Competitive sorption of Cu and Cr on goethite and goethite–bacteria complex

Sorption of Cu and Cr in single and binary sorbate systems on goethite and goethite–Bacillus thuringiensis complex was studied. It was observed that the initial sorption rate and sorption capacity of heavy metals on goethite–B. thuringiensis complex were greater than that on goethite in single system at studied pH. The competitive ability of Cr in the sorption on both goethite and goethite–B. thuringiensis complex was stronger than that of Cu in binary system. Greater intensity of competitive sorption between heavy metals was found on goethite–B. thuringiensis complex than on goethite. The percentage of sorbed metals desorbed by Ca(NO3)2 from goethite was lower than that from goethite–B. thuringiensis complex, conforming the higher sorption affinity of heavy metals for goethite than that for goethite–B. thuringiensis complex. For each sorbed heavy metal, the desorption ratio was slightly higher from single sorption system than from binary sorption system, indicating the release of loosely sorbed metal and the retention of tightly bound cation during competitive sorption. The results obtained in this study are of significant importance for the assessment and remediation of multi-heavy metal pollution.

► Sorption of Cu and Cr on goethite and goethite–B. thuringiensis complex was studied.
► A high sorption capacity was observed for the goethite–B. thuringiensis complex.
► Differences existed in rates and sorption capacities between sorbents.
► Sorption of single metal vs. mixtures exhibited different behaviors.
► Desorption was less effective in sorbents loaded with binary Cu and Cr mixtures.