Remediation of cadmium and lead polluted soil using thiol-modified biochar

Thiol-modified rice straw biochar (RS) was prepared by an esterification reaction with β-mercaptoethanol and used for the remediation of Cd and Pb polluted soils. Modified biochar was characterized through elemental analysis, BET analysis, FE-SEM, FT-IR and XPS. These analytical results revealed that thiol groups were successfully grafted onto the surface of the biochar and were involved in metal ion complexation. Batch sorption experiments indicated that Cd²⁺ and Pb²⁺ sorption onto RS described well by a pseudo second order kinetic model and a Langmuir isotherm. The maximum adsorption capacities for Cd²⁺ and Pb²⁺, in the single-metal systems, were 45.1 and 61.4 mg g^-1, respectively. In the binary-metal systems, RS selectively adsorbed Cd²⁺ over Pb²⁺. Cd²⁺ and Pb²⁺ were removed mainly through surface complexation. In the soil incubation experiments (28 days), RS reduced the available Cd by 34.8-39.2 %; while, RS reduced the available Pb by 8.6 %-11.1 %. This research demonstrates RS as a potentially effective amendment for the remediation of heavy metal polluted soils.

Poly(ester amide)s from Soybean Oil for Modulated Release and Bone Regeneration

Designing biomaterials for bone tissue regeneration that are also capable of eluting drugs is challenging. Poly(ester amide)s are known for their commendable mechanical properties, degradation, and cellular response. In this regard, development of new poly(ester amide)s becomes imperative to improve the quality of lives of people affected by bone disorders. In this framework, a family of novel soybean oil based biodegradable poly(ester amide)s was synthesized based on facile catalyst-free melt-condensation reaction. The structure of the polymers was confirmed by FTIR and (1)H -NMR, which indicated the formation of the ester and amide bonds along the polymer backbone. Thermal analysis revealed the amorphous nature of the polymers. Contact angle and swelling studies proved that the hydrophobic nature increased with increase in chain length of the diacids and decreased with increase in molar ratio of sebacic acid. Mechanical studies proved that Young's modulus decreased with decrease in chain lengths of the diacids and increase in molar ratio of sebacic acid. The in vitro hydrolytic degradation and dye release demonstrated that the degradation and release decreased with increase in chain lengths of the diacids and increased with increase in molar ratio of sebacic acid. The degradation followed first order kinetics and dye release followed Higuchi kinetics. In vitro cell studies showed no toxic effects of the polymers. Osteogenesis studies revealed that the polymers can be remarkably efficient because more than twice the amount of minerals were deposited on the polymer surfaces than on the tissue culture polystyrene surfaces. Thus, a family of novel poly(ester amide)s has been synthesized, characterized for controlled release and tissue engineering applications wherein the physical, degradation, and release kinetics can be tuned by varying the monomers and their molar ratios.

Crosslinkable polyesters based on monomers derived from renewable lignin

Crosslinked polyesters based on renewable resources have been successfully prepared, they have better tensile property and biodegradability.