No abstract

Cat manure (CM) possesses high level of nutrients for growing food crop. However, animal manure may contain toxic elements that may contaminate food crop. Spent coffee ground (SCG) may be used to reduce mobility of heavy metals and reduce crop uptake. In this study, SCG was composted with CM for 31 days to produce a co-compost (SCG-CM) for growing spinach ( Spinacia oleracea ). The growth rate of spinach was assessed until its maturity, and the metal uptake of spinach shoot was determined thereafter using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The effect of soil treatment with SCG-CM on the height and elemental composition of spinach were compared with that of chicken manure compost (CMC). The prepared composts were primarily organic matter (72.9–81.4 % w/w) with the rest are ash (13.3–23.4 % w/w) and moisture (1.2–2.6 % w/w). Zinc content in SCG-CM (1261 ± 0.1 mg/kg) is significantly higher than that of soil and CMC (p < 0.05) and has exceeded the maximum permissible limit set by European Union Standard (2002) and the Malaysian Compost Quality Standard and Guidelines (2000). Matured spinach reached maximum plant height after 33 days. The amendment of SCG-CM significantly increased the height of spinach (32 ± 6 cm) compared to that of CMC (13 ± 1 cm) (p < 0.05). However, contents of Zn, Cu, Pb and Cd were not increased for spinach grown in the SCG-CM-amended soil, and the level of those elements are below permissible limit set by the Malaysian Food Act 1983 and Food Regulations 1985. This study shows that SCG-CM is effective in improving yield without causing accumulation of toxic trace elements in spinach.

Polyaniline (PANI) is one of the unique conducting polymers due to tunable conductivity, acid-base chemistry and optical properties. In this study, commercial PANI was used to prepare PANI/shell composites to enhance the sensitivity of PANI in ammonia (NH3) gas detection. Three types of waste shells were utilized to incorporate into the PANI matrix such as egg shells (ES), crab shells (CS) and mussel shells (MS). The characterizations were done by Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectrophotometer. FTIR spectra confirmed the presence of CaCO3 in the PANI/shell composites’ backbone. Whereas, UV-Vis spectra further confirmed the PANI/shell composites were in the doped state by exhibiting a characteristic peak at ~790-820 nm. Sensor performance of commercial PANI and PANI/shell composite films were studied in terms of sensor measurement and sensor performances (selectivity, reusability and long-term stability). The sensor performances of commercial PANI, PANI/ES and PANI/CS exhibited correlation coefficient of >0.95. In addition, commercial PANI and PANI/CS films exhibited good selectivity for NH3 gas detection in the presence of interfering gases. In conclusion, PANI/shell composites were successfully prepared for NH3 gas detection and PANI/CS exhibited the highest sensitivity compared to other films.