Study On Biosorption Performance Of Cu²⁺、Cr⁶⁺、Cd²⁺and Ni²⁺ By Sargassum Fusiforme

While environmental problems caused by industrialization has gradually become aworldwide problem. Water pollution gradually entering its crisis stage in China. Heavy metalpollution is a major aspect of water pollution.The non-active algae assay becomes the focus ofscholars’attention because of its unique advantages in recent years.This paper selectsSargassum as study material,which collected from Wenzhou city in Zhejiang province. Thebiosorption characteristics of Cu²⁺, Cr⁶⁺,Cd²⁺and Ni²⁺by sargassum and adsorptionthermodynamics and kinetics were studied, the main conclusions are as follows:（1） The removal rate of Cu²⁺, Cd²⁺, Ni²⁺increased gradually with the increase of pH;When the pH exceeds a certain range, the metal removal rate will be decreased. There is anoptimum adsorption range; pH effects on Cr⁶⁺somewhat complexly, which has a directrelationship with the variety form of Cr⁶⁺in the water environment. When the value of pH isfrom1to6, Cr⁶⁺removal rate decreases as the pH value increases; When the value of pH isfrom6to8, the metals removal increased; When pH is more than8, the metal removal rategradually reduced; The optimum pH value of adsorption to heavy metals copper, chromium,cadmium, nickel ions is4,1,5,5respectively.On the one hand,the high acidity increases thecost of sewage treatment. On the other hand,it is easy to lead to secondary pollution, sochromium ions is adsorbed under the conditions at pH=2in this paper.（2） Sargassum inputs affect the adsorption effect. Metal ion adsorption rate increases asthe amount of adsorbent gradually increased, while the adsorption capacity graduallydecreased; The best adsorbent dosage adsorption of heavy metals Cu²⁺, Cr⁶⁺, Cd²⁺, Ni²⁺were1,4,5,5g/L.（3） The initial concentration of heavy metal ions in solution is an important factoraffecting the adsorption efficiency of Sargassum fusiforme. With the gradual increase of theinitial concentration of heavy metal ions, its adsorption rate fall, and its adsorption capacity issignificantly increased.The adsorption capacity will become increasingly smaller, which iscloser to saturation; The removal efficiency of cadmium ions and copper ions is higher,whoseabsorption rate has been greater than80%in the range of10-60mg/L. （4） When the ionic strength increases, the adsorption rate of Cu²⁺, Cr⁶⁺,Cd²⁺,Ni²⁺showeda downward trend; When the concentration of NaNO3from0mol/L to0.01mol/L, copper ions,chromium ions, cadmium ion, nickel ion adsorption rate decreased by6.17%,1.78%,2.5%,4.4%; when the concentration of Ca（NO3）2from0mol/L to0.01mol/L, copper ions fusiforme,chromium ions, cadmium, nickel ion adsorption rate decreased by19%,10.07%,14.7%,11.4%respectively; Under the same experimental conditions, as the effect of calcium ionsto the solution of Sargassum fusiforme are larger than sodium ions.（5） Metal ion adsorption capacity increases with increasing initial concentration,whichaccord the Langmuir adsorption model. The adsorption capacity of copper ions, cadmiumionis larger at25℃; while the adsorption capacity of chromium ion, nickel ion is largerer at35℃.At25℃, the maximum adsorption capacity of copper ions, chromium ions, cadmiumions,nickel ions were127.38mg/g,73.09mg/g,76.74mg/g,45.37mg/g under fitting forLangmuir adsorption model; At35℃, the maximum adsorption capacity of copper ions,chromium ions, cadmium ions,nickel ions were108.22mg/g,85.76mg/g,79.11mg/g,68.11mg/g. Inactive sargassum to copper ions have larger adsorption capacity.（6） The larger the initial concentration, the shorter the reaction time spent to reachequilibrium. At different concentrations,the optimum adsorption time of copper ions,chromium ions, cadmium, nickel ion was60min,50min,60min,60min. Adsorption timeshould not be too long, resulting in unnecessary waste of resources.On the one hand,it mayaffect the adsorption effect.Cu²⁺absorption rate has declined in the last10min, which isprobably caused by desorption occuring in solution.The specific mechanisms need to beexplored in the future.