Pemanfaatan cangkang kepiting (Portunus pelagicus Linn) sebagai bahan dasar adsorben selektif logam Cu(ll), Cd(ll), Ni(ll), dan Zn(ii) dalam medium air laut

Sehol, Muhamad, Prof. Dr. Narsito; Prof. Dr. Sri Juari Santosa, M.Eng

2024 | Disertasi | PROGRAM STUDI S3 ILMU KIMIA

Rangkaian penelitian dalam disertasi ini meliputi studi proses deproteinasi, demineralisasi, dan deasetilasi cangkang kepiting untuk memperoleh kitin dan kitosan, yang dilanjutkan dengan optimasi kualitas kitin dan kitosan melalui pengkondisian beberapa parameter, seperti konsentrasi HCl dan NaOH, waktu retluks, serta suhu perlakuan. Produk hasil optimasi, khususnya kitosan selanjutnya dikembangkan dan dikonversi menjadi kitosan beads dan turunan kitosan. Berbagai hasii tersebut dikarakterisasi dan diuji kemampuan adsorpsinya sebagai adsorben, dan selanjutnya dimanfaatkan sebagai adsorben selektif logam Cu(ll), Cd(ll), Ni(.ll), dan Zn(ll) dalam medium air, khususnya medium air laut baik dengan sistem batch maupun sistem solid phase extraction (SPE). Melalui teknik SPK, beberapa adsorben terpilih digunakan pula imtuk prekonsentrasi logam Cu(II) dan Cd(II) yang berkonsentrasi sangat rendah, Dari hasii kajian optimasi kitosan menunjukkan bahwa 3 parameter yaitu, peningkatan konsentrasi NaOH, waktu refluks, dan suhu perlakuan cukup berperan dalam meningkatkan kualitas (dearajat deasetlasi) kitosan. Dalain adsorpsi sistem batch, faktor pH sangat mempengaruhi proses adsorpsi, khususnya adsorpsi logam berat pada setiap adsorben, dan secara umum adsorpsi mencapai optimum pada pH 5-6. Parameter yang terkait dengan kinetika adsorpsi seperti laju adsorpsi menunjukkan adanya kesesuaian sitat keras-lunak asam-basa dan ukuran ion antara sebagian besar adsorbat dengan adsorben, sedangakan parameter yang terkait dengan isoterm adsorpsi seperti kapasitas adsorpsi menunjukkan kecenderungan peningkatan setelah kitosan dikonversi menjadi turunan kitosan, serta sitat adsorpsi dipengaruhi oleh kesesuaian sitat keras-lunak asam-basa dan ukuran ion antara adsorbat dengan adsorben. Adsorben kitosan, kitosan beads, dan beberapa turunan kitosan menunjukkan tingkat kestabilan adsorpsi meskipun direndam dalam berbagai pH, dan secara umum kondisi pengadsorpsian tidak dipengaruhi pula oleh tingkat konsentrasi garam (NaCl). Secara umum, adsorben-adsorben yang dihasilkan menunjidckan tingkat selektivitas yang cukup baik terhadap sesama logam berat ataupun terhadap logam utama. Desorpsi dapat berlangsung secara baik dan menunjukkan adanya mekanisme adsorpsi kirnia (kemisorpsi) yang lebili dominan daripada mekanisme adsorpsi fisika (fisisorpsi). Proses adsorpsi-desorpsi melalui sistem SPE menunjukkan adanya adsoipsi yang dipengaruhi oleh laju dMr/flow rate larutan adsorbat, sedangkan proses desorpsi setiap adsorbat dipengaruhi oleh tingkat konsentrasi HCl. Secara umoin, kondisi perairan laut tidak mempengaruhi nilai % recovery adsorbat pada xvii proses adsorpsi-desorpsi antara adsorben dengan adsorbat. Melalui teknik SPK, adsorben kitosan dan beberapa turunan kitosan menunjukkan tingkat selektivitas yang cnkup baik terhadap beberapa adsorbat, dan mampu memekatkan konsentrasi adsorbat Cu(II) dan Cd(II) pada tingkat konsentrasi pgL"' menjadi mgL"'

The chain of this dissertation research includes the study of the chitin and chitosan preparation from crab shells by deproteination, demineralization, and deacetylation processes, and then followed by optimization of their quality by maximization the condition of HCl and NaOH concentration, as well as time and preparation temperature. The product of optimation result, especially chitosan was developed and converted further become chitosan beads and chitosan derivatives. All products were characterized and tested their adsorption ability as adsorbent, then were utilized for Cu(II), Cd(II), Ni(II), and Zn(II) selective adsorbent in waler medium, especially sea water medium by batch and solid phase extraction (SPE) systems. In very low concentration of Cu(II) and Cd(II), some adsorbents chosen were used for preconcentration via SPE system. The result of chitosan optimization showed that three conditions i.e. NaOH concentration, reflux time, and preparation temperature were affected the improvement of quality (degree of deacetylation) chitosan. The adsorption experiment in batch system figured out that pH factor affected the adsorption process, especially at the heavy metals adsorption on every adsorbent, and reached their optimum conditions at pH 5-6. The parameter related to adsorption kinetic, such as adsorption rate revealed the suitability of hard-soft acid-base character and ion size between adsorbate and adsorbent, whereas the parameter related to adsorption isotherm, such as adsorption capacity showed the enhancement results after chitosan was converted to chitosan derivatives. Generally, adsorption characters were influenced by the suitability of hard-soft acid-base character and ion size between adsorbate and adsorbent. Although chitosan, chitosan beads, and some chitosan derivates were soaked on various pH, adsorption processes were showed the stability of adsorption, and was not affected by salt (NaCl) concentration. Generally, adsorbents produced showed good selectivity for heavy metals and main metals. Based on the desorption process, adsorptions were dominated by chemisorption mechanism. The adsorpiion-desorption experiment via SPE system showed that the adsorption of adsorbate on the adsorbents was influenced by adsorbate solution flow rate, whereas the desorption of adsorbate was influenced by HCl concentration. Generally, sea water condition did not affect the value of adsorbate recoveiy percentage, and by the same method, chitosan and chitosan derivates revealed good selectivity for some adsorbates, and were able to used for preconcentration of Cu(II) and Cd(n) adsorbates.

Kata Kunci : cangkang kepiting, absorden seletif logam