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SUMMARY Name : Mawardi Study Programe : Chemistry Title : Studies of Biosorption of Heavy Metal Ions By Green Algae Spirogyra subsalsa Biomass

In this research was studied utilization of green algae Spirogyra subsalsa biomass for biosorbent heavy metal ions, specially Pb2+, Cu2+, Cd2+, Zn2+, Cr3+dan Cr6+ cations. Algae S subsalsa sp. biomass, that was take from Batang Air Dingin River, Padang City, West Sumatera, Indonesia. Several variables affecting the degree of heavy metal ions biosorption by algae biomass, i.e: solution pH, biosorbent particle size, rate of shake, affect of heated biosorbent, contact time (rate of sorption), and initial cations concentration. Affect of binary cations system, i.e existence of cations Pb2+- Cu2+, Pb2+- Ca2+; Cd2+- Cu2+, Cd2+- Ca2+; Cu2+- Pb2+, Cu2+- Cd2+ and Cu2+ - Mn2+ in solution, to biosorption capacity of biomass were evaluated. The affects of key parameters such as solution pH, contact time (rate sorption), and initial cation concentration. The biosorption of Pb2+, Cu2+, Cd2+, Zn2+, Cr3+ cations increase rapidly with pH in the range of 2,0 to 3,0; the maximum sorption was seen at pH 4,0 and than constant at the higher pH. Biosorption of Cr6+, exist as Cr2O72- anion, decrease by increase of solution pH. Also, increasing the metals concentration increased the final metal uptake. At a sufficiently high cations concentration of 200 mg/L; 150 mg/L; 150 mg/L; 100 mg/L; 50 mg/L and 50 mg/L for cations Pb2+, Cu2+, Cd2+, Zn2+, Cr3+ and Cr6+ , respectively. The Langmuir adsorption isotherms were used to fit the experimental data. The maximum biosorption capacity was estimated to be close 9,04; 6,03 ; 3,56 ; 2,91 ; 1,82 and 1,51 mg per gram dry biomass. The biosrption process of Pb2+, Cu2+, Cd2+ and Zn2+ cations was a rapid process, wherein 87,5%; 99%; 94,7% dan 97,2% of the final uptake value occur within the first 5 min of the contact time, recpectively, while Cr3+ and Cr6+ cations, 37,4%; and 21,9% uptake occurred whitin the first ten minutes of exposure. Generally, particle size of biosorbent, rate of shake, and heated of biosorbent relatively little affecting the capacity of biosorbent, (3 - 10 %). Existence of binary cations system Pb2+- Cu2+ ; Pb2+- Ca2+ and; Cd2+- Cu2+; Cd2+- Ca2+ and; Cu2+- Pb2+; Cu2+- Cd2+ and Cu2+ Mn2+ in solution was decrease of the amount of Pb2+, Cd2+ and Cu2+ cations binding 32,8% ; 19,2% and 21,3% ; 13,60% and 18,5%; 9,8% ; 8,2% respectively. It has been found that metals biosorption (Ca2+, Pb2+, Cu2+, and Ag+) by green algae S. subsalsa biomass is selective and, in some cases, competitive. Also, the mechanism involved in biosorption resulted ion exhange between cation metals, as counters ions present in the biomass and heavy metals ions and proton taken up from eluen. In this studies was learned about function of functional group in algae S. subsalsa sp biomass in course of biosorption each Pb2+, Cu2+, Cd2+, Zn2+, Cr3+ and Cr6+ cations, by treating biomass by chemical modification of carboxyl, carbonyl and amino groups, that is methanol 99%, glicol, and mixture formaldehyde and formic acid, influence of immobilization of biomass within polysilicate matrix to

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absorption capacities. Optimation condition of regeneration column by nitrate acid, HNO3, and recovery column and application of column to remove and preconcentration trace element from waste waters. Among the most important that have to be evaluated in biosorption study, are : treating of biomass by chemical modification, that is methanol 99%, glicol, and mixture formaldehyde and formic acid to cause decrease in cation sorption capacity of biomassa for Pb2+, Cd2+, Zn2+, and Cr3+ cations. The exemption for Cu2+, which the biomass treated by methanol, and Cr6+, which the biomass treated by glicol, and mixture formaldehyde and formic acid increasingly in cation sorption capacity of biomassa, 10,46%; 116,50% and 41,78%, respectively. The biomass was treated by mixture formaldehyde and formic acid showing very keen sorption capacity degradation to each Pb2+, Cd2+, Zn2+, and Cr3+, that are 91,27; 85,39; 79,96; 91,30 and 55,91% respectively, except to Cr6+, what is in condensation of there are in species Cr2O72- anion, sorption capacities increase 41,78%. Generally, immobilization biomass by sodium silicate cause to increase sorpsion capacity of biomass, specially Cr6+, sorption improvement more than 100%, that is 2,27 mg/g for pure biomassa and 5,77 mg/g for immobilized biomass. The increase of sorption capacity immobilized biomass each Pb2+, Cd2+, Zn2+, and Cr3+ cations are 4,25; 15,95; 8,84 and 3,49%. While for metal Cr6+ absorbtion increase to 153,74 %. Desorption of the adsorption Pb2+ significantly proportional with used nitrate acid concentration, that is more 89% at 0,5 M HNO3, while for Cu2+ at 0,05 M HNO3 have desorbed about 60%. While desorbed Cd2+ and Zn2+ cations were washed once with HNO3 0,5 M more than 80%. The biosrption process of cations by immobilized biomass was a rapid process, wherein more than 50% of the final uptake value occur at rate flow 2,5 mL/minute. Keyword : S. subsalsa sp, biosorpsi, methanol, glikol, formaldehid, asam formiat. Corresponding Author: E-Mail: [email protected]