RESUMO
The increasing rate of industrialization, anthropogenic, and geological activities have expedited the release of heavy metals (HMs) at higher concentration in environment. HM contamination resulting due to its persistent nature, injudicious use poses a potential threat by causing metal toxicities in humans and animals as well as severe damage to aquatic organisms. Bioremediation is an emerging and reliable solution for mitigation of these contaminants using rhizospheric microorganisms in an environmentally safe manner. The strategies are based on exploiting microbial metabolism and various approaches developed by plant growth promoting bacteria (PGPB) to minimize the toxicity concentration of HM at optimum levels for the environmental clean-up. Rhizospheric bacteria are employed for significant growth of plants in soil contaminated with HM. Exploitation of bacteria possessing plant-beneficial traits as well as metal detoxifying property is an economical and promising approach for bioremediation of HM. Microbial cells exhibit different mechanisms of HM resistance such as active transport, extra cellular barrier, extracellular and intracellular sequestration, and reduction of HM. Tolerance of HM in microorganisms may be chromosomal or plasmid originated. Proteins such as MerT and MerA of mer operon and czcCBA, ArsR, ArsA, ArsD, ArsB, and ArsC genes are responsible for metal detoxification in bacterial cell. This review gives insights about the potential of rhizospheric bacteria in HM removal from various polluted areas. In addition, it also gives deep insights about different mechanism of action expressed by microorganisms for HM detoxification. The dual-purpose use of biological agent as plant growth enhancement and remediation of HM contaminated site is the most significant future prospect of this article.
RESUMO
This study points out the method regarding the removal of Pb (II) ions from water by treatment with Lantana camara leaves' biosorbent (LCLB). The sorption process was investigated by varying different parameters pH, contact time, adsorbent dose, initial metal ion concentration, and temperature. For a 5.00 g sorbent dose and a 45 min of the contact period, a Pb (II) ion solution with an initial metal ion concentration of 10 mg/L resulted in 90.7% maximum elimination at an optimum pH 6 and temperature 298 ± 1.5 K with LCLB. The adsorption process was spontaneous and exothermic. The maximum monolayer adsorption was 3.5 mg/g for Pb (II) sorption using LCLB. Adsorption of Pb (II) ions using LCLB (R2 > 0.999) followed the pseudo-second-order kinetics. The spectroscopic characterization was done by fourier transform infrared (FT-IR) analysis, while scanning electron microscope (SEM) images were captured for the morphological characterization. Desorption experiments revealed that hydrochloric acid has a strong potential as an eluent for Pb (II) ion desorption. The findings proposed that LCLB can be used as an effectual and cost-effective biosorbent for the expulsion of Pb (II) ions.
