{'fraction_non_alphanumeric': 0.02588686481303931, 'fraction_numerical': 0.0019175455417066154, 'mean_word_length': 5.251497005988024, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Experimental study on the adsorption of dissolved heavy metals by nano-hydroxyapatite.

Bioretention system is an effective way to solve the problem of urban water environment pollution. In this paper, the difficulty of the existing biological retention system to effectively remove dissolved heavy metals was studied. By comparing the adsorption effect of acid quartz sand filler layers with nano-hydroxyapatite (N-HAP), medical stone, nano-carbon, and biochar, the conclusion is drawn from the static and cylinder dynamic experiments that N-HAP has the best effect of removing Cu2+ and Zn2+, and the effect is long lasting. The scanning electron microscopy results showed that the N-HAP particles were rough and the surface was more rod-shaped, which increased the specific surface area of the N-HAP particles, promoted the complexation and electrostatic interaction of the additives and heavy metal solutions, and facilitated the adsorption of heavy metals. The research results help to improve the technology of filler matrix modification.