Biodegradation of thermo-oxidative pretreated low-density polyethylene (LDPE) and polyvinyl chloride (PVC) microplastics by Achromobacter denitrificans Ebl13.

Microplastics pretreatment of prior to biodegradation is an efficient approach for their bioremediation. We isolated Achromobacter denitrificans from compost and used it for biodegradation of thermo-oxidative pretreated polyvinyl chloride (PVC) and low-density polyethylene (LDPE). About 12.3 % and 6.5 % weight loss, and 326.4 and 112.32 mg L-1 extracellular protein were observed in bacterial flasks with PVC and LDPE, respectively. The pH in treated PVC reached to 5.12 and the thermal stability increased by 29 °C. The chemical modification in LDPE was demonstrated through oxidation of antioxidants (Phenol group), formation of new groups (Aldehyde group), and chain fracture in the main backbone by Fourier transform infrared spectroscopy. Formation of peaks at the range of 1700-1850 cm-1 in LDPE attributed to formation of carbonyl groups as the degradation result. Scanning electron microscopy confirmed LDPE and PVC degradation by surface alterations. Consequently, thermo-oxidative pretreatment can be considered as a suitable strategy for improving microplastics biodegradation.

Adsorption of cadmium from aqueous solutions by novel Fe3O4- newly isolated Actinomucor sp. bio-nanoadsorbent: functional group study.

A novel bio-nanocomposite was prepared by the combination of fungal biomass and Fe3O4 magnetic nanoparticles. The result of XRD and EDAX analysis indicated that Fe3O4 Actinomucor sp. bio-nanoadsorbent was prepared. Our experiments showed that the adsorption kinetics and isotherm of this material comply with the pseudo-second-order and the Langmuir models, respectively. The maximum adsorption capacity (qmax) of this novel bio-nanoadsorbent was obtained as 29.49 mg/g. The thermodynamic analysis revealed that the adsorption of Cd2+ is spontaneous and exothermic. The optimum temperature, initial concentration, contact time and pH for adsorption system of cadmium were about 45 °C, 400 mg/L, 120 min and 7, respectively. Pretreatment of adsorbent by NaOH and SDS significantly increased cadmium adsorption capacity. SEM images showed that Fe3O4 nanoparticles were immobilized successfully on the fungus cell surface. Contribution of the carboxyl, hydroxyl, amine and Fe-O functional groups of the bio-nanoadsorbent in the binding to cadmium ions was revealed by FTIR analysis. Results from regeneration studies indicated reusability of the adsorbent up to 91%. According to experimental results, it could be claimed that bio-nanocomposite of Fe3O4-Actinomucor sp. is a novel efficient adsorbent for removal of metal ions from aqueous solutions, and hence it has potential to be used in the environmental pollution cleanup programs.