Biosorption of Hg (II) from aqueous solution using algal biomass: kinetics and isotherm studies

Abstract

The present work investigated the ability of algal biomass Chlorella vulgaris to remove mercury from aqueous solutions. The mercury biosorption process was studied through batch experiments 35 C temperature with regard to the influence of contact time, initial mercury concentration, pH and desorption. The maximum adsorption capacity was registered at pH 6. The adsorption conduct of Hg(II) was defined by pseudo second order well rather pseudo first order as the experimental data (q e ) come to an agreement with the calculated value. The kinetics of adsorption was fast and a high capacity of adsorption occurred within only 90 min. The adsorption data were signified by many models but Langmuir (q max ¼ 42. mg g À1 ) & Freundlich fitted well having regression coefficients near to unity. The thermodynamic parameters were also suited well as negative value of free energy cope up to spontaneity, positive value of the randomness described by ΔS attributed to affinity of Hg þ2 towards algal bioadsorbant and high positive value of heat of enthalpy designates that the adsorption process is expected due to robust interactions between the Hg(II) ions and various functional groups on surface of algal bioadsorbant. Field emission scanning electron microscopy integrated with energy dispersive X-ray spectroscopy analysis before and after adsorption of Hg(II) reveals the adsorption of metallic ions over the surface. FTIR study supported the existence of various functional groups (carboxylix, amines, hydroxyls, amides etc.) helped in adsorption. Continuous adsorption desorption experiments proved that algal cells was excellent biosorbents with potential for further development.

Biosorption: A Review of the Latest Advances

“…Algal biomass (Chlorella vulgaris UTEX 2714) was also tested for remove Hg(II). This biomass used as dead biomass presented a rapid kinetics of adsorption (90 min) and with a capacity of 42 mg/g [104]. In addition, this biomass presented a good regeneration: this property is important for a biosorption process to be viable.…”

Mercury (Hg) Contaminated Sites in Kazakhstan: Review of Current Cases and Site Remediation Responses

“…The proposed remediation technology, in comparison to the conventional method, minimizes the probability of solidified agents to re-dissolve within the contaminated matrix. [6,112] Copper or brass shavings Water Removal of Hg 2+ from water by the amalgamation 96-98% [48,113,114] Ex situ soil washing Soil Washing the excavated soils with a special solution, scrubbing, and separating clean soil up to 99% [6,100,115] Excavation or dredging with removal Soil, Sediment Removal and off-site storage of the contaminated material not applicable [48,116] Immobilized algae Water Accumulation of the contaminant from aquatic media in certain species of algae up to 90% [100,102,117] In situ thermal desorption Soil On-site heating soil to very high temperatures to release contaminant in gaseous/vapor phase 99% [6,112,118] In situ flushing/washing Soil Flooding a zone with a flushing solution to mobilize contaminant 35-90% [50,112] In situ electrochemical/electrokinetic recovery Soil…”

Formation and availability of methylmercury in mercury-contaminated sediment: effects of activated carbon and biochar amendments

“…Furthermore, the apparent high THg-remediation effect seen in the first half of the experiment, i.e. 91% and 84% after 1 month and 93% and 88% after 6 months for A-AC and A-BC treatments, respectively (Table S1), might be partly due to biosorption of inorganic Hg by the Chlorella algae biomass (Kumar et al 2020;Spain et al 2021). However, as the algae biomass decomposes over time, biosorbed Hg could be released back to solution, contributing to the low remediation effect recorded at the end of the experiment (A-AC 53% and A-BC 0%; Table S1).…”