subjected to EDC-HOBT coupling to bind with microbial cell surface. FTIR, TGA, BET, FESEM-EDAX, HRTEM, XPS and confocal microscopy were the investigative techniques used to characterize the developed biosorbents. Experimental variables such as pH, adsorbent dosage, kinetics, isotherms and thermodynamics were investigated and it was observed that the system follows pseudo second order kinetics with a best fit for Langmuir isotherm. Electrostatic interactions between the functional groups in the microbial cell wall and hydrochromate anion at pH 2.0 propel the adsorption mechanism. The lab scale column studies were performed with higher volumes of the Cr(VI) contaminated water. Sodium hydroxide was used as the desorbing agent for reuse of the biosorbents. The sustainable biosorbents show prospects to treat chromium contaminated water.