Eco-friendly silver nanoparticles (AgNPs) were synthesized using a carboxymethylated gum kondagogu (CMGK) as capping and reducing agent by microwave irradiation method. Synthesized AgNPs were analyzed by TEM, showed spherical in shape with an average particle size distribution of 9 ± 2 nm. XRD results showed that the cubic-structured AgNPs with crystallite size of 8.6 nm. The synthesized CMGK capped AgNPs was tested for catalytic activity using hexacyanoferrate(III) in the presence of NaBH₄ and the impacts of catalyst dose and temperature were examined. The synthesized AgNPs demonstrated a huge antibacterial action on both Gram-positive and negative groups of microorganisms with inhibition zone of 23, 25 and 28 mm, respectively, for Bacillus subtilis, Bacillus cereus and Escherichia coli, they showed moderate antibacterial action (zone of inhibition 15 mm) with Pseudomonas aeruginosa. In addition, the ability of the AgNPs scavenging activity with different concentrations was studied using the DPPH radical scavenging.

Microalga, Isochrysis galbana, biomass was entrapped into alginate gel by liquid curing method in the presence of Ca(II) ions. The biosorption of chromium(III) by the entrapped live algal biomass was studied in a batch system. The effect of initial cadmium concentration, pH, temperature and liquid and solid ratio on Cr(III) removal was investigated. The maximum experimental biosorption capacities for entrapped live algal biomass were found to be 335.27 mg Cr(III) g⁻¹ of dry algal biomass. The kinetics of chromium biosorption was slow; approximately 75 % of biosorption took place in 2 h. The percent adsorption increased with increase in pH; pH 5 of the solution was found to favor adsorption very strongly. The equilibrium biosorption data were evaluated by Langmuir and Freundlich isotherm models, and was best described by Langmuir and Freundlich isotherms. The biosorbent was characterized and evaluated, the functional groups –OH, –COOH and C=O were involved in the biosorption process. Since binding capacity was relatively high for immobilized live algal biomass, those algal forms are to be considered as suitable biosorbent for the removal of chromium in wastewater treatment.

Gold nanoparticles (AuNPs) were synthesized by the green method with activated Cochlospermum gossypium (carboxymethylated Cochlospermum gossypium gum or carboxymethylated gum kondagogu: CMGK) as stabilizer and reducing agent. The obtained size of AuNPs was 11 ± 2 nm. The impacts of HAuCl₄ concentration, CMGK concentration, and reaction time on the synthesis of AuNPs were investigated. The techniques, UV − visible spectroscopy, FTIR, DLS, TEM, and powder XRD, were used for characterization. The reducing capacity of the synthesized CMGK-AuNPs was tested for reduction of 4-nitrophenol (4-NP) along with NaBH₄. The effects of NaBH₄, catalyst dose, and temperature were studied for reduction of 4-NP. The AuNPs showed good antibacterial activity against E. coli and Bacillus subtilis. The outcomes of the study indicated that CMGK–AuNPs have notable antimicrobial and environmental applications.