Biosorption of Nickel from Metal Finishing Effluent Using Lichen Parmotrema tinctorum Biomass

Presence of heavy metals in industrial discharge warrants the adoption of efficient and cost-effective treatment technologies. In this work, lichen Parmotrema tinctorum biomass was utilized as biosorbent for removal of Ni (II) from metal finishing industry effluents. Optimal adsorption was observed at pH 7, stirring speed of 300 rpm, 120 min incubation from independent batch experiments. Adsorption isotherm at optimal conditions followed Langmuir model (R-2 > 0.974) with a maximum adsorption capacity of 33.92 mg g(-1). Adsorption kinetics could be described with pseudo-first-order model (R-2 > 0.98). Fourier transform infrared spectroscopy of pristine and metal loaded P. tinctorum biomass indicated electrostatics and ionic interaction in the adsorption process. Biosorbent treated water showed no inhibition against agriculturally important microorganisms like Phosphobacter sp. and Azospirillum sp. in microbial toxicity assay. Similarly, biosorbent treated water offered better germination and growth for Vigna radiata than the untreated water in greenhouse phytotoxicity assessment. Though the result suggests detoxification of industrial effluents following P. tinctorum biosorption, reusability of treated wastewater in agricultural practice warrants multi-tiered ecotoxicity assessment, and long-term environmental impact analysis.

Automated summary

The study utilized lichen Parmotrema tinctorum biomass as a biosorbent for removing Ni (II) from metal finishing industry effluents. Optimal adsorption conditions were observed at pH 7, stirring speed of 300 rpm, and 120 min incubation, with a maximum adsorption capacity of 33.92 mg g(-1). The adsorption process followed Langmuir model and adsorption kinetics were described with a pseudo-first-order model.