Removal of hexavalent chromium from synthetic wastewater by adsorption on coffee ground and mixed waste tea

Name: Wachiraphorn Cherdchoo

LCSH: Burapha University.Bioengineering

LCSH: Sewage -- Purification -- Chromium removal

Abstract: Hexavalent chromium, Cr(VI) found in industrial effluent is a serious concern problem due to recalcitrant and persistency control. Removals of Cr(VI) by conventional technologies are not economical and further generate huge quantity of toxic chemical remaining in environment. Biosorption is emerging as a reasonable alternative method for Cr(VI) removal because of its low cost and minimal chemical used. Coffee and tea are one of worldwide-consumed beverages average billion cups daily liberating considerable waste. Some waste is recycled into cosmetic production with remainder unused and, in many instances, posing a disposal problem. One solution to recycle these wastes is using them as alternative useful materials. According to the facts that coffee ground and waste tea contain oxidizing organic chemicals that are basic materials involved in Cr(VI) reduction. Hence, to overcome the disposal problem, this study aims to apply coffee ground and waste tea as alternative low-cost adsorbents for decontamination of Cr(VI) from synthetic wastewater. Batch experiments were conducted to study the effects of adsorbent dosage, pH and temperature, agitation speed, initial Cr(VI) concentration and contact time. Complete adsorption of 10-30 mg/L Cr(VI) from the synthetic wastewater was found with 2 g/L of mixed waste tea or coffee ground used at pH 2.0 for 180 minutes, 30 °C and 250 rpm. With the increase of initial Cr(VI) concentration (50-250 mg/L), the removal percentage decreased but the efficiency was still half-detected. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy revealed that the nature of the mixed waste tea and coffee ground was altered after Cr(VI) adsorption and noticeable chromium accumulation was detected on adsorbent surfaces. No significant changes in the surface functional groups were observed from fourier transform infrared spectrometry except that the CH stretching was replaced with bending on the surface of mixed waste tea after Cr(VI) adsorption. Reusability of the adsorbents for Cr(VI) adsorption exhibited the efficiency >70% in the third cycle. The most common isotherms and kinetics of adsorption were used to describe the Cr(VI) adsorption equilibrium studies of mixed waste tea and coffee ground at 30 °C. The Freundlich sorption isotherm model correlated best with the Cr(VI) adsorption equilibrium data for the 100-250 mg/L concentration range, for both adsorbents. Analysis of kinetic studies indicated Cr(VI) adsorption by both adsorbents was consistent with the pseudo second-order kinetic adsorption model. Experimental data demonstrated a sorption capacity of 87.72 mg/g of coffee ground and 94.34 mg/g of mixed waste tea. Study on a 100 L of packed-bed reactor showed the breakthrough time of adsorption for mixed waste tea as 30 minutes in 100 mg/L Cr(VI) concentration. According to the high efficiency of Cr(VI) removal, this finding renders the potential of mixed waste tea and coffee ground as alternative adsorbent for chromium decontamination in the future.

Burapha University. Library

Address: CHONBURI

Email: buulibrary@buu.ac.th

Name: Jittima Charoenpanich

Role: Principal advisor

Name: Srisuda Nithettham

Role: Co-advisor

Created: 2018

Modified: 2020-03-20

Issued: 2020-03-20

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: Th 628.3 Wa113R

eng

DegreeName: Master of Bioengineering

Level: Master's Degree

Descipline: Bioengineering

Grantor: Burapha University

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