The 16 776 bp mitochondrial DNA (mtDNA) of Crocodylus niloticus was sequenced by PCR methods. Comparing with the complete nucleotide sequences of the mitochondrial genome of other crocodiles, no variation on gene arrangement or quantity was found in the mtDNA of Crocodylus niloticus, however, the control region varied greatly. In addition to the analyses of complete sequences, partial sequences of 12S rRNA, 16S rRNA and Cyt b gene from other 13 crocodile species were combined and analyzed. We attempted to diagram phylogenetic relationships among crocodile species to provide convenience for following research.
An untried,low cost,locally available biosorbent for its anionic dye removal capacity from aqueous solution was investigated.Powder prepared from peanut hull had been used for biosorption of three anionic dyes,amaranth (Am),sunset yellow (SY) and fast green FCF (FG).The effects of various experimental parameters (e.g.initial pH and dye concentration,sorbent dosage,particle size,ion strength,contact time etc.) were examined and optimal experimental conditions were decided.At initial pH 2.0,three dyes studied could be removed effectively.When the dye concentration was 50 mg·L -1 ,the percentages of dyes sorbed was 95.5% in Am,91.3% in SY and 94.98% in FG,respectively.The ratios of dyes sorbed had neared maximum values in all three dyes when sorbent dose of 5.0 g·L -1 and the sorbent particle size in 80～100 mesh was used.The increasing the ion strength of solution caused the decrease in biosorption percentages of dyes.The equilibrium values arrived at about 36 hour for all three dyes.The isothermal data of biosorption followed the Langmuir and Freundlich models.The biosorption processes conformed the pseudo-first-order rate kinetics.The results indicated that powdered peanut hull was an attractive candidate for removing anionic dyes from dye wastewater.
