SINTESIS GARAM HIDROKSI BERLAPIS NIKEL-SENG TERIMOBILISASI ASAM SALISILAT (Sal-Ni-Zn-LHS) DAN PENGGUNANNYA UNTUK ADSORPSI REDUKTIF [AuCl4]-

MUHAMMAD ROBITH TA, Prof. Drs. Sri Juari Santosa, M.Eng., Ph.D.; Dr. Suyanta, M.Si

2019 | Tesis | MAGISTER KIMIA

Bertambahnya laju kemajuan peralatan elektronik mengakibatkan melimpahnya limbah elektronik yang dihasilkan. Usaha pengurangan limbah dapat dilakukan dengan melakukan recovery pada logam yang bernilai ekonomi tinggi seperti emas. Metode adsorpsi telah banyak dikembangkan untuk recovery logam karena mempunyai selektifitas yang baik terhadap ion-ion logam hasil destruksi limbah elektronik. Material Ni-Zn-LHS yang mempunyai muatan positif besar pada strukturnya mengindikasikan potensi yang baik untuk menjadi adsorben [AuCl4]-. Modifikasi material Ni-Zn-LHS tersebut dengan asam salisilat dapat meningkatkan efisiensi proses recovery berupa proses adsorpsi reduktif. Penelitian ini bertujuan mempelajari proses sintesis Ni-Zn-LHS terimobilisasi asam salisilat dan penggunaannya untuk adsorpsi reduktif [AuCl4]-. Untuk mempelajari proses imobilisasi salisilat, dilakukan interaksi material dengan asam salisilat pada beberapa variasi pH medium. Hal ini juga dilakukan pada adsorpsi reduktif [AuCl4]- oleh material terimobilisasi. Selain itu, dilakukan pula penentuan model isoterm adsorpsi yang menggambarkan dengan baik proses imobilisasi dan adsorpsi reduktif tersebut. Masing-masing material dasar (Ni-Zn-LHS), material terimobilisasi (Sal-Ni-Zn-LHS) dan material pasca adsorpsi reduktif emas (Au-Sal-Ni-Zn-LHS) juga dikarakterisasi dengan instrumen FTIR, XRD, dan SEM-EDX untuk mengetahui perubahan yang terjadi pada masing-masing proses. Hasil penelitian menunjukkan proses imobilisasi dan adsorpsi reduktif dipengaruhi oleh pH dan keduanya mengikuti model isoterm Langmuir. Telah didapatkan bahwa kapasitas imobilisasi salisilat bernilai 64,93 mg/g sementara kapasitas adsorpsi [AuCl4]- menunjukkan nilai 71,43 mg/g. Spektra FTIR material Sal-Ni-Zn-LHS menunjukkan keberadaan puncak vibrasi karakteristik gugus-gugus fungsi asam salisilat terimobilisasi. Difraktogram X-ray material Au-Sal-Ni-Zn-LHS menunjukkan kemunculan puncak karakteristik Au(0) yang membuktikan terjadinya adsorspi reduktif oleh material Sal-Ni-Zn-LHS. Dari hasil yang didapatkan, diketahui material Ni-Zn-LHS terimobilisasi asam salisilat mempunyai performa yang baik untuk adsorpsi reduktif [AuCl4]-.

The increasing rate of electronic equipment utilization has resulted in the abundance of generated electronic waste. Waste reduction efforts can be done by recovering metals with high economic value such as gold. Adsorption method has been developed for metal recovery because of its selectivity towards metal ions resulted from electronic waste destruction. Ni-Zn-LHS material has a great potential to become an adsorbent of [AuCl4]-. The modification of Ni-Zn-LHS material with salicylic acid can increase the efficiency of the recovery process to reductive adsorption. This research aims to study the synthesis process of Salicylic acid immobilized Ni-Zn LHS and its use for reductive adsorption of [AuCl4]-. To study the process of the immobilization of salicylate, the Ni-Zn-LHS material was interacted with salicylic acid in several pH values. That was also carried out on the reductive adsorption [AuCl4]-. In addition, determination of an adsorption isotherm model that best describes the immobilization and reductive adsorption processes was also conducted. Each basic material (Ni-Zn-LHS), immobilized material (Sal-Ni-Zn-LHS) and gold reductive post-adsorption material (Au-Sal-Ni-Zn-LHS) were also characterized by FTIR, XRD, and SEM-EDX to find out the changes that occur in each process. The results showed that the processes of immobilization and reductive adsorption were influenced by pH and both followed the Langmuir isotherm model. It has been found that the salicylate immobilization capacity is 64.93 mg/g while the adsorption capacity of [AuCl4]- possessed a value of 71.43 mg/g. The FTIR spectra of Sal-Ni-Zn-LHS material showed the presence of characteristic vibration peaks of immobilized salicylic acid functional groups. X-ray diffractogram of Au-Sal-Ni-Zn-LHS material showed the appearance of the characteristic peak of Au(0) which proves the occurrence of reductive adsorption by Sal-Ni-Zn-LHS material. From the results obtained, it is known that Sal-Ni-Zn-LHS material has good performance for reductive adsorption of [AuCl4]-.

Kata Kunci : Garam hidroksi berlapis Ni-Zn, imobilisasi, adsorpsi reduktif, emas