Pharmaceuticals as emerging contaminants and their removal from water. A review

Remediation of water pollution caused by pharmaceutical residues based on electrochemical separation and degradation technologies: a review.

Valorization of native birch wood lignin into monomeric phenols over nickel-based catalysts has been studied. High chemoselectivity to aromatic products was achieved by using Ni-based catalysts and common alcohols as solvents. The results show that lignin can be selectively cleaved into propylguaiacol and propylsyringol with total selectivity >90% at a lignin conversion of about 50%. Alcohols, such as methanol, ethanol and ethylene glycol, are suitable solvents for lignin conversion. Analyses with MALDI-TOF and NMR show that birch lignin is first fragmented into smaller lignin species consisting of several benzene rings with a molecular weight of m/z ca. 1100 to ca. 1600 via alcoholysis reaction. The second step involves the hydrogenolysis of the fragments into phenols. The presence of gaseous H2 has no effect on lignin conversion, indicating that alcohols provide active hydrogen species, which is further confirmed by isotopic tracing experiments. Catalysts are recycled by magnetic separation and can be reused four times without losing activity. The mechanistic insights from this work could be helpful in understanding native lignin conversion and the formation of monomeric phenolics via reductive depolymerization.

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Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Electrochemical processes have been extensively investigated for the removal of a range of organic and inorganic contaminants. The great majority of these studies were conducted using nitrate-, perchlorate-, sulfate-, and chloride-based electrolyte solutions. In actual treatment applications, organic and inorganic constituents may have substantial effects on the performance of electrochemical treatment. In particular, the outcome of electrochemical oxidation will depend on the concentration of chloride and bromide. Formation of chlorate, perchlorate, chlorinated, and brominated organics may compromise the quality of the treated effluent. A critical review of recent research identifies future opportunities and research needed to overcome major challenges that currently limit the application of electrochemical water treatment systems for industrial and municipal water and wastewater treatment. Given the increasing interest in decentralized wastewater treatment, applications of electrolytic systems for treat...

Challenges and Opportunities for Electrochemical Processes as Next-Generation Technologies for the Treatment of Contaminated Water

Electrocoagulation for the treatment of textile industry effluent--a review

Separation of pollutants from tannery effluents by electro flotation

Removal of sulfide, sulfate and sulfite ions by electro coagulation.

Role of electrolyte on anodic mineralization of atenolol at boron doped diamond and Pt electrodes

Anodic oxidation of ketoprofen-an anti-inflammatory drug using boron doped diamond and platinum electrodes.

The removal of tannins and their basic molecules such as catechol, pyrogallol, phloroglucinol and resorcinol was studied by electro-flotation and electro-oxidation techniques. Iron rods and triple oxide (TaO2/RuO2/IrO2) coated titanium rods were used as electrodes for electro-flotation and electro-oxidation respectively. Interaction of tannins and polyhydroxy phenols with iron oxy-hydroxide formed by anodic dissolution of iron was studied by UV-Visible, FT-IR and zeta-potential measurements. GC–MS was used to identify the intermediate compounds formed during electro-oxidation. Catechol, pyrogallol, phloroglucinol and resorcinol were found to be mineralized in the presence of triple oxide (TaO2/RuO2/IrO2) coated titanium electrodes. Catechol and pyrogallol were found to form insoluble organo-metal complexes while resorcinol and phloroglucinol were found to adsorb on iron oxy-hydroxide. The sludge thus formed was simultaneously separated from the aqueous phase by hydrogen bubbles. It was observed that the power consumption is relatively high for electro-oxidation compared with electro-flotation. The effects of pH and reaction time on their removal were also studied and the results are discussed. Copyright © 2005 Society of Chemical Industry

M. Murugananthan

Papers

Separation of pollutants from tannery effluents by electro flotation

Removal of sulfide, sulfate and sulfite ions by electro coagulation.

Role of electrolyte on anodic mineralization of atenolol at boron doped diamond and Pt electrodes

Anodic oxidation of ketoprofen-an anti-inflammatory drug using boron doped diamond and platinum electrodes.

Removal of tannins and polyhydroxy phenols by electro-chemical techniques